R200 LSD Z31 CV binding noise

[zgeezer]

Ok, before I break down this differential I would appreciate some idea of what I should be looking for.

 

Here are the facts:

 

1. R200 3:36 with Z31 lsd & CV axles. The 12mm carrier is shimmed with stainless steel tubing to fit the 10mm ring gear bolts. An item I purchased from a member.

 

2. Modern Motorsports rear disk brakes using MM early welded companion flanges.

 

3. R200 disassembled, inspected, and reassembled using all new bearings. Back lash set and contact pattern well centered. R200 filled with gear oil, pinion rotated to spread lubrication and then installed in vehicle with differential side "stubs" installed. At this time all bearings and seals in the rear struts were replaced with Nissan replacement parts. Car sat for 4 years,

 

4. 18 months ago, Z31 Lsd installed along with the additional friction clutches purchased from member on this forum. Spacers eliminated.

 

5. Interior of differential clean, LSD very clean and nothing appeared out of place. LSD broken down and assembled using gear oil as lubricant. Assembly and disassembly performed by experienced mechanic showing me step by step the process. When reassembled, the differential rotated smoothly by hand.

 

6. Filled with differential oil and GM LSD oil supplement.

 

7. CV axles dissassembled. Cages on wheel side reversed as per MM instructions. All boots removed/replaced. Cage and balls cleaned and inspected. No apparent wear or galling. CV axles reassembled and installed in Z.

 

8. Installation of CV axles was tight on both sides, but doable by hand without the necessity of dropping the rear control arms.

 

9.. Z was parked in garage for last six months, being moved from time to time as work progressed on body. Moved by hand and appeared to roll smoothly.

 

10. Last night, I put the Z up on stands and began to remove struts/differential for new shock inserts. The rear suspension is at full droop.

 

11. I removed the wheels and rotated the stub axle by hand. Smooth rotation for about 90 degrees and then a bind for another 45 degrees or so and then smooth rotation for for almost a complete rotation at which time I feel a "bind". The axles rotate smoothly through the bind. What I call a "bind" is an increase in the torque I need to turn the axle. My judgment is that if it takes another 50% of effort to turn the axles through the "bind". I can turn the axles using my bare hand (one hand) spanning the lug nuts. My thought was that this is the bind I've been reading about and the cure would be shorter axles.

 

12 I moved to the passenger side and rotated that axle. It turns smoothly by hand, but at about 25 degrees of rotation I hear and feel a substantial "clunk". The "clunk" does not seem to be at the initiation of rotation. It occurs during rotation and at different places.

 

13. I do not have the drive shaft installed and, as this is an LSD, both axles and the pinion turn together. I can observe the pinion flange as I rotate either axle: it rotates smoothly, but when I hear and feel the "clunk" the pinion flange appears to slow down and then pick up rotation speed.

 

14. Now, when I rotate the passenger side axles it still "binds" but the difference of perceived torque is substantially less to pull it through the "bind".

 

15. In trying to isolate which of five assemblies (differential ,two CV axles, and two sets of hub bearings) might be the culprit, I observe the following anomalies:

 

a. There is no audible clunk or felt clunk when the assembly is rotated by turning the passenger side axle. The 'bind" is still there, buy no perceived difference in rotation of the pinion flange.

 

b. There is both and audible clunk and distinct feel of a disconnect when rotating the driver's side axle by hand.

 

As this assembly turns as a unit, I don't understand why I hear and feel this clunk when the assembly is rotated from the driver's side, but not from the passenger's side.

At any rate, I don't wish to begin disassembly without having an idea of what I should be looking for. Does anyone have suggestions for a flow chart or procedure I might employ to isolate the offending part(s). Is this a common problem? In short,...Heeeeeeelp.

 

g.

[JMortensen]

The bind that I'm trying to fix is a bind in the length of the CV axle. The CV axle is just too long to fit without some load on the diff when you use stock control arms and stock Z31T CV axles. Having figured out the bind and fixed it before actually assembling my own car I've never actually tried turning the wheel and feeling for resistance with the bind in place, but honestly I don't think you're all that likely to feel resistance from the bind by turning the wheel.

