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Discussion Starter · #1 ·
A couple of weeks ago, my MS6 started making a clunking or thumping sound during acceleration. The sound seems to be coming from the back of the car, and only occurs when the torque application is moderately high (or higher). Gentle "grandma-style" acceleration produces no noise. The sound is repetitive (I'd estimate about 3 cycles per second) as long as acceleration continues. The sound does not appear to vary in pitch or frequency as the car's speed changes.

I brought the car to the dealer, and took one of the techs out for a ride to demonstrate the issue. He speculated that the noise could be originating from one of the carrier bearing on the driveshaft. Seems logical to me.

They spoke with Mazda's Technical Line about the problem. Mazda indicated that they have experienced drivetrain clunking under aggressive driving, but have not identified a cause or solution.

The techs noticed that the heat sheild near one of the carrier bearings may have been contacting the bearings during driveshaft flex. They bent the sheild slightly to increase the clearance.

We then took the car for another spin, and the problem persists. We did discover an interesting bit of information, however. If I slightly engage the e-brake (which de-activates the center coupling), the clunking does not occur. This suggests to me one of to explainations:
1. The clunking is occuring somewhere in the drivetrain from the coupling back. This would include rear differnetial, axles, hubs, etc.
2. The clunking is coming from the driveshaft, but only occurs when the driveshaft is loaded by the rear section of the drivetrain. In other words, when the driveshaft isn't sending any torque to the rear wheels, the driveshaft no longer produces the sound.

Until Mazda comes up with a cause (and solution) for this problem, I guess I'm stuck with the sound (until something breaks). Dos anyone have any other ideas of what I should check to try and identify the problem?

Today I started thinking about the broken differential mounts that some people's MS6s have encountered. If the mount on my car is starting to fail, would it be likely that movement of the differential could cause this type of clunking?
 

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Discussion Starter · #3 ·
perhaps the start of a rear axle problem
[/b]
Could you be a bit more specific?

The rear axles appear to be in fine condition on my car. Even if they were failing, I wouldn't expect a problem until they actually broke.
 

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I experienced the same noise. However mine was usually only one clunk, and it sometimes occured on spirted DE-acceleration as well. The dealer could not figure it out at first. The noise continued, but was joined by a vibration in the driveshaft, felt through the steering wheel and gearshift, when comming to a stop. It felt like I was still in gear and the car was going to stall. My first reaction was to take it out of gear, but it was already out of gear. Shortly before I stopped completely the vibration "balanced out".

I called Mazda NA directly, and armed with some research (and reprints of a few threads from this forum) I went back to the dealer and the tech was able to confirm that the diff bracket had broken. No additional damage was found. After a three week wait for the new updated bracket, I am back to as good as new LOL.

Hope this helps, good luck.
 

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Discussion Starter · #5 ·
<div class='quotemain'>
perhaps the start of a rear axle problem[/b]
Could you be a bit more specific?

The rear axles appear to be in fine condition on my car. Even if they were failing, I wouldn't expect a problem until they actually broke.
[/b][/quote]

Well, I'll eat my words with a fork and spoon. atc5 was right.

Sunday night I heard a sharp BANG from the rear of the car, and the clunking noise stopped. So did the transmission of torque to the rear wheels. Sure enough, the driver's side rear axle snapped.

Fortunately, the car remained drivable, and my Mazda dealer found an axle to order. With any luck, the part came in today and I'll get my car back later.

I am a bit concerned to have an axle fail at 23,500 miles. I don't track the car or perform high-rpm clutch drops. Although I'd like to avoid having another part replaced, I would be somewhat relieved if it turned out the differential mount was failing and that's what led to the axle failure.
 

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Could you be a bit more specific?

The rear axles appear to be in fine condition on my car. Even if they were failing, I wouldn't expect a problem until they actually broke.
Well, I'll eat my words with a fork and spoon. atc5 was right.

Sunday night I heard a sharp BANG from the rear of the car, and the clunking noise stopped. So did the transmission of torque to the rear wheels. Sure enough, the driver's side rear axle snapped.

