rotating clunk - R33 gtst

[hardsteppa]

hey team

so car is a '96 S2 R33 gtst, with a Cusco 1-way lsd.

Having an issue with a clunkclunkclunk pulsing feeling coming through the car from the rear when driving in a straight line, present between 25-35kph then goes away, and a grindy/vibraty feel between 1-10kph. But, when going through the 25-35kph range under any reasonable acceleration, can't feel any issue present - although goes through that km range very quickly.

Things done so far

- rebuilt rear driveshafts just recently, thinking this might have been the issue - no change

- replaced centre bearing in tailshaft

- replaced all wheel bearings with gen nissan

- every single bush replaced with poly, and solid diff front bushes

At low speed 1-10kph, the grindy feel is the same as you get from normal operation of the lsd when turning, it's just happening when in a straight line, so thinking it could be the plates are worn and not enough initial torque keeping it 'locked'? Measured the plates and all of them measured as worn by 0.05mm but haven't been able to find out any info about cusco lsd's to see what they class as the min thickness, and when to be replaced. 

[GTofuS-T]

Looking through the Cusco LSD guide (specifically pg9, fig 9 from the lnk below), it seems the initial torque is provided by either the Cone Spring (MZ) or Coil Spring (RS), for which seems to have a life and point at which a rebuild is required (which i assume is just replacing these components not necessarily the plates themselves?)

http://www.cuscousainc.com/downloads/dl/file/id/190/cusco_lsd_guide.pdf

[hy_rpm]

Using the correct oil?

[hardsteppa]

On 9/28/2017 at 4:59 PM, GTofuS-T said:

Looking through the Cusco LSD guide (specifically pg9, fig 9 from the lnk below), it seems the initial torque is provided by either the Cone Spring (MZ) or Coil Spring (RS), for which seems to have a life and point at which a rebuild is required (which i assume is just replacing these components not necessarily the plates themselves?)

http://www.cuscousainc.com/downloads/dl/file/id/190/cusco_lsd_guide.pdf

yes definitely, have some new springs on the way along with a rebuild kit.

[admS15]

How many $ for springs and rebuild kit?

[hardsteppa]

Springs are about $6 each. Rebuild kit is $250ish, plus about 70 postage, direct from JPN.

[hardsteppa]

so is anyone else here using a Cusco lsd or disassembled one? In the attached diagram Item 9 is a plate (washer of sorts, really) that goes between the clutch plates and housing. I got my lsd 2nd hand and it didn't have these end plates in it. 

As shown at 1:24min into this video though, doesn't look like it uses them for this particular centre for r200 diffs

 

[GTofuS-T]

Nope. but it is on my wanted list!

Just the other day however I was reading an article on motoiq where they rebuilt an R200 diff for a 350z (http://www.motoiq.com/MagazineArticles/ID/4627/Rebuilding-a-Nissan-R200-Differential-to-Be-More-Drift-Happy-With-Z1-Motorsports-Part-2-Tuning-the-Differential-and-Installing-the-Ring-and-Pinion.aspx)

Based on this I'd guess no.9 plates are optional shim's to change to locking characteristics.

[hardsteppa]

ok so the clunk/grind i'm feeling isn't to do with the lsd it seems.

Fitted the new clutch plates and springs - went to 8 springs now instead of 6, and 100% lock on the plates. 

The feel of the lsd seems smoother rather than harsher with more springs - it's clunky and noisy and many ppl would hate it, but goddamn i love the lsd...much performance drive, much enjoy.