Chevrolet Volt 4ET50 Transaxle Components and Operation (2011-2015)

[@WeberAuto]

Corrections and Clarifications: 1. I made an error on the Motor B to tire gear ratio, it is actually 7.001:1. The planetary gear reduction is (1+(83/37)) = 3.243:1 The transfer gear reduction is (67/79) = 0.848:1 overdrive The final drive gear ratio is (79/31) = 2.548:1 The result is 3.243*0.848*2.548 = 7.001 2. There are four possible transmission operating states (Modes) to move the vehicle in Drive and Reverse: Mode 1. One Motor Electric Vehicle (Series Mode Engine Off) - The Variable Low &1,2, R Brake is used (Ring gear connected to case). Drive motor/generator B is driving the vehicle Mode 2. Combined (Two Motor) Electric Vehicle (Output Split Engine Off) - The Variable High & 2,3,4 Clutch used (Ring gear connected to Motor A). Drive motors/generators A and B are rotating at variable speeds to obtain underdrive, direct drive, or overdrive to drive the vehicle. Mode 3. Series - Series Hybrid (Series Mode Engine On) - Variable Low & 1,2, R Brake and 1,3, R Clutch used ((Ring gear connected to case) and (Engine connected to Motor A) ) Same as mode 1, but with the engine driving motor A to provide power to motor B rather than battery power. Mode 4. Combined - Series-Parallel Hybrid (Output Split Engine On) - Variable Hight & 2,3,4 and 1,3, R Clutches used ((Ring gear connected to Motor A) and (Engine connected to Motor A)). Same as mode 2, but with the engine driving motor A.

[@thomasmclaughlin3236]

It would be great if you did a video that was more granular about each component. Bearings seem to be the weak link & it would be interesting to know if the fluid filter sealed in the transmission, gets clogged & wipes out the bearings.

[@islandfd3s]

in "range extending" mode, if the traction battery is at a low SOC, and you set the driving mode to "mountain mode" the Engine will actually be used to charge the drive battery up to about 40% SOC, if you then enter "normal" or "sport" mode it will allow the car to be driven as an EV again. This is handy with a low battery in the winter, if you know you're going to go on a longer trip than you have existing range, to get cabin heat *now* with gasoline and then drive on electricity after, instead of using up the electricity heating the cabin and then driving on gas after, wasting the extra energy the gas engine otherwise throws away.

[@AllieGee95]

@@islandfd3s Gen 1 (in my case 2015) Volt uses what they call ERDTT (Engine Running Due to Temperature) when below 2°C or -10°C (setting can be changed in infotainment screen). Below such temperatures, it starts the engine to generate heat via its normal operation and also by generating current for the electric heating system. In such a mode, the RPM can vary a little but will never drop below 1400rpm (actually I’ve never seen a volt “idle” below 1400. It’s always loaded a bit when it runs and always à that minimum rpm). Above 56 km/h (35mph) it can connect everything together to “kinda” operate in mode 4 (combined series-parallel hybrid), but in doing so it always pulls most of the driving power from the battery. This way you end up conserving battery power longer since you’re no longer using it for heating and are instead using the engine’s heat & power for the electric heater. Anyways, this has been my experience with my Volt. It always amazes me how quickly these cars get hot. So with that in mind, it’s not necessary to switch to drive mode “mountain” (or also hold for 2013+) to get heat AND maintain battery power. That said, if you do want to maintain battery power at say 70% indicated, then yes Hold is a good idea. Or Mountain if you expect to be driving in mountainous terrain above 105 km/h for extended periods of time.

[@mmr1412]

Question: is the differential situated on the car's midline and are the driveshafts equal length?

[@alaznispireli7481]

Professor one question: is there possibly to turning system as the two motor driving mode pull the full power both motors? it gives us much more power than 110kw

[@bonniebrown8701]

I've owned a 2012 Volt since 2015 and I've always found it hard to explain to people how my car works. Your video is very helpful! It also taught me things I didn't even know and now I understand why I drive my car the way I do (I use all 4 of those modes intuitively). I love my Volt and I love this video. Thank you!

[@WeberAuto]

Glad it helped

[@captlarry-3525]

John has a mind like a steel trap. He gives an elegant presentaion of complex systems and mechanisms, which is invaluable. I dare say priceless. Bravo ! We were lucky enough to buy a used 2012. An incredible machine.

[@computernay]

This is a great video, thanks for making it! I haven't found such a thorough and technical explanation of the gen 1 Volt drive train anywhere else online.

[@WeberAuto]

Thank you!

[@GavinM161]

Mind.... blown.... Normally I find Professor Kelly's explanations easy to follow but there's so much going on with the clutch packs I just couldn't get it. I think I need to have it in front of me to try and figure it out myself... Or just watch this video ANOTHER five more times! :-)

[@Trades46]

GM has crafted a very remarkable transaxle from the get-go with the Volt mk1. The Volt mk2 with its 5ET50 is even more interesting and seems like a rationalization between a more efficient hybrid drive mode & the EV operation of the 4ET50. That I can't wait to see.

[@WeberAuto]

Thanks for the feedback!

[@louspinelli1745]

I agree completely. I can’t wait to see the difference.

[@toddtonis]

Thanks for making this video. Having the hardware there and disassembling while you explain function made it very easy to understand a fairly complex drive system.

[@12voltvids]

I found a few inaccuracies in here. Mostly correct though. From my understanding the 4 modes of operation are MG B driving the sun gear, the ring gear locked by clutch pack 1.For high speed cursing at low torque, the ring gear is unlocked, and the second clutch pack connects the rung gear to MG A. This allows a variable drive ratio by controlling the speeds of the 2 motors, so MG B can be run at a slower speed and thus consume less power. Once the battery pack is exhausted the ring gear is locked again by clutch pack 1, clutch pack 2 is released, disengaging MG A from the ring gear, clutch pack 3 closes and connects MG A to the gas engine, and is used to start the engine, which it then is used to generate power to maintain the low state of charge of the battery, and supply power to MG B. For high speed cruising under low load, clutch pack 1 unlocks the ring gear, and both clutch packs 2 and 3 are closed, which transfers some power from the gas engine into the ring gear, which allows the MG B to turn slower and use less energy.Mountain mode runs the engine at a higher speed to place additional charge in the battery pack, and will add up to 10 miles of reserve to the battery so the car can get over the highest mountain passes.I own a 2012 volt, and have done several experiments on the operation under various conditions, including monitoring the various modes through the OBD2 port. Under normal operation the engine runs 1800 to 2000 RPM, in mountain mode while the engine is charging the battery it will run between 3600 and 4000RPM.The first gen volt is unlike any other car ever produced. Very complex, but very well engineered. Over 100,000 miles and not a days trouble.

