Mazda 6 MPS Differential problems and/or solutions

[kmh001]

Shakes back in January when Mazda had my car for 6 weeks one of the things they did was install a prototype rear diff mount in an attempt to resolve the vibration. They refused to tell me how it was different to the original, but it didn't feel any different to me. It was probably the softer one you have.

They seem to be in a catch 22 between wanting to go softer to resolve all the vibration issues, and wanting to go harder to resolve the broken mounts.

I recently wrote to customer service and told Mazda about the two cars in Germany that had the vibration resolved by changing the gearbox. I'm betting they wrote to Mazda in Germany for confirmation because a couple of weeks later they agreed to replace my gearbox, clutch and flywheel.

My clutch isn't damaged, but the vibration did first arise suspiciously close to when they did the clutch TSB so maybe they suspect it's a contributing factor.

Waiting on the parts to come from Japan, but I am so looking forward to not having to drive a vibrator any more.

[BCMPS]

kmh, is your car still cover under warranty? Will the CP-E or SU diff mount help to rectify this issue? I think I am the lucky one not having this diff mount issue but start worrying. Currently have 60000km on the clock.

[shakespeare]

kmh, is your car still cover under warranty? Will the CP-E or SU diff mount help to rectify this issue? I think I am the lucky one not having this diff mount issue but start worrying. Currently have 60000km on the clock.

BCMPS, I've ordered a CP-E diff mount and waiting for this to arrive, so once it's fitted I'll provide some feedback. As to the improved diff mount from Mazda, it's actually worse than my original before it broke! Out of interest what tyre sizes are you running with?

[BCMPS]

Thanks shakespeare, I am running 225/45/18, you can see that on my signature.

I really don't think tyre size is a problem. as long as they are the same at 4 corners.

[BCMPS]

I finally notice the diff whine today, it only happens at 70km/h and engage handbrake slightly will eliminate the noise. But I have to pay so much attention to it in order to hear becoz road noise and radio can easily cover it. My question is, will that be any harm to leave it?

[lazydog]

If you don't get it looked at, you will drop a rear diff like I have recently.

Just driving normally and then bang.... massive shudder from the rear.

Do yourself a favor and check if there rear diff is leaking oil from the drivers side drive shaft. If so, then it's only a matter of time till you cop it.

To prolong the life of the diff, disconnect the sensor to the rear diff(there is a plug that you should be able to get to - this will keep the car in "FWD" mode, not really FWD, but won't push excessive power to the rear.

If the car is under warranty, take it back asap.

I'll be honest, I gave mine 1 too many 5k launches and that's why i think mine broke. Also, I only replaced 2 tyres on my car, when i should have done all 4. Those 2 things and a combo of my rear diff bolts always coming loose caused it to stuff up.

Anyways, don't drive around with your handbrake up 2 clicks- it will only wear ur rear pads!

[kmh001]

What broke lazydog?

[nissanman]

Try getting Mazda to replace your diff under warranty.. goodluck

[shakespeare]

Update!

After the numerous problems with my diff, which I'll list below and some of my findings I've gone back to my stock rims (in black) with stock Potenza's 215/45/18 and it now feels like it did when I bought it I'm now thoroughly confused but hoping it stays this way.

1) Since new have had some resonant vibration when cruising at 100-110 kph, which Mazda could not fault and when they drove it advised this was normal!

2) Changed to 225/40/18 on 7.5" wide rims +45 offset around 35,000kms (all 4 corners)

3) Sheared forward diff mount bolts at 42,000kms, Mazda replaced bolts and service manager advised of Diff windup due to non-standard wheel/tyre diameters.

4) New bolts worked loose at 43,000kms, service guys re-torqued and loctited.

5) Changed to 225/45/18 on same rims at 47,000kms

6) Snapped rear bracket of diff at 49,000kms, Mazda ordered and replaced with a new improved bracket, again diff wind up due to incorrect tyres was mentioned

7) Horrible vibrations under any kind of acceleration, checked diff and found movement of +2mm (left to right). After perservering with this and more visits to Mazda who confirmed the bracket is fine and nothing is broken, I thought it's time to go back to stock to see what if? Incidentally diff whine seems to have gone!

8) Changed back to stock wheels and tyres (at all 4 corners) at 50,600kms after persevering with the vibrations for the last month, thank goodness for the MPS3 switch!

9) Haven't had much opportunity to test fully, however initial findings over the last 100kms today.

a) no diff whine
b) no more vibrations under any kind of acceleration, including Wide open throttle (WOT)
c) Only a short test but no resonant vibration (yet)

So I am now starting to wonder if the Mazda service manager was not telling porkies when he was concerned that non-standard wheel/tyre sizes are causing diff wind up?

Apologies for the long windedness, but I feel that there is more to this dilemma than meets the eye! However for the moment I am thoroughly loving my car again as I can accelerate without my teeth falling out!
Cheers
Chris

[foxy]

I think you are probably right. I heard many years ago that AWD cars are acutely sensitive to wheel and tyre set ups. So far I only have the "standard" diff whine but have noticed a slight volume increase. Could be that my rear tyres are nearing the end of their lives and have altered the resonance characteristic because of the depth of the tread OR a worn tyre effectively reducing the aspect ratio from 45 to 44 or 43.

Just a thought.