LSD or no LSD ???

drola · 03-26-2011, 08:08 AM

my recently aquired 87 coupe came with the factory lsd option. my tranny was rebuilt once by a reputable shop. i also have an invoice from a "less" reputable shop where they changed out the diff and slave cylinder. part cost for the diff (rebuilt) was $1000, slave $49, and $450 labor.
is there a way that i can verify if they used an actual lsd diff? without tearing the tranny apart?

KTL · 03-26-2011, 09:14 AM

Jack up the rear of the car and get both wheels in the air. With the transmission in neutral, turn one wheel. The other wheel should turn in the same direction. If the other wheel spins in the opposite direction, you have an open diff (or the LSD is completely worn)

drola · 03-26-2011, 10:18 AM

when i spin the driver's side wheel, the other kinda wants to go in the same direction but doesn't actually spin.
when i spin the passanger side, the other spins in reverse.

spuggy · 03-26-2011, 11:41 AM

Quote:

Originally Posted by drola

when i spin the passanger side, the other spins in reverse.

Then "no, you don't have an LSD".

Joe Bob · Joe Bob's Garage

Sounds like you have a loose part in someone else's ride.

I rebuilt my 915 with help from friends. When I took the box to a reputable shop one of the wrenches commented that I shouldn't leave it sitting around as it would disappear very quickly.

Wasn't funny, made me paranoid and put me on my guard. LSDs are a rare and valuable option. I didn't let that puppy out of my sight.

Sounds like you need to call Cousin Guido and make a housecall.

Matt Monson · 03-26-2011, 03:17 PM

Be sure you spin the wheel with a fair bit of force when testing it. The ZF LSD used in your gearbox has a pretty low preload and is only 2 plates. A good hard jerk on the wheel (think Price is Right finale wheel spin) will make the LSD lock up a little bit if it's present. Just casually spinning the wheel by hand on that diff won't work in the same way that it would on a 915 or 930 LSD.

ivangene · 03-26-2011, 03:26 PM

do a "burn out" on loose surface....if you spin one wheel, take pistol to shop that did the "rebuild"

DonNewton · DonNewton's Garage

Why do I hear the Moody Blues singing in the background?

drola · 03-26-2011, 08:22 PM

i have the driver's side shaft out right now for c.v. boot and bearing replacement. when i get it back together i will try turning it with some force and see what happens. and i can't resist a good reason to do a burnout.
that shop did the diff swap back in 2004. the girl who owned the car before me (she owned it for 18 years) would never have known the difference anyway. so now the question is: did they change it out knowing that they were putting a non-lsd and keeping the original or did they not even pay any attention to the fact that it did have lsd and just swap it out for whatever they had on the shelf?
anyway, she got screwed and in turn i got screwed. hard to go back to them after 7 years and complain though.
this is a perfect example of why i think people who don't know these cars and how to work on them should stick to hondas or toyotas. ok maybe even bmw's (they are great cars).
but leave the p-cars to those of us who love them!
other p-car owners often tell me "if you need a good mechanic i know just the guy." i just laugh. the thought of someone else touching my baby - not a chance!

ljowdy · 03-27-2011, 05:35 AM

Doing a burnout isn't a conclusive method of determining if you have a LSD.

With a non=lsd differential, If for some strange reason, both tires have the same coefficient of friction, both tires will spin and leave rubber

Mitch Leland · Mitch Leland's Garage

I have a low mileage car w/ the LSD option, but some shop had "borrowed" it from the previous owner. I've subsequently replaced it, but they're are to find and not cheap...

Matt Monson · 03-27-2011, 06:26 AM

Quote:

Originally Posted by drola

i have the driver's side shaft out right now for c.v. boot and bearing replacement. when i get it back together i will try turning it with some force and see what happens.

Then you are already through the hard part of what it would take to crack open the gearbox and have a look see. Just remove the drive flange and the side cover bolts and take a peek at your ring and pinion (drain your gear oil first.

). Then you'll know for sure whether it's open or LSD.

tcar · 03-27-2011, 08:45 AM

What does the ZF LSD look like.

I know they are VERY expensive... worth a lot of $$$$