xupkid2

So I've read through the older posts and couldn't find a decent answer. Im hoping someone here can help me though.

Last winter I had my stock LSD rebuilt on my AOR trans. I did about 10-12 track days on it last summer. I pulled the trans out this winter and just bench tested the LSD. I used the 8mm allen bolt in teh center of the "cup" to test the torque. I held the other "cup" with a vice so it didnt move. I was able to get around 19 ft/lbs on my torque wrench.

Anyone know if this is an acceptable level. The car is a dedicated track car and I would rather not put in a new LSD this year if I dont have to.

Thanks in advance
Brian

gt37vgt

I posted a thread ages ago asking about that break out torque spec . the only reply i got was 30-100ftlbs so i guess that 19flb seems a bit low ..
how did it feel last drive ??

Bri Bro

Should be good to go. 19 Ft lbs =25.8 N M

xupkid2

So according to Brian's test I am ok. Brian, where is that test from?

Bri Bro

Volume 2, section 39-122f of the 944 shop manual, 40% lockup differential.

When I tested mine, it came in around the same torque values you are seeing.

333pg333

I would think that if you have it out lying on a bench somewhere, you may as well rebuild it, no?
The info that I received and made me switch to a 50/80% was that these LSD units were not designed for trackwork and would wear out frequently. When I had one it was rebuilt I think twice in 2 years.

xupkid2

Brian, thanks so much. I had looked in the shop manual but did not see that info.

Patrick, I really would like to replace the LSD with a GT one but I've spent soooo much $$ this winter between a body work, motor rebuild, cage work, SFR headers, interior gutting, etc.... my pocketbook is a bit worn out. If I can make this LSD last for part of this season I will be ok.

gt37vgt

its not out of the trans axle Pat perhaps not even out of the car ..
rebuilding the diff is not so hard but there is a bit involved in getting in and out of the trans-axle

vette951s

Here is my experience on this subject:

https://rennlist.com/forums/944-turb...ited-slip.html

Bri Bro

I use my car for DE events and I had a LSD unit installed 5 years ago and so far the LSD is still ticking for over 30 events. What appears to be hard on the factory unit is when you go to large rear tires and run slicks in racing conditions without an oil cooler loop.

If I was trying to make a unit last under these conditions, I would change fluid on a regular basis and try to improve the cooling on the trany using fans and a external oil cooler. TonyG and John Hajny (Redlineman) have posted on how they did this.
Links are below,

https://rennlist.com/forums/racing-a...ml#post2700423

https://rennlist.com/forums/944-turb...ns-cooler.html

333pg333

Good points.

TonyG

You can certainly rebuild the stock LSD. Probably the cheapest way to go.

But it won't hold a candle to a Guard 50/80 LSD on the track (for many reasons).

I'm classed in GT2 and I run against the fastest of the fast cars with really good drivers. That said the Guard diff is an easy (not cheap) "advantage".

I say "advantage" because all the other CUP, RSR, etc.. cars are running a similar assemetrical LSD. It's almost a must have item.


TonyG

User 52121

Interesting. I think a new LSD is in order for my car next winter as well. The car has the LSD option code, the previous owner told me it had LSD, but then the previous owner also had a rebuilt trans installed. The trans does NOT have an LSD in it (or at least, it's not functioning) as I learned from auto-X'ing it last summer and the few "spectator" laps I did at the Octoberfest DE @ Blackhawk. 1-wheel-wonder everywhere.