Power Flow - ZF 9HP 9-Speed Transaxle Operation - Part 2 of 2

ABOUT US:
Weber State University (WSU) - Automotive Technology Department - Transmission Lab. This episode demonstrates the operation and power flow of the ZF 9HP 9-speed transaxle used in select Chrysler, Jeep, Acura, Honda, and Land Rover vehicles.
This transaxle uses 4 planetary gear sets, 2 clutches, 2 brake clutches, and 2 dog clutches.
www.weber.edu/automotive
This video was created and edited by Professor John D. Kelly at WSU. For a full biography, see www.weber.edu/automotive/J_Kel...
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Please consider a donation to the Department of Automotive Technology at Weber State University here: advancement.weber.edu/Automotive

[@miguelash886]

This man deserves an award for making such a complex functioning device easier to understand and give a thorough explanation on how all the gears work. Heck, he even goes the extra mile and demonstrates all the gear ratios in action!

[@WeberAuto]

Thank you very much!

[@Kebekwoodcraft7375]

Great teacher 👨‍🏫 😊

[@STARNOLICIOUZ]

Amazing Teacher

[@danielnation9123]

8 year later and I’m watching for 2nd time.. I’m a classic entrepreneur workaholic that don’t take vacations. Somehow, this is really relaxing for me.

[@scottydavis1813]

I have a SUV with this transmission and it is really smooth but 9th gear is kinda useless for a 4 cylinder engine. I find it a very interesting set up.

[@eddiefrank3319]

I work at a Honda dealership and this guy knows more than my techs.

[@rscranman2002]

How reliable are these transmissions? I have one in my passport (2020). Love it. I don’t love the clunking nose on steep hills going from park to drive (with parking break on). Have you heard of this?

[@Ganbala]

@@rscranman2002 is normal ..the reason why is the way this trans is packed.... Is a big house in small house .

[@tabibito60]

@senior mobile fitness I am on my third 9HP in my 2019 Honda Odyssey with 68k mile. those sounds are not normal for a transaxle. John made a wonderful video, but in believe the ZH is a okay transaxle with crappy software.

[@VikasKesavan]

Awesome! I had no clue about complexity involved in this transmission - thank you, professor Kelly for this presentation .. viewed after 9 years !

[@Trades46]

Breaking it down and going into each individual part & running through the gears you realize how complex this 9spd trans-axle is. Arguably the most informative video on the net showing how this super-wide ratio transaxle works, thank-you.

[@WeberAuto]

+Trades46 Thank you very much!

[@bobolulu7615]

Who are the clever people who designed this? We need their names and they need a medal!

[@samaanam76]

I don't understand why someone doesn't like this perfect demonstration!

[@WeberAuto]

It is confusing at times, thank you

[@QiuyuanChenRyan916]

maybe they had the problem with this transmission, but the more gears in a transmission would need drives to dump some bad habit that was able to tolerate in a 4 speed.

[@randomguy3579]

I work for ZF and you did the 9HP justice

[@WeberAuto]

+randomguy3579 Thank you very much!

[@francom6230]

Turn out you are building a piece of shit. "Swap Shifting" never made for a good trans. ie: Hydo250, 4r44 etc. are bad enough. NOW y'all are trying to swap 4 planetaries for 9 ratios apparently doesn't work well and ZF claims it's software. Still can't seem to get it right in 2018. JUNK.!!

[@cmontes7961]

@@francom6230 It's not perfect by any means but that's being a little bit harsh don't you think.

[@hedydd2]

@@francom6230 Software is tuned by the car manufacturer not ZF. Some brands have had firmware issues but my 2015 Honda CRV diesel is tuned perfectly. It is predictable and smooth in every ratio and change and its downhill engine braking is just perfect. Honda UK just got the firmware right. One thing though, despite being 'sealed for life' mine is now subject to a factory directive to change the fluid at the next service free of charge. So there may have been a few durability issues at higher mileage that has indicated fluid changes to be necessary.

