R200 OBX LSD "chattering" in tight turns

[Marc280]

I've only just got my car back on the road after a long rebuild and engine swap (it's an 81 280zx) and as a part of the build I installed an R200 OBX centre. I had all new bearings put in it and the backlash etc setup by a driveline shop but it is chattering or more like banging and poping under tight turns at car park speeds. When driving in a straight line it seems to be fine and there are no abnormal noises. I replaced the bolts and washers with the rbryant kit and setup the belleville washers as described in on the page

 

http://rbryant.freeshell.org/obx_washers.htm

 

Here is the section from that page

The Nissan R200 differential is an example where I completely changed the washer kit from what OBX provides. After trying a bunch of options and testing them I finalized on a kit that includes 8 small washers and 2 larger washers in the center that are used to hold everything in place. This is necessary because the R200 unit's retainers do not properly surround the stack and hold the washers in place. The center washers sit outside of the retainer and their larger cup holds the inner washers in place. OBX attempted to solve this with a strange and suboptimal stack configuration with many washers in parallel instead of changing the machining of the unit. In most cases only 7-8 of the outside washers should be used and should be stacked (()()()()) where the red washers are the larger center washers. The two outside yellow washers should be removed if the stack is too tall. This configuration solves the retainer issue and is working great on dozens of cars.. Note that the center washers are stronger and therefore will not compress and are not counted in the number of turns required to compress the outer washers when calculating preload.

 

Could having too much preload cause this? I did notice that when it is poping and banging if you accelerate hard it seems to go away but before this it feels like the diff is about to fall out of the car! Something definitely feels very wrong with it the way it is now especially when other people are saying that you hardly know it is there.

 

Any other suggestions?

[johnc]

Too much preload/breakaway.

[NewZed]

Isn't the first answer - more limited slip additive?

 

My mistake - re John C's Post #6.

Edited September 22, 2012 by NewZed

[HowlerMonkey]

I believe the driver's axle shaft is shorter than the passenger side.

 

I'm not sure if it would cause the noise you hear and it's pretty hard to install the longer one on the shorter side.

Edited September 21, 2012 by HowlerMonkey

[RebekahsZ]

I have had same problem, there are a lot of posts out there from me and a bunch of guys helped me with advice. Mine is a R200 Z31 CLSD with 6 new clutches and 4 shims for a tested preload/breakaway torque of 63 pounds wet. I still have an occasional pop/bang and shudder but it is much better than when I first did the mods. First thing to do is take car to a parking lot and do circles clockwise for 15 minutes then counter clockwise for 15 minutes. Turn as tightly as you can but not so tightly that it bangs. Yes, you will get dizzy and bored. This dramatically reduced my popping. I have no idea why it helped. If it bangs too much, drain off your diff. oil then refill after putting in 2 tubes of friction modifier. Filling diff. on the car is a real PITA. I was able in my 240Z to pull a drain plug in the spare tire well and run a 3/8" hose down to the diff. using a funnel at the top end. This winter, I plan to remove some shims to reduce breakaway torque. Hope that helps.

[johnc]

The OPs diff is an OBX. Its not a CLSD but a gear driven LSD.

 

http://forums.hybridz.org/index.php/topic/88099-obx-differential-inspection-and-installation/

[Marc280]

Thanks for the suggestions, as John mentioned it is a OBX (helical) style diff centre, so from what I can tell I don't think a limited slip additive will change much. I setup the diff as suggested in the link above, but as you can see there, people have installed the washers that give the diff the preload in so many different ways. Anyway the car is in for 'engineering' at the moment which we require for registration here and I should get it back by the weekend. Once I've got it I'll be pulling out the diff for an inspection and to set it up with less preload and we'll see how that goes.