GTgears

Sure, I'll snap some shots and post them when I get to my office on Monday...

The 8:41 is what Porsche used in the 935 back in period. I've never seen one break. I've seen a few wear out, but break? It doesn't happen very often.

chiplynch

Attached are some photos of my rebuild which I just finished a few months back. I used the Porsche factory manual which I have on CD as reference. i took over a huindred photos as I went along as my own reference.

I started out just changing the clutch..and then put the tranny on an engine
holder and then just started taking it apart. Besides gear pullers and bearing
splitters, the only tool I needed was a h. press which I got at local harbor freight shop. I had tranny apart in about 6 hours. I found the parts I needed
not really expensive , except for some of the bearings. I replaced syncros, sliders, dog teeth and other items. for example the lare differenential bearings
were less than $80.00, but the one mainshaft bearing was over $550.00.. it did not look much different than the input shaft bearing which was only $200.00. I did not change any of the gears or the r&p ratios, but it did cost me over
$5,000.00 just in parts.

If you can do an engine, you can do a tranny,, I guess..


Phillip

GTgears

Woops, I had forgotten about this thread. I'll snap those photos today for you guys to look at.

Fast82930

I installed Andials 8:39 R&P in my 82 930 many years ago. It’s primarily a track car and it was a big improvement except 1st gear is almost useless now. If I were to do it again, I’d probably opt for shorter 2-4 gears….

Here’s what my gear chart spread sheet shows for 4th gear. I run 315/35-17 Hoosier out back and they have a 25:8” diameter…

RPM Gear Diff Ratio
4th 9:38 8:39 8:41
ratio 0.625 4.22 4.875 5.125
7000 204 176 168
6750 196 170 162
6500 189 164 156
6250 182 157 150
6000 175 151 144
5750 167 145 138
5500 160 139 132
5000 145 126 120
4500 131 113 108
4000 116 101 96

blackboy

Chiplynch, that's $5 grand just in parts? to do yourself?

MUSSBERGER

Even if the clutch is in that number that's a lot of dough.

GTgears

Here you go. On the left is the stock 9:38 r/p set. On the right is the 8:41. Just as a point of reference the base diameter of the 4.22 is 66mm. The diameter of the 5.13 is 58mm. So there is a difference between them in size.

From another view:


Here's the 5.12 pinion side by side with a 915 gearbox's 7:31 4.43 pinion, which is 53mm in base diameter:


And just for good measure, a picture of the factory's solution to the weak 915 r/p. For the late RSRs and SC-RS they introduced an 8:35 4.375 ring and pinion set that was stronger than the 4.43. It was also 58mm at the base (on left):

SEW QUIK

I had Jerry Woods shorten gears 1-3 in my 4 sp. 930 box. Makes a big difference. Left 4th alone for highway cruising (car is a daily driver). My motor makes about 400 rwhp with EFI. EFI also helps the driveability immensely but is not cheap. If the gears need to be redone, the additional cost of shortening is not that much at the time.

fullquack

Hey guys,

Take your old, tired, expensive bearings to a good, industrial bearing supply house before you shell out all the big $ from a auto supply place.

A good bearing supply house, can cross reference most of the bearings, and save you HUNDREDS of dollars.

All in all most bearings out there, are in one form or another, an industry standard size & type. There really are very few propriatary bearing designs used in cars. Yes there are some, and yes these will cost you.

My .02 worth.

Mark