Help Me Find Bearing (w/Pics)

[dentist90]

Surprises just keep coming with this project. I posted previously how I found a crack in my diff housing necessitating it's repair or replacement. I got a replacement housing from a Vancouver Porsche dealership who could not give me any info as to how they came to posess it. I noticed the casting part #s were slightly different (7R vs 9R as last digits). I also noticed the trans model # is different, 74F vs 74E. My Bentley doesn't list a 74F so I don't know what it came from but it's non-oil cooler.
Q: What case have I got now and where can I find the appropriate sized bearing. I like the idea of the thicker webbing between the two bores as my old case cracked right there.



I am preparing to swap my old diff (complete with ring gear and bearings) into the new case. I had just removed the old output race from the case when I noticed that the bores are different for the mainshaft, 60mm for my old case vs 55mm for the replacement. See photos:





I had heard of a smaller diameter bearing for the turbo but Pelican lists the turbo and non-turbo input shaft roller bearing as the same part (999-110-146-00).

[B]

[Jeff Alton]

Call Bert's kinsway and see if they can help you out.

Umm let me guess, John found the replacement part for you... did it come on an MCL invoive?

Cheers

[dentist90]

Jeff... it was the other Porsche place. I'm checking with Wayne's parts guys here. The WEVO site mentions that the later 915 trannys came with an upgraded (smaller) bearing and gave me a part # (their racing case insert also uses the smaller main bearing apparently). However, that part # shows up as the PINION shaft roller bearing in PP catalogue. BIG difference. They stopped using the 915 in 1987, and mine is an 84, so I don't know when the bearing changed.
Q: this isn't a 4-speed diff cover for a 930? The stamped case # seems right for a 915. There must be someone with experience in this.

PS: forgive my ignorance, but who is Bert's?

[Jeff Alton]

Berts' Automotive on Kingsway. There is a couple of franchises is town but they are the originals and the only ones who might be able to help. They were the only guys in town who could set my ring and pinion.

Now back to your question...

Does the case have the notch for the sensors that a carrera requires?

I am guessing now you got it from Weissach? Stuart should know or Uli (sp) should know where to get the parts.

Maybe send Grady a PM as well, if he does not see this thread, he is pretty darn knowledgeable about 915's. So far I am stumpded, but if I get some time tomorrow I will start digging for you.

Cheers

[dentist90]

Hey, well, thanks for your tip for the inevitible pinion and gear setup. I am presently taking some 'at home' measurements to see if there's a way to get this old ring and pinion back into the same relation in the new case. ( I might post on this later if I feel the urge to be ridiculed) I've e-mailed Uli and Pelican to try to identify the new bearing.

The bell housing has all the cutouts, although they do look a bit different. My old one looks like they were cut out after casting, whereas the new (74F) case has a lip around the cutouts. Curious. See for yourself:
OLD


NEW


Side by Side:


I think this will be a better case... stronger in the bore bulkhead. Once I find the proper bearing my next question will be how to get the old one off the input shaft without wrecking the 4-point ball bearing

[Jeff Alton]

I talk to Uli nearly everyday so I will pick his brain on the phone too! You are right, the new case looks "updated".

I just went out to the shop to look at my Transmission case. It is an 84 also and is a 74E case but has the cutouts like your 74F case-they look cast in. It is all put back together so I can't take any internal measurements for you though to compare.

Cheers

[dentist90]

Thanks, man. Appreciate any help you can give. Remind Uli to check his e-mail. He's missed some of my mail in the past.
Jeff... what is the part number cast into the side of your bell housing?

[Jeff Alton]

There is not one there that I could see, only on the bottom. I noticed your 74F case doesn't show one on the bell housing either, but the 74E case does.

Cheers

[Jeff Alton]

Oops, low and behold when I look on the other side there it is!!

915 301 101 9R

The "E" cases were model year 84 and the "F" were 85's. It appears yours is earlier production than mine was.

Cheers

[MBEngineering]

HI where is the crack/damage to the diff case that you had to change it? and the replacement is a 3.2 case, your original looks like a modified SC as for the bearing the 55mm is 930 302 391 00 and the 62mm is 999 110 032 00 both could be fitted to that year, do not forget you will need a full diff set on a case change , is the pinion bearing tight in the diff case or that loose that it takes no effort to get out??? check the size in the case as it may have gone egg shaped.

regards mike

[dentist90]

The crack was between the bores of the old final drive housing, through and through. The pinion bearing race was indeed loose (very loose) and the pinion bore pummeled.



The new case is in much better shape. The pinion race in that one was still in and I had to tap it out, although it didn't take much effort. I'll use some loctite race and bearing restorer when i put the new bearing in. The race that came out of my old case (goes with the pinion shaft) is a snug fit in the new case, but not quite an interference fit.

I do have the matching pinion and ring gears. I plan to swap ALL the internals from one case to the other. More like I plan to swap the diff case out on my original tranny. The only reason I opened it up was to repair 1st and 2nd synchros. Not too happy to find the cracked case. I had no symptoms, such as gear whine on load or overrun, to indicate something was going out of alignment.
I think that part # you gave me is the same one I got from WEVO, but Pelican describes it as the pinion bearing. I'll look into that. It's definitely the 55mm (outer) one I need.
If the case that came from my car was from an 83 or older someone re-stamped the bottom with 74E. My Bentley manual doesn't have a description for 74F... jumps from 74E to 74G, which would also be stamped 915/73. I'm guessing the new one came from a late 84 or early 85... doesn't matter as long as I can get the updated bearing

OK: How do I get the old one off?

[afterburn 549]

http://www.pelicanparts.com/MotorCity/marcesq3/TrannyRebuild.htm see if this helps

[MBEngineering]

HI If you have a press not a prob'. if not you will need a replacement copper block from a copper hammer or a block of soft all'y, get the nut loose(looks like some one has been in before you with the stilsens/pipe wrench) put the block on the floor and turn the shaft so the gears are at the top and shock the gears off on the block, as in the photo,


If you have a press or can get to one push off the gears from behind 2nd, like this,



to get the nut off if you can get a 41mm socket and turn the end off, then weld on a pipe approx 12-13" long and a old/worn/never used that socket (until you weld it in), in to the end of the pipe, to hold the shaft I have the tool, but you can use a old 5th gear or Rev' gear if you can get hold of one as not to damage the shaft, this way you can torque up the nut correctly on re assembly,


the tools and below holding the shaft,



you can use a old clutch center plate and some pipe wrenches/adjustable, just you do not then know if the nut is tight correct or not , I have pulled box's apart and the pinion and the input-shaft nut are not tight, only nipped or they have been tight and have backed off because the previous had no idea how tight it was and how tight it should be, the gears have then been loose on the shafts, the other thing that gets over looked is that the shafts and EVERY thing on them should be clean and dry on assembly, NO oil any where , hope this bit of usless info' is any good to you .

regards mike

[dentist90]

Very useful. Getting the flange nut off should be no prob. My retired heavy duty mechanic neighbor has a 1 11/16 (approx 41mm) box wrench that will slide right down the shaft. Torquing a new one back on will be a bit trickier without that extended socket, but I thought I might try standing on a bathroom scale while I torque on the wrench until my weight is reduced by an appropriate amount for the length of wrench.
I'm still waiting to hear from Pelican re: the bearing. I think they have it mis-described. I'm all set once I confirm they have it. Thanks for your input guys!
I was having a brain-fart when I asked how to get the bearing off... this is exactly how I got the pinion shaft apart!! I guess I was just thinking I could somehow get the roller bearing off without disturbing the 4 point bearing. Not practical or necessary.
I wonder what awaits me next?