cygnusx1 Posted April 17, 2006 Share Posted April 17, 2006 My fuel tank is leaking so I got the rear end up on stands and drained the tank for repair. While I was underneath the car I decided to inspect the drivetrain. The driveline clunks when I get on-off the throttle in the lower gears. Now I know this is a trait of about every S30 ever built but I think I want to get to the bottom of it. It's not one of the usual suspects. NOT: U-Joints (CV in my case) Diff Mount Mustache Bar Wheel Bearing Stub shafts Splines MAYBE: Backlash in the diff gears Bearings in the diff (I doubt it because they are quiet) If I take one of the rear wheels and rotate it gently, I can go about 10 degrees before the other wheel turns opposite direction. If I grab the driveshaft and twist it, I can get about 2-3 degrees of play out of it. Trans in neutral. Is there normally this much lash stacking in the spiders, ring and pinion? Are modern diffs this loose? Should I run sawdust in the diff. Quote Link to comment Share on other sites More sharing options...
jt1 Posted April 18, 2006 Share Posted April 18, 2006 That's pretty normal for a diff that's got some miles on it, just the accumulation of wear in the gears and bearings. It will probably run quite a while still. If the clunk bothers you, you can rebuild it, but if the clunks bearable I would probably run it a while. jt Quote Link to comment Share on other sites More sharing options...
skipzoomie Posted April 18, 2006 Share Posted April 18, 2006 I've seen the spider pinion shaft come out and trash the diff. You might want to remove the cover and take a look. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted April 18, 2006 Share Posted April 18, 2006 My R200 does the same thing. When I got this diff from a JY, it had the least amount of play out of the 10 or so pumpkins I looked at. I have always wondered how big a problem this is, especially now that I am going V8. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 18, 2006 Share Posted April 18, 2006 You've got 4 gears to get the slack out of when you're turning one wheel and looking for the other to turn, so it will take a bit of rotation. If you measure backlash at the ring gear (took the cover off and grabbed the ring gear itself and felt the play between it and the pinion) it would be a lot less than you get when you twist the pinion. There are some diffs where you have to set the backlash with pinion rotation, and I don't have a specific example, but it might be 1/8" of twist on the pinion to equal .012" backlash. It's not at all a 1:1 ratio. What you've got there sounds normal to me. Quote Link to comment Share on other sites More sharing options...
bjhines Posted April 18, 2006 Share Posted April 18, 2006 The halfshaft stubs have a loose fit into the differential side gears... and the gears move around/ have clearance when they are not under pressure... this causes some.. if not all of your clunk.. assuming you already know that the rest of the mounts and bolts are tight. check the condition of the splines on the stubs and in the side gears... if your clunk is worse than normal.. this could be an often overlooked source of noise. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 16, 2006 Author Share Posted November 16, 2006 Good point. I suppose this Winter I should also pay a visit to the driveshaft and the splines in the rear of the transmission too. It just seems like too much play in the overall drivetrain but not alot of play in any one part. Maybe it's time for an overhall of all these rotating parts. Quote Link to comment Share on other sites More sharing options...
gogriz91 Posted November 17, 2006 Share Posted November 17, 2006 I'm putting a new CLSD from the group buy into a donor R200. What else should I look at replacing while the diff is out of the car and apart? Is it customary to media blast and powdercoat the diff? Quote Link to comment Share on other sites More sharing options...
datman Posted November 23, 2006 Share Posted November 23, 2006 I just fixed the loud clunk on my car, it would clunk as I backed on and off the power and from going forward to reverse. It was the 2 nuts that bolt the Diff to the Moustache bar, once they were done up really tight the clunking stopped, took me months to figure that out Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 9, 2008 Author Share Posted October 9, 2008 Old thread and yes the diff has held up with all the clunking, however it is getting worse and I noticed some play in the right side output hub. With the car on the ground and in gear, if I roll the car forwards and backwards, the right hub shifts in and out along the axis of the axle about 1/32" thus making a clunk. It looks like this is where most of my clunk is coming from. I've got all the external sources of clunk tied down pretty good. Any idea why the output hub would want to thrust in and out of the diff under forward and reverse torques? I run 280ZX Turbo CV axles. I am going to have the drivetrain out of the car in a month or two for the Z32 trans swap and want to get ready if I need diff work also. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 9, 2008 Share Posted October 9, 2008 If the wheel moves in and out the first place to look would be the wheel bearings. As to why it would move in and out, it could be that the toe is causing it to move one direction then the other. If the bearings are bad, I'd take a close look at the splines on the stub axles and companion flanges when you're in there replacing the bearings. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 9, 2008 Author Share Posted October 9, 2008 Jon, it's not the wheel, it's the inner CV joint moving in/out relative to the diff case. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted February 17, 2009 Author Share Posted February 17, 2009 Old thread but I want to revive it because I just took apart the entire drivetrain and re-assembled it with the OBX LSD center. Here's What I noticed. 1st Biggest Culprit: (bjhines called it) The axle splines are definitely not a snug fit into the diff. They were somewhat loose in the spider gears and equally loose in the OBX. 2nd The ZX Turbo CV shafts that I am using had noticable play in the outer tulips when I cleaned out the grease. 3rd The OBX has some lash inside of it because of the nature of the backlash of all the helical gears involved....and relatively loose tolerances in manufacturing. 4th The rear u-joint in the driveshaft has a tiny tiny bit of lash to it. 5th My rear wheel bearings have some play...within spec but it's there. I just finished the assembly and still need to install the transmission. I should be test driving it next week, pending weather. I expect as much or more clunking that I had before, due to the helical diff. At least I know it's not a failure. It's just a tolerance accumulation. Side note. My dad is retired and offered to help me out by doing some work on the car during the week. I discussed fabricating a stainless strap to hold the front of the diff down. Well, he thought it a good idea to drill two holes front to back, clear through the front diff mount and crossmember, and install two horizontal 3/8" carriage bolts. Effectively making a solid diff mount! Ughhh. I didn't want a solid diff mount but leave it to an old Italian engineer to go overkill! I need to keep my eye on the holes he drilled for stress cracks now. If it's too noisy, I'll re-engineer his method. LOL. Quote Link to comment Share on other sites More sharing options...
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