Moderator: martauto
I have the same problem, and would like a replacement top cap (skimmed or not doesnt bother me).Demlotcrew wrote:I believe you can buy them from ZF directly. I have a stock one going spare if you're interested?
Sadly it won't work with a stock 2 clutch LSD as its been shaved down.
It's the dynamic locking torque between the output shafts as a percentage of the torque applied to the LSD spool itself. As you add more power, the diff locks up harder. Hence it's not locked solid at low throttle loadings but will lock up when you give it 'the beans'. Self regulating if you likeMartin347 wrote:Interesting post. I have never heard of the % lock being worked out like this before. Its a shame the post hasn't been answered. I have allways wondered exactly how it is measured, preload is simple but % lock is more tricky.MillRat wrote:A question; the "percentage lock" is not an accurate method to describe the amount of resistance as "percentage lock" relates to the engine power/torque. Therefore, isn't stating the breakaway torque a better measurement?
I ask this because as I understand it, 70% lock equals a breakaway torque of something like 120 ft lbf (160 Nm) and is thus 70 percent of the engine torque (160-170 ft lbf or 220-230Nm for a standard 325i). If I was to build a much more torquey M20 (or use another more torquey motor), the "percentage lock" becomes some smaller number (depending on the torque of the new engine that is). One would then think that the 2 LSD's are different as the % lock values would be different, when in fact they are exactly the same LSD. Therefore, to accurately compare one LSD to another, the breakaway torque should be stated instead.
As I said above, this is my understanding.
Breakway torque has so many data variables:- tyre compound, road surface, suspension geometry, weather conditions, mechanical downforce etc, it is not common unit of measure.Martin347 wrote:Interesting post. I have never heard of the % lock being worked out like this before. Its a shame the post hasn't been answered. I have allways wondered exactly how it is measured, preload is simple but % lock is more tricky.MillRat wrote:A question; the "percentage lock" is not an accurate method to describe the amount of resistance as "percentage lock" relates to the engine power/torque. Therefore, isn't stating the breakaway torque a better measurement?
I ask this because as I understand it, 70% lock equals a breakaway torque of something like 120 ft lbf (160 Nm) and is thus 70 percent of the engine torque (160-170 ft lbf or 220-230Nm for a standard 325i). If I was to build a much more torquey M20 (or use another more torquey motor), the "percentage lock" becomes some smaller number (depending on the torque of the new engine that is). One would then think that the 2 LSD's are different as the % lock values would be different, when in fact they are exactly the same LSD. Therefore, to accurately compare one LSD to another, the breakaway torque should be stated instead.
As I said above, this is my understanding.
Driftnething wrote:Ahhh yes, it was just stuck
Thanks !
Ok, nicely put. Makes it easy to understand what millrat was originally saying about. The more powerful the engine that is driving the diff, the More grip required (I.e friction plates/shallower ramp angles) the diff will need to lock the diff. If you put one of our 188mm diffs in a robin reliant, it would Never get locked, but put it in a 500bhp m3 and it would almost be like a welded diff (on acceleration).gareth wrote:In short, it's near impossible to measure it without a dedicated test rig. The spool would need to be loaded up to various torques, held against the output shafts, then the torque resistance between both shafts measured by independently rotating them... Not an easy task!
This is why the lock is expressed simply as a percentage. It's a ratio of applied torque from the prop (or more specifically by the crownwheel onto the spool as the final drive ratio will vary this) to the braking torque between the output shafts. 0% = no lock, 100% = locked solid. 40% will be 40Nm if 100Nm is applied, 400Nm if 1000Nm is applied.
It's like saying: "How tight will this spanner tighten this nut" well it has design limits but at the end of the day it's directly proportional to how hard you pull it
) sitting on my bench which needs a refresh. It'll have an S62 sitting a few feet in front of it, and be surrounded with E36 HSD coilovers and whiteline ARB's. The car's going to do a few track days, but it'll very much mainly be a road car. I was thinking of new standard BMW plates and perhaps the thicker Porshe dog ear plates, though having had a read through this thread, perhaps standard dog ears would be adequate?
Dave. 
Very reasonably priced too. )
