Learn me - rebuilding manual transmissions for dummies (that'd be me)

Last big job on the MR2 that I'm aware of so far is a transmission seal that needs replacing.

Typically for this car it's the input shaft seal and the whole transmission is built around it. Some research suggests that the input shaft seal tends to wear a little grove onto the input shaft which is causing this leak. There is a part available to fix that, basically a ring/collar that goes onto the input shaft for those of us who don't want to try and buy an OEM shaft.

My original plan was that I was going to pull it and have a local shop rebuild it, until I found out there wasn't a local shop that would touch manual transmissions. I could just buy one from Toyota, but someone has been in that transmission before and E153 don't normally break before 65k miles, so I'm guessing there's another, more interesting reason for someone tearing into the transmission[1].

How feasible is it for someone who's never done it before to go through the transmission and at the very least, reseal it? I'm not planning a massive overhaul unless it's busted (in which case I'll probably use a low-mileage used JDM transmission), but I still have to strip it all the way and build it up again, hoping that it'll still work afterwards.

I do have the OEM Toyota shop manual for the car and the Youtube videos showing the trans rebuild don't seem to indicate that I'd need a ton of special tools either.

[1] Like a proper LSD. I'd be really mad if I used that transmission for a core at the local Toyota dealer if it had, say, a Quaife or a TRD LSD in it.

93 should have an lsd oem, not a bad unit either.

So what info are you needing? Do you have to use that trans? I don't now what gen mr2 it is, but I know most of them use a c30/31/32/33 (or whatever) trans. And those are found in every FWD Toyota ever made, even with LSD.

It's '93 Turbo, which did come with an E153 trans. Yes, you can get used ones for fairly cheap but given that the car is eventually going to see some track use (plus the input shaft seal leak being a common problem) I'm not super keen on just sticking an ebay trans in.

The info I'm looking for is more along the lines of, anybody here rebuild their own manual transmissions without being an ASE certified manual trans expert with 40 years experience, or is there just too much voodoo in there?

Keep in mind that from a "how it works" perspective I still think there's more voodoo in an automatic transmission than a manual one, but I've never rebuilt either.

The local trans shops certainly seem to think the latter, but they most likely wouldn't get a lot of manual transmissions to rebuild even if they did work on them, which they don't.

I know that I have been trying to build a transmission for years now and always chicken out. The last few in particular needed to be a slam dunk and get it right the first time. I figured I would end up with 4 bushings and three springs left over in a box not knowing where the heck they came from.

https://www.youtube.com/watch?v=C5yKPGRfUFQ this help? Looks like you don't even need to buy any special tools, pretty straightforward job. Speed sleeve is an option, or you could get an industrial part number for the seal and see if an undersized or offset seal is available.

I have been through 14 or 15 manual transmissions by now. They aren't particularly complicated things, less than an engine I would wager. The only special tools needed are a hydraulic press and a torch or shop oven or bbq for the heat to expand type bits.

If there is nothing wrong with the box a refresh with bearings, synchros and seals is all they really ever need.

Being a transaxle you run into the issue of setting up pinion and ring gear lash when you replace the pinion bearing. This can be a nightmare on some gearboxes requiring assembling and tearing it down 5 or 6 times to get the shims just right.

Any transmission with non caged needle bearings is a trick sent by the devil. Old Ford, really old mercedes and others. I hate those things. Just when you think all is good they start falling out and you have to tear the whole box apart to retrieve them.

Jumper K. Balls wrote: Being a transaxle you run into the issue of setting up pinion and ring gear lash when you replace the pinion bearing. This can be a nightmare on some gearboxes requiring assembling and tearing it down 5 or 6 times to get the shims just right.

Doesn't that really only apply to longitudinal transaxles, not the transverse one we're talking about? Pretty sure its all helical gears in there and the only differential related shims (if any) will be one stack for the carrier bearing preload.

I'm comfortable working on transmissions that I can get a good rebuilding manual for. The two that I have opened up have been the common T5 series and the VW 020. I am currently working on a Chevy Camaro V6 version of the T5.

I know my father, who was a high school shop teacher, normally rebuilt his own manual transmissions but when he tried to rebuild the one from our 4wd tercel he had to take a box of parts into a Toyota dealership to get the job done. Something about needing some special tools that no one had.

Usually, there's some latitude regarding how deep you drive the seal. In other words, there may be more space behind the present seal location. when you mount the new seal, just drive it in a tad deeper so you can start the wear process again on a virgin piece of the input shaft.

Jerry From LA wrote: Usually, there's some latitude regarding how deep you drive the seal. In other words, there may be more space behind the present seal location. when you mount the new seal, just drive it in a tad deeper so you can start the wear process again on a virgin piece of the input shaft.

I have had to shim behind oil seals to get to a fresh portion of the shaft but I usually go to an industrial bearing source and get a double lip seal

At least one of the sealing lips one usually falls onto an unworn area of the shaft.

One particularly unobtanium w187 Mercedes had original seals that were twice as thick as most modern metric seals so I went ahead and stuffed two in. I doubt that would be an option on a modern toyota box though.

In reply to Jumper K. Balls:

Double lip seals. I forgot about those, definitely use one rather than a sleeve.

Double lip seal for sure but there's nothing wrong with speedie sleeves IF you can get it on with out wrinkling it.

Oh someone here literally wrote the book on manual trans repair / rebuilds (4-5 years ago). I bought one of the 1st copies and it was very well written, wish I had had it when I was younger and just dove it site unseen to several trans. YOU CAN DO IT. Take your time keep the area clean and well lite you'll be fine.

jimbbski wrote: I'm comfortable working on transmissions that I can get a good rebuilding manual for. The two that I have opened up have been the common T5 series and the VW 020. I am currently working on a Chevy Camaro V6 version of the T5.

Front drive transmissions are usually pretty simple, you unstack them. Have done a bunch of Saturn input shaft seals too.

T5s are born of old school American transmissions and are also simple to disassemble/reassemble. Take off the tailhousing and side/top cover, remove the input shaft, lift the mainshaft out... Easy-peasy.

Endloading RWD transmissions suck. I can buy bearing/synchro sets for Mazda transmissions for $100-200, but they suck so hard to disassemble/reassemble that I'd rather pay $200-300 for used transmissions even though I seem to get a bad one every third trans. You could completely rebuild s T5 in the time it takes to get a Mazda "M-type" trans's tailhousing and bellhousing chunk off.

In reply to 44Dwarf:

Got a link to the book?

I don't mind taking a few weeks to do the rebuild as it'll be a substantial savings over shipping the transmission out and having it rebuilt (even after potentially springing for an HF 20 ton press and the small torque wrench I need to set the bearing preload), plus I'd be doing it for the experience and hopefully the fun of it anyway.

I changed the input shaft seal in a 83 sentra when I was 20. Requiring tear down I had not even changed a clutch at that time. I only had a chiltons book and was able to reassemble and drove it 5 more years before the Trans gave up. Just jump in with both feet. Now I feel old that was 25yrs ago.

This interests me because my E36 is hard to get into reverse sometimes, it's hard to get into 2nd gear when the gear oil is cold.