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What is the proceedure to set the preload?

I.m not shure if you have the "wavy or spring"washers in your diff--Jim,maybe you can elaborate?--These are normally found in the cage and go on last before you tighten up the cage.This spring washer or disc together with a shim of a certain thickness determines your preload or breakaway piont of your diff. For daily street driving I would suggest a loose diff,ie. no preload.This makes for a very predictable car and handling.To test preload you will require 2x stubb axles to go into either side of your diff.Clamp one into a vise and slip your diff over it.Next fit the second stubb and attach a fixture that will allow a torque wrench to be used to turn the top stubb.Where the torque wrench clicks is your preload on the diff packs.If you are adament about running preload,I would suggest no more than 20 or so N/Meters.The more preload,the more understeer you should encounter.

Hope this helps.

Barry

Reading this through,I must correct myself.Where the diff breaks loose when turning it with the torque wrench is your preload.

Thanks Barry, you saved me the trouble of writing the sermon! Our diffs DON'T have the spring washers.As it comes from the factory (theoretically) the preload AR gives in the specs is 1,5kgm (about 15Nm) for 25% lock. This is fine for the street but for track use you may want 47% (advocated by AR, even from the old Giulia days!). It is true,as Barry says,this way you get more off-throttle understeer, therefore more aggressive driving is required! I have to admit, that my 47% (with about 30Nm preload) requires more caution when driving quickly in the streets.
Various race and rally cars (usually powerful to say the least) run up to 70 or even80%!
Regards,
Jim K.

Ihave still to understand why anybody would like preload in the LSD, surely the way to go is to alter the ramp angles? Then you can customize the lock in both acceleration and overrun...

Hi guys,
On the subject of preload, the minimum should be used,in order to make sure that there is uniformity during the transition between on and off lock operation and the diff will positively limit slip when one wheel is totally slipping. THIS value of preload is the one quoted in AR manuals (its a ZF spec of course).
Regarding ramps, unfortunately,the 45/45 degree type used in Alfas is not very desirable. I would be a lot happier with an 80/30 degree setup,with MUCH less off-throttle understeer and more lockup under power. Strangely enough, the Montreal had 30/30 angles! That would lead to crazy amounts of corner braking understeer! Its not dfficult for a good machine shop to change the ramp angles, or make new ones in between the existing ones. This way,if you're not satisfied with the results, you can always revert to the original slots. One thing you must be VERY careful about when using different on/off angles: make sure you assemble the pack correctly,because if you install things the wrong way, you will have suicidal understeer!!
Regards,
Jim K.

here we go again, preload vs rmp angles . . . .
i agree with mats. preload does effect the amount of lock up, but its not what its intended for. overall lock up is a funtion of preload and ramp angles. however it is the ramp angles that ultimately govern the behavior of the lsd. imho any ramp angle BUT 45/45 would be an improvement 80/30, 80/45 would possibly be better i know of someone using 60/30 but he is a very very good driver and can control it at the limit. the fact that we are talking about how to dampen trailing throttle UNDERSTEER tells alot about the 45/45 setup. we should all be using 60/30 ramps and be talking about how to dial out the trailling throttle OVERSTEER.

cluthes in a lsd are designed to control the transition of the diff from closed to open and vis-versa. ie the rate of transition to trailing throttle, on power understeer etc etc. more preload makes the car less twitchy as opposed to altering the overall behavior of the diff, although i can remember either jim or barry talking about how the cars drive like pigs if the preload drops out
in a perfect world they would only control this but in reallity they also add to the overall lockup thus behavior of the diff. the well engineered but expensive solution is to change ramp angles or fit a torsen. . . .