Blakt Out Posted December 19, 2010 Share Posted December 19, 2010 Hey guys: I live in Knoxville, TN, and the car was built in N. Wilkesboro, NC, and the drivetrain was built in Wilmington, NC. So, in other words, I'm far away from anyone who has put hands on my car during the build. I still have one issue that I need help resolving. Any and ALL help is appreciated. Despite the fact that I had others build this car, I'm fairly mechanically inclined, and my buddy has a very nice shop that I can use, including the lifts and such. I need to get this figured out and done. I'll give you all the info that I have: The diff is an R200 LSD... old-school type. The CV shafts are Z31 turbo. They are a right and a left. I've read before that you put the driver's side one on both sides, or something like that. This could be my issue. I have the Modern Motorsports 4130 stub axles - 5 lug. Then, I have the AZ Z Car diff mount and such. When I first started driving the car, I had a rotational humming/scraping noise in the passenger side, plus some clunking that I'll explain in a sec. I took the cap off the end of the axle (term might be wrong, in the bearing area) and it had shavings everywhere because the shaft was cutting on the inside of the dust cap. I cleaned it all up, regreased it, and pushed the cap outward a bit. This took away the rotational sound. But the clunking - I still have that. I hate it. If I have pressure on the driveline (as in, acceleration) then it's wonderful. I can have some pressure on it and then throttle it in high boost and there's still no clunk. But if I have just a bit of maintenance throttle and then put more on, it clunks on the passenger side. Here's a real-world situation: Driving down the interstate - accelerate to 70mph. All is well. Try to maintain that speed (not accelerate) and I can feel the pressure on the driveline go away, then when I roll on the throttle again, it clunks HARD. Could this be my diff? Or a wrong/bad CV shaft? I don't think there's really anything else it could be. All help is so very much appreciated. I'll do my best to answer all questions during the troubleshooting. Thanks fellas. Jared Quote Link to comment Share on other sites More sharing options...
johnc Posted December 19, 2010 Share Posted December 19, 2010 Then, I have the AZ Z Car diff mount and such. The cheapest, quickest, and easiest check is the front diff mount. Make sure it hasn't pulled out or or torn the front diff crossmember. Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 19, 2010 Author Share Posted December 19, 2010 Great. I'll check that within the hour. Other ideas? I know this is silly, but when I'm troubleshooting something, I don't assume anything. So, this IS a longnose R200, right? Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 19, 2010 Author Share Posted December 19, 2010 Well, it looks like everything is nice and tight under there. Here are some pics that I just took. It's a bit grimy under there, since I recently drove it 300 miles. Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 19, 2010 Author Share Posted December 19, 2010 Is it correct to have right and left axles? Quote Link to comment Share on other sites More sharing options...
jhill Posted December 19, 2010 Share Posted December 19, 2010 Not helpful but.. "It's a bit grimy under there, since I recently drove it 300 miles." -I only WISH my car ever looked liked that underneath Quote Link to comment Share on other sites More sharing options...
Oddmanout84 Posted December 19, 2010 Share Posted December 19, 2010 Yeah, that's a "bit grimy" enough to eat off of. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted December 19, 2010 Share Posted December 19, 2010 (edited) Some driveline clunks can be VERY difficult to find. My 280Z has had the clunk since I bought it all original with 69k miles on it. Since then, over 20years, I have changed: engine, clutch, trans, entire diff, diff guts, half shafts, CV shafts, diff mounts, RT mount, mustache bushings, wheel bearings, trans mount, and STILL have the CLUNK. I gave up. The only thing original is the drive shaft, and that checks out physically. OTOH, my 240Z with totally stock drivetrain, asides from the L28, new factory mounts, and poly bushings, has ZERO clunk. Go figure. Edited December 19, 2010 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 19, 2010 Author Share Posted December 19, 2010 I have no idea whatsoever, but I have to find it. It's killing me. Maybe I put it on a dyno and then get behind it and find the noise when accelerating. That's all I can think of. So, am I supposed to have both a right and a left Z31 turbo shaft? Is mine a long nose diff? I don't think the diff was rebuilt. Could be that. Geesh, I hope to be done dumping money into this car soon... Quote Link to comment Share on other sites More sharing options...
