915 Rebuild (Part II) - Time for Assembly
 

I'm starting a new post for the assembly portion of my 915 rebuild. You can read the disassembly post and all the disasters I came upon here:

http://forums.pelicanparts.com/porsche-911-technical-forum/458853-getting-ready-915-rebuild-its-my-turn.html?highlight=915+turn

I figured the other post has gotten so long, I'm sure people are tired of looking at it.

So, I've got my parts back from the shop and I'm ready to start rebuilding.

Here is the differential case all cleaned up:

http://forums.pelicanparts.com/uploa...1239793995.jpg

And here is the sleeving job to fix the spun pinion shaft bearing race. I also had them install a new input shaft bearing race as well.

http://forums.pelicanparts.com/uploa...1239794044.jpg

Here is my old races pressed into my new intermediate cover.

http://forums.pelicanparts.com/uploa...1239794092.jpg

And last night I assembled my main shaft. Could you guys take a look and see if anything looks amiss before I torque the nut.

http://forums.pelicanparts.com/uploa...1239794146.jpg

http://forums.pelicanparts.com/uploa...1239794164.jpg

One thing I noticed is that the location of the shaft nut is different than in the Bentley manual. It seems that the nut should not go past the hole in the main shaft like it is doing.

http://forums.pelicanparts.com/uploa...1239794546.jpg

Did I press everything on too tight? Am I supposed to the a space somewhere? The Bentley manual didn't mention anything and all the bearings and gears turn freely. So I'm not sure what's wrong.

I just took this photo of my input shaft and new 42mm nut I sourced from our host. I haven't dis-assembled this shaft yet...

The part number is: 930-302-281-00-M100

As you can see the new nut is thinner than the original one on the shaft.
Looks like I'm going to have the same problem if I use the new nut.

http://forums.pelicanparts.com/uploa...1239796914.jpg

More...

The original part number for this nut is :91530228100 (Peter Zimmerman provided this number)

When I search for "91530228100" the search result states "Part Superseded to 99903403300"...
Part number: 99903403300... Lock Nut, For Transmission Main Shaft/Pinion Shaft, 911 Carrera 2/4 (1989-98), 911 Turbo (1989-98),

Looking at the description this one is for the later G50 Gearbox.

I think I (we) ordered the wrong nut... I'll send a message to support to confirm and post the results.

You are right. I think we have the wrong nut. This is the second time Pelican screwed me up with there descriptions. The bearings for the P/S and M/S are reversed in their descriptions.

I'm going to have to start checking the part numbers carefully.

By the way...when I look at my PET....99903403300 is the right number.

Just to clarify.. Did you order 99903403300 or 93030228100M100?

...and I just bought a nut to complete a repair kit, and my supplier still sells it under the 915 302 281 00 number - without mention of the 999 number. Let me see if I can get some info for you...

Is the nut with the short collar micro-encapsulated, or just clean threads?

Mine new one has just clean threads. The photo on our hosts site of 99903403300 has what looks like a blue locking compound on the threads.

http://forums.pelicanparts.com/uploa...1239809713.jpg

Looking at the photo now it looks very similar to my original one on my input shaft.

I got the 930 part number.

I think it is just clean threads.

Matt: I just talked to my supplier, and the 999 number is a legit supersession (they still have the old number in stock so they haven't updated their system as yet). The 281 00 nuts have been micro-encapsulated (blue thread locker) for many years, I assume that the correct replacement also will be.

Ok. I'll have to order the correct nut. We have to let Wayne know he's got a few bugs on the website.

John Chi from Pelican replied to my question.

He said part number :99903403300 is the correct one.

Maybe there is supposed to be a spacer or washer in between the bearings and the new style nut? What is the purpose of the hole in the shaft? Does it have a pin in it to lock the nut into place?

Matt

Can you please tell me more about the pinion bearing fix you went with? It's clear my bearing has been turning in the case also. If I was in the US I'd just go with the Wevo fix, but over here in Oz I need to consider other options.

Cheers

No...it's just the wrong nut. The hole is where you stake the collar of the nut into to lock it in place. I have to order the right nut.

Basically a machine shop bores out the case where the old pinion shaft race was. Then they install a steel sleeve in the bore which they then press the bearing race into. The cost to do that here is $ 250 - $ 300. Peter could tell you a lot more as he was the one who turned me on to this. The race is very tight now...no more turning.

Progress Update and a New Question
 

Ok.

So the mainshaft is back together...minus the correct nut...but other than that I think it is all fine.

I put the pinion shaft back together tonight without incident. The M/S and P/S seem to mesh together nicely. So once I get the new nut I'll be ready to start put the tranmission back together.

Then I started working on replacing the carrier bearings on the differential. The one on the opposite side of the ring gear came off easily and I pressed the new one on with no problem.

