Here's how a 4x4 Jeep Wrangler Transmission Works

Here’s a full teardown on what’s inside a 4x4 Jeep 8 speed automatic transmission and how it works!
The Jeep 850RE is an 8 speed automatic transmission used in the 2018+ Jeep Wrangler JL amongst other models. It features 5 clutch packs activated by pistons and 4 planetary gearsets to achieve 8 forward and 1 reverse gear ratio. It is longitudinally mounted for rear wheel drive, with the 4X4 transfer case attached to the rear of the transmission and a traditional torque converter and fluid pump at the front. It also features an external cooler and traditional shifter linkages for the parking pawl.
Inside, the transmission pan does not include a drain port, but has a serviceable filter. The valve body has 9 valves, in addition to an accumulator to help pressurize fluid once engine start-stop is engaged. Traditional planetary gearsets are employed. The casing is one piece, with the bell housing non-removable. There is an abundance of snap rings that are difficult to disengage upon disassembly.
Similar to other automatic transmissions, the 8 speed uses a combination of the planetary gearsets to achieve its ratios by turning on and off its clutch packs. The clutch packs are typically the wear point on all transmissions, in addition to failing solenoid valves and clogged lines. The exclusion of a dipstick and drain port ever so reinforces the fact that Chrysler does not have confidence in this vehicle’s longevity, although Jeep Wrangler enthusiasts will typically upkeep.
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[@gabrielpuebla5930]

Imagine the mind of the man who had to design the valve body. Absolutely fascinating.

[@speedkar99]

I'm sure a computer designed it!

[@mann_idonotreadreplies]

its not that complex kid. its not one man that designs it all.

[@gabrielpuebla5930]

@@mann_idonotreadreplies I bet you're fun at parties

[@johnw3379]

The computer should make it reliable

[@abdul-kabiralegbe5660]

I think most inventions are incremental involving building on the work of others, so it's unlikely the valve body just popped into existence in one go. And yes, I'm literally not fun at parties. 😂😂😂

[@josuerod9997]

Bro this guy has too much knowledge I’ve been watching him for years subscribe to this dude he deserves more!

[@sheffun1ted]

You my friend are a mechanical genius. I love your videos and learn so much

[@speedkar99]

Thanks

[@colchronic]

Still sounds like black magic to me

[@speedkar99]

Haha

[@OutsideTheTargetDemographic]

"The eight gears here are for fuel efficiency" lolol 😂 Gotta achieve that 18 mpg!

[@speedkar99]

Yeah especially when people are lugging around these 4x4's

[@zaraak323i]

Automatic transmissions are black magic. I'll grind my gears myself, thankyouverymuch! 😃

[@Wtfinc]

Nah, not at all. They just look scary but you get used to it quick. That valve body is massive tho. Now microwave radio is some black magic. Heck even gravity, magnetism, and time. Oh, and any maths i cannot comprehend yet

[@zaraak323i]

I've watched enough Precision Transmission to know, leave it to him!

[@uhtred7860]

Meh, its just two fans slinging fluid around, and some other stuff.🤣🤣

[@speedkar99]

It can appear daunting at first. But start with one planetary gear set and understand it's ratios and soon you'll nest them together and watch as they multiply

[@beny8]

yea, even the dual clutch automatic seems way more straightforward compared to this

[@nateflorea9009]

I was about to ask if it's a ZF transmission, but I've read about it and it seems that it's a ZF transmission made in collaboration with Chrysler, and it's one of the better transmissions when it comes to not only reliability but also efficiency and smoothness

[@nateflorea9009]

Also despite it's lower weight than the competition it's very good for towing

[@fordfiveohh]

Yeah I'm not crazy about the 948 TE ( I think that's the one) in the Jeep Compass and the Jeep Cherokee. ZF can make some fabulous transmissions, But so far the only fabulous ones I've seen were for rear wheel drive applications.

[@speedkar99]

Exactly. The rwd ones are more robust.

[@ccloutiutube]

The ZF transmission is definitely the most reliable part in my wife's 2007 BMW 335i with the N54.