[@WeberAuto]

Thanks for your feedback. Yes, I described a few things inaccurately. See the video comments for corrections and further comments. Have a good day!

[@kellyfarrell7891]

Kelly farrell

[@oisiaa]

@@WeberAuto The Volt's drive modes are very complicated. It's a marvel of engineering.

[@MURD3R3D]

Thank you so much for the in depth videos. I just bought a 2012 volt and I can not find anything else like your content anywhere online. Thank you

[@rja777]

Thank You so much for this well explained demonstration!Makes me love my volt more.

[@WeberAuto]

Thank you!

[@wayneanderson1866]

Amazing that this ALL works and is so very trouble free! I love my 2012 Volt!

[@WeberAuto]

Thanks for your feedback!

[@compu85]

Prof. Kelly, I thought you might like some observations from my 2014 Cadillac ELR: When driving in EV mode the dash reports 130kW is being sent to the wheels at WOT. If HOLD mode is activated and the engine starts, 160kW is delivered. If the battery is depleted, and the engine starts, activating SPORT will recharge the battery some, enough to show one indicator on the cluster. I've not noticed how much power is available to the wheels when in MOUNTAIN mode, but I do know it dampens the accelerator pedal mapping some. It will start the engine when the battery reaches 50%, and if the battery is below that will run the engine harder to build up to 50%. The "kickdown" feeling going from the small motor to the large motor is quite noticeable. I wish there was a way to lock it into using the large motor only. I also notice that the power delivery is "damped" compared to the GenII Volt, which will really throw you back in the seat if you mash the pedal. The ELR's power ramp is much more gradual.

[@WeberAuto]

Great information, thank you for sharing!

[@louspinelli1745]

@@WeberAuto we would all love a follow-up video on the similar, yet different 5ET50 second generation transaxle and the differences of the Cadillac ELR version that has more power in operation.

[@joebass5163]

@outofspecdave1554

[@energyexecs]

At my community college, I took a 1 year course in Automotive Engineering and Technology. This was way back in 1975 to 1976, We complete dis-assembled engines, rebuilt to spec, and reassembled. It was fascinating. I went on to get regular BA and Master degrees in Science and Business. However, that class was still my favorite.

[@WeberAuto]

Thanks for your feedback. This is fun and interesting stuff.

[@ngl-kd7tn]

Another great video Professor. I do enjoy these in depth, stripping down of the hybrid transmissions. I am just a lay person but I appreciate the detail and love the disassembly of the parts to explain what is going on. Cheers.

[@WeberAuto]

Thank you!

[@dewiz9596]

Yup. I’m a lay person too! Great exposition!

[@corystansbury]

Professor Kelly is a treasure and this is a wonderful video

[@WeberAuto]

Thank you Cory

[@dplummer35]

Excellent video and commentary describing the workings of the Volt transaxle. I drive a gen 1 Volt and have never seen the inside of the casing in such detail - thankyou

[@WeberAuto]

Thank you very much!

[@brunosemedo81]

Great to "understand" how my usual service car works! Thanks for the awesome video.

[@WeberAuto]

Thank you!

[@ericcindycrowder7482]

Also i want to make another comment. One nice feature of this unit is before any clutches are engaged, the motors will synchronize BOTH sides of the clutch to the same RPM then engage the clutch, thus virtually eliminating any clutch wear! This is something that's impossible to do with a conventional vehicle transmission with out electric motors. GM says to change transaxle oil every 100,000 but i imagine could go long past that amount because zero clutch wear. Time will tell

[@WeberAuto]

Thanks for your feedback, I agree

[@hyperlexis]

I changed my Volt's trans fluid around that mileage. There are still gears and bearings inside there grinding and wearing and 'glitter' being produced. Gd forbid anything happens to anything in the drive unit/trans. I imagine the dealer repair cost will be more than the car is worth. Protect it as much as possible. A $200 fluid change is a small cost vs a Volt trans.

[@SpectrumSurvivalist]

I bet most of that glitter was produced the first 5k miles or so, I don't even own a hybrid yet but when I do I would treat it like I would a fresh ICE engine build and have that fluid changed after the first 5k miles, 10k max, but of course engine oil after first 500 miles.

[@spikester]

@@hyperlexis Since the Volt was discontinued you can find used 4ET50 transaxles all over the used market for $500-900. It turns out the Volt isn't so complex to 3rd party repair after all if you have the know-how and paid access to GM technet. GM has done their homework on this car and it shows. The most complicated job one can think of in this car is having to pull the battery and work inside of it yet people have already done just this, even in their home garage, replacing individual dead sections of battery pack. Front end damage however will cost you more than the 4ET50, you'll be well above the cost of a used transaxle just for used RF/LF headlamp assemblies...

[@utah133]

It seems very reliable. We have two 2013 Volts. No issues. It seems to be a great car for the Wasatch Front. Lots of city driving, but sometimes one wants to go to St. George.

[@Diegoalvarezar]

Excelent explanation John Kelly, as always!!!

[@Diegoalvarezar]

I liked this system a lot, cause the electric only mode feels very similar than the hybrid mode, so you don't lose a lot of power, like is the case of Ford and Toyota systems. Now, after understanding it, I think it's unnecesarily complicated and prefer the simplicity of the Honda system for that matter (engine - motor generator A - clutch - motor generator B - wheels). What do you think is better or more reliable? Thanks for the videos again!

