I recently installed a 1.5 way mechanical LSD in my car. Performance wise i am very happy, although there is one thing bugging me - the noises. I am familiar with the usual clunks and skips, which are fine by me, but for some reason on very tight turns i get a grinding/whirring sort of sound coming from the left or right depending on which way im turning. Im not sure if this is normal... it basically only happens with u-turns and at things like round-abouts. Its definitely coming from the diff.

I also noticed when i installed it, in the middle of the diff where the output shafts meet as a washer. it seemed to be floating around, but definitely meant to be in there... i tapped in one shaft, lined the washer up in its seated position inside, and tapped in the other. Could this be the source of the problem/noise? How can i tell if the shafts are sitting on 100% correctly?

nobody???

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Please forgive my ignorance, but what is a 1.5 way mechanical LSD, & how is it diferent from the non mechanical 1.5 way LSD's?
I'm familiar with Detroit lockers, as well as clutch type & cone type, "spin resistant" diffs, but this one defeats me
Perhaps i should be reading more of the hot car magazines.

I assume this is an H190 you are using or an R200?

There is a thrust block in the diff centre of some these diffs that the axle is located against. The axle is located with a tapered bearing and clearance adjusted by shim plates to provide clearance against the block.

These axle types are used to minimise axle movement and prevent pad knock-off on rear disc axles.

In a clutch pack LSD the plates provide friction as a servo unit to energise the cross that forces the hemispheres to further clamp on the clutch pack.

The amount of clamping force created by the servo action of the clutch plates is determined by the angle of the wedge on the end of the cross.

In a 1.5 way LSD the angle on the drive direction cross face varies between 40 - 45 degrees.

To prevent the axle becoming solid on trailing throttle the angle on the trailing face of the cross is 65- 70 degrees.

I would be checking axle clearances onto the thrust block for starters.

yeah pretty much spot on with your description... and yes its a R200

each side of the diff centre uses a a tapered bearing with shims either side. inside the diff there are pressure plates and clutches, and you can tell its a 1.5 just by looking at the ramps on the wedge, like you described.

so regarding the clearances on the thrust block.. im having trouble visualising it. either side of the tapered bearings you have the race, then on one side a thick shim about 15mm wide, and then on both sides thin shims about 3mm wide. everything seems to be a tight fit...

Has this diff been adapted to another vehicle? If so are the drive shafts not bottoming out on travel of the slip joint during bump.
Also if you are adapting other R200 dummy shafts say from a Z, then the block has to be removed to allow the axle to seat properly as the dummy shaft splined sections are longer than the later CV splined sections.

this diff is on my S13... only the centre has been changed. the housing and shafts are the original parts.

which the shafts fully in, should they be touching in the middle at all?

If you still have the original centre check for a thrust block. If one is fitted the difference in thicknesses of block may require shim adjustments to give the correct clearances.
If so the axles would not be seating properly and this could be the source of your noise.

but i thought the shims either side of the bearing races were just to align the ring gear with the pinion.

what does the thrust block look like? its not the 15mm shim i was talking about, because there is only one in there.

I am not talking about centre adjusting shims, but any shims on the diff outer surface that are used to position the axles?
The thrust block is a solid piece of case hardened steel shaped like a thick disc located in the centre by circlip.