Fortunately, the car remained drivable, and my Mazda dealer found an axle to order. With any luck, the part came in today and I'll get my car back later.

I am a bit concerned to have an axle fail at 23,500 miles. I don't track the car or perform high-rpm clutch drops. Although I'd like to avoid having another part replaced, I would be somewhat relieved if it turned out the differential mount was failing and that's what led to the axle failure.[/b]
I have yet too see a driverside rear axle break that wasn't caused by a broken differential mount.. I'd have them order a new diif mount just incase..
 

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Discussion Starter · #7 ·
I have yet too see a driverside rear axle break that wasn't caused by a broken differential mount.. I'd have them order a new diif mount just incase..[/b]
When I brought in the car with the broken axle, I mentioned the updated differential mount to the service manager. He said they'd inspect it while working on the axle.

When I picked up my car yesterday, I found out the dealership had gone ahead and replaced the mount and the bolts even though neither had failed on my car. I guess Mazda figured avoiding any potential issues with those parts was worth the expense.
 

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A couple of weeks ago, my MS6 started making a clunking or thumping sound during acceleration. The sound seems to be coming from the back of the car, and only occurs when the torque application is moderately high (or higher). Gentle "grandma-style" acceleration produces no noise. The sound is repetitive (I'd estimate about 3 cycles per second) as long as acceleration continues. The sound does not appear to vary in pitch or frequency as the car's speed changes.

I brought the car to the dealer, and took one of the techs out for a ride to demonstrate the issue. He speculated that the noise could be originating from one of the carrier bearing on the driveshaft. Seems logical to me.

They spoke with Mazda's Technical Line about the problem. Mazda indicated that they have experienced drivetrain clunking under aggressive driving, but have not identified a cause or solution.

The techs noticed that the heat sheild near one of the carrier bearings may have been contacting the bearings during driveshaft flex. They bent the sheild slightly to increase the clearance.

We then took the car for another spin, and the problem persists. We did discover an interesting bit of information, however. If I slightly engage the e-brake (which de-activates the center coupling), the clunking does not occur. This suggests to me one of to explainations:
1. The clunking is occuring somewhere in the drivetrain from the coupling back. This would include rear differnetial, axles, hubs, etc.
2. The clunking is coming from the driveshaft, but only occurs when the driveshaft is loaded by the rear section of the drivetrain. In other words, when the driveshaft isn't sending any torque to the rear wheels, the driveshaft no longer produces the sound.

Until Mazda comes up with a cause (and solution) for this problem, I guess I'm stuck with the sound (until something breaks). Dos anyone have any other ideas of what I should check to try and identify the problem?

Today I started thinking about the broken differential mounts that some people's MS6s have encountered. If the mount on my car is starting to fail, would it be likely that movement of the differential could cause this type of clunking?[/b]

Every thing that you just said about this its exactly whats happening to my MS6, I'm scared and don't know what to do, but the thing its that it all happened while I was racing this WRX then after that I'ts been doing that same noice under neat the car from the back!!! I' scared but I don't want to take it to the dealership cuz I don't have my stock wheels anymore, I have aftermarket 18's with 40's and I'm thinking they will blame it on that...
 

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Some owners have run into real assholes, but there's no way wheels could cause your axle to fail. Racing a WRX, well that's another thing, but you don't have to mention it ;).
 

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The whole driveline issue is really worrying me. I still do not believe a few bolts are the right answer, but it would be nice. Has anyone had any rear end problems after the upgraded bolts been installed?
 

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A couple of weeks ago, my MS6 started making a clunking or thumping sound during acceleration. The sound seems to be coming from the back of the car, and only occurs when the torque application is moderately high (or higher). Gentle "grandma-style" acceleration produces no noise. The sound is repetitive (I'd estimate about 3 cycles per second) as long as acceleration continues. The sound does not appear to vary in pitch or frequency as the car's speed changes.

I brought the car to the dealer, and took one of the techs out for a ride to demonstrate the issue. He speculated that the noise could be originating from one of the carrier bearing on the driveshaft. Seems logical to me.

