How hard is it to install ring/pinion? + bonus diff Q

[beepbeep]

Hi there!

Mattias just bought meticulously cleaned/rebuilt 930 transmission for our little project:

http://project911.luminasweden.com

We got it pretty cheap from a renowned local porsche builder beacuse he assembled it from a different parts he had in his "bin" and fitted it with brand new muff's, synch-rings, bolts etc. (actually, front-case is from 84' and front and diff-housing is from 86') (Un)fortunately, he didn't have lock on diff-housing and didn't actually need the tranny so he sold it to us with all parts minus plate itself (which we sourced and will have in couple of weeks).

Pic of tranny (black stains is just tar underbody-coating that didn't go off with after bead-cleaning, case is perfect):


However, quick check in factory manual revieled that just dropping ring-gear and differential into the case and tightening the bolts is out of question.

There is ring-gear and backlash to be adjusted with couple of special tools so i wonder if it's something that is worth trying at home? If not, is it expensive/lenghty to do in the shop? Can we use generic tranny-shop or are there special Porsche mumbo-jumbos to be known there?

Bonus question:

...having a diff out and all, we (actually, it was mostly me ) were toying with idea of using a second diff to make a "100% limited slip" ... a.k.a. "AGA-diff" (AGA is swedish weld-gear manufacturer). 935 used no differential at all and i wonder how it would affect handling on track for light 911... :-) It's just a mental-experiment, so don't flame me!


Hihihihahahahuhuhehehe (mad-scientist laugh in the background)

[dean]

I would think you could do it yourself if you were very lucky and tried many times to set it up. There are so many variables like how many shims go on each side of the spool. And how deep to set the pinion. I think that is what they use the tools for. To limit the # of time the thing comes apart.

I also think that with a locked diff. the car likes to go straight. She don't turn so good

[addictionMS]

I have driven a car with a locked diff, on the track it is not so bad, tight corners are a bit rough, but other than that it was fine.

I do believe that a locked diff is hard on the car, we did a 8 hours of a 12 hour race ( we had fuel problems for the four missing hours) and after the race the car had shaken the CV bolts loose. So it does add a bit more stress.

I am building up a spare trani for my car and will probably put a locked diff (actually a welded up open diff) in the spare, good enough for a spare and a lot less expensive.

Jim

[jluetjen]

One thing to keep in mind is that the suspension set-up for a car with a locked diff will often be different then a car with a LSD or open diff. Basically the locked diff will make the car brake in a straight line, but push as soon as the throttle is picked up. So you need to set the car up to be "looser" to bring back a balance.

I haven't played around with them enough to know any specifics.

[IROC]

I would recommend getting someone who has the specific knowledge in setting up Porsche ring and pinions to do the installation. From what I've been told, special tools are required and it's definetely not for the do-it-yourselfer or even the local transmission shop. I talked to one guy (who does alot of these) and he said he has a whole pile of ruined 915 gearboxes out in the back of his shop from people who tried to set up their own R&P....

Beautiful case though!!

Mike