[@MrManuel1329]

@@hedydd2 being diesel it's probably way easier for the transaxle to shift because it has torque to work with and it's at low RPM which makes for clutch brakes and dogs to engage easier also CRV is way lighter then the Odyssey, Ridgeline and Pilot which Honda is utilizing the 9HP over here in the States. Our CRV's are gas powered and use CVT.

[@laser4398]

I'm so grateful for your clear and precise explanations of this very complex transmission. I am amazed at the expertise and patience you must use to get an understanding of these systems. As a retired lecturer in electronics, I applaud your ability to make these systems understandable. Thank you.

[@shubhamsasane6381]

Came across this video while prepping for an interview with ZF. Thank you, Professor!!

[@CS-iv6hp]

It’s humbling to affirm that somewhere someone infinitely smarter than me designed this. Listening to Prof. Kelly explain it is amazing.

[@sanmanDC050]

Thank you. Now I understand this transmission a lot better. Yes. Ppl complain that it’s hunting for gears but it’s not. it just a busy transmission. Thanks

[@pmo5821]

A more precise way to describe planetary gearsets instead of "turn one, hold one, and the remaining is output" is to say that it has 2 degrees of freedom. If you dictate the speeds of any two elements then the speed of the third element is determined. So, you can dictate the speed by driving one/holding one, but also by driving both of them.

[@IBMara]

Thank you John. Very nice and thorough demonstration of a complicated mechanism. You made it seem simple and understandable; the sign of a good teacher.

[@WeberAuto]

+Leo M. Mara Thank you very much!

[@xolanigola8091]

Thank you John I am not a mechanics. My BMW F30 320d(year 2013 - FZ 8HP45 slips the second gear. What might be a problem please help. (It drives on drive train)

[@Roman-xb9xn]

Thank you John, awesome and simple demonstration. In my opinion manufacturers overcomplicate things to the point where even their technicians are not able to keep up with the repairs

[@WeberAuto]

Thank you

[@glengriessler8597]

Wow. I never in my wildest dreams could understand this 9-speed in my 2016 Honda Elite. Now makes sense. John - You are amazing. You make it look easy. Thank you sir!

[@WeberAuto]

Thank you very much

[@georgeheri895]

John, you are amazing to watch, I enjoy all of your videos. Thank you for sharing this.

[@WeberAuto]

+George Heri Thank you so much!

[@940360]

It's always great and a pleasure to learn from you! As a mechanical engineer, I must admit that you're most professional that knows how to explain complex systems in a simple manner!

[@serranc11offgrid17]

Amazing video. I have that same transaxle on my 2015 Chrysler 200c AWD vehicle (ZF 9HP48)with 40,000 plus miles. At the beginning I was not used to the way it shifted until I read more into it and understood what was going on in there. This video made it even more clear. Thanks again sir for this video. Blessings to you and yours.

[@billanderson3192]

John, you always take the most complex, and make it look simple. Your videos are excellent.

[@WeberAuto]

Thank you Bill!

[@TheNetToffee]

Thank you for this excellent demonstration

[@taktautomobili]

I am amazed of your patience and covering of details explaining how this transaxle works.As a mechanic who repairs automatic transmisions myself i find these videos very useful and entertaining.Greetings from Croatia.

[@WeberAuto]

+Takt Osijek Thank you for watching!

[@forrestjo]

By watching your videos. They helped me to passed the ASE A2 test. Thank you again. John, you are a great teacher.

[@WeberAuto]

+Forrest Jo Congratulations! I am happy they were helpful for you.

[@rec1435]

Awesome video John...Just bought a 2021 Passport...shifts likes its going through butter!!!!! Simply amazing technology and your video!!! Thank You

[@WeberAuto]

Congratulations on your new Passport. Thanks for watching

[@blackericdenice]

There was a guy name Larry Bloodworth who did a video on the A604. He showed how it shift 4 gears and reverse. When I 1st heard about this 9 speed. I didn't think anyone could explain this unit like he did. I was wrong and I think you very much for doing it. I feel a lot smarter now.

[@WeberAuto]

+blackericdenice Thank you! I know Larry, he does good work.

[@cambioautomaticoumcaminhos7434]

Amazing work, congratulations Jhon...