However, the bearing on the other side (ring gear side) is harder. The problem (that I'm having) is that I cannot find a good place to grab the bearing from with the puller. On the other side there are two access holes through the speed sensor plate that let you get a good grip on the bearing.

But on the ring gear side there is only one flat spot to get you in there. All I'm doing is pulling the bearing by the edges and destroying it.

How do I get this thing off?

What are you planning on using to seal up the case?

I have done some searching and "Loctite 574 Case Sealant" seems to be the one to use.

That is a good choice.

I hadn't gotten that far yet. But whatever you guys recommend.

Anyone have any recommendation for getting the carrier bearing off? I was looking at the factory manual and they just show using a gear puller to do it. I just don't understand how to get under the lip to grab the race with a gear puller.

There is a note next to the picture that indicates the puller arms may need to be machined.

I've read here that if you heat up the side plate the carrier bearing will just about fall out. If it was me I wouldn't go any higher than 100 Celsius - 212 Fahrenheit

Would your wife/girl friend let you use the kitchen oven to do this?

I'm divorced so I don't have that problem but my kids complain if their pizza tastes like "Simply Green" ;)

I have also used my dishwasher to clean alloy castings like the gearbox cases... Works a treat... lol

Matt described the reinforcement process, necessary even with the WEVO clamping plate! The good folks at WEVO told me that their plate offers a fix for the NLA double plates used by the factory, but that their plate will not fix the loose pinion bearing race problem.



I've never had a problem with the ring gear side bearing, but I use the factory puller (shown in pics #1-3). The large round section fits over the bearing, and is then tightened (the part is two pieces - one turns inside the other) until the steel rings grip the bearing. Then the other section is screwed into the large part, and tightened against an insert (not pictured), which pulls the bearing off.

The other two pics show the puller, with ground/modified jaws, that I use to pull the bearing at the speedo ring. I imagine it would also work on the ring gear side, the trick is to grind the tips until they can grab the exposed lip on the bearing.

http://forums.pelicanparts.com/uploa...1239899829.jpg
http://forums.pelicanparts.com/uploa...1239899875.jpg
http://forums.pelicanparts.com/uploa...1239899903.jpg
http://forums.pelicanparts.com/uploa...1239899930.jpg
http://forums.pelicanparts.com/uploa...1239899959.jpg

I used a large gear puller to get the speedo ring side off. I used a end cap of a pipe to cover the opening where the flange is installed and give the puller something to push against. Then I used my impact wrench to turn the bolt.

I went to do the same thing on the other side, but I can't find a way to get a grip on the bearing race.

Also, in regards to the case sealant...the manual only indicates to use a new gasket. Is more than that required?

Oh, yeah! My favorite for aluminum cases has always been Curil T. All surfaces should be cleaned with lacquer thinner (or MEK), then a thin coat of Curil to each side of the gasket (don't leave any bare spots) does the job. I have been tempted to use 574 but have not as yet. I'm not sure how it will work with a gasket because everything that I use 574 on has no gasket (cam tower to heads, engine case halves, etc.).

For the diff side cover, I coat the entire o-ring with a thin application of every day dino engine oil, and I use white lithium grease on the outside of the flange seals for installation, and more grease on their inside sealing lip before the flanges are installed.

I've done several drip free 915's with Loctite 574. With and without paper gaskets. And one Hudson engine. ;)

Theoretically all you need is the paper gasket. I prefer to be safe and add some sealant.

What "theory" is that? The one that states every single person who's opened that tranny has treated it with the utmost of care and has never made any kind of nick in the original machining, so that the case pieces meet in perfect alignment and won't leak?

:D

Hi Pete

This is the bearing race machining fix to the final drive performed by Wevo that I was referring to - not cheap, but obviously solves the problem. http://www.wevo.com/Products/TransmissionProducts/WevoTransmissionProducts-RaceCaseFinalDrive.htm

I can't get that job done here, but I might be able to get a less comprehensive machining job done once I know what to ask for and how to direct my machinist :D

Cheers

Not my fault your car is beat to schit. ;)

Success! I got the other bearing off. The exhaust clamps I got for removing the dog teeth also works for removing this bearing.

First I broke off the part that holds the rollers so that only the race was left. Clamped the exhaust clamp to the top lip of the race and used my gear puller against the exhaust clamp. Pulled it off with my impact wrench and done.

Here's a shot with the new bearings on.

http://forums.pelicanparts.com/uploa...1239994167.jpg

Next order of business is to put all the bits and pieces back on my differential case and get the differential back in there.