They spoke with Mazda's Technical Line about the problem. Mazda indicated that they have experienced drivetrain clunking under aggressive driving, but have not identified a cause or solution.

The techs noticed that the heat sheild near one of the carrier bearings may have been contacting the bearings during driveshaft flex. They bent the sheild slightly to increase the clearance.

We then took the car for another spin, and the problem persists. We did discover an interesting bit of information, however. If I slightly engage the e-brake (which de-activates the center coupling), the clunking does not occur. This suggests to me one of to explainations:
1. The clunking is occuring somewhere in the drivetrain from the coupling back. This would include rear differnetial, axles, hubs, etc.
2. The clunking is coming from the driveshaft, but only occurs when the driveshaft is loaded by the rear section of the drivetrain. In other words, when the driveshaft isn't sending any torque to the rear wheels, the driveshaft no longer produces the sound.

Until Mazda comes up with a cause (and solution) for this problem, I guess I'm stuck with the sound (until something breaks). Dos anyone have any other ideas of what I should check to try and identify the problem?

Today I started thinking about the broken differential mounts that some people's MS6s have encountered. If the mount on my car is starting to fail, would it be likely that movement of the differential could cause this type of clunking?[/b]
u snapped a few bolts on the rear diff bracket........how do i know? been there done that
 

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I've started asking the technician to check the rear-dif and a few other things when I take it in for oil changes. They're making notes in the computer and writing the extra inspections I've asked for on my invoices... just for some history.
 

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reviving this thread... this same thing recently happend to me.. i have patched maps from cobb that fix the WOT shift stutter that i went out to log. i think that may have been the last straw. the next morning after making WOT logs (after flashing the patched map) the rear end started clunking above parking lot speeds, with the ebrake off. my rear upper diff mount (Stock one stupid me) let go and the diff was cocked to the left. im thinking this put a bind on the driverside axle.

i alread have a new DSS axle in hand, just need to find an axle seal.
 

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reviving this thread... this same thing recently happend to me.. i have patched maps from cobb that fix the WOT shift stutter that i went out to log. i think that may have been the last straw. the next morning after making WOT logs (after flashing the patched map) the rear end started clunking above parking lot speeds, with the ebrake off. my rear upper diff mount (Stock one stupid me) let go and the diff was cocked to the left. im thinking this put a bind on the driverside axle.

i alread have a new DSS axle in hand, just need to find an axle seal.
When you say cocked to the left, how obvious was it? I'm paranoid now lol.
 

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I have something similar, yet quite different. Whenever I go over a bump in the road, or a dip, it sounds like I am carrying a dozen 2x4's in the trunk. It makes the sound as if they rise up and crash back down against each other.

Same sort of thing happens under medium to hard acceleration from a stop, but the going over a bump or into a dip thing happens regardless of speed.
 

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Fine time to insert the "OEM Rear Diff Mounts Suck" notes-

If you're an enthusiast driver, and most likely you are if your reading this, your OEM diff mounts are not up to snuff. Period.

If you launch or race at all you need aftermarket mounts. Period

If your a momentum driver, you still need to at least strap the rear diff until you purchase mounts (and the rear sway, install both the mounts and sway at the same time)

If you do neither, it's only a matter of time. Not if, but when....
 

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Yeah Don't be stupid like me do the rear sway while getting the diff mounts installed. Thanks for pointing that out TiGRaySpeed6. I mean I coulda read a few threads before jumping in but that be to logical. Good luck guys your gonna feel a lot more comfortable jumping on her when It's all done.
 

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When you say cocked to the left, how obvious was it? I'm paranoid now lol.
if you can push the diff up and down freely, theres a problem
 
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I dont know if this is the same issue im getting but basically if i decide to punch it from a rev of 2.5 or 3 or maybe even higher at times i receive a "clack clack clack" noise which goes away quickly if i decelerate or continue accelerating, i think im not allowing boost to build up, im not sure but its a bit worrying, only happens randomly, noise sounds like its coming from front passenger side, im assuming axle gets frozen up. dont know.
 
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