How do you tell if a mechanical LSD unit is worn out?
06-27-2013, 11:22 PM
#1
Racer
Thread Starter
How do you tell if a mechanical LSD unit is worn out?
When we had the 89 GT I just bought up on the hoist I was spinning the rear wheels looking over the torn CV boots and the mechanic commented that the rear wheels were turning opposite directions so it can't have LSD.
The car was in gear when they went opposite directions. When in neutral they go the same direction. The mechanic went a step further and with the car in the air and the tires spinning in 2nd gear at 25 and 60mph he was able to stop one wheel with moderate effort.
This lead to a lot of research and verifying that the build tag had the M220 code, the cert from Porsche listed the limited slip option and the code on the trans was stamped G2855. This lead me to believe that the car had been built with LSD, but the clutches were worn out.
However, I just went out for a drive and the roads were very wet. Heavy throttle in 1st gear around a sharp turn spins both wheels and the rear steps out on left and right turns. If the turn is less sever and not enough throttle to completely break the tires loose the inside tire chirps/skips a bit as I accelerate. This seems to indicate that the unit is working properly.
Confused?
What is normal behavior of the LSD and how do you tell if the friction plates are worn out?
The car was in gear when they went opposite directions. When in neutral they go the same direction. The mechanic went a step further and with the car in the air and the tires spinning in 2nd gear at 25 and 60mph he was able to stop one wheel with moderate effort.
This lead to a lot of research and verifying that the build tag had the M220 code, the cert from Porsche listed the limited slip option and the code on the trans was stamped G2855. This lead me to believe that the car had been built with LSD, but the clutches were worn out.
However, I just went out for a drive and the roads were very wet. Heavy throttle in 1st gear around a sharp turn spins both wheels and the rear steps out on left and right turns. If the turn is less sever and not enough throttle to completely break the tires loose the inside tire chirps/skips a bit as I accelerate. This seems to indicate that the unit is working properly.
Confused?
What is normal behavior of the LSD and how do you tell if the friction plates are worn out?
06-28-2013, 12:09 AM
#2
thats a good one. if you know you have LSD (taken off the cover and looked), then it sounds worn out to me. the propper way to test it is to take the unit out, stick the axle subs back in a vice and use a torque wrench to test the "give". ill have to search for the numbers, but if you go that far, rebuild it anyway.
06-28-2013, 12:58 AM
#3
Racer
Thread Starter
Couldn't the same thing be accomplished with it still in the transaxle by lifting one tire and using a torque wrench on the center axle bolt?
I got a break from the sell on the price of the car assuming the unit needed a rebuild, but I can't seem to get one tire to spin. I'll have to find some gravel on the shoulder and see if one tire on the gravel and the other on the pavement allows a one wheel peel.
I got a break from the sell on the price of the car assuming the unit needed a rebuild, but I can't seem to get one tire to spin. I'll have to find some gravel on the shoulder and see if one tire on the gravel and the other on the pavement allows a one wheel peel.
06-28-2013, 08:02 AM
#4
Rennlist Member
Couldn't the same thing be accomplished with it still in the transaxle by lifting one tire and using a torque wrench on the center axle bolt?
I got a break from the sell on the price of the car assuming the unit needed a rebuild, but I can't seem to get one tire to spin. I'll have to find some gravel on the shoulder and see if one tire on the gravel and the other on the pavement allows a one wheel peel.
I got a break from the sell on the price of the car assuming the unit needed a rebuild, but I can't seem to get one tire to spin. I'll have to find some gravel on the shoulder and see if one tire on the gravel and the other on the pavement allows a one wheel peel.
Yes, but the break free torque is stupid low.
14FtLbs _at best_.
Here ya go:
https://rennlist.com/forums/928-foru...-lsd-test.html