[@AZsmoothrider]

Prof John: Thank you for your excellent videos! I watched this 7 or 8 months ago before I bought my 2013 Volt. I've watched it several times since and my mind is blown each time! This combined with some cool animations I've seen give the whole picture on the modes and amazing engineering. I've driven a few prius's and have a cmax at work. They dont hold candle to the volt...once you know, YOU KNOW. Ps- I love your super clean shop and your clear presentation. If you're interested check out my Volt/Morimoto HID installation. Cheers!

[@WeberAuto]

Thank you very much!

[@shaunpowelluk]

Fantastic video! Thank you for helping understand the innards of my Ampera/Volt.

[@WeberAuto]

Thank You!

[@hermanvonsprudelwasser]

Top video! I drive a Opel Ampera for 220.000 km. Great car.

[@DmiA]

Thank you so much for your work! Thanks to you I can broaden my horizons, while on the other side of the globe.

[@WeberAuto]

Glad to help. Best wishes

[@ralfoide]

Thanks for your careful and very clear description. This was really awesomely presented and real easy to understand.

[@youvprotection]

Thank you for providing this very informational free video. Your time and effort.

[@WeberAuto]

Thank you very much! Have a good day!

[@restomania3287]

Thanks for this video. Very informative. I own a Vauxhall Ampera which is basically the Chevy Volt with some styling differences. It's really interesting to see the system explained like this. I've found it to be a really great system; powerful and versatile. It's a real shame that we won't get the new version over here in Europe.

[@WeberAuto]

Thank you!

[@SpectrumSurvivalist]

We got the same problems over here, only ours is trying to get a diesel hybrid. We also get limited models of foreign cars.

[@bigblockcutlass123]

Thanks, your great. I have learn some much in the last few years from watching your video's. I have a 2009 Prius and a 2012 Lincoln mkz hybrid.

[@WeberAuto]

Thank you!

[@solarenergynow08]

Super useful video, thanks. Please keep them coming. From your description of stage (or mode) #3, one could question GM's claim that the "Volt is not a hybrid.." as it is using the ICE to power (move) the vehicle. It was my understanding (from GM mkt I guess...) that the ICE was only used to charge batteries, hence GM's "extended range" description.

[@WeberAuto]

Yes, they didn't tell the truth. Thanks for your feedback!

[@toso5593]

Thank you so much for this very informative video. In fact all your videos are fascinating. I always wondered about the Volt. I certainly enjoyed this one!

[@WeberAuto]

You are welcome!

[@rogerjarrell2121]

Thanks you for a very nice description of this transaxle

[@WeberAuto]

Thank you!

[@FilterYT]

You are a credit to your profession, thank you.

[@patrickflohe1193]

Thanks for the interesting video! Hoping you can do a Generation 2 Volt soon!

[@romanjanke5923]

It's a very interesting construction. Chevrolet goes another way, even it does look like Prius transaxle of 3-rd generation with axles separated through additional clutches (brakes). Thank you for video!

[@energyexecs]

Excellent learning video. Very impressive engineering. It would be interesting to interview the GM engineering design and development teams.

[@WeberAuto]

Thank you, it would!

[@energyexecs]

I drive a Chevy Volt I(2103 Version 1 ) and and also the Ford CMAX.

[@justinsaeger181]

Thank you so much for your helpful videos!!

[@WeberAuto]

Thank you!

[@JOfAllT]

nice video. and nice job of explaining the different parts of this rather complex drive train. however, mountain mode is not explained correctly. blended (or parallel) hybrid mode was described as mountain mode. mountain mode in actuality is a user selectable mode that is used to maintain a higher soc level, thereby providing more battery buffer for negotiating extended steep inclines.

[@WeberAuto]

You are correct, mountain mode is used selectable. It starts the ICE and uses whatever SOC you currently have to provide more battery buffer for negotiating extended steep inclines, but it does not maintain that SOC, it still decreases. Thanks for your feedback!

[@JOfAllT]

WeberAuto Mountain Mode actually charges the battery to about 40% SOC and maintains it there.

[@WeberAuto]

Thanks again. Where are you getting your information about the 40% SOC? That is good to know.

[@JOfAllT]

It was close to 45% SOC actually, when I measured it over OBDII many years ago. I don't use gas a lot (less than 18 gallons over 33,000 miles, on your 2013 Volt) but if I ever run MM again, I can take screen shots and share. There are many articles on the net that confirm this. Gm-volt.com is best because actual owners contribute to it, for the most part.

[@computernay]

As a 2013 Volt driver, I can confirm that the user-selectable mountain mode will charge the battery up to roughly 50% SOC and maintain it there. You can then switch back to the user-selectable normal mode and drive on electric-only until the battery reaches 0% SOC, when the engine starts to maintain the battery level again.

[@oisiaa]

The Volt's motors are huge compared to other hybrids!

[@georgemartin1436]

How did I not find this before? Thank you so much....I bought a used, highly depreciated 2014. Yes, I have a Buick with the 3800, and a Sky Turbo.....and love them too...in their own way. But I want to learn more of the Volt....like how to replace the washer reservoir.....THANKS I will go back and search all your stuff for anything about the vehicle......

[@WeberAuto]

Thank you!

[@michaelmiller9050]

Fascinating video. I always wondered how the Volts work. Thanks for making this! Makes me wonder why Chevy killed this awesome product D:

[@Thegonagle]

It's awesome, but after Honda responded with Accord Hybrid v2 that does 95% of the same thing with far fewer components, it makes me wonder if someone at GM said "this powertrain is too complex to ever build as cheap and durable as we'd like, and it's a transitional technology no longer worth further development," and threw in the towel.

[@captlarry-3525]

Bean counters and marketing wonks Drive Policy, those monsters are shallow shits. Hughes/GM is responsible for the early 3 phase electric system everybody uses. They showed how to tame the Lithium battery with cooling and limiting charge depth excursions and make it last. But they throw away every gain by not taking the long evolutionary approach VW took with the Beetle . Their engineers must have a high suicide rate.