[@a.r.walker6255]

Excellent demo of how the 9 speed works. Great video!

[@WeberAuto]

+A.R. Walker Thank you! And thanks for your feedback too!

[@AlexandreOliveiraAlex]

You are an amazing teacher, thank you John.

[@greenbudkelly2820]

Fantastic presentation! Stellar job demonstrating how this transmission works. And hats off to the engineering team.

[@nickmayo2974]

Thanks so much for this! I'm an Acura dealership technician and we don't repair the 9 speeds, we replace them with reman units. How awesome to get a better understanding of the inner workings of this transaxle!

[@WeberAuto]

Thank you! I am glad it was helpful.

[@blackbeard1653]

Fantastic video! Such a great and informative lesson to convey a complicated design in an easy to understand way. Keep up the great work!

[@daver4590]

Fantastic demo & explanation! Thank you! I have a 9HP in my Acura. This video answered all the questions I had....and even a few I didn’t have.

[@WeberAuto]

Thank you! I am glad it was helpful for you

[@kimsvalebeck8210]

I Finally understand how this transmission worked ..thanks.

[@WeberAuto]

Thank you!

[@kimsvalebeck8210]

Have just bought a Honda cr-v with this transmission and hope it will be long life time of it :-)

[@geojor]

always enjoy your videos, thank you...

[@jasdeepsingh6078]

Perfection! Mr. Kelly!

[@fluke9]

Thanks for the dedication and sharing with the internet, looks like you take your profession really serious !

[@WeberAuto]

Thank you very much!

[@monteau60]

Outstanding presentation for a layman, thank you Professor

[@srdporter]

wow! what an awesome piece of engineering!! I thought the Aisen 8 speed was impressive enough but this does more and looks so compact. Thank you so much for sharing your vast knowledge.

[@WeberAuto]

+Andrew Porter Thank you!

[@Freezframe]

Excellent explanation and presentation!

[@ge69rh]

An amazing video, actually felt like I learned something.

[@WeberAuto]

+Gary Hylton Thank you!

[@MrSeemaan]

Hello John! The cast iron part that holds output gear is called by ZF "bearing bracket".

[@lilshawn2]

I have a vehicle with this transmission. i never plan to ever take it apart.... but learning how it works was super fascinating.

[@WeberAuto]

Thanks for watching

[@lilshawn2]

@@WeberAuto man, these last couple days though... Driving down the road...thinkin' about how the clutches are engaged and disengaged as the car shifts through gears. You really nailed how to explain this! Going to be a while before this brainworm leaves! Good job! I'll be browsing through your other videos for sure!

[@WeberAuto]

@@lilshawn2 Awesome! Thank you

[@hedydd2]

As a humble Welsh farmer, I appreciate these videos of yours very much. As it happens I very nearly bought a Land Rover Discovery Sport with this transmission a few weeks ago, but decided against it for reasons unconnected with the quality of the product. Instead, I've got a Volvo on order with the Aisin eight speed front wheel drive high-torque transmission linked to the Borg Warner-Haldex axle. How Aisin manage a reasonably heavy duty eight speed transmission, able to handle around 500Nm torque in a transverse front wheel drive installation only the Lord and you could know. As an aside, it would be interesting to see the operation and contrast between the Haldex and GKN [fitted to Range Rover Evoque] rear axles some day. Keep up the great work and thank you.

[@WeberAuto]

Thank You!

[@FranciscoJimenez-bb7fk]

Thx for your legit content. Thx weber state for the legit content. Looks like zf is autobahn worthy

[@skoll9004]

Well done. Bravo. I watch the whole thing

[@andrewcammer2535]

Nicely demonstrated!

[@Helo735]

Thanks for this demonstration John. Taught me everything I was curious about with my newly purchased 2015 Chrysler 200C.

[@WeberAuto]

Thank you

[@Natethegreat200c]

How’s the car doing.

[@ElectricDanielBoone]

That was great! I'm glad I got the lifetime oil changes for my Cherokee. I didn't realize that's what you had to go through to check the trans fluid level and I'll make sure they do that procedure, which I'm sure they do! I watched both videos and enjoyed both!

