Peter Zimmermann

This thread is an extension of one from a while back that you'll probably remember...

https://rennlist.com/forums/911-foru...ht=915+rebuild

The 915 differential housing provides a mounting surface for the primary, rear pinion shaft bearing. The outer race for that bearing becomes loose in the housing, and must be repaired for a long-life result. That bearing race is loose in, from my experience, 95% of diff housings, and there are many ways to correct the problem. Unfortunately, most of those "repairs" are defective either (1) aesthetically, or (2) functionally. Pictured below is easily the most horrific of both...

Picture numbers 1&2 are the ghastly mess that I discovered inside a 915/68 transmission. a mess that should cause great concern in the mind of any DIYer! This "repair" was done by someone who had no idea of the internal stresses, assembly dimensions, or other factors in play inside the 915, and this transmission had numerous other problems as well. I have a hunch that this 915 didn't last very long since its previous repair.

Picture numbers 3&4 show the result of a technically correct repair that will allow further use of the diff housing. The outer bearing race (from a new bearing), has been installed into a steel shim, which was machined for this particular application. The bearing now sits perfectly perpendicular to the pinion shaft, and its center will perfectly match the design dimension between the pinion shaft and main shaft.

Amber Gramps

Wow Pete, I did better work than that on my ATC110 when I was 12 years old and installed a cam who's lobes exceeded the size of the race. Who would do that? How would you do that? Is there not an versized race that could be fitted? Some people should just be shot.

Toby Pennycuff

Someone must have had a drill press and LOTS of spare time on their hands! Good grief, that "mechanic" needs to be identified and asked to "step away from the toolbox please!"

Amber Gramps

That isn't the work of a drill press, it's the work of a hammer and punch! Someone wacked on it with a sledge hammer and center punch!

Someone needs to scream in his ear "This isn't Detroit"...

Brads911sc

That is sad. Thanks for the pics Pete.

Peter Zimmermann

Exactly, and this one is easily the worst I've ever seen. The way that the metal was displaced was so bad that I just stood there and stared at it. That, and other elements of the "rebuild" were so bad that I probably should have done a video!

theiceman

yeah but holding up that 40lb Beta camera would have been a strain ..

but seriously folks......

Is that a readily available shim Pete ? and how do they go about pressing it in ?

Ed Hughes

Reinforcement of the fact that anytime you see a car ad that states "rebuilt transmission", one needs to immediately ask: BY WHO????????

84_Carrera

Or, BY WHOM???????

Daniel Dudley

A good example of how there is never enough time and money to do it right the first time, but always enough time and money to do it over again. That repair looks better than new. Maybe you should peen it in, just to be safe.

Peter Zimmermann

LOL! I considered that, but I can't find a punch as big as the one the last guy used !

The Brewmeister

Man that's ugly. Thanks for the nightmares.