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HybridZ

Whats that noise??


John Scott

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After last of the season T&T at Bandimere last night, just behind me developed a smooth scraping, hissing noise. Sounds like a stick rubbing on the drive shaft or brake drum. Pulled off twice on the drive home, no heat from drums, shoes not sticking. Noise doesn't change with brake application, turning, shifting to neutral. Speed dependent.Thought e-brake cable, no contact, bolt loose on drive shaft loop, no. Lots of rubber under the wells, build up? Weeds stuck underneath? no. Seemed to lessen slightly when I got home. Tried running on jack stands, couldn't hear again, checked all areas for contact, plenty of clearance, then had cops called on me for noise....#$%@ neighbors, it was 9AM and barely idling. Any ideas? Plus side, 1.8 60's can be had from skinny 225 60 16s..maybe 1.7s! This is the end of the car I'm clueless. Where should I start?

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Took drums off ran it in the air. Drums backing plates OK. Really hard to hear when elevated, but obvious when car is running down the road. Would pinion or side bearing cause sound like this? I figured it would make more of a racket if rear internals were going....update: no question coming from rear. Noise consistant regardless of left or right turns, load or coast. Like I said a smooth hissing scraping. Any diagnosis tips on determining whether side or pinion bearings before pulling it apart? If side I'll dig in, NBD. I suppose easier to find another rear than set up again with new pinion bearing(S)

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The little dust cover on the pinion flange didn't get bent or anything, did it? Just unusual that the noise wouldn't change with load or turning.

 

This might help with a diagnosis:

http://www.ringpinion.com/content/technicalhelp/default.asp?pid=109

http://www.ringpinion.com/content/technicalhelp/default.asp?pid=110

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Chilton...hate to go there, says low pitched scraping or whirring starting at low speed most likely Pinion bearing :( Looks like I'll be searching for another R200. Two of our local salvage have crushed the whole pick and pull yards, I had just located a good Z donor in Loveland a few months back, just new cars now.

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There are 3 pinion bearings. The inner is pressed onto the pinion bearing. The middle one is not a press fit and there is a long spacer tube between it and the outer which is a ball bearing pressed into the case just inside the pinion seal.

 

The ball bearing is the one which I think tends to go out most frequently. In the two R diffs that I've driven that had a bad bearing there, they had a high pitched whining noise, almost a squeal, and the faster you went the higher pitched it got. The ball bearing is NLA, but the others are still available IIRC.

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Thanks Jon. I've heard some still successfully replacing by taking the numbers off the bearing to a bearing supply rather than an auto parts store so they can match the dimensions, rather than just showing a discontinued # for an old car. We have a great place that only deals in bearings, seals, and hydraulic lines. I probably hear more since I have solid mount, its suddenly, obviously different. I can't determine this is the cause, but since the tapered ones seem to make noise on load or coast....

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