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Shake down run - yikes!


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A quick summary:

This Winter, I installed a 4.11 R180, a 280 ZX 5 speed, new rear KYB's, new urethane bushing kit and refurbished (cleaned, painted) my rear control arms. The diff. was nice and tight when I installed it, no play. The u-joints are all original, but none of them had any slop at all. The driveshaft u-joints had no slop either. Everything from the tranny back came out of the car during the process, except the fuel tank. I didn't have any rear end noise with the original set-up.

I know that I need to go back and re-torque the rear suspension bolts, because I had the car up in the air when I torqued them, and I now know that's no good. But I figured it would be OK for a 1/2 mile cruise down the road just to shake the dust off.

Its 65 in MA today, so I took her out for a quick shake down, and I'm getting a really bad noise from both rear wheels. It almost sounds like the emergency brake is rubbing, but it's not, both wheels spin without resistance.

I didn't replace (or re-pack) my rear wheels bearings, and I'm wondering if this is where I screwed up. It sounds a bit like it could be gear/bearing noise. I did need to use some heat to remove spindle pins, etc. I'm wondering if I overheated the bearings, or cooked away the bearing grease.

The only real hint I can give, is when one side of the car is "unloaded" the noise seems to go away from that side. In other words, if I take a hard left, taking some load off the right rear side, the noise seems to go away from the right rear wheel.

Any ideas?


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Who built the diff? It should have a bit of play in it (backlash) between the pinion and ring gear. It most definately should not be tight. Other than that you say the wheels spin freely but can you hear any rumblings when you spin them?

I bought the diff from a local Z car guy, who I've bought stuff from before. The noise seems to be coming from the wheels, not the diff. Tight may have been an exaggeration, but there was no play or wobble in it.

I have to put the car up on jacks today and diagnose some more.

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Hi Paul,

Those brake drums look new. Or have they just been painted? Anyway, it could be that the drums are rubbing on the backing plates, or on the shoes themselves. I had that problem when I first got my car back on the road.

And that problem definitely manifested itself in the exact way that you're describing. Take a hard left, you'd only get the noise from the left wheel. Then it was both wheels, with a lighter scraping noise, and then you'd take a hard right and you'd only get the noise from the right wheel.

Keep us posted.


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The drums aren't new, but I did glassbead them to clean 'em up. It really does sound like a brake thing to me Brian. Since you had the same symptoms, I'll investigate a brake rub/backer plate issue first.

I never got to work on it today because I'm finishing up a few Winter carpentry projects. I'll update when I take a look tomorrow.

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Looks like you might have nailed it Brian. I finally got a chance to put the rear end up and investigate some more this afternoon. The wheels spun OK, with a little "rub" on the shoes, but I still backed the emergency brake off a bit til there was no rub at all.

However, when I removed the drums, I could see where the backer plates were clearly rubbing against the fins on the drum. It looks like I managed to bend the backer plates slightly when I had them out. I bent the backer plates back to straight, and the rubbing seems to have gone away. Of course, it SNOWED again in Massachusetts today :angry:, so no test run.

I can spin the diff. easily with the drums off, no noise, no bind. I think it was just the backer plate, thankfully. I'll report back for sure when the latest snowfall goes away and I can try another shake down run.

Thanks as usual for the help.

BTW, I agree with the post last week that pointed out that the help we get on this site is worth something, so I got my screen name back "in the red".

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