 

I would guess, and it is just a guess, that you have a rotor that is moving on the studs as you turn the axle. You could fix this by putting a couple lug nuts on to hold the rotors in place on the stub axle while you are turning them. This would explain both the clunk (rotor shifting) and the tough spot (pads dragging on the rotors).

 

If you have MM's Extreme kit you might also look at using a dial indicator to true the rotors before you run them. This has been discussed previously, but basically it involves using stainless shims between the rotor and hat to get it trued to less than .002" runout. This will ensure no brake shimmy, and it's not that hard to do.

 

I do think you would be well advised to buy my short shafts regardless of whether an out of true or loose rotor ends up being the cause of your issues. Based on my calculations there should be no way that you can run the welded adapters and the stock shafts without significant bind unless you have a control arm that is something like 3/4" longer than stock, and at that point it would JUST BARELY clear. I've got some shafts on order right now and they should be here in a few weeks. You can get the group buy price if you sign up before they arrive.

[zgeezer]

The bind that I'm trying to fix is a bind in the length of the CV axle. The CV axle is just too long to fit without some load on the diff when you use stock control arms and stock Z31T CV axles. Having figured out the bind and fixed it before actually assembling my own car I've never actually tried turning the wheel and feeling for resistance with the bind in place, but honestly I don't think you're all that likely to feel resistance from the bind by turning the wheel.

 

I would guess, and it is just a guess, that you have a rotor that is moving on the studs as you turn the axle. You could fix this by putting a couple lug nuts on to hold the rotors in place on the stub axle while you are turning them. This would explain both the clunk (rotor shifting) and the tough spot (pads dragging on the rotors).

 

If you have MM's Extreme kit you might also look at using a dial indicator to true the rotors before you run them. This has been discussed previously, but basically it involves using stainless shims between the rotor and hat to get it trued to less than .002" runout. This will ensure no brake shimmy, and it's not that hard to do.

 

I do think you would be well advised to buy my short shafts regardless of whether an out of true or loose rotor ends up being the cause of your issues. Based on my calculations there should be no way that you can run the welded adapters and the stock shafts without significant bind unless you have a control arm that is something like 3/4" longer than stock, and at that point it would JUST BARELY clear. I've got some shafts on order right now and they should be here in a few weeks. You can get the group buy price if you sign up before they arrive.

 

Thanks for the reply. Yes, a set of short axles is on my short list as soon as I determine whether or not life and my mechanic have given it to me in the shorts as regards to my rear end.

 

The rotors and calipers have been removed. I still have the clunk from the driver's side. The passenger side seems to be smoothing out, with resistance pretty close to constant as I rotate the stub axle. When I move underneath and rotate only the pinion left and right there is a slight clunk and the pinion flange has a slight free movement before it rotates the ring gear. Unlike the passenger side, when I rotate the assembly by turning the pinion flange it turns smoothly and quietly... no perceptible change in resistance and no clunk. In a properly set up R200, how much free play at the pinion flange could I expect to see... or feel?

 

G

[JMortensen]

There would be a little bit, if you have the driveshaft and halfshafts disconnected, might be 1/8" or something like that. If you still have all the rest of that connected, then it's very very difficult to feel anything accurately as described here:

http://forums.hybridz.org/index.php/topic/105207-the-dreaded-diff-clunk/

 

If you really wanted to see what the backlash is, the correct way to do it is remove the diff, pull the cover, and measure with a dial indicator.

[zgeezer]

There would be a little bit, if you have the driveshaft and halfshafts disconnected, might be 1/8" or something like that. If you still have all the rest of that connected, then it's very very difficult to feel anything accurately as described here:

http://forums.hybrid...ded-diff-clunk/

 

If you really wanted to see what the backlash is, the correct way to do it is remove the diff, pull the cover, and measure with a dial indicator.

 

Thank you for directing me to your previous post. I searched, but didn't hit that one. The pinion flange rotates just a bit less or at 1/8" as you describe..

 

So, this weekend, I'll pull all assemblies for paint, take one last look inside the differential and reinstall, less the CV axles. As I have the MM stub axles and and the RT mount, I lack only your short axles. No $ at the moment, but all in good time.

 

Thanks,

 

G