[@oisiaa]

From my understanding, Motor A never propels the vehicle by itself. At speeds above ~70mph, Motor A will begin running (opposite engine direction) to reduce motor B's RPMs to a more efficient zone. It's a very complex system and I might have details wrong.

[@giveabighand]

Thank you for your work.

[@WeberAuto]

Thank you very much!

[@junebug1701]

Wow! Thank you for this excellent video, professor! I feel like a real gearhead now. So, is the housing full of transmission fluid, and is there anything special about the type of fluid used?

[@WeberAuto]

Thank you. The housing is not completely full of fluid, only about 1/5 full. The fluid must be Dexron VI, never use any other fluid or additives. You do not want the fluid to become conductive.

[@junebug1701]

Thanks again! You have given me an even greater respect for the engineering prowess that went into the design of my beloved 2015 Volt.

[@4cutler]

Hi there John. Many thanks for your in depth videos. Great work. I have a question if you ever get to see my posting. I have a 2012 Chevy volt and it has the dreaded service high voltage circuit code. I fixed the problem the coolant sensor but can't reset the error code. Chevy dealership won't look at it as it is has a salvage title. Where on earth can I go to get the error code reset. Or how can I reset it Thanks Dave

[@WeberAuto]

Check service bulletins for a coolant level sensor issue. A factory scan tool is required to clear latched codes. Thanks for watching

[@louspinelli1745]

Hi John Kelly. I’m fascinated by this first generation Volt transaxle. I’m curious about the second generation Volt transaxle if you could ever demonstrate the difference, I would greatly appreciate it. Thanks for your consideration in advance.

[@ELGee1]

hey weberauto what i know from my own and what i have read is that its a little different. the drive mode you call mode 2 is where the motor A and B work together and both run on a really low rpm and so are more efficient also mode 4 is not mountainmode that just a software setting telling the car to charge the batterpack to a SOC so it will have a lot of reserve for climbing mode 4 the ICE will be driving the motor A and motor A will also be connected to B so in a way the ICE in thats stage is connected to the wheels. ( its kinda what you explain at the end where you do say motor B and motor A drive the car ) that happens only under some situations. then when you are in extended mode with a depleted pack or when on HOLD mode. ( later also a software mode telling car to hold SOC ) i see with lower speeds highway drives it wil charge the batterpack a little and then complete shutoff the ice and repeat. i talk about the volt 1.0 not the new 2.0

[@WeberAuto]

Thanks for the feedback, I do not mean to be rude, but your information on mode 2 and mode 4 mountain mode is mostly incorrect. The information I used for this video comes from GM's own service training, service information, and from GM Powertrain's own technician guide on the 4ET50. I do not want to argue over the details, but you might check your sources of information. It is hard to beat the manufacturer's own information. I also own a Volt. Thanks again!

[@billcorn5172]

@@WeberAuto I bought my 2015 Volt 2 weeks ago. Being an engineer, I have enjoyed your explanation of everything inside and how it works. Thank you so much! Just experimenting, when the battery is at 0 range. I have discovered that when driving in Mountain mode for about 20 miles, mostly flat interstate, it will charge the battery to exactly half full, then the engine will shut off. I can switch to normal and the display says I have 17 miles of electric driving. Strangely, this really didn't reduce the gasoline range miles much more than the 20 miles that I had traveled. I was also using L instead of D, which helps pump more current into the battery. When the battery is charged to 50% in Mountain mode, it can be switched to Hold mode. This could be useful if you didn't have anywhere to plug in and wanted to have electric only propulsion when you get somewhere that you wanted to be quiet, for some reason. You didn't mention Sport mode. Does motor A & B work together or is that really a software thing to just give more torque? It really is peppier when in Sport mode, running in electric only or even when the battery is depleted with the gas engine running.

[@ricardofelippe834]

Prof. very helpful vídeo, tips and explanation. Congratulations

[@JSprayaEntertainment]

these videos are great , Thank You for sharing

[@WeberAuto]

Thank you!

[@alexrodriguez3211]

Thanks for the video. It really helped me understand the dynamics of how the 2 motors and the gas engine are coupled to produce motion. Question: does the 2nd gen Volt still use the same principle of an A and B electric motor coupled to the gas engine. I ask because your description states that gen2 uses a different design. I wonder if you could add a video on the main differences between gen 1 and 2. Thanks again. Subbed and liked.

[@WeberAuto]

Thanks, The Gen-2 Volt uses the same A and B motors, but it uses a chain drive to bypass the counter gear and directly drive the final drive. This makes the unit lighter weight and a little more efficient. There are other changes as well, but that is the major one. Thanks for the feedback!

[@SpectrumSurvivalist]

"This makes the unit lighter weight and a little more efficient." I wonder if the chain may be less reliable though.

[@louspinelli1745]

@@WeberAuto I understand that there are 2 planetary gear sets instead of just 1 and the engine does add drive torque to the wheels on occasion?

[@shahid10891]

Sir you are Awesome. I learned a lot about transmissions. Is there any chance for a detailed video on GM gen2 5ET50 transmission? Thank you!!

[@alapar73]

Great video Professor. I have already seen it several times and now have a few questions: 1. Theoretically what speed is the most economical for range extended charge mode? 2. Which part of the video is about the transmission bearing with the plastic cover that breaks down on most high mileage Volts/Amperas?

[@spikester]

The bearing is the large ring bearing atop of MG/Rotor B. Visible @ 3:15 The plastic bearing retainer was changed to a brass one sometime in 2013, however that revised bearing still popped out the brass retainer ring which simply sticks around on the MG/B cover. I don't know if there is a 3rd revised bearing with a properly secured retaining ring.

[@alapar73]

Thank you

[@tomamihai-ei9rk]

Great video. Quick question: is the stator SENSOR located inside the transmission? Can't really see that in the video... Operation of starting the car is controlled by that sensor Thanks

[@louspinelli1745]

Hello professor. Can you explain the difference between the Volt transaxle and the Cadillac ELR transaxle? Supposedly there is a noticeable difference in power even though it is supposed to be the same drivetrain? Perplexing!