[@markhalden3922]

From my limited research, the 392 uses the proper ZF, no idea what shares it.

[@rajanjagtap8502]

🙏How efforts you do disassemble this 👏 really informative videos thankyou

[@jonnijames]

AHahahah my god brother, you were right, check out the 8speed jeep auto trans and wow i think its more complicated than the CVT transmission now that i think about it, coming away from this i have learnt that you are the G.O.A.T of all time mechanic, explaining that auto trans like it was childs play just blew my mind, love ya brother! :)

[@kingdaddymaster5094]

Can you please make a Toyota Prius 2023 full in depth mechanical review and showcase all the new changes for the new generation? That would be an amazing video!

[@speedkar99]

It sure would. I have to get my hands on one.

[@EnergySeeker]

great video as usual

[@speedkar99]

Thanks

[@mahmoodghorbani8329]

دمه بچه های تورنتو گرم.خسته نباشی و ممنون از بابت ویدیو. 👍👍👍

[@humorss]

I have never been able to understand how the zf8 work exactly. its a stack of gear clutch and cage stacked together. so neat and compact.

[@speedkar99]

It sure is compacted in there!

[@pgilb70]

Geniuses design this stuff.

[@speedkar99]

Hey it's not that hard once you break everything down.

[@vVeazel]

Surprised to not see the precision rotary snap ring removal tool come out.

[@ahmedalkhatib1410]

Went through it fast appreciate consistency though...

[@speedkar99]

Thanks

[@manuelli1294]

Thanks for the interesting video. Please, do you know how to tell if my WK2 has ZF845RE or ZF850RE?

[@vladdutz20]

As far as i know the torqueflite branded transmissions have zf8hp internals in a custom chrysler jeep housing Also the oil pan seems metal

[@speedkar99]

Makes sense

[@joebaucom4537]

Great !

[@josegarciaatencio7274]

Great video. I have a question for you hopefully you can reply : ). I serviced my transmission recently. Oil change and oil pan change. After that was done the transmission has a very mild whining noise going from 1st gear to 2nd gear this sound was not present before doing the service. I'm concern about the noice but the mechanic that did the service says is "normal" in this type of transmission is that true? I'm worried my transmission will die eventually and that this can be prevented. Thank you in advance. I drive a Jeep Wrangler JL with this automatic transmission.

[@jorenethmanangkila9223]

Thank you

[@speedkar99]

Welcome

[@josuerod9997]

I also like how he replies to everyone

[@liudas5377]

Your a sharp dude. How many miles typically do those clutch packs last?

[@speedkar99]

Thanks. There's no mileage set for a transmission, it's based on wear and tear and useage

[@masoudshaghaghi5744]

My wrangler 23 has abrupt downshift 3 to 2 sometimes, especially on hard braking, most of the time is ok but absolutely not like other SUVs, is it the nature of 850 RE or it has a problem? Only 15000 miles on it

[@speedkar99]

No, take it back to the dealer and have them flash the transmission controller.

[@JasonLuther1]

yo Kar, what's your opinion or thoughts on the bucket lifters on older Toyotas like 5sfe. I changed my valve cover gasket and was staring at my valve train. since they're sitting on shims do they ever need adjusted? it has 240k on it, runs fine but I really think it could run a bit more peppy. Its not a fast engine by any means.

[@speedkar99]

Technically they need to be adjusted but no one does because there isn't much need to tear down the engine that far. I much prefer the bucket design over the more complex roller rocker arm setup. It's more simple 😊

[@fordfiveohh]

This guy is sort of like a doctor practicing on a cadaver. One of the smartest people I've ever met made straight A's his whole life - even through a masters degree in math. Even that guy said automatic transmissions make his brain hurt

[@speedkar99]

It sure is complex!!

[@notsoserious0944]

Mind boggling.

[@speedkar99]

If sure is

[@greathey1234]

10:18 lol

[@speedkar99]

🤣

[@chrissimmons9969]

The humans responsible for inventing the automatic transmission must have been certified geniuses. I struggle with how bicycle gears work. 😂

[@speedkar99]

It sure is interesting! However this is evolutionary... It starts with one planetary gear set and stacks up. I'm sure computer design helps!

