Pop/Chatter doesn't describe it! R200 Nissan LSD - 38420-RS660-US

[inline6]

I drove my car for the first time in a year or two the other day.  And, I gotta say, the behavior of the rear driveline is brutal.  Let me just say right from the start that I searched through this forum and found all kinds of posts about people complaining of popping and chatter from their CLSD units.  Popping and "chatter" doesn't even begin to describe what mine is doing.  Some background:

 

I bought this Nissan Clutch type LSD unit (see pic of box with part number below) and installed it in a NOS (New Old Stock) R200 4.11 open differential.  It's been about 8 years, so my memory is kind of rusty, but basically, I followed the instructions that came with the carrier...  I took the back cover off, removed the bolts holding the stock carrier to the diff, swapped out the ring gear to the LSD unit and put the LSD carrier with ring gear in the diff.  The instructions provided a spec for backlash - as long as the backlash was within spec, there was indication that going deeper into the diff (redoing pinion gear shims) was not necessary.  I used the fluid which came in a container in the box.  This pic (which I found on the web) is the same stuff - Veruspeed 80W-90 synthetic for LSD.  

 

 

My recollection of driving the car with it the first time and to and from a couple of track day events was that it made the rear end jiggle a bit on tight turns but it was not too obnoxious.  Fast forward a bit, the car has been sitting for a few years and I get my new engine in it.  I take the car for a first drive with the new engine and the rear end behavior is much more severe than I recall.  I did Ground Control rear upper camber plates while the engine was being built... and having read about the 300ZXT axle shafts being too long on some of our S30's, I became convinced that that was the new problem.  

 

So, I organized a group buy with The Driveshaft Shop and got some shorter custom axles made.  Well, I have some engine problems... so fast forward another couple of years to last weekend when I take the car for a drive.  

 

So... backing up the car is none too fun.  Put it in reverse, rev it up a bit and slip the clutch a lot if you don't want it to shudder like the rear brakes are on...  Take a tight left or right turn and the rear binds up badly until Gozilla kicks the ass of the car a couple of inches to the side...  Do that two to three times and congrats, you've executed a 90 degree turn at a stop sign.  

 

And here is the really odd one.  Drive down the road in a straight for miles... and then come to a stop just by using the brakes, (no downshifting) put the clutch in as you come to a stop like normal, say, on a completely flat road.  Wait for traffic to clear and as you rev the engine slightly and let the clutch out, the rear has to "unlock" before you can go.  This is repeatable every time I stop, even from a straight line... to get going again the driveline shudders upon take off.  You can elminate this with lots of clutch slippage... by the way.

 

So, that's basically what is going on.  Looking up the specs on the part number, there appears to be little info available as to what this lsd unit is, but best I can tell it is a 2-way Nissan LSD unit with 70 ft/lbs break away pressure.  

 

Based on my hybridz searching, my next step will be to check fluid level.  I do recall some evidence that fluid escaped the vent when I was checking things over at one of my track day events... After that, I'm considering switching to Redline and adding some friction modifier.  

 

Anyone else have experience with this particular LSD unit?

 

Edited February 20, 2015 by inline6

[johnc]

You most likely have surface rust or corrosion on the clutch plates, Swap out the rear diff fluid to Motul 90PA and add two bottles of friction modifier. Find a large parking lot and drive in a fiver 8 for about 5 minutes.

[inline6]

You most likely have surface rust or corrosion on the clutch plates, Swap out the rear diff fluid to Motul 90PA and add two bottles of friction modifier. Find a large parking lot and drive in a fiver 8 for about 5 minutes.

 

Thanks for the response John. I'll do as you recommend.

[DREW RBZ]

I let my LSD  r200 diff sit for 3 years while rebuilding the car.  The diff also has the extra clutches in place of the stock spacers.  I had similar to what you describe when I put the diff back in and took it for a drive. Didn't seem to matter how many figure eights I did.   I then took the diff apart and sure enough the surface rust/corrosion as described by JohnC was the issue.  Noise was horrible when turning slowly...sounded like someone hitting the pumpkin with a hammer.  Cleaned it up, put in new fluid with added friction modifier and problem solved.