[@WeberAuto]

Thank you!

[@roro560v8]

brilliant demonstration, please keep it up

[@WeberAuto]

+MoH ALO Thank you! very much!

[@LORD-DEBMALYA]

I love your videos. Thank you for sharing your knowledge with us. God bless you..

[@justiphonique]

Hello John. Thanks for the great explanation.

[@WeberAuto]

+Justi Phonique Thank you!

[@don.timeless4993]

sir, thank you so much for the effort. this is really amazing

[@TheTech9]

38:40 You're right. My Cherokee needs to be doing 80 with a good tailwind to get 9th (doesn't help it's the heavy complicated Trailhawk model). This explains that!

[@cheahkaikooi2753]

fantastic video!

[@douglas.turner]

Hello John Excellent video. We have this unit in our 2018 Cherokee and after 53,000 kms have yet to see 9th gear. The shift from 4 to 5 is always noisy as the dog clutch releases, otherwise it's great. Thank-you for the very informative talk.

[@chekelley6861]

Great video!! Keep em coming!!

[@WeberAuto]

+Che Kelley Thank you!

[@boczarionut1981]

Very nice presentation

[@WeberAuto]

+boczarionut1981 Thank you!

[@zeuss194]

As always, clear and instructive video. You deserve more viewers and followers, thumb up

[@WeberAuto]

+zeuss194 Thank you!

[@jannuns3555]

WeberAuto

[@rafihussain]

Thanks. It's was amazing explaination

[@69Taros]

Супер! The best lesson! Regards from Russia!

[@adriannewman1322]

I have a 18 jeep renegade with 2.4 4 cylinder. The 9th gear doesn't even come on till around 88 mph but you have to be on level ground and no wind blowing against you any slight change going uphill it drops back down. Great video

[@juanvicentemedina9110]

Very good video and amazing explanations. Thanks for sharing your knowledge and God bless you.

[@WeberAuto]

Thank you!

[@leonardocampos5137]

Thank you very much for the videos so well explained, my best wishes for you, greetings from Argentina

[@jasonsong86]

Amazing, I have this transaxle in my 2021 Honda Passport. I can clearly hear the dog clutch disengaging when going from 7th to 8th.

[@DougHanchard]

I've watched this video three times. My head hurts! I'm still spinning trying to understand how the sun gears don't 'lock up' against the other one with only ONE tiny split gear on the main shaft. I'm going to go lie down now..... all I know is you must be right. 9 forward gears made by ZF. That's good enough for me.

[@WeberAuto]

+Doug Hanchard Thanks for watching! it is an amazing design.

[@marcinmorris]

I love your videos. You got that gift to transfer knowledge to young automotive enthusiasts like me :) God bless you :)

[@WeberAuto]

+Marcin Wojciechowski Thank you very much!

[@johnnyrotton40]

John first great job with the video,I work for WEBER AUTOMOTIVE we machine both the 9hp transaxle housing and the 8hp transmission housing I found your tutorial very informative thank you .

[@WeberAuto]

Thank you! That is cool that you do the machine work!

[@sapphirepilot]

Thanks. Nice work.

[@hddm3]

your students are lucky to have you!

[@WeberAuto]

+hddm3 Thank you very much!

[@active200m]

Thank you very much for your very good videos and good explainnig, it's very good that you didn't hurry in your videos and explaining all in details. i am from moscow and after your videos i know much more about auto T. Can you please make video and explain how to use auto T to have longer life? For example before long time red light (traffic light) put on "N" is good or not? Sorry for my long comment. Have nice time and i hope to see more videos from you.

[@naughtyUphillboy]

At the end you clearly explained to Jeep compass owners.

[@user-ux2sr9sz5r]

thank you for all of video

[@WeberAuto]

+Eng.jameel akel Thank you!

[@ggerely]

Excellent presentation like always, thank you very much. I see these installed on many BMW, Mercedes, Range Rovers etc over here in Europe, and a couple of guys I know launch a lot on these. Anyone have any input on the longevity of the clutch packs?