[@iroekyjHD]

to be honest, its really cool that bikes just drop chains onto different sprockets lol

[@Migmaqiw]

I had a rock prevent my transmission from shifting into park the other day… I have a 2024 2dr Willys… trying to figure out where this rock landed and prevented the shift. Any insight?

[@speedkar99]

Definitely on the shifter cable or shaft.

[@TonyLing]

You must never run dry of spare bolts

[@speedkar99]

I have shelves full of them. I throw the odd stuff (Volkswagen torx, rusty Chrysler, and imperial GM) stuff out and keep the Japanese brand metric bolts for later.

[@ginog5037]

Wow, no wonder techs don't want to rebuild transmissions anymore. What year and milage on that??

[@speedkar99]

2018 Jeep JL. Didn't get mileage information.

[@nickchannel5364]

If I had as much money as I do interest in speedkar channel, I would send him fancy engines to explore.

[@speedkar99]

Please send

[@uhtred7860]

I wanna send him a Ford "Barra" inline 6, one of the best engines Ford ever made. But i'd have to sell a kidney to afford the shipping from NZ to the U.S.😆

[@juandenz2008]

Interesting, but it made my head explode ! Imagine the brains of the people who first came up with these ideas.

[@regperatrovich9406]

That looks like an absolute nightmare to service.

[@speedkar99]

Usually you just replace them

[@151bradhatt]

How many forward gears are there?

[@speedkar99]

Eight

[@Aleks_Mechanics]

Notification Squad!🔥🔥🔥

[@speedkar99]

Thanks!!

[@tunespt]

Brilliant piece of engineering... But I prefer manuals :)

[@supamannn99]

Why would they not put a drain port?

[@neilwalker8686]

It’s considered a sealed unit filled for life. The life expectancy is the warranty period.

[@speedkar99]

Less chance someone will put the wrong fluid in. So dumb

[@abdul-kabiralegbe5660]

For once you used one of your old clothes as a rag.😂 Good info in the video, as always. 👍

[@speedkar99]

Haha yep. Found an old disqualified pair of pants for this one

[@RolandoMarreroPR]

Holy washers Batman! A manual transmission is like 4 gears and two washers!

[@speedkar99]

Haha true. Much simpler

[@davemarks7322]

Superfrikkingcomplicated. Other auto components are simple by comparison. Very interesting video; now let's see you reassemble it (haha).

[@speedkar99]

Thanks. I like to break stuff, not put it back together haha

[@Henry_Jones]

ZF transmissions in chrysler cars are license built by chrysler. The zf units used by other OEMs are built in ZFs south carolina factory. The 9 speed Honda uses is the same as the one Nissan uses and theyre built there but the same unit used in fca vehicles like the 9 speed in the cherokee are built by chrysler. Not suprising the chrysler built units have a worse reliability record.

[@speedkar99]

Thanks for the info...good to know

[@glock18supercharger]

My pink brush Thanks 😂✌️

[@speedkar99]

Welcome

[@PSWii360onBaSS]

10:46 Part of the reason why neutral drops are bad for your health.

[@Pinkielover]

Junk would be awesome to see you melt it down

[@speedkar99]

It's already at the scrapper

[@dragancrnogorac3851]

4 clutch packaging... I think 8 gears should be on 40 ton truck. I can live with 6 gears just fine

[@speedkar99]

I feel like after 6-8 gears it's enough. Fuel economy doesn't take a drastic downturn after that

[@johnraley5713]

Want me to put it back together for you? 😆

[@speedkar99]

I'd love to see that!

[@edwardranno7119]

I can’t believe how complicated transmissions are,I bet the people who invented it went crazy

[@Pinkielover]

It's over complicated for a reason so the average person can't repair it

[@edwardranno7119]

@@Pinkielover there is no possible way I could fix that!! I would be willing to bet top mechanics couldn’t fix it either

[@mann_idonotreadreplies]

complicated because you dont understand it. and this is FCA 8 speed not the more reliable toyota 8 speed. FCA is garbage.