[@AlainHubert]

Fascinating. Ingenious design by GM. I Don't know why they would go back to a chain in their more recent model though ? Must be purely a question of weight. But, personally, I don't like to see the word "chain" in any transmission design... But that's just me I guess.

[@WeberAuto]

Thank you and thanks for the feedback!

[@SpectrumSurvivalist]

I don't like to see chain period. I own a 2.8 Audi Quattro, and it's an interference type Engine, I always worry the chain will break and if that ever happens that Engine is toast. My pistons will go right through the deck. I'll take gears over a chain every time, I don't care if they weigh more.

[@mglmouser]

An interesting distinction between the Voltec(1) and Voltec2 is final drive to the differential. Pictured here in this Gen1 is a transfer gear assembly to the diff ring gear. On the Gen2 (which I own), final drive to the diff uses a chain. Personally I think that's kind of lame but it's admittedly a pretty heavy (5-link) chain. I understand a chain drive might be cheaper than machining two more gear and a shaft but I was wondering if you had any thoughts on chain vs gears?

[@WeberAuto]

GM claims the chain drive is lighter weight than the counter-drive gear method. The 2001-2009 Prius transaxles also used a chai with no problems.

[@glassglowz]

Great explanation! Does anyone have any information about the long term durability of this unit? I'm wondering how well it stands the test of time. Thanks!

[@corystansbury]

Other than a motor bearing that can go out (and is replaceable by competent DIY'ers), these things are known to be pretty bombproof. Seems like they were incredibly overbuilt.

[@tuomomakitalo5128]

A question regarding the operation of different gears: D&L and Neutral. When trying to get the highest mileage out of the charge, I have noticed that the most economical is to actively switch between L and D, but also on long downhills to switch to Neutral and let it roll. I have understood that this wouldn’t do any damage to the car, but it turns out that it is quite difficult to find correct answers. What do you recon, am I doing more harm to the vehicle than I’m gaining in added range? The above description is with EV-mode and enough state of charge. Thank you in advance!

[@WeberAuto]

It will not hurt anything. The oil pump that cools and lubricates everything works in neutral too. Best wishes

[@spazzman90]

If you switch to Neutral, don't touch the brake pedal or you are instantly wasting heat as energy. Neutral fully disables the regen.

[@MRGMM]

this is a great video! question. the damper at engine....is that only for engine damping or does it act for the motor also? Would it be needed if there was no engine?

[@WeberAuto]

Thank you! The damper is used when engine power is transferred into the transmission to run the generator. It would not be needed if there were no engine.

[@Mr.landon466]

Hello! I loved this informative video! What do you think could be the problem with a 2012 volt that struggles very hard to get to 30 mph in either electric or internal combustion mode but drives well once you hit that speed? It was diagnosed as either the tcu or 1-2 clutch pack. Tcu was replaced and reprogrammed, still same problem. I’d like to fix it myself or buy a used transmission. Thanks!

[@improvsax]

As always- another great video from you. I certainly hope to see the gen2 setup some time (even though they say they are discontinuing the car)

[@WeberAuto]

Thanks, it is on my "to do" list

[@KTPurdy]

Question for WeberAuto - as I think about how the Volt works, I've always thought that that the highest wear point of the car are those clutches which are constantly engaging/disengaging. As such, my assumption has been to preserve the Volt as much as possible that I should change the transmission fluid more frequently than recommended to keep the viscosity level like new as well as clean. Thoughts? .

[@WeberAuto]

No, the Dexron VI fluid is designed for that specific use, it is not a problem. Just follow the service schedule in your service manual

[@fmccloud]

There is a comment elsewhere here saying that the Volt synchronizes before braking the gears. If true, the clutch wear will be minimal.

[@KTPurdy]

@@fmccloud Clutches are used to mach gear speeds?

[@carterrealty5619]

Could you make a video going over the valve control (TCM) portion of this drivetrain and how it is related to this? Getting a P0700 DTC so any info you have on it would be greatly appreciated..

[@WeberAuto]

Thanks for your feedback. P0700 is just a code telling you to check codes in the HPCM1. You need a special scan tool for that. OBD-II scan tools will not work.

[@artemkaramurza4899]

Hello mr Kelly, I have a question about 2012 volt transmission, but firs I want to say Thank you for your job, its great! So my question is: do I need reprogramm my new transmission after replacing? Which tool You can recommend for that, thank you

[@scorpio2nyc]

love your videos good job. keep up.

[@WeberAuto]

Thank You!

[@cyrenecai]

Definitely a more complex design than the Toyota/Ford designs are, with all the additional clutches/brakes; I imagine it probably cost more to manufacture too. I wonder if the switch to chain drive from geared drive in the 2nd generation was a cost reduction step? One other thing I've wondered - how do twin-motor hybrid transmission like these compare in size and weight to conventional automatics? Thanks for the video!

[@WeberAuto]

Thanks for the feedback. In regard to the chain, the training I have seen states that the chain is for quiet operation, but I do not believe it. Chain drive transaxles have always ended up being noisy. I think they were trying to reduce the size and weight of the transaxle. A countershaft probably weighs more than a drive chain, so the chain was used for overall efficiency and increased battery range. These transaxles are the same size or slightly smaller than traditional automatic transaxles, but they are a little heavier. Thanks again!

[@Dreamco13]

Thank you Sir!

[@WeberAuto]

Thank you!

[@PC_CERTIFIED]

good video stright information just subscribed awesome information now I know what I might be buying before I buy it

[@erics3596]

I'd love a tear down of an 2016 ELR to see what they did actually change (its been said there were mechanical changes as well as the software tweaks to get the first gen Voltec to finally have some oomph).

[@WeberAuto]

Major differences! I have a 5ET50 apart right now working on a video. It should be out in the next few weeks.

[@erics3596]

Awesome! Really looking forward to it! I've been hunting a 2016 ELR to replace my 2014 Spark EV. Would you call the 2016 ELR drivetrain Voltec 1.5? Its how I've referred to it from everything I have learned.

[@erics3596]

Ah, the 2016 ELR used a 4ET55 - so...those changes are what I was curious about. However I will watch the 5ET50 teardown as well.

