LSD woes: can a stock lsd slip when accelerating?
 

To elaborate the thread title: I have reason to believe that while my car accelerates, the lsd is not delivering power to the tires. I am fairly sure the lsd is quite worn. While accelerating in first thru third gears, my speedometer will rise very fast, and the car doesnt pull any harder to justify the speed increase. Note that the clutch is fairly new, and the rpm's will always justify the speedo, but doesnt justify how fast you go. Also, while driving at slow speeds, where you may be on/off throttle very often, there is a fair amount of slack in the drivetrain, and have heard the lsd can be to blame.

Summary of symptons:
-rpm's and speed's rapid increase doesnt make you accelerate faster
-lsd or possibly drivetrain slop
-doesnt happed all the time (accept first gear)
-always happens during full boost around 4-5krpm

Whats been done to the car:
-'86 Sport w/ a full turbo convertion (engine, tranny, diff, etc etc)
-engine is a S5 (japan import), with FD rotor housings, and a mild streetport, turbo is a s4 (I think)
- Fuel cut defensor
-fmic (front mount intercooler)
-3" Downpipe, w/ Bonez cat (from an NA), w/ a Borla muffler
-ACT clutch (stock replacement I believe)
-Boost levels are around 5-7psi (aftermarket gauge) and full boost by 2650 rpm in 2nd gear
-Tires are 225 series Yokohama Es100 's (fairly grippy)

did you properly break in your clutch when you replaced it? Try going around 20-25mph in 5th gear and nailing on the gas, if your rpms go up and you dont accelerate, its probably your clutch. Not sure if this applies because i am a honda enthusiast, and JUST bought my first RX7, but i thought my clutch was gone in my civic, only to find out my CV boot tore, causing my axel to slip, many of the same signs of having a bad clutch, but a much cheaper fix.

No, the LSD can't do that.

It is either your clutch sliping or wheel spin.

it is your clutch. why would you suspect lsd? do you know what a lsd is or does?

I do know what a lsd does, its just that the symptoms dont add up to the clutch.

I have my doubts about the clutch failing... :( Its been working fine since last winter's purchase. Back then my car was non turbo, so perhaps the wear and the power increase have done it for the clutch. What gets me is that the rpm's will be constaint to the speed for that gear, which should mean the clutch keeping the engine rpm consistant to the gear. I guess it may be wheel spin, but I can hardly break em loose from a stop. Also wheel spin from a stop almost always results in wheel hop. I cant think of anything else that can slip. Anyone else have input?

It's the clutch. /thread.

Well the rear end can't slip,.. it's a direct mechanical connection like the transmission when its in gear.

I'm gonna have to say your clutch is slipping. My car had similar symptoms with a "new" clutch. Of course, I did alot of "spirited" driving. My 3-puck lasted about a year, before it would slip occassionally.

Clutch slip: RPM increases without Speedometer increasing proportionally, speedometer indicates actual road speed.

Tire slip: RPM increases _with_ speedometer increasing proportionally, speedometer indicates higher than actual road speed.


Given what you have described, that both the tachometer and speedometer climb appropriately - yet the car is not accererating, I would suggest getting new tires and/or checking the tire pressure... or just accept that cold and salty winter roads don't provide good traction.

If your differential - open or limited slip, were actually failing in this fashion you would hear grinding and not be moving very much.

However, a worn limited slip can cause low-traction situations to be even more problematic, allowing most of the torque to get directed to only one tire rather than both, once one tire loses traction.

Ok, the more I think about it the more it sounds like tire spin. The tires are fairly new and have been really grippy when its dry, but this issue only has happened during slight misty and/or cold conditions. It just seems really odd that it can be so smooth when at speed, while during hard launches tire spin is rather violent.

you are right - i missed the speedo part.
that is the hard thing about using internet on pocket pc

from what i have re-read, it could be wheelspin - although your car doesnt make neough power... could it be wet when you tried it?

the lsd could slip and only spin 1 wheel at the beginning - btu when that does, it is usually because of worn out clutchs and cones and not enough pressure to grab.

If the LSD is bad, your right wheel will spin and the left one will not see engine power. It just free loads basically. The LSD is bad in my GXL. Also it had well worn tire tread on the right and plenty tread on the left which was an indicator as well.

wait just a minute...
does this mean you have a non turbo clutch in a turbo tranny?

It is a turbo clutch. I failed to mention I've had all turbo components in my car (clutch, flywheel, tranny, diff, etc) prior to the turbo engine swap. The engine was just the very last item on that list.

Your rear end can not "slip", No matter how worn it is, at least not slip smoothly without a lot of grinding and clunking, and at that point i would suggest replacing it. If the lsd isnt working, your car will just do 1 wheel spins, it wont slip altogether. It has to be your clutch, I would get it checked out.

After testing out different road conditions, it turns out its wheel spin. It was just the road surface.

The clutch is not to blame for this.