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Low rumble from the rear


madmanperez
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A while ago I started to notice a low frequency rumble coming from the rear. It's not RPM related. seems more speed related. Faster equals louder, take the car out of gear RPMs drop sound remains. Bring the car to a stop, sounds stops gun the engine in neutral engine roars but no rumble sound.

 

Thant's all the detail I have. As always any and all responses are appreciated.

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Kinda like a growl? If so, that sounds to me like a bad bearing somewhere in the diff or the torque tube. Could also be either of the rear wheel bearings. Not sure how one could test the former, so someone can chime in there, but for the latter, one of the things you can do is find an empty stretch of road, get it up to speed where you can clearly hear the noise, then start swerving side-to-side to see if the noise changes. If it gets louder in one direction vs the other, then the side with the most load at that time has the bad wheel bearing. If no difference, it's most likely something at the diff/torque tube.

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I would get it in the air and start twisting things around by hand. Sure sounds like a bearing. Should be able to hear/feel that by turning the driveshaft and/or wheels by hand. Might help to have a buddy to lend an ear. 

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  • 3 weeks later...

It tock a while but I finally Got the rear of the car up. The only noise I heard was a slight scraping on each wheel which was the brake pads. Nothing else. As EDDE mentioned, The tires in the rear are new (not the most expensive rough $75 ea) I'm starting to think it could be them. Short of cracking the diff cover and draining the grease and resealing and refilling. I'm stuck. Not willing to replace new tires with more expensive ones on a hunch.

I appreciate everyone's input When the rare tires where and I have to replace them I'll then look at slightly more expensive tires.

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Really sounds like a wheel bearing to me, however you said it doesn't change when swerving which seems odd.  The rear doesn't see the sudden change in side loading when serving like the front does.  These cars also seem to have a pretty heavy duty rear bearing setup compared to more modern stuff, at least from my browsings of the FSM.  

My 87 I just got running has a similar sound but it goes away when it gets driven a little bit.  I have looked at replacing the rear bearings due to this and the odometer reads 192,000.  The bearings seem cheap enough but I haven't been able to see if you really need a press to do them or if the FSM is being dramatic ha. 

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Thanks for the input BlueCuda.  If  it is in fact a bearing issue I'm kind of screwed in that I don't have any place to do that level of work and that leaves me with having to go to a mechanic (uhg🥵). Same would be true if I had to do any work on the diff.

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On 1/8/2022 at 5:56 AM, BlueCuda said:

Really sounds like a wheel bearing to me, however you said it doesn't change when swerving which seems odd.  The rear doesn't see the sudden change in side loading when serving like the front does.  These cars also seem to have a pretty heavy duty rear bearing setup compared to more modern stuff, at least from my browsings of the FSM.  

My 87 I just got running has a similar sound but it goes away when it gets driven a little bit.  I have looked at replacing the rear bearings due to this and the odometer reads 192,000.  The bearings seem cheap enough but I haven't been able to see if you really need a press to do them or if the FSM is being dramatic ha. 

You could probably do it without a press. It's SOOO much easier with one though. 

I bought this a few years back and has worked like a charm for many jobs. I also have a normal shop press. 

https://www.amazon.com/Orion-Motor-Tech-Replacement-Automotive/dp/B01FLVOAZI/ref=sxin_14_pa_sp_search_thematic_sspa?cv_ct_cx=wheel+bearing+press&keywords=wheel+bearing+press&pd_rd_i=B01FLVOAZI&pd_rd_r=f29ee619-4af3-4c74-9d8a-e140fba32ac4&pd_rd_w=GgkMM&pd_rd_wg=9taxh&pf_rd_p=4ad71b32-b810-4124-8735-d02a39478d0c&pf_rd_r=3JTMYEH43EGQQNF39KEN&qid=1642350651&sr=1-1-a73d1c8c-2fd2-4f19-aa41-2df022bcb241-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExVURRQTVVU0JXUERHJmVuY3J5cHRlZElkPUEwMDc0NzY5RjVaVzdRUDAwNFAwJmVuY3J5cHRlZEFkSWQ9QTA4ODU5NjkyN1VXWk1SNk9FSjQ3JndpZGdldE5hbWU9c3Bfc2VhcmNoX3RoZW1hdGljJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Edited by psu_Crash
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