Lizard928

JV, I think it would make more sence to machine the ring gear on a mill as supposed to a lathe.

Mark Anderson

Guys this is pretty straight forward. My trans guy has been doing this for years for us and a few other customers. As I told Carl you just need to offset the carrier with shims. Hopefully Carl can make these and offer them to everyone to make this simpler. The 78-82 LSD is better and easier to come by.

BC

Is 80% too tight for track days?

slate blue

By JV
Hi John and others, I have done this job, as I wanted to have the option of switching the lockup rate.

You shouldn't machine the crown/ring gear. I agree with Lizard if you were going to do anything you would grind it rather than cut it. Regardless none of that is necessary and all of it my not last a full service life.

You buy the shims from Porsche and then just machine one small surface which unless you really botch it won't effect the runout, as I said my runout was 0.02 mm and the max allowed is 0.05 mm. Make sure you get the preloading of the bearings right, I wouldn't say it is beyond the home mechanic but you will need to have a good understanding of what you are doing plus a dial gauge and some bearing blue. MAKE SURE YOU READ THE W/MANUAL when doing this job.

Greg

Carl Fausett

Thats my plan.

mark kibort

probably great for the snow, but terrible for a medium power track car. I think Joe and Mark might need it due to the 500+ rear wheel power.

open diff is a joke on tight turns and I have the standard late model LSD for S4s. Its 90% good. there is 10% of the time. (one turn on a track) where the LSD will give way if the turn is off camber and a little faster than a tight turn.
so, for DE or open track, the stock LSD is near perfect.

mine is so weak, if im leaving a gas station and i have one wheel up in the air leaving the driveway (due to the cage stiffining the chassis) i can often get stuck and not be able to move.

mk

Steve Cattaneo

How many do you need.


The enclosed pictured Shim is the Intellectual property of, Steven Cattaneno and Master Tech transmissions ®

Steve Cattaneo

I can FedEx next day air tomorrow, E mail me your shipping address, Mastertech@mastertechtrans.com

Carl Fausett

Steve: I sent you a direct email.

Carl Fausett

We finished our "kit" design that allows the early 8-disk LSD to be fitted into the late-model transaxle, and we took the car to a 2-day PCA event to proof-test it before announcing it.

Saturday was coolish with temps in the 50's and 60's, and it drizzled. Sunday it flat-out rained. Both days were excdllent for testing LSD as the tires had a hard time coming to temperature, and of course, it was wet.

Suffice it to say, when I bested my personal best time at BHF raceway in these conditions, we were very happy with the results.

On the 90-degree corner #7 at BHF, I could still make the inside rear tire spin a little bit if I really tried, I did not have to lift out of the throttle to correct it as I always did with the softer 4-disk setup.

Our design allows a 928 owner to install the LSD upgrade without taking the transaxle out of the car - and I am writing the installation instructions now.

The parts are in manufacturing now, and I should have the kits available for sale within 2 weeks.

Steve Cattaneo

Have you check ring and pinion depth contact pattern, by moving the ring gear towards the driver side you open the contact pattern. You my need one of my shims.

Carl Fausett

First, we took the two LSD's (early and late) to a CMM machine to measure to the ten thousandth of an inch the location of the ring gears relative to the bearings. Then we swapped the ring gear over to the diff and measured again.

This let us know precisely what we had to make up in shims and in which directions.

Upon installation, we checked ring and pinion backlash agian and found it was spot-on at the Porsche spec.

We also used Prussian Blue to check the smear pattern on the gear teeth, and it was also spot-on.

But finally, we mounted it in the car and went and ran seven 30-minute race sessions with it. We were testing the LSD and also our brand-new solid transaxle mounts (photo below).

Both perfromed flawlessly. The serial port on my accelerometer is not working right, and although it recorded the sessions, we have been unable to get the files off of it. We will. And I am sure the traction circles they produce will show clearly the lateral and acceleration forces were improved by the improved limited slip.

Before everybody gets all excited about solid transaxle mounts - they are for cars equipped with rollcages only. There is twist in the unibody, and a solid mounted transaxle would be a mistake when the body is permitted to twist.
However, if rollcaged, the cage has augmented the unibody and will have eliminated the need for rubber mountings so the transaxle can float. I was surprised at how much the solid transaxle mounts improved the shifting accuracy and speed. More on that product later.

Lizard928

Carl, do those mounts have the tranny sit in the factory location, or lower?

Carl Fausett

In the factory location. Our front solid motor mounts will lower an engine about 1/4" from a stock rubber mount in good condition.

We have toyed with lowering engine and transaxle, but then all of a sudden your headers do not fit, the collectors hit pavement, the heat shields are in the way, etc. Only the very serious fabricator would not care about these things and proceed anyway. And those are not our customers, usually.

So, in order that these parts work with most of our other parts - the stock drive train location is maintained.

belgiumbarry

Carl, you send me please all that LSD stuff as soon as possible !
all i need from a NON-LSD transaxle...