Bags

I picked up a 97 C2S with option 220 which is "locking differential". I assume this is a limited slip or LSD as we know it. My mechanic said there was no LSD on the car or it was blown out, non functioning. When up on the lift out of gear he rotated the rear tire and the other rear tire did not rotate. He said with LSD it should be rotating in the same direction. Is this correct? How often does a LSD burn out? Any idea on a cost to fix it?
Thanks
Mike

Jack Ennuste

Mine rotates in same direction. I got LSD.

Jeff96-993

Mike,

Yes, you have LSD. And yes they do wear out, quite readily as others have experienced. I know there is a more detailed check in the shop manual, the "spin one wheel" trick is not the way to check it.

I have an LSD in my car, and it passes the shop manual test, so it's functioning, however it doesn't pass the "spin one wheel" test.

Others can add info on the cost... hopefully I won't need that information for awhile.

Good luck

DJF1

Mike, the factory LSD is known to fail after some miles on the car and especially under track conditions. You have 3 options really. 1. To rebuild your LSD ,last time I heard someone do it cost him around $1000, 2. Use a new Factory Motorsports LSD at a cost of around $1500 for the unit alone 3. Use an aftermarket LSD.

Your decision should be based also on the type of driving you are going to do. if you plan on doing DE's you should really look at options number 2 and 3 as with a rebuilt standard LSD you will be back to square one...

Finally do a search here on the 993 forum, type on the search field "LSD" and you will see many many threads with good advise that will help you make your decision.

Good luck.

Jack Ennuste

Jeff & others

Is there available better DIY test than "spin the wheel"-test?

viperbob

Do a burn out and count the number of black stripes you leave on the ground.
<img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" /> <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />

Two stripes starting at approx the same time, OK. One stripe, not ok.

Steve Weiner-Rennsport Systems

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Jack Ennuste:
<strong>Jeff & others

Is there available better DIY test than "spin the wheel"-test?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Jack:

Not really.

When these 2-plate LSD's get worn, they will feel just like an open differential and the only way to truly confirm whether you have one, is to look inside. The diff is pretty easy to remove with the tranny in the car so its not a big deal.

Some of these can be updated/modified with improved drive and driven plates to make them more durable, but the real solutions are as Danny prescribed above.

Jack Ennuste

Thanks for professional info, Steve

DJF1

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Steve Weiner-Rennsport Systems:
<strong>
Some of these can be updated/modified with improved drive and driven plates to make them more durable, but the real solutions are as Danny prescribed above.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">This is something you have told me Steve along with my mechanic
You are as always right on the spot in technical feedback and once more WE all appreciate VERY MUCH your expert advise! <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

JohnM

I had a set of sintered plates put in mine (originals were no longer doing anything worthwhile), they seem to be holding up just fine and much cheaper than replacing the whole diff! Parts and labour came to approx £400, about $600.

Tim Ashfield

Originally posted by JohnM

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> I had a set of sintered plates put in mine </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">John

Where did you get these? Which manufacturer and what was the cost of the plates. This is on my list of jobs to do.

Many thanks. <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

chris walrod

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Bags:
When up on the lift out of gear he rotated the rear tire and the other rear tire did not rotate. Mike[/QB]</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">On the bottom of the gearbox casting is a gearbox type stamping. If the suffix is 2 or 02 (I dont remember) then it was built with a LSD at the factory. I doubt anyone changed it to a open diff. When the clutch plates are new, there are very small 'high-spots' on the friction disks. Once the diff wears-in, the high spots are worn off and the preload set-up (clutch stack height) is partially lost.

I have not had my diff out (yet), but I am under the impression these diffs are the ramp type diff, so when pressure (torque)is applied to the ramps, they 'squirt' (for lack of a better term) outward and apply pressure on the clutch plates.

My diff is worn like you describe, virtually failing the static test of turning a wheel when both are off the ground. When driving, the LSD is definately working as I have tested it a few times in the rain. Its difficult (IMHO) to test on dry streets.

Greg H.

Check the public ads under race cars. Someone has a rebuilt LSD unit for sale. Don't know anything about it. No Affiliation.

Greg

JohnM

Tim,

Was done by G-Force Motorsport, give Alan Wright a call 01296-434-084 for the full story.

Bags

You guys are great. Excellent info and a good start to figuring out if I have a problem. I'm in the process of changing over from my 87 911 to the 97 C2s. It is a different beast!!
Thanks again, you'll probably be hearing from me.
Mike