[@YourTransmissionRepair]

I agree with John in that it's hard to describe into words how a compound (or "stacked") Simpson geartrain can get so many ratios in the normal sense. This is because we normally think of either a planetary member being in of only 1 of 3 states: Drive, Driven, Held, or Reactionary. When we think of a member being driven, we think it's at turbine (input) speed and when we think of a member being held, we think of zero RPM. What would happen if a member that is normally being held in one Simpson gear set was really turning slowly by the output of another Simpson gear set? You would actually have 2 inputs into the gear set; one by the turbine shaft (main input) and one by the output of an adjoining Simpson geartrain in the stackup. A split torque path, essentially. If that's clear as mud by now, perhaps looking at this vintage 1953 B&W US Army training film will help other visualize how this works. Although the video is 14:29 long, I have it start at 9:12 where they are driving 2 members of a planetary gear system model. Check it out: kzbin.info/www/bejne/iaPOq5SHh6mnq68m12s

[@WeberAuto]

+Tanner Transmissions Thank you for the feedback. It is pretty cool stuff (as well as complicated). Aisin's 8-speed transmission uses a similar idea for the input. See my video at kzbin.info/www/bejne/h5mslImDbpJ5aas

[@traqnsavov822]

thank you for all of video`s :))

[@WeberAuto]

+Traqn Savov Thank you!

[@naughtyUphillboy]

Thank you so much Sir.

[@maxnguyen22]

I'm wondering if it reliable. Amazing video.

[@eurotmautoparts898]

It was a great help to me.

[@WeberAuto]

Thank you

[@hedydd2]

For all practical purposes the driver can regard this as an eight speed with an overdrive ninth that doesn't engage at all unless at over 70mph. So in ordinary driving it is no more busy than any common eight speed transmission. Mine is so smooth that I seldom notice any change when driving normally.

[@user-py1tp6we1d]

Videos very handy. Thank you. Best regards from Moscow (plz read this comment with strong russ accent)

[@WeberAuto]

+Сергей Ренов Thank you!

[@syedsalahuddin5392]

Hi sir. I am watching your videos regularly. Your videos is very helpful god bless you and keep you healthy AMEEN

[@WeberAuto]

Thank you

[@430CMB]

Good morning John. I just watched both videos on the ZF 9spd. Great work. I would be tired after stating so many planetary gear set names! For what it is worth, to your point on the super high 9th gear ratio, I have a real world fact. I ordered my 2015 Jeep Cherokee Trailhawk with the 3.2L brand new. Currently it has over 60,300 miles on it with about 38,000 miles on the new transaxle. The first one suffered from the poor software due to the weak C-clip design from the first generation transaxle. Having driven it all over, including a 15,000 mile road trip up to Alaska, I have NEVER seen 9th gear. If you would not mind, would you desire to do a video on the rear drive module (RDM) on the Jeep Cherokee KL? I find it very interesting how they use the clutch to distribute power to it, while also utilizing a true electronic locker. Thank you for your videos. I recently discovered your Channel and will be spending more time on here. To yours in health.

[@WeberAuto]

Thank you for the information and feedback. I do want to do a set of videos on the three different RDMs and 4WD systems available in the newer Jeeps. They are difficult to obtain. Have a great day!

[@sticx89]

Love these videos :)

[@WeberAuto]

+sticx89 Thank you!

[@mannypacheco5583]

not much to say except your a genious

[@WeberAuto]

Thank you and thanks for watching!

[@hddm3]

very cool

[@jonatasfelipe2095]

que aula incrivel

[@pmo5821]

It does seem curious that despite all the “tricks” ZF used (nested gearsets, 2 dog clutches instead of friction clutches, eliminating one-way clutches), the ZF9 is not appreciably smaller or more compact than competitive 9- and 10- speed units like GM’s and Honda’s.

[@WeberAuto]

I agree, at it has had a lot of problems too. Thanks for watching

[@Rumblebee2144]

dude, you are amazing at what you do! keep up the good work! I'm curious about the new ten speed from ford and gm thats in the new 2017 camaros.... hopefully you will get one soon.