[@WeberAuto]

True, I forgot the ELR did not update to the 2016 Volt powertrain with the 5ET50, it kept the older powertrain with a modified 4ET50 called the 4ET55. The only description I could find comparing the 4ET50 from the 1st gen Volt/ELR and the 4ET55 is found here gm-volt.com/forum/archive/index.php/t-248874.html

[@erics3596]

After finding my 2016 ELR and purchasing it, I can say the 4ET55 is a very significant upgrade over the 4ET50...I really do enjoy this car. Given there were less than 500 sold I doubt you will get ahold of a transaxle to compare the difference. I suppose it might be worth a comparison to the 5ET50 though!

[@Trades46]

I just realized that the highly popular Mitsubishi Outlander PHEV sold in Europe since 2013 (now on sale in Canada & USA for 2018), the front axle shares some similarities. The S61 front mounted transaxle also has a 2 motor + ICE gasoline engine which operates either on EV, serial hybrid (ICE powering a generator but no connection to wheels) and parallel hybrid with the gasoline engine driving a 3.425 reduction directly to the wheels. Professor Kelly, are you likely going to do some videos on the Outlander PHEV now they arrived stateside?

[@WeberAuto]

Hi, I would if I could get my hands on one, but it is unlikely. Thanks for the feedback

[@adamford54]

Very well done, do you happen to know at what load drive motor B is activated, it would be helpful to know for the geeks that are trying to get 100 miles on a charge like me.

[@WeberAuto]

Thank you!, I do not know the exact answer to that, but it is a light steady state load.

[@portagepete1]

I think drive B turns on at 70 mph but not noticeable while driving.

[@portagepete1]

By the way model 2013-14 and 15 have a read out on the dash of how many amps are being used while driving and how many amps are charging the battery when braking.

[@quartermilefreaks]

small correction...when the hood is open and the engine starts and let it "idle" or when you press down the accelerator it will definitely fully charge the battery

[@WeberAuto]

Thank you for your feedback. Have you actually experienced this charging? According to the service manual "The hybrid/EV battery pack is neither charged nor discharged" when the hood is opened. I have owned a Volt since 2011, but have never tried what you are describing. Thank you.

[@quartermilefreaks]

WeberAuto yes i have.we as a dealer (Opel Ampera) have experienced this after replacing a rotorbearing..engine running for checking the oil level at temperature..to speed up the temp raise we just sit in the car and press the accelerator to get higher revs..after a while the state of charge of the HV Batt went up by several miles

[@compu85]

@@WeberAuto I've found on my 2014 ELR that, with the battery at a low SOC, and the transmission in park, the engine will start and begin charging the battery up to 50%. I recall it puts about 20kw in. If you press the accelerator the engine will rev up some and increase the charge rate to around 30kw.

[@Inviktus94]

Thank you for the video. I think about to puchase a Opel Ampera/Chevy Volt. Did you ever have problems With your volt? What about battery life? If I get problems with the battery, can I fix it( I am a motorcar mechanic )?

[@WeberAuto]

Thanks, I did not have any problems with my Volt, it was a great car! My new one is too.

[@cjones4512]

Very interesting. Does it shift gears or is it always one drive ratio?

[@WeberAuto]

It is always one ratio, 7.575:1 motor to tires. Good question!

[@cjones4512]

WeberAuto Thanks.

[@SpectrumSurvivalist]

I thought a video I watched the other day on this, you said it was a 2 speed transmission, low and high, now I am confused.

[@guillaumelouvel1956]

What an exposé !!!!

[@TheDisgruntledMechanic]

I told you in a previous video comment I have 2 Volts. A 2011 and a 2017. I did a youtube video with comparing some cosmetic difference in them. Do you know if there is much drivetrain difference in the 2 different generations. thank you and love the videos!

[@WeberAuto]

Thank you! Yes, the 2nd generation Volt uses a chain drive between the ring gear of the power split device and the final drive differential case. The chain eliminates the need for the counter-drive gear that the first generation Volt uses. This makes the transaxle lighter. There are other minor differences, but that is the big difference. I hope to get my hands on one soon and shoot a video on its operation as well.

[@TheDisgruntledMechanic]

That would be cool! I do know that my 2011 Volt seems to switch into gas from electric much smother. The 2017 seems a little harsher and has a bit of a "jerk" when it switches especially at 65 to 70 MPH. Once again thank you for the videos and all your responses!

[@TheDisgruntledMechanic]

Sorry. I had not watched the very end of video until now. and you did explain about the difference in the 1st gen to 2nd gen drive. maybe the chain is why I feel the switch more from gas to electric in the 2017? Thanks again.

[@WeberAuto]

I am not sure why the switch to gasoline is more noticeable in the 2017 model. I will investigate further when I get my hands on the newer transaxle. Have a good day!

[@SpectrumSurvivalist]

Yea, that's what concerns me about long term longevity, chains tend to have slack, and slack leads to stretching and more slack, and finally to replacement. I bet the slack being drawn up is what you are noticing.

[@damianralph2632]

The video is cut at 16:35 and it looks like motor/generator rotor B moved about half an inch. Can you explain what happened between cuts? I'm having issues since we replaced the bearing on motor/generator rotor B and are now unable to reinstall the cover.

[@cedr381]

Hi thanks for the video. Would you say that 4ET50 is better than the other hybrid's trans axle?

[@WeberAuto]

Thank you! Yes, it is far superior in my opinion.

[@cedr381]

Thanks for the reply!

[@spikester]

@@cedr381 Other than things like solenoid and the outer bearing whine issues, any physical catastrophic failures of the gen1 volt geartrain were few and far between. Does GM plan on resurrecting Voltec in larger vehicles in the future? Something that the population is actually buying? Heck I was surprised to see how larger the Bolt was in comparison to the Volt side by side... surely there is a larger vehicle market for SUV/crossovers with a Volt style drivetrain... seems such a waste otherwise.

[@tavakolmeskini3028]

great video. thanx man

[@WeberAuto]

Thank you!

