915 front cover removal, How?

tbitz · 01-02-2002, 05:54 PM

OK I've decided to try and rebuild my 915 myself (gulp!). I haven't done this before but I am willing to try. I removed the engine and transmission. Boy was that easy compared to my Saturn Wagon which needed a clutch.

I have the 915 on an engine stand. All front nuts are removed but the cover does not want to come off. It has broken lose, slides out about 1/8" but then hits something. I've also removed the cover to the shift fork. I'm starting to think, if I can't get the front cover off, maybe I should stop here

What could be the problem? I don't want to damage it by prying it. I've given it a few good smacks with a rubber mallot, but nothing.

Here is a pic:

Here is a pic from the fork cover opening. It looks like the dog teeth are rounded. These are supposed to be sharp, right? This may explain why I have a hard time putting it in 1st when stopped.

rcwaldo · 01-02-2002, 06:22 PM

If you have any "crud" built up on the selector shaft, it might bind on the sleeve bearing that it rides in. Its right behind that seal. You can scotch-brite the shaft to clean it up. There souldn't be anything else holding you up.

I hope this helps you out!

Chris

tbitz · 01-02-2002, 06:55 PM

Thanks Chris,

The selector sleave easily slides in and out. No crust on it.

So your saying nothing special needed after all the front nuts are removed?

It sure seems like the cover is hitting something when I pull on it. Could the speedo gear be catching on something? Does the tranny need to sit vertical for the cover to come off?

Jim Sims · 01-02-2002, 07:36 PM

My son and I just did this a few days ago.

Here are the steps we followed to where you are now from our notes:

Mount on engine stand.
Removed drain plug (has magnet insert on inside) and drained oil.
Removed backup light switch and accuating pin (small end of pin was towards switch).
Removed nine nuts total with washers fron nine studs; two of the nine studs carried small brackets in addition to a washer and nut, a third stud (of the nine) had two larger washers with the ground strap sandwiched in between and a nut.
Knocked off front cover with moderate blows from a soft faced (rubber face) hammer.

Check to make sure you have all the nine nuts and washers removed; a washer can cock on a stud and jam on the housing.

Later you'll need to lock up the transmission by engaging fifth gear and one other gear (we pushed in the end of the 1/2 shift rod to engage 2nd gear). Before doing this orient the input shaft so that the roll pin in the castellated nut may be driven out without hitting the adjacent reverse idler assembly. Then you can remove the flange nut from the pinion shaft ( I found a 36 mm GM spindle nut socket for ~$24 at a local auto parts store that fits this nut). Next drive out the roll pin and loosen castellated nut (a 1-1/16" socket fits) on the input shaft. Had to put cheater pipe on the breaker bar! Cheers!

Jim

Jim Sims · 01-02-2002, 07:41 PM

Also transmission was horizontal (input and pinion shaft axes approximately parallel to the ground) during this time and all subsequent dissassembly steps except later when gear housing was placed in a vertical orintation on workbench to drive out roll pins securing 5th gear detents . Jim

tbitz · 01-02-2002, 08:12 PM

Thanks Jim,

All nine nuts and washers are off. The cover is not binding on the studs.

Looking through the opening I see that as I pull the front cover, the 5th/reverse gear seems to want to come off with the cover. Looking at pictures in the Bentley manual, it does look like the 5th/reverse gear should come out with the cover. Somehow 5th/reverse seems to be attached to the front cover? How could this be?

Jim Sims · 01-02-2002, 08:42 PM

Tony, I went out and looked at the parts and our notes. The only items which come off with cover are the speedometer drive gears/shafts and the backup light switch and pin if you do not remove them first. In our disassembly there was also a thrust washer stuck in the oil on the inside of the case but it could have just as easily remained on the shaft. The fifth/reverse shift fork and rod stay with the gear housing (the middle section of the transmission in the Porsche terminology), in fact one can't remove the 5th/reverse shift rod until one drives out roll pins in the gear housing to release the 5th/detent assembly. You may be hanging up on the main shift rod somehow. We did not have the cover and guide fork off when we removed the front housing. You may try replacing the cover and guide fork ensuring that the lever pivoting off the shift rod is correctly placed back into the shift guide (this guide is mounted on the 3/4 shift rod). Then try and remove the front housing. I have further information about a non-obvious detent between the 1/2 and 3/4 shift rods when you get to the step of removing the gear housing. Cheers. Jim

