Is my tranny hosed?

[Happy Face]

After much trial and error I've finally gotten around to a bench test of my 4-speed tranny for my '72 'O2 (I pulled it out a while back).

The car stopped going several months ago and I've ruled out the diff.

When put in all gears, the main shaft will still turn in either direction when you rotate it by hand. It turns when it shouldn't.

I'd like to pull the rear shaft out without opening up the entire tranny. The large bolt pattern (where the guibo bolts on) has a 30mm (I think) nut holding it in. But, it looks like it has to be removed with a deep-socket.

Any helpful comments out there on whether it is worth pulling this to look for damage?

thanks

[Guest Anonymous]

I think the bolt you're refering to is a 30 or 32mm. A fellow board member recently pulled mine out for me with his impact gun. Definitely couldn't have done it just with muscle, at least not my feable muscles. I just pulled my 4-speed out to swap for a 5-speed. If yours is indeed blown and you want another 4-speed let me know, I've got one you can have cheap. I'm in the SF Bay Area.

[cj]

How far did you get Grover?

Cris

[Guest Anonymous]

Cris. I was ready to bolt things back together when I realized that the release bearing was the wrong size for my clutch. Hopefully tomorrow when the stores are open I can get the correct one and get the job finished. I'll keep you posted.

[cj]

Should've called me. I have a new one with my clutch kit at the warehouse. You could have borrowed it and had Dave send a replacment. Oh well!

Cris

[TobyB]

In fact, you're working on the wrong end!!!

To pull a 4- speed apart, take the throwout bearing collar off,

and remove the snap ring from the input shaft.

Then remove the bolts in back (6? 8?) that hold the rear 'cover' on- the rear

cover is actually the main plate for the whole shee- bang. (If you've taken other 'plate' trannies- like nissan- apart, this makes sense)

Now support the bellhousing, allowing the rest of the case to hang free, and start whalloping on the INPUT shaft with a soft- faced hammer. The input shaft should go in a little bit, then stop.

Now you have to break the case gasket seal- it's a booger. BMW glues these things together. I use a thin, stiff scraper, but be careful.

Once the rear case cover/plate is separated from the box, support the bellhousing again and start whalloping. Eventually the input shaft will drop through the input bearing, and there you are, with a big mess 'o gears and oil.

At this point, you should be able to determine if all of this was worth it, or if you just need a new gearbox.

It all makes sense AFTER you do it.

Disclaimer- with all of this beating on things, you may very well break something big, like the case. If you're not experienced in the fine art of mass destruction, and think you might want to rebuild the thing instead of replace it, then let a pro pull that front bearing with the very special (really insanely expensive) BMW- was- on- crack- on- this- one bearing puller. Then the gearbox comes apart without the aforementioned whalloping... I trashed an already- mangled 'box in the interest of experimentation before I came to appreciate how USEFUL a brass- faced hammer can be.

Toby

[canadapierre]

The nut is 30mm ( at least it is on both my 4 and 5 speeds ). I needed a thin wall socket to get mine out. I bought a cheap socket and ground it down till it fit. Impact gun a good idea as it is hard to keep the shaft from spinning..

[Guest Anonymous]

I second what Toby said. Getrags open up throught he front first - and getting them back toghethehr without damaging the caged roller bearing between the imput and output shaft is a real booger. I'm trying to fabricate a leaverage press to do the install job on the front carrier bearing.