[@curtn7076]

Great video! I'm considering buying a 2014 volt.The average distance I drive is around 25miles round trip.. So, the Volt doesn't have a traditional automatic transmission to go bad?.. and lastly, do you think the Volt is a good trouble free cars? Thanks!

[@geojor]

enjoyable video, thank you ...

[@WeberAuto]

Thank you!

[@rafaelkrauss]

Are you planning to do the same type of content with the Voltec 2nd Gen? Would be interesting to see a comparison from your point of view :) Thanks!

[@WeberAuto]

Yes, I have the 5ET50 disassembled on my bench right now. Hope to have a new video in the next month. Thanks for your feedback!

[@martik778]

Any idea when the video of the 5ET50 will be available?

[@ericcindycrowder7482]

Also i have a question related to the electric auxiliary oil pump. Of course they needed an electric oil pump to generate hydraulic pressure because the mechanical pump only operates when the ICE is running. The main drive inverter module supplies power to the aux pump (same inverter that supplies power to MGA and MGB) the inverter is a box above the transaxle in Gen 1 Volt, but in the Gen 2, its inside the transaxle housing. I think a possible concern with high milage gen 1 Volts is if an oil seal inside the electric aux pump was to fail, there's a possibility that oil may be pushed or injected under pressure inside the high voltage electric cabling and end up dumping inside the inverter module. The oil could possible travel inside of the cables, ie travel along the wire strands inside the insulation jacketing. If the inverter filled with enough oil, i could imagine could cause a catastrophic malfunction of the inverter. Has there been reports of thus kind of thing happening and should owners of high mileage gen 1 Volt drivers be worried? Thanks

[@WeberAuto]

I have not heard of any failures like that. Anything is possible though. That used to happen with coolant temperature sensors and diesel fuel injector control modules.

[@compu85]

@@WeberAuto That happened on some 1999-2002 VWs, the pins on the coolant level sensor would leak letting coolant get into the vehicle wiring harness. It happened on my 99 Jetta, there were coolant stains on the hush panel below the fuse box! Amazingly, after the dealer chopped the ends off of harness, spliced on new ones, replaced the instrument cluster, coolant temp sensor, expansion tank, and vehicle speed sensor it never had another problem, even though the harness itself was probably still full of coolant.

[@energyexecs]

Mr Weber Auto - I worked in the Lubricants business at Chevron. Can you mention type of lubricants if any in the gears and such. Thanks.

[@WeberAuto]

The only lubricant for this transaxle is Dexron 6 automatic transmission fluid.

[@energyexecs]

Excellent. Thank you.

[@ericcindycrowder7482]

I like your video. But I want to clarify.... in mode 2, EV only steady state low torque, it uses BOTH MGA and MGB. MGB is splined to sun gear, and MGA is clutched to ring gear. Doing this reduced the RPM of BGB, this is what achieves higher efficiency because lower motor RPM. IF MGA and MGB both turn at same RPM, then the ring gear is essentially a 1:1 direct drive.

[@WeberAuto]

The combination of both motors at variable speeds per motor gives a variable gear ratio.

[@ericcindycrowder7482]

WeberAuto yes I understand its variable. Its just it seemed to me if someone watched who had no previous understanding of the transaxle, it sounded like you were saying in mode 2, its MGA ONLY. But as we know its blending MGA with MGB through the planetary creating a variable ratio

[@KefirTView]

Are there actual clutch packs in this transaxle that have clutch material that can wear over time? What are the clutches comprised of? I'm trying to understand where wear and/or slippage can occur in this transmission. Thanks!

[@andreilibman9620]

Is it possible to equip Volt 1, Volt 2, Bolt or Spark EV with differential lock to improve to improve acceleration and front wheel traction in corners ? Diff lock helps to drive safetly and do not get stuck in slippery surfaces: gravel, sand, snow, dirt.

[@JustinOhio]

How much does that entire transfer case weigh? Also, any plans to do an update video talking about the Gen2 transfer case differences? Nice video!

[@WeberAuto]

I do not know how much it weighs, but I suspect is 250 lbs. I do plan on acquiring a second generation model ASAP. Thank you!

[@joshmaier18]

Does the regenerative brake wear? On my ELR with 95,000 ive noticed the paddle braking doesn’t slow the car down as quickly as it used to.

[@WeberAuto]

No, it is electronic. Thanks for watching

[@darbrandt3847]

how does the computer control the variuos clutches? Is it transmission fluid pressure or maybe electronic control?

[@WeberAuto]

Hydraulic pressure

[@nakata607]

Is this composition is similar to opel ampera?

[@WeberAuto]

Yes, exactly the same transmission

[@rkan2]

Same car, (only slightly) different bumper.

[@optiskeptic4746]

So... technically, the ICE can possibly work as a parallel hybrid drive, as it CAN connect to the physical output through the ring gear, in parallel with the sun gear from Motor B (which is powered by battery and/or motorA/ICE?

[@NotOftenPoliteGuy]

yes and no. There is only way to transfer power from gasoline engine to the wheels by adjusting motor B speed. The slower motor B is spinning the more power goes to the wheels from gasoline engine but it is impossible to lock motor B in place. Motor A is always generating power when engine is running to support motor B. So even if you could stop motor B completely you will need to apply power to hold it. It will not be as efficient as Volt 2nd gen or Prius where you can switch off electric motors completely and drive wheels directly. But at the same time is not as bad as generating electricity using motor A to power motor B. My answer will be it is something in between. 1st Gen is quite efficient anyway normally my consumption for long trips on a highway going 50-60mph stays around 4.7l/100km = 50MPG US or 60MPG UK. Most newer cars produced in 2024 is not even close to Volt.

[@vevenaneathna]

so cool that this info is just online in good detail free. i was driving my volt and tried an experiment. had a long flat spot on the hwy before a steep hill, ran the car in mountain mode to charge up the battery before switching to electric only mode to get up the hilly part for a few miles. idk I know there are losses moving electricity from the generator to the battery then back to the motor, but i almost wonder if having the generator run in the most efficient range for a lot longer period of time, and then just going easy on the electric mode to get up the hill, starting at a speed of ~77 and letting it slow down to like 60 at the top of the hill, if it would be easier on the car and get better equivalent fuel economy. just bugs me when the generator starts and revs up as high as it can to get up hills. feel like thats the worst case scenario... really iteresting car, probably will never be something like it again

[@martik778]

I wonder how strong those gears are. Would repeated jack rabbit starts risk breaking a tooth?

