Limited Slip Differential, always locked?

[TomFraser]

I am doing my brakes (new calipers, rotors, hoses, pads, hardware) and have my supra up on jackstands on the back only (both back wheels up, fronts chocked)

I turned one of my rear wheels and noticed that the other immediatley turned with it. If my understanding of a LSD is correct, it should turn a little before the other side begins turning.

I tested the LSD by turning the car on and putting it in drive. Both wheels immediately begin spinning (both up in the air).

I thought there should be more "play" between the wheels than that for when turning... am I correct, or is my little knowledge on the subject poorly understood?

 

[IJ.]

Wheels shouldn't turn independently until you reach the breakaway torque of the diff.

If they do it's either an open diff or a Torsen.

 

[TomFraser]

Wheels shouldn't turn independently until you reach the breakaway torque of the diff.

If they do it's either an open diff or a Torsen.

Good news for my diff then...

So if one wheel is grounded I should only be able to turn the other wheel in the air with a helluva lot of force, correct?

I appreciate the quick reply, you're the best around here

 

[IJ.]

Yep if it turns easily the clutches are just about done, stock break away (ie: If you lock one side and put a torque wrench on the centre nut on the other side) is usually around the 45>50ft/lbs for most LSD's, in the past I've built my diffs to have 85>90 but they get a bit ugly to drive as they chatter/skip the inside wheel on tight corners and make the car understeer/push badly.

 

[TomFraser]

Cool my LSD is working like new then... my car was babied it's entire life (reciepts show the LSD fluid changed 3 times at a toyota dealership in Florida, 4 counting my doing it, and at almost 130000miles I would say thats pretty good.

I appreciate the help, thanks!

 

[hvyman]

^very good and most people never change there fluid.

 

[TomFraser]

^very good and most people never change there fluid.

this car was 2 people's baby... The first owner did all the maintenance and more, and whenever he had an inkling of something going wrong he brought it to the dealer, I have EVERY reciept and many have things saying "idle seems high" or "when turing owner thinks he heard a noise"

The second owner did all kinds of things to refresh the car, and whenever he had a taillight out he brought it to a shop that charged 46 dollars to replace a bulb (again, I have EVERY reciept).

The third owner had the head decked and a felpro headgasket put it, changed all fluids (except LSD) and put in new suspension brushings, it then sat for years.

Someone bought it, brought it to new hampshire, it sat for 1 year and I bought it (for 1400, in my opinion a steal), changed all fluids, new fuel filters, pump, new suspension, new rotors/calipers now, new exhaust, and a bunch of other upgrades.

Only thing bad about the car is the paint, and the hatch/hood struts

I'm hoping that since it has been babied all it's life (with reciepts to prove it) it is good to me

 

[toyzforme]

I just bought a complete rebuild kit (new shims, washers, clutches, spring) from champion for 200 bucks. Going to rebuild it and get ready for another season of autocross. Going to try and kick some subaru ass