Transmission rebuild

[mspiegle]

Assuming a tranny has all of its gears intact, what is involved with a rebuild? Just syncros and seals? Could this be a DIY project, or very difficult?

[DEV0 E30]

Well if it's an auto, I personally see it as a waste of time. The Bentley manual says overhaul and replace transmission on wayyy too many lines for my taste. Would be worth it to swap in a 5spd if the car means anything at all to you.

[Madhatter]

lol. Have you seen what force is required to remove gears? you are talking tons of force, not pounds.... tons!

No, without a decent shop press, a good set of calipers and a whole bunch of circlip pliers, it definately isnt a DIY thing.

[mspiegle]

Its for a 5spd tranny. So, you're saying that the gears have to be removed from the shafts to replace the syncros?

[Jarvis]

There's a reason why there are specialty shops that do nothing other than rebuild transmissions.

I would never try that at home by myself.

[Q5Quint]

I almost took a class about rebuilding manual transmissions at my community college... then I didnt. I dont know anything about it, but I would learn fast If I was faced with dropping 3 grand on a rebuilt one. I know there are some guys that do it all the time, so I am thinking it doesnt require anything more than the right know how and the right tools, but how much and what tools do you need? and where do you order synchros from? It would be a lot of trouble for sure.

[RobertK]

I always thought learning how to rebuild a transmission would be kinda fun. I also always wanted to learn how to change gear ratios inside one as well.

[mspiegle]

you can get the syncros easilly. The only thing i'm worried about is the special tooling required.

Maybe this is a good opportunity to take that tranny rebuild class at my local college... I can bring an old 250k+ mile tranny and tinker with it.

[Madhatter]

Yes you do need to remove gears from shafts to get syncro's off.

[Operator62]

Well, most manuals are much simpler than automatics, and I've rebuilt an automatic before without ever going to school for it, and it was EXTREMELY easy. Well, it was for me anyways. Basically take it all apart and put back together with new parts. Reassemble tranny, adjust the bands to spec, and put the pan back on. Though I know that with the manual tranny you gotta get the spacing right so it goes in gear and doesn't pop out or whine.

[nando]

you could probably bring the shafts/gears to a shop to have them pressed off. I did this when I rebuilt the transfer case on my car, and the guy did it for free. (although it's MUCH simpler than a tranny).

[Madhatter]

yes, there are a bunch of shims in the gearbox which require you to put it together, check clearences, then change/refit shims as needed.

[mspiegle]

Well maybe this is when that cheap press from Harbor Freight will come into use?

Here's my situation... I have an '89 325i parts car for a 5spd swap on my '89 325is. I don't wanna use the '89's tranny cuz it has 277K miles and the shift-centering spring is broken/non-existent. I'm going to get a tranny from Dave, and I wanna take apart the '89 tranny beacuse it would go in the trash or sold for $50.

You know what... i'm not loosing anything by taking the '89 tranny apart, so maybe i'll try it and see what happens. If I end up trying to rebuild it on my own, i'll definately make updates here.

[AndrewBird]

When Josh's (Eurospeed88) tranny went out, the guy at the tranny place said he didn't even want to attempt it. And no, he wasn't a moron.

We ended up just swaping the tranny from anohter car.

Which reminds me, if you need a tranny, PM Josh. He and I have one from a parts car for sale.

[mspiegle]

That bad huh? Guess i'll have some fun tinkering because I just ordered my press yesterday. I decided to get something a little fancier... I bought the 20-TON A-frame. They claim a 10-14 day shiptime, so we'll see what happens....

I figure with all of the suspension stuff I need to do on 2 cars (including wheel bearings), and my friend's M3, it isn't a horrible investment.