Rear end vibration still.

Alfissimoint.

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08' CX-9 AWD
Rear end vibration still.

So after new front axles which I now think were not the issue, I repaired the rear diff bushings to be a solid bushing until new ones come in. Problem still exists. It vibrates from 20-40mph and that's it. I need new tires but I doubt that is the issue.

I am thinking it may be either the rear diff? or the support bearing for the main shaft.

Any thoughts?
 
Sounds more like a universal joint to me. Have you inspected them closely for any slop? If the bearing were bad, I'd expect a little noise. But vibrations that comes and goes at different speeds just sounds like a U-joint. But, if it ends up being a u-joint, then you might want to replace the those bearings anyway "as long as you are in there."
 
I need new tires but I doubt that is the issue.

Any thoughts?

Tires can wear unevenly and do weird things. A broken belt in the tires can cause similar vibrations. I would still bet on the u-joints, but you might try rotating the tires front to rear and see if the vibration moves to the front and the rear settles down. At least you can rotate the tires yourself without spending any money.
 
Thanks all. New tires on tomorrow. Will see how that pans out. I am thinking something like U joint as well. I hope it is not transfer case or something more expensive.
 
I feel like a fool. I know better than this. New tires cured the problem even though I still need rear diff. bushings installed!
 
Well glad it wasn't anything more...and you needed tires anyway. And while your axles weren't the root of your vibration, they probably had a limited number of miles left on them. So don't look at them as money thrown away. They were just replaced a little early.

Might be a good idea to get an alignment with the new tires now just in case that contributed to their vibration.
 
Still have a slight issue. I have not replaced diff. bushings yet so that may be the problem. When I turn left and under load a slight vibration occurs. Not turning right and not straight.
I think the Diff is moving too much, I hope!
 
The saga continues. New front axles, new diff mounts and I get a slight vibration between 20-25mph. Left turns make more vibration and right not. Straight it does it more when car has been driven more. Not so much vibration at first drive. Such a strange issue. No idea what it could be at this point. Main shaft seems fine. Not a ton of movement.
 
Vibration under load and in right turns under load. I am thinking driveshaft or rear axles. Removed driveshaft and it does not do it. What the hell?

Any clue?
 
Thats how they diagnosed my rear end issues. Removed the driveshaft, and my shudder's around corners still happened. It was binding up in the rear end. So it sounds like you at least isolated that from being a cause.
 
So you had bad diff? Some strange issues. The vibration is at higher speeds as well. I also hear squeaking from the front end area. Like a rubber rubbing.
 
They already boxed up the rear end when i went to pick up the car from the dealership, so i never got to see the exact failure. I was told it was a bearing issue to blame.
 
My vibration is gone in cold and comes in when hot. Must be a fluid issue. I will try the transfer case fluid change and ATF trans fluid change. Rear diff has new oil, about 2 1/2 years on that and seems fine.
 
Vibration caused UJoint to fail

I have the same vibration in my CX-9. It happens between 20-40 mph. with light acceleration. This has been going on for several months and thought it was the driveshaft out of balance. Before I got around to replacing the driveshaft the problem got alot worse last week. The entire car shook at all speeds so i got under the car and discovered the drive shaft u-joint closest to the differential was shot. Bearings were gone. Also found out the u-joint is not serviceable so had to get a new driveshaft. Checked with Mazda and they told me they are on national backorder and did not know when they could get one. So i got one from a salvage yard for $200 and put it on. This resolved the major vibration issue but did not fix he vibration that occures between 20-40mph. So now thininking there is an issue with the rear differential or drive shafts. But i think the vibration from 20-40 over time caused the rear u-joint to finally fail. I will try fluid changes next just to rule those out.
 
Yeah. I am not sure mine is that. I think mine is a motor mount in combo with a wearing transmission mount.

I have now sold the car as we needed to downgrade anyway and with 135+K on it I think it's time to move on. I will pass this info on to new owner. But my rear diff has new oil in for the last 3 years and I do not think it is that. If anything the transfer case needs new oil and I am not going to bother with that as that's just a guess.

Good luck ya'll been fun. Great car. I will miss it. It has been near zero problems for us in the last 4 years. Nada, nothing. Then some minor issues now. Not a big deal in my book. I think motor mounts and transmission mount is the issue, worse case drive shaft and mounts which the drivesahft mounts can be bought through FEBEST bother for $100, them remove drive shaft and replace. Pretty simple as long as the u-joints are fine which in my case they are.

Take care
 
Thanks for all the research you've done @Alfissimoint on this vibration issue... Hopefully it helps people in the future to diagnose their issues.

What did you end up replacing it with? CX-5? :D lol
 
The other vibration is likely the rear differential mounts. Apparently they go as a result of the drive shaft going. And to add to it my diff output shaft seals are gone too. Unlike you I hate this vehicle in the year I've owned it it has cost us about 2500 dollars. Sticking with Honda now

Sent from my SM-N900W8 using Tapatalk
 
The other vibration is likely the rear differential mounts. Apparently they go as a result of the drive shaft going. And to add to it my diff output shaft seals are gone too. Unlike you I hate this vehicle in the year I've owned it it has cost us about 2500 dollars. Sticking with Honda now

Sent from my SM-N900W8 using Tapatalk

Based on your post, I just checked mine in the garage and sure enough my U-joint is shot also, I believe this is the cause of the rear vibrations I've been feeling during acceleration and deceleration for the psst month, I thought it was my catalytic going bad.

BUT I've got it worse than you, in one more day my car will be ILLEGAL to drive , I can't even pass inspection. emissions failed for monitor not ready . Mine is a 2013 with 115,000 miles. But I live in NY where the salt on the roads during winter is absolutely brutal my whole underside is rusted, all the stamped steel have rust on the edges, even the indicator dial for rear alignment is entirely rusted, can't even see the numbers on the dial. Everything is stamped steel welded together , no machined aluminum at all, the stamped steel starts rusting at the edges then start spreading like a virus. there's no full plastic aerodynamic panels like the new CX-9 to somewhat protect from salt. the U-joint is fully exposed to the environment.

If I can't pass inspection, I'll trade it in and let Mazda deal with it. I suspect it's a bad ECU or PCM ? whichever controls the emissions monitors
 
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