[@WeberAuto]

Thank you! I also hope to get my hands on one soon. Have a great day!

[@blackericdenice]

Here it is May 5th 2018 and I still have not driven a 9 speed. I did rent a 2017 Ram 3.6 8 speed and a 2017 Camaro v6 8 speed. I love them both. Sense my last comment. I bought a 2016 F165. I wish it didn't shift like it was made in 1989 at light throttle.

[@WeberAuto]

Great feedback, thank you!

[@jorgenunez5367]

Excelente explicación, tengo una pregunta, en esta transmision es normal que el motor suba las rpm cuando por ejemplo se baja de D5 a D4? o cual puede ser el problema

[@akmo23]

Amazing video. Just to clarify, On a full open throttle with all stock 2015 Cherokee 3.2. I didn't hit 9th until 115mph. Flat surface. I noticed 8th doesn't like to let go and you can cruse 80-90 in the 2100Rpm range. The unique things he mentions that lets components slip is very problematic, reversing and downshifting.

[@WeberAuto]

+AKMO E Thanks for the feedback!

[@hedydd2]

I've just changed a manual Honda CR-V to a new diesel twin turbo with this nine speed automatic. It exceeds my expectations with smooth predictable shifts both up and down. I don't believe it has yet engaged 9th though LOL. As such it compares nicely with any 8 speed transmission with an extra overdrive for 80mph plus at light loads. Honda seem to have nailed the software for smooth and rapid changes plus sensible downshifts for engine braking down hills. Also its engine start-stop feature is entirely controllable via footbrake pressure, in contrast to the otherwise excellent Aisin 8 speed on my Volvo, which kills the engine at every stop no matter how lightly I brake and even before the car rolls to a stop sometimes.

[@WeberAuto]

Thanks for your feedback!

[@AmericanLocomotive1]

Great video! It's tough to visualize what's going on inside an automatic transmission!

[@WeberAuto]

+American Locomotive Thank you!

[@toddthomas3226]

Hi. I have a jeep cherokee sport 2015. I've been having problems with it delaying charging gears. Mainly 1st to fifth. I've heard this problem can be from degraded fluid. How can the state of the fluid detect the trans axle? Your video was very informative especially going the the gears and their ratios. What else could cause delayed gear changing. Thanks

[@ctawab]

Thank you professor. If I may make a suggestion if that, it would be better to split the videos into smaller segments. especially a small separate video on which you discuss which car models use the transmission and what are the differences.

[@WeberAuto]

+ctawab Thank you for your feedback and thanks for watching!

[@honalo1]

nice video. you could reach the 9th speed depending on the final drive ratio from the transaxle through the differential gears. with that many ratios wouldn't a CVT transaxle be better? keep up the good work. your videos are clear and give good information.

[@WeberAuto]

+Dennis McConkey Good thinking. The CVTs don't seem to be able to handle the increased torque of V-6 engines. I also read they have more frictional losses than the 9 speed does. Thanks for watching!

[@ElectricDanielBoone]

My 2017 Jeep Cherokee has this transmission and I've been getting a 2nd gear ratio incorrect code lately. It goes into "limp Mode" by staying in 4th until I shut it off and wait a few minutes. Dealer is going to look at it, but i wanted to review how this transmission works. I watched your video before I bought my Jeep too. Not sure if it's having trouble between 1st and 2nd, or 3rd to 2nd, but the dog clutches aren't involved in either shift. Maybe the solenoid/valve for the C brake isn't applying it all the way for some reason? I don't know what kind of piston applies C brake, but seems like it'd code more often it that was leaky. Dang thing only has 28k miles on it too. It goes to the dealer Wednesday. I do think its an amazing design though! So compact!

[@gregorytolson4621]

Whats a recomended fluid level drain and fill for these transmissions? I bought a 2021 jeep cherokee inline 4 with one of these in it. The owners manual of course says its lifetime fluid

[@leonardocampos5137]

I will do my best to spread your knowledge in this part of the world

[@dannation8837]

Great video. You said clutch pack does it have regular clutches? the factories saying never change the fluid what's your opinion?