ChrisBennet · ChrisBennet's Garage

Besides the shift rod there is another shaft that pokes into the end cover and the end of it is exposed. It's above the shift rod about 4-6" higher on the nose cover. The O-ring on this shaft will cause some resistance when removing the cover. Try pulling on the cover while someone taps on the end of the shaft.
-Chris

tbitz · 01-03-2002, 05:19 PM

Chris, you're the man!

The exposed part of the shaft that holds the 5th/reverse gear was rusted and had welded itself to the case. It came off after I placed small pieces of wood in the opening and smack the shaft inwards. They way it looked from the outside, I didn't even know it was part of a shaft.

Thanks again.

Jim Sims · 01-04-2002, 05:41 AM

Tony, When you reach the point where you are ready to remove the input and pinion shafts off the transmission housing (right after you've marked and measured the installed postion of the shift guide and 1/2 and 3/4 shift forks on the shift rods) I found as per the Haynes manual and the factory shop manual you will have to remove the bolt and washer and loosen the 1/2 shift fork. I was told it was possible to avoid doing this and instead pull both shafts and shift rods from the transmission at the same time. There is a third dentent (In my Haynes manual: "21 Remove the plug and short detent from the top of the transmission housing.") between the 3/4 and 1/2 shift rods which cannot be removed until the 3/4 shift rod is removed. Therefore, I had to follow the Factory and Haynes manual procedure and loosen the 1/2 shift fork. It may be possible to do it the other way by "wiggling" the rods and some how getting by the detent, but the softness of the magnesium case made me reluctant to try this. I have the shift fork setup template so I'm somewhat less concerned about re-establishing their positions. However for good measure, I did mark and measure the original installed position of the 1/2 shift fork and left the 3/4 shift fork and shift guide in their original installed positions on the 3/4 shift rod. Cheers

Jim

tbitz · 01-04-2002, 06:40 AM

Jim,

I sent you an email yesterday, not sure if you got it.

I removed the main housing and pulled both shafts out. I followed the Haynes procedure. I did measure the position of both shift fork.

I also noticed that I did not really need to remove the shift fork from the shaft for 1/2 as it could have easily come off the rear housing together with the gear sets.

I am now ready to remove the front bearing from the pinion shaft. I don't have the "special" tool that is described in the Bentley manual. The Haynes manual describes a procedure for removing it.

Jim Sims · 01-04-2002, 10:51 AM

I don't believe I received the e-mail but I'll check again. The special tools to remove the pinion shaft bearing (be sure you don't move the bearing closest to the pinion gear or you'll have to get the final drive set up redone) in our case was a piece of 3" plastic ABS drain pipe and a hydraulic shop press. The piece of ABS pipe was 3" ID and 3-1/2" OD (1/4"wall) by 5-3/4" long. Once the input shaft was seperated from the final drive we used an old clutch disk mounted in vise (put four 3/8 hex bolts and nuts through existing holes in disk) and Stilson wrench (with cheater pipe) to get input shaft flange nut off. I have a flare nut crowsfoot wrench coming from Snap-on to put this flange nut back on with the proper torque. Cheers, Jim Sims

tbitz · 01-04-2002, 09:27 PM

Got the front bearing off from the pinion shaft. It wasn't that tight. Just held the bearing and hit the shaft with rubber hammer.

I took the circle clip of the 1st gear. Now I need to remove the dog teeth from the 1st gear. No I don't have the special porsche tool. I'm thinking a simple bearing puller could do the job. The bearing puller will connect where the circle clip attaches. (may have to grind the grove a little bigger, but that is ok since it will be thrown out). I'll look for an appropriate bearing puller tomorrow.

The teeth for my 1/2 slider look nice. I am wondering if I really need to replace it. Do you have the spec on what the inside diameter should be? I guess this is the part that would wear out by rubbing on the synchro.

Any specs on brake bands, thrust blocks?