Rebuilding my 915. Any helpful hints

[SC-targa]

I dropped the engine and tranny in my 82 SC last weekend. I'm going to rebuild my gearbox over the next few weeks. It had been shifting into second with a clunk, and a bit back it made a nasty noise and stopped going into 2nd gear.

So far I've just pulled the end cover off and exposed 5th and reverse.

Regards,

Jerry

[BURN-BROS]

I just did my tranny 2 weeks ago for the first time. The main thing is to try and avoid is disassembling the shift forks from their respactive shafts. Prices have gone up for gasket sets too. Good luck on the rebuild.

[Eugene at Pelican Parts]

It wasn't a big deal to me to realign the forks. You've probably read through some of the archived posts by tbitz, Jim Sims, and JanusCole, but here are some of the highlights off the top of my head:

Removing/installing large lock rings holding the synchro rings on take some getting used to. Either get a really strong pair of lock ring pliers or gradually pry them off the hub like I did. I reinstalled them working them in slowly with a vice and a clamp.

When loosening the shaft nuts, lock the shafts in place by engaging two gears simultaneously.

Disassemble the shafts by using inertia. In other words, repeatedly drop the shaft onto a heavy piece of softer metal until everything falls off. An iron disk weight worked for me.

An old clutch disk is useful to hold the input shaft steady.

The right way to remove the 46mm input shaft nut is with a special super-deep socket. I used a large crescent wrench and the weight of my body.

If you're planning on replacing some synchro hubs, some have had luck chiseling them off. I did not. The special tool is a piece of steel that holds the hub by the groove. You can then either hammer or press the hub out. Instead of buying this tool, I sacrificed a couple of lock rings and made a wooden 'jig' that had some cheap wrenches screwed onto it to support the hub. I then hammered the gear off the hub using a large socket. It'll take quite a number of violent strikes with the sledge to get them moving. By the mercy of Thor, they will come off.

To reinstall the hubs, it would be best to have a shop press them back on. I had a Powerbar and used a small bench vice. By the might of Hercules, they will go on.

A high range torque wrench isn't necessary if you calculate the correct distance from the center of rotation to apply your full body weight to. You might want to have a spotter handy.

Be real careful pressing (or banging) the bearings back onto the shafts. Um, sometimes they break.

During reassembly, make sure the lips of the mainshaft seal don't get flipped when poking the splined end through.

After it's back in one piece, you could test the shifting by using the shift coupler as a handle. Not very ergonomic, but it worked for me.

That's all I can remember for now. It's really not too bad. Did I say 'hammer' enough times? Good luck!

[1fastredsc]

Another option is to do what i did. Take it apart down to the gear shafts then have someone inspect and replace as nessecary. Not cheap as doing it all your self but not as expensive as having the whole thing done. Kind of the middle ground.

[kiwior]

I had a friend at work weld up a socket for the removal of the 46mm input shaft nut. (the clutch disk was a must have for holding the shaft) The socket is made using a 1 5/8" socket and a short 1/2" drive extension....below are some pictures.


To reassemble the bearings onto the shafts I heated the bearings in our oven and bought a hydraulic shop press for a couple hundred bucks and pressed them on. I figure I will always be able to use the press for bearings, bushings or whatever. My uncle also went on half for the press. It's really not a hard job just follow the steps in Bentley. I also used these tech articles for reference:
http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=57371
915 rebuilding - DYI?
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