porscheracing

hey guys,

i currently reassemble a lsd and want to upgrade the locking rate!

besides using other preasure rings i want to add more clutch packs.
the easiest way would be to just remove a 4mm spacer on the bottom of the lsd-case and instead use a third clutch pack.

but doesn't an uneven amount of clutch packs mean, that one wheel is locked more than the other. ie you have 35% transfer in right corners (because of the second clutch pack on the one side) and the standard 25% in left corners, as you have not changed the clutch packs on the other side.

or am i wrong and you can tell me, how and why the 3 clutch diff behaves the same in left and right corners?!

any lsd specialists here?

GTgears

Specifically which LSD is this? Does your LSD not have matching 4mm spacer rings on both sides?

You do want to keep it symmetrical. I suspect that you've got a 2 plate LSD? Is it a ZF or a GKN version?

porscheracing

it is a zf 006 lsd unit (actually for a bmw... but 951 ie had quite similar zf 006 lsd).

i do habe only one spacer at the bottom of the housing. so if i remove this one i could put in a third pair of clutches.
but then i do have an uneven count of clutchpairs.

to fit in a fourth pair, i would need to machine the cover what i cannot do myself.

and as i will change pressure rings to 30° angle, i would habe a locking rate of ~60% with 3 clutch packs what would be quite ok for not having any machining trouble!

but i wont do three clutchpacks if it doesnt make sense because also the locking rate is uneven und the car will behave differently in left and right corners or on accelleration!

GTgears

Interesting. So is the spacer up in the nose (non-ring gear) end of the housing. That's what would make sense, and then they likely offset the spacer height with an extra 4mm of material on the end cover, keeping the gears centered within the body.

I wouldn't mess with it, other than to rebuild it and maybe add some more aggressive belliville washers to introduce a bit more preload.

porscheracing

yes, the spacer is on the non-ring gear side!
and yes, the end cover is 4mm thicker comparing the space for the small washers.
so they made a thicker cover instead of a second spacer :-(

the problem is, that really very few people know lsd's in detail and even these guys do not have the same suggestion concerning that point. so i wanted to try my luck here as i hope, some performance enthusiasts with deeper knowledge of lsd stuff are here around!

if i dont come to a final conclusion, i will try that out myself. i do have a variety of lsds here and i will set them up differently and compare them with each other.

but i dont want to try silly things if someone can tell me that it is silly before ;-)

porscheracing

i definitely dont want to use thicker/more aggressive washer discs for more preload as preload means more understeer and puts more permanent stress on the clutches as they always need to work quite hard and they dont get enough fluid/cooling then.
i have already less cupped washers here as when i upgrade the locking rate via the new pressure rings, the preload automatically rises a lot when i would use the old washers!

GTgears

What is the thickness of the center cup section with the gears and pins in place?

What is the thickness of the clutch stacks on each side? Belleville washer thickness?

porscheracing

center section: ~65,7mm
each clutch stack: ~4mm (1.9/2.0/2.1mm floater (as required) / 2,0mm frictional disc)
cupped washers: 2.5mm each