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Automatic transmission compatibility for an 1985 Brat


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8 replies to this topic

#1 vwzzuk

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Posted 11 March 2010 - 08:40 PM

My son has a 1985 Brat 4x4 with the 3 speed automatic (3AT or M41 I believe) with the 4x4 activated by a single switch on the shifter.
The transmission has no 2 or 3rd in the drive position but will work manually in 1 or 2 but not 3rd. checked and replaced the modulator with no success. I figure it would be easier just to find another used one instead of forking out the 1200 bucks to have it rebuilt.

My question: Can I put another auto 4x4 3 speed transmission from an EA82 Subaru in our EA81 Brat? Are they the same transmission with out modification? From the research I've done, it looks like the same tranny was in XT model subarus and other standard mid 80's wagons.

For the last couple of weeks, I have not been able to find another auto 4x4 tranny from any EA81 car here in the Portland area. Crazy. A year ago there was plenty.

Any suggestions? Thanks, Dave.

#2 GeneralDisorder

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Posted 11 March 2010 - 08:48 PM

Yes - all the 3AT's for EA81 and EA82 are the same - compatible transmissions can come from any '80 to '89 GL (excluding 4EAT Turbo automatic's), and from 90 to 94 Loyale's. There may be slight differences in wireing but nothing that can't be swapped over easily.

But - have you checked the governor? It might be a simple fix to clean and dress the governor piston.

Also - if I were pulling a tranny out - I surely wouldn't put the auto back in. Get a pedal assembly, flywheel/clutch and a manual and convert it. In fact my friend is doing an EJ22/5 speed conversion to his '85 Brat here in my garage and has a good 4 speed and driveline that is ready to go. Already has my shifter linkage-slop mod done to it. I'm in West Linn if you are interested. I know I have a brand new pressure plate and probably a flywheel around here too. Could make you a great deal and all you would need is a pedal assembly and clutch cable.

GD

#3 vwzzuk

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Posted 11 March 2010 - 09:27 PM

Thank you for the information on the auto and for your pointers. I'll look into the governer that you mention. I don't know anything about the auto trannys or where the governer is. I guess I need a service manual for the details. Thanks for your help, eh!

Right now, I just need to get the Brat back on the road again so my son can get to school and work. We have a lot of drivers in our family and when one car goes down, it messes our schedules up quite a bit. I like the idea of putting in an EJ motor and the 5 speed in it. I think I will do what you recommend after the end of the Semester ends.

I had a black 84 Brat for a while and put a BYB lift in it and a 5 speed D/R from a Loyale, if i remember right. It had a two piece driveline. I sold it to a fellow in the Military to pay my taxes about a year ago. The fella was in Beaverton. I regret selling it. It was a lot of fun. License plate said BRAAAT.

#4 GeneralDisorder

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Posted 12 March 2010 - 01:28 AM

The governor is on the passenger side of the transmission behind a cup-shaped cover. It's held on by three bolts IIRC. The governor has a spring-loaded piston that needs to slide smoothly in it's bore or it will stick and the transmission will not upshift on it's own. They also have a bad tendancy to "apple core" the driven gear on the governor and that is an indication of wear on the matching drive gear inside the transmision - typically that's a bad sign as even replaceing the governor will not make the transmission work for long.

When you are looking at a replacement transmission make sure you pull the govenor and check the gear for apple-coreing. If you see much wear on it walk away since that almost always means the drive gear on the inside is bad as well. Many people have replaced a governor due to a 'cored gear like that and only had the transmission work for a week or two before destroying the replacement.

As for the transmission swap - the 4 speed would go right in without any mods. Just mount up the flywheel and clutch and mount the transmission - same amount of work as replacing the automatic. The driveline is already the right length - this 4 speed came from a Brat, etc. The pedal assembly is 6 bolts - takes about 10 minutes to swap. It's the same amount of work - you are swapping a transmission either way. The big job is dropping the old one and putting in the new one. If you swap to the 4 speed you are halfway to a 5 speed swap in the future since all that requires is a different cross-member and driveline.

GD

#5 MilesFox

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Posted 12 March 2010 - 10:08 AM

I have a loyale trans with 105,000 miles in WI, if you ever had to replace it.

Follow GD's advice with the governor shaft.

for repair books, the HAYNES book does not cover any transmission service

for the work/money involved in replacing/rebuilding the trans, you could source a 4 or 5spd trans for the same effort. you will nned the manual trans, flywheel abd flywheel bolts, along with clutch and pp for the trans you use. along with the driveshaft and trans mount. you can use the same axles, and the rear diff if its a 3.9 gear

if you do a 4spd trans its all bolt in. if you do a 5spd trans, you will have to massage the trans tunnel to clear the rear of the trans, or even space the mount from the body by stacking a few washers

#6 Gloyale

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Posted 12 March 2010 - 01:07 PM

Check final drive ratios

IIRC, the early 3ats had a 1:1.1 transfer ratio, so the front drive is 3.9, but the rear drive is 3.7 or vice versa...... I can't remember all the details

But the good news is that you have a sticker on your rear diff that tells the ratio. check it, and get a 3at from a car with a matching rear diff ratio. Or, swap the rear diff to match the trans you get.

#7 GeneralDisorder

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Posted 12 March 2010 - 04:29 PM

I have a 3.9 diff that would match the 4 speed we have here. As I said we would make you a smokin deal on all the parts. I need them out of my garage and although this 4 speed is a good one, they aren't all that desireable since most folks go for the 5's and the 5's are more plentiful. I think we have every part you need besides the pedal assembly and I know where to get one locally for probably $20 - a friend of ours is parting an '82 wagon. We even have the good clutch from the Brat since he's going with the EJ22 and doesn't need any of that stuff.

It's an easy bolt-in operation. I assure you it doesn't take any longer than messing with those automatic's and the 4 speed is lighter too! You can borrow my transmission jack and have it done in a day or a weekend if you are taking your time.

:)

GD

#8 vwzzuk

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Posted 12 March 2010 - 05:48 PM

Well, I did the Governor clean up and found the parts in pretty decent shape. No apple core, or muck to clean off. I did polish any scuffing on the parts with some emery cloth and rounded off the edges to ensure movement without sticking.

I'm amazed that it solved the problem, at least in the short term, so far.

However, I think I will be doing the EJ swap that GD is talking about in the near future.

I'm really surprised. I didn't think that the governor needed needed a significant enough amount of polishing to make a difference since it was in such good condition.

Thanks to all for the pointers and the information, eh. Problem solved. Hopefully it will last until the EJ swap.

#9 GeneralDisorder

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Posted 12 March 2010 - 07:14 PM

That's great! Glad it was a simple fix for you. That's a classic problem with the 3AT's and I bet more than one has been replaced when all it needed was a little governor maintenence.

Hope it lasts till you get an EJ and 5 speed for it. You might want to give it a flush - change the fluid, drive it 10 miles, and then change it again. It helps them shift smoother and that can give them a bit longer life.

GD




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