need a favor especially from guys with garage queens 7gt3/rs, never tracked, low miles preferable but DDs are fine too:

with car in neutral (engine off) and handbrake off.
1. jack up one side of rear. (don't forget to wheel chuck)
2. spin the raised wheel.

can you turn it with very little resistance? both directions?

mines turn with very little resistance on both directions. there's a thread over on RL that this is how you test LSD if good or both. if it turns with little resistance (as-in you can turn it with your finger), then supposedly your LSD is fried. so far, i have yet to hear anyone who cannot spin it.

 

No luck yet. would be nice to know what the base line is. I do track my car and I get no LSD resistance If they are really into it they could put a torque wrench on one of the lug nuts and see how few ft lbs it takes to start the wheel turning.

 

Correct me if I am wrong, but on an LSD car, shouldn't the opposing wheel turn in the opposite direction? Wouldn't this demonstrate that the LSD is in fact doing its job?

Or does the gt3 use a clutch type, and these clutches may be 'fried' (as you put it) causing decreased performance?

I'm just trying to understand this, as it seems difficult to imagine that you have broken the LSD on such a new car. Every BMW I have owned has an LSD, and all were easily spun (for cars that are 20 or so years old). If all associated parts were new, I imagine one finger could easily spin them, but I know the LSD works.

Maybe some more people will chime in.

 

Limited Slip Differential (LSD) - turn one wheel and the opposite wheel turns in the same direction

Open Differential (no limited slip) turn one wheel and the other turns in the opposite direction

That's it.

 

It's been a rough night...when I first read this post...my brain must have been in the gutter, but I thought LSD?!?

 

What we are looking for is a quantitative test as to the amount of torque it takes before the wheel moves. If you jack up the car one rear tire, leave the other tire on the ground and then take car out of gear no e brake, and put a torque wrench on a lug nut and find out how much torque it takes to move the tire. We are testing if the friction disks in the LSD are grabbing or if they are fried. Stock GT3 is a 20/40 lsd which should produce some decent reistance. I tested my car it takes 8.5 ft lbs to move the wheel. Ok for street, crap for track.
A guy who has a Guard 50/80 LSD was at 60-70 ft lbs of torque to move the tire. So what we are thinking is the the stock LSD in the GT3 and mabye GT2 are crap after about 2 -5 track days. they build durable friction disks but they don't lock up.

 

frank, i haven't tried to measure with torque wrench. i'll try tonite. it felt like there wasn't much of a resistance to turn the wheel but then again it wasn't like how the front wheels would spin so easily. i can turn the raised rear wheel both directions. does that mean anything?

really would like to hear from people with garage queen 7gt3/rs but not sure if they know how to work a jack. j/k

 

I believe Porsche spec is 10 foot lbs. I'll try and verify. Mine was shot- I have a Guard now.

 

My Porsche tech at Downtown L.A. Porsche tells me the preload on the GT3 diff is supposed to be low, according to his recollection about 5 ft-lbs. Mine with 9k miles measures in around 12.5.

 

12.50ftlb sounds great. I don't know the numbers but I really like the feel and performance of the Guard. Takes it's set- confident feel. Nice.

 

Turning the wheel both directions does not mean anything in our little test. its the resistance in either direction we are interested in. The OE unit has friction disks and the torque is generated by a spring system that compresses the disks. its a combination of the friction surface of the disks and the spring tension. that is giving up. so if the LSD is shot it will spin freely. my 8.5 is an ok reading for strictly street use, but if you are tracking your car, do high speed braking or like to trailbrake in the corners, you will really like more preload. 20 ft lbs would be reasonable, 40 would be better. I am not sure the OE unit would get to that point new.

I agree with other posts hear and at Rennlist, it is not worth the time to go to dealer and just replace the unit with the OE clutch pack, you want to go with high performance parts.

 

Nicely stated.

 

My torque wrench can only go as low as 12 ft/lbs and can still turn the wheel with it. I did probably about 10 rotations with no sign of hardening. But it definetely doesn't spin freely.

 

I love this car, and I love to track it but I have to say this is my second disappointment. first was getting my head around the RMS issue. it took awhile but I am ok with it. Now, I find that they put a under performing LSD in this so called high performance track car. Its not like there is not a solution to it, but that is the compromises you have to live with when you buy a machine that is a street legal machine. I just expected the best out of the MFG'er and got average.

 

Don't feel so bad frank. The 996 guys went thru the same thing. :P