That's beautiful, but a bit of overkill in my opinion - I've never seen a loose M/S bearing outer race. To do the P/S bearing you need to index the bearing opening, machine it to the appropriate size to accept a steel ring, press the ring in with the diff housing heated, then press the outer race of the new bearing into the steel ring. Because I don't do this repair myself I'll decline to tell you the steel grade, or the "press" requirement to put the ring into the housing, then the race into the ring. You'll have to work with a machinist who you trust, then let him take the concept and run with it.

Maybe you can call EMS (Pete's place) or California Motor Sports (CMS) and have them give you (or your machine shop) all the info they need to do it. I'm sure they would understand since you live too far to ship it to them (at a reasonable cost).

Believe it or not, EMS deals with Japanese customers. You might want to check shipping prices to Los Angeles!

So I've been assembling my differential case. Putting all the misc. pieces and seals on it before I put the differential back in.

Here's a pic of the new flange seals.

http://forums.pelicanparts.com/uploa...1240331239.jpg

I also put the new shaft input tube and seals in and the clutch release fork.

http://forums.pelicanparts.com/uploa...1240331331.jpg


I can move the clutch release cross shaft up and down after I installed the roll pin into the clutch release fork. Is this right? It doesn't seem right to me and the Bentley manual is kind of slim on details.

NO!!! WARNING, WARNING!!! DO NOT install the M/S seal & guide tube until the trans is done! As you slide the M/S in and out the clutch splines will cut the sealing lip on the seal, and you will have a nasty oil leak shortly after you put it in the car.

The clutch fork will move. However, you are missing a dirt seal at the top of the fork. Check your PET for the part #...

Ok...so I should take the guide tube off and reinstall it once I have the M/S installed?


I'm looking at the PET and the Bentley manual and I can't find a seal at the top of the fork. I do see a seal, but it looks like it goes on the bottom of the shaft before the spring is installed. Am I reading this wrong?

http://forums.pelicanparts.com/uploa...1240337956.jpg

This is what I'm looking at.

Shouldn't he also build a silicone dam and drill an oil 'drip' hole in the guide tube?

I do not believe in a "silicone dam," or drilling an extra hole in the guide tube. The latest generation M/S seal will outlive the clutch if it's installed correctly.

Ok....now we are starting to move.

I got my correct nut today for the M/S and torqued that on.

I put the differential back into the case. Now here is the thing. The factory manual says to torque the side cover nuts to 15 - 18 ft-lbs. I don't have a torque wrench smaller than 20 ft-lbs so I torqued them to 20 ft-lbs thinking that would be close enough.

Not so! I could turn the axle flanges, but the ring gear would not turn inside the case. So I loosened the nuts a bit and then the ring gear could turn freely and feels the way it did before I removed it. I'm pretty sure this all has to do with PRELOAD. How much do I tighten these nuts???

At any rate it's starting to look like a transmission again.

Next question. Before I start putting the gear stacks back in. Could someone give me a quick crash course on what the detents should look like inside the differential case.

You're doing the pre-load test completely wrong. The factory makes a washer that fits onto the axle flange before the flange is installed. When the flange is tightened the washer locks the diff and you can measure diff bearing pre-load using an inch/pound torque wrench (non-click type).

Torque specs should never be exceeded, I highly recommend that you get over to Sears or find a SnapOn truck and buy a 3/8" drive torque wrench tomorrow. You don't want to be pulling studs out of the housing, along with the aluminum threads!

It's great that you're getting things back together and I don't want to appear negative or pedantic but...

I'm concerned that a difference of 2 to 5 foot pounds would stop the ring gear from turning. The side cover has a machined surface on it that mates with the transmission case. Tightening the nuts to 20 foot pounds is above the recommended torque setting but it should not stop the ring gear turning. The worst that could happen (IMO) is that you may pull the studs out of the case.

After reading your post (highlighted in bold txt above) it sounds like you have zero backlash and the ring gear is being forced against the pinion gear when the side plate is tightened against the transmission housing.

The factory manual states that you must check the backlash and pre load after replacing the differential carrier bearings.
To change the backlash you need to change the spacer shims under the differential carrier bearings (your new ones) with different thickness spacers as required. Re assemble and confirm the backlash and pre load...

If you can't do this yourself you may have to get the backlash checked and adjusted by a transmission professional with the correct tools to resolve the problem.

Peter Zimmerman would know for sure but this is an educated (via this site) suggestion from an enthusiastic amateur.

Apologies in advance if this turns out to be a "Red Hearing".

More info: Tools for checking backlash... (I pinched these off Rennlist)

Peter Zimmerman:

Could you please post some picks of these actual tools if you can.
What's the distance from the dial indicator clamp to the centre of the axle flange bolt?

(I'm making my own)
Thanks in advance.

http://forums.pelicanparts.com/uploa...1240385324.jpg

http://forums.pelicanparts.com/uploa...1240385350.jpg