ModernS30 Posted December 19, 2010 Share Posted December 19, 2010 You have a long nose 300zx Z31T Clutch Type R200 limited slip differential. You are supposed to have a right and a left side CV shaft. The clunk could be in the bearings or it could be the clutches in the differential catching. I have trouble imagining a car built to the specs like yours should have any mechanical problems. Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 19, 2010 Author Share Posted December 19, 2010 (edited) Thank you very much. Then, if this is the case, I may have a diff issue. It's not the bearings, as I've taken them out and checked them already. If it's the diff, then I need to find another to try it out. I had a Quaife in another car. Maybe that's the solution. By the way, we didn't rebuild the diff, as it was stated to be perfect. It also wasn't doing this during tuning on the dyno. So, maybe about a hundred runs on a dyno with 435+whp sent the diff over the edge? Edited December 19, 2010 by Blakt Out Quote Link to comment Share on other sites More sharing options...
Leon Posted December 19, 2010 Share Posted December 19, 2010 It may be the angle of the photo in your third post, but how close is the rear ARB to your half-shafts? I had a bunch of clunks and rattles in the rear of my 260Z so I investigated. Mine was missing a diff strap bolt and had a lonely end link on the left rear control arm with no ARB attached. WTF? I removed the end-link and the metallic clanking was gone. Then I attached the diff strap and acceleration clunk was gone. So, check the ARB and end-links as another simple thing to do before tearing things down. Quote Link to comment Share on other sites More sharing options...
ModernS30 Posted December 20, 2010 Share Posted December 20, 2010 It may be the angle of the photo in your third post, but how close is the rear ARB to your half-shafts? I had a bunch of clunks and rattles in the rear of my 260Z so I investigated. Mine was missing a diff strap bolt and had a lonely end link on the left rear control arm with no ARB attached. WTF? I removed the end-link and the metallic clanking was gone. Then I attached the diff strap and acceleration clunk was gone. So, check the ARB and end-links as another simple thing to do before tearing things down. Differential strap is present. If you didn't rebuild the differential remember they were for stock turbo 300zx power. You could have just worn out the clutches. A typical thing to do is go through and actually add clutch packs to the differential to make it engage better and last longer. I personally have a OBX limited slip in my car. Only have about a mile on it so far but from a could hard shifts and a 4k clutch dump it seems to engage great. Quote Link to comment Share on other sites More sharing options...
jt1 Posted December 20, 2010 Share Posted December 20, 2010 LCA good and tight with no signs of movement, esp at the inner mounts? Spindle sliding back and forth on the spindle pin? Upper strut nuts tight? The solid diff mounts don't make any noise, but they transmit what's there to the tub very well. If it's in the diff itself, a rubber mount might reduce it. jt Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 20, 2010 Author Share Posted December 20, 2010 LCA good and tight with no signs of movement, esp at the inner mounts? Spindle sliding back and forth on the spindle pin? Upper strut nuts tight? The solid diff mounts don't make any noise, but they transmit what's there to the tub very well. If it's in the diff itself, a rubber mount might reduce it. jt Sorry to ask, but what is the LCA? Everything seems tight though, yes. I invited the guy that has done some work on it here in Knoxville to read this thread last night. He said that he had already diagnosed it as "axle slop". He said he put the car in gear and rocked it back and forth to diagnose this. I assume this means that they had play in them (the CVs). Is this how the rest of you would interpret this too, or could this also possibly indicate that the diff is bad? The CVs were simply remanufactured for me. We found them in a junk yard on an '87 Turbo and had them rebuilt, though they had no fancy extra-strong parts to build them with. Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 20, 2010 Author Share Posted December 20, 2010 So, with the diff I have, this should work fine, assuming that it's the diff and not the CV shafts, correct? http://www.jayracing.com/index.php?main_page=product_info&products_id=4374 Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 20, 2010 Author Share Posted December 20, 2010 (edited) K, so I'm just reading up on everything I can find here... I'm not going to assume that the shop that built the car flipped the end cage of the CV shafts around to shorten them up the necessary 3/8", as noted in other posts (by Ross at Modern Motorsports too). Thing is, I don't know what they looked like before. So, can you guys tell from any of my pics if this has been done or not? Again, thanks for ALL the help, fellas. I'm thinking that this, if it hasn't been done, could be why I had shavings in the cap, which then might have messed something up, causing there to be slop. Edited December 20, 2010 by Blakt Out Quote Link to comment Share on other sites More sharing options...
mark Posted December 20, 2010 Share Posted December 20, 2010 If you are also using arizona Z cars rear 4 to 5 lug adaptors, make sure the adaptors are tight. They are the allen head bolts on the rear hub. Quote Link to comment Share on other sites More sharing options...
Blakt Out Posted December 20, 2010 Author Share Posted December 20, 2010 Will do. I'll check that out this morning. Thanks! Quote Link to comment Share on other sites More sharing options...
mark Posted December 20, 2010 Share Posted December 20, 2010 Getting to the nuts on the back of the hubs can be a PIA but that lift will make it much easier. Quote Link to comment Share on other sites More sharing options...
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