Testing LSD - gearbox out of car
Discussion
Is there a definitive way of testing an LSD (993TT) now that the gearbox is out of the car? I can turn the input shaft with it ingear and both drives spin the same way. Holding one still isn't too difficult but I can feel torque being applied.
Strangely, holding the viscous output while turning the input shaft is impossible. But then I generate about 0.001bhp and it's designed to cope with 400 odd
Strangely, holding the viscous output while turning the input shaft is impossible. But then I generate about 0.001bhp and it's designed to cope with 400 odd
Alan, i am pretty sure the LSD is a plate type with assymetric ramp angles.
externally the only thing you can check is the pre-load on the plates. As the plates wear and they can wear pretty quick with hot sticky tyres on a track, the pre-load disappears quickly.
I would check with a knowledgable LSD rebuilder what pre-load you can expect.
For track use the pre-load usually is much higher to stop the LSD "burning" out. A visual inspection of the plates is generally required plus a method of re-establishing and probably increasing the initial pre-load.
Be a little careful though cos higher pre-load will give you understeer and vice-versa. Even if you restore the diff to its factory settings it should be good for a few thousand track miles..
Hope this helps....
PS Just had my BMW rally diff rebuilt, we have machined out the housing and installed double the amount of plates, its now the business...
externally the only thing you can check is the pre-load on the plates. As the plates wear and they can wear pretty quick with hot sticky tyres on a track, the pre-load disappears quickly.
I would check with a knowledgable LSD rebuilder what pre-load you can expect.
For track use the pre-load usually is much higher to stop the LSD "burning" out. A visual inspection of the plates is generally required plus a method of re-establishing and probably increasing the initial pre-load.
Be a little careful though cos higher pre-load will give you understeer and vice-versa. Even if you restore the diff to its factory settings it should be good for a few thousand track miles..
Hope this helps....
PS Just had my BMW rally diff rebuilt, we have machined out the housing and installed double the amount of plates, its now the business...
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