[@WeberAuto]

They are large gears, equal or larger in size compared to the gears in a typical automatic transmission.

[@numutekwipu2006]

I would like to request if you can do about the 2014 Cadillac ELR and the 2016 Cadillac ELR same from volt but more upgrades

[@igorvorobjov]

Does the petrol engine have connection with wheels (not through electric engines) in one of that for modes?

[@michalkowalczyk3361]

I'v got opel ampera with DTC P079C is Transmission clutch 3 slip detected,what can be problem,clutch pack or tcm module ? Car drive only on electric engine, no gasoline engine start.

[@WeberAuto]

Clutch pack slipping can be caused by low fluid level, low oil pressure, worn clutches, a solenoid or TCM problem. Begin with checking the fluid level. Best wishes

[@michalkowalczyk3361]

thank You WeberAuto for quick reply,i'll check and let You know. Can you show solenoid responsibility for control for clutch no 3 ? Where is located solenoid block and what is corect presure fluid ?

[@keithw32123]

I enjoyed this video and the Fusion Hybrid video.. Thank you. I drove a Fusion Energi Plug-In hybrid for 3 years. Our family also has a 2001 Toyota Prius. and now I am driving a 2017 Volt which has a lot of torque! I posted the link to this video on the gm-volt.com forum under propulsion. Do the clutch-brakes ever wear out? Can they become defective and cause the power to the output drive to vary at constant input? What does moving the shift lever to position L do? I have driven 70 mph in Low no problem..

[@WeberAuto]

Thank you! I am on my second Volt, a 2014. The 2017's look pretty nice. Yes, clutches and brakes can wear out over time, but I am not aware of any common issues with this transaxle, they seem to be lasting very well. The L position of the shifter is similar to the B position on the Prius, it turns up the regenerative braking force to help slow the vehicle without using the hydraulic brake system. It seems like cruise control may not work in the L position. Thanks again for your feedback!

[@Inviktus94]

The Chevy volt forum says, the clutches engage only with the same speed "04-03-2012, 09:29 PMI would believe that the fluid will not get "dirty" unless there is plenty of clutch wear. Someone posted before that the clutches inside of the Volt engage while both surfaces are at the same speed or with little torque differences, so there will be less wear."

[@floobertuber]

Hi, great video! The engineers that come up with this stuff are mind-blowingly smart! I'm curious about your statement that Cruise+"L" may not work together. I also have a 2014 (owned) and had a 2012 (leased) and in both Volts, I was able to use my Cruise with "L" mode. Can you say a bit more about that? Perhaps yours had a malfunction?

[@HQBergeron]

@@WeberAuto Cruise works well in Low in my 2013, though at the highway speeds where I normally need cruise control I find it more efficient and comfortable to run in High. But thanks to this video and the understanding it imparts, it seems clear that all Low does is remap the throttle control and regenerative braking through software control of the electric motors, so there is no “shifting” of mechanical gears that would cause wear. The 2013 Volt Manual says not to use Low over 35 mph, so I was wondering about this question as well.

[@ranxerox10]

Mode 2 ist what you say at 28:10 not what you say at 9:30, you can´t disconnect MGb. I like your videos, i have a Volt too (Ampera). Greets from Austria

[@WeberAuto]

Thanks for your feedback! It is true, MGB cannot be disconnected from the sun gear, but its rotational speed can be slowed to almost a stop making MGA the primary driving motor in mode 2 (Electric Only Combined Engine Off (EV)). The following statement comes right from Hydramatic's own 209 page technical guide for the 4ET50 "Depending on driver demands and road conditions, the vehicle can enter combined mode. During this mode the variable hi and 2-3-4 clutch is applied allowing generator/drive motor - unit A and/or drive motor/generator - unit B to provide output torque. If the required torque to propel the vehicle is low, then generator/drive motor - unit A can supply the torque needed to move the vehicle. If the demands increase, then the primary torque supplied comes from drive motor/generator - unit B." I hope that helps clarify things. Remember, the planet carrier is the output to the final drive. Technically MGB and MGA can be inputs or reaction members. Best wishes!

[@ranxerox10]

Aha, so in Mode 2 it can change the MGa/b Power split ratio, by changing the MGa/b speeds. i wasn´t aware of that. Thank you.

[@portagepete1]

It will be interesting to see which will last longer the 2011-15 or the 2016 and up. With that drive chain in the 2016 i think the first generation 11-15 will last longer, chains are always a problem at high milage.

[@WeberAuto]

True, but it does make it lighter weight without the need for a counter gear.

[@kevinschrage9447]

GM has been using drive chains since the TH425 in the Oldsmobile Toronado. They've proven to be no more problematic than any other component.

[@Stelios.Posantzis]

I've gotta say after watching this presentation I've reverted back to preferring the GM solution after a short break spent admiring the Prius engineering feat. Although the 4th generation Prius transaxle appears to be a marvel of economy in design and the elegance of its concept is unquestionable, it does, however, leave me with some questions over e.g. economy gone too far for one thing. By comparison, the GM transaxle appears a much more robust design, more powerful and with simplicity as its major strength. The built also appears much sturdier. I guess you get what you pay for. I still wonder why GM didn't continue with this design by simply adding more battery storage. From what I've been able to find out from the press, I'd say I'm still keener on the initial Volt concept rather than the Bolt design. Is there going to be a similar presentation of the Bolt transaxle? I'd be very interested on a comparison between the two GM transaxles and the (engineering) reasons behind the change in the design. A great presentation once again!

[@Stelios.Posantzis]

I rushed to comment unaware there was a 2018/19 Volt model. It does, however, appear after a quick glance only minimally different to the previous Volt edition. I don't think it's available or will ever be available in Europe so it's probably only of academic interest to me.