[@edwardranno7119]

@@mann_idonotreadreplies my dad was an inventor of complicated equipment in the printing business,I learned a lot from him,I can’t imagine the first few people trying to get the transmission to work

[@speedkar99]

Yes and no. This is based off of an evolution of automatic transmissions...they added an extra planetary gear set which gave the full 8 speeds.

[@markwilliams2620]

Glad I stopped with TH350's.

[@kclefthanded427]

It's like slamming 2 GM 4L60-E in a smaller package

[@speedkar99]

Kinda

[@Henry_Jones]

I miss 4 speed units.

[@ronsereda4242]

Pardon me. Would you mind repeating that. (joke ) Wow, your most complex explanation yet. Was there an identifiable failure reason why this transmission was taken out of service? Clutch packs, valve body or solenoids should be repairable, or not? Coincidentally about an hour before this video came up I just had forked out $321 for the one piece pan/filter and $220 for 4.7 litres of fluid for a similar 8 speed ZF in 2017 Grand Cherokee. $601 with tax!!!

[@speedkar99]

The engine attached to it wore though its camshafts so I bought them both. See my last video on pentastar engine.

[@victorwilks88]

Looks like it gives problems 😮

[@speedkar99]

Most rwd transmissions are laid out this way

[@TheXextreem]

This looks so complicated. If you got something broken just replace the whole thing lol.

[@speedkar99]

That's the society we live in

[@ryanwiles6255]

"Yah I was cheating, this is the diagram I was using while disassembling" -- bro that was one diagram that explained literally nothing.

[@speedkar99]

Sorry

[@ryanwiles6255]

@@speedkar99 no I meant it as in I didn’t think you were cheating at all lol. You basically just took apart an engine with no reference.

[@jamesreno3321]

This is a lot to take in, but I honestly don't find it too hard to understand. It's really the same mechanical concepts repeated over several times, with a few changes for each gear ratio. I study engineering, so that probably helps, but if you're mechanically inclined, I'd say it looks worse than it really is because of the number of parts. Not saying I'd want to work on that though 😂 And designing it probably required some ridiculous brain power

[@speedkar99]

I agree. It's not that difficult once you break it down. Everything is just sacked and multiplied which makes it seem puzzling

[@markhalden3922]

The general operation is pretty straight forward but it's all the small things that make them space magic. The electrohydro units make sense, it's the pre 1990 pure hydraulic units, the engineers that designed those are fucking wizards.

[@The_R-n-I_Guy]

None of the components look very durable. Really thin metal everywhere. I guess that's the price you pay for all those gears. The more gears, the smaller and thinner/weaker everything is.

[@humorss]

when in use they are fine as the structures support each other. but taken apart for service and reassembly the barrel gears with very thin walls get damaged by hand tools easily.

[@iroekyjHD]

what a nightmare of a transmission, I think ill stick to buying 2005's and paying for slightly lower mpg

[@speedkar99]

Good idea

[@jackblackmamba3465]

Obvious Colgate product placement

[@speedkar99]

Haha

[@Nesylver]

This thing is a mechanical nightmare!

[@speedkar99]

To rebuild it might be daunting but most will just replace it.

[@Nesylver]

@@speedkar99 I'm in agreement

[@mann_idonotreadreplies]

and FCA sucks!

[@speedkar99]

Sure....

[@nickayivor8432]

Speedkar99, thank you very much for sharing your knowledge with us Speedkar99 👍 QUICK-WITTED Speedkar99 From Nick Ayivor from London England UK 🇬🇧 ⏰️ 20:10pm

[@speedkar99]

You are welcome!

[@bigniqqa4511]

I wanna see the massive brain on the guy who thought of this concept. an actual mechanical marvel of engineering. its a shame they chew away at power output, otherwise theyd be perfect

[@speedkar99]

It sure is mind boggling. However this is an evolutionary design, not thought up in one sitting