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Thread: Mazda 6 MPS Strange Rear diff issue

  1. Default Mazda 6 MPS Strange Rear diff issue

    Hi everyone,

    Not a frequent poster as you may tell, but this forum has been my holy grail since I first bought my MPS6 a little over 9 months ago. It's my baby (see what I did there )

    Tonight on a cruise through the city of Melbourne, driving normally with DSC switched off, I was cruising at a low speed in 2nd gear and a gap opened up in front so I put the boot in it to jump in. To my surprise the front wheels lit up and on my dash the 4WD light was flashing. I thought that was weird so I slowed down, popped it back into second and gave it the boot again, again the front wheels lit up, tyre smoke everywhere and the 4WD light was flashing at me.

    I rolled up slowly to the car park where I was picking some people up from and I could hear a rattling noise coming from the rear diff. I turned the car off and went outside to have a look underneath and nothing seemed to be out of order. Diff wasn't angled and nothing was loose or hanging from it. I started the car back up and drove off and the rattle was gone, so being a curious person, I popped it into third and put the boot in it and even in third, the front wheels started slipping and the 4WD light started flashing at me.

    It seems like I may have a problem with my rear diff.... I have never had a problem with this car before and it seems weird that my diff would be the first thing to go... I have done the normal first checks, like tyre pressure and measured the wheel heights, both rear and fronts are exactly the same....

    Has anyone else experienced similar problems with the rear diff, and what could I try to do to fix this?

    Any input is much appreciated. This seems to be a weird problem and one I can't quite put my finger on as to why it is doing this.

    Cheers

    -Pete

  2. #2
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    sounds like the magnetic clutch in the rear diff has gone not the diff itself but i think you have to replace the whole diff unit, i'd call formaz in NSW as they are wrecking a 6 mps at the moment

    ---------- Post added at 07:02 AM ---------- Previous post was at 06:46 AM ----------

    it should be throwing a code if the 4WD light is popping up check which one it is and post up here

    All these codes will stop the awd system working
    P1887 - Wiring malfunction
    P1888 - Rear diff oil temp to hot
    U0073 - CAN system coms failure
    U0100 - PCM coms failure
    U0121 - DSC coms failure
    Coms = comunication

    ---------- Post added at 07:06 AM ---------- Previous post was at 07:02 AM ----------

    i would also look at your axles and drive shafts
    05 VR 6 MPS LUXURY - WHATS STOCK????
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    Remember pay by the 16th of November and get free lunch and drinks on day
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  3. Default

    Thanks for the early morning response! I like the dedication to the forum

    Is the magnetic clutch itself in the diff or inside the transfer case up front?

    I did a scan with my obd tool last night after the light showed up but no error codes came up. I should probably note that the 4WD light was only flashing for about 10 seconds before stopping, but would start flashing again every time I gave it a bit of power. From how she was driving though, it definitely felt like she was in front wheel drive mode

    This might be a dumb question, but what exactly would I be looking for on a visual inspection? Shearing, breakages, oil leaks etc??

    Thanks,

    -Pete

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    ---------- Post added at 09:31 AM ---------- Previous post was at 09:28 AM ----------

    Is it possible the noises are from transfer case? The drive is separated at the diff.

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    Do you have different sized tyres on the car?
    Recently get new ones?

  6. Default

    The noises were a tapping/rattling kind of noise coming from the rear end of the car. Correct me if I'm wrong but isn't the transfer case at the front of the car where the driveshaft connects to?

    Also, the noises stopped and didn't come back after a shutdown, wait 10 minute and restart... though instead of fix itself it looks like I have no 4WD.

    Thing is, when it happened, I didn't hear any loud noises/thuds/cracks, just a rattle as I went to park a few kms down the road. If i had snapped something or sheared something, surely it would have made some kind of very noticeable sound wouldn't it?

    -Pete

    ---------- Post added at 09:37 AM ---------- Previous post was at 09:36 AM ----------

    Tyres are all the same, didn't change them or move them around. They all seem to have even wear and are all inflated to 35. Height from ground is equal on all 4..

    -Pete

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    Good chance you prob is in the back then, few people have stuffed drive shafts in the rear... Transfer is at the front yes, but the power is sperated at the diff though. Jack the rear up, leave stick in neutral and jam hand break on, turn the prop shaft and feel how much friction it has, should be pretty stiff to turn. To check the drive shafts jam it in gear, release hand brake and turn read wheels, you will some one to hold other side wheel. See if anything feels odd
    Last edited by MPS2NV; 19-08-2012 at 09:51 AM.

  8. Default

    I'm hoping its a problem at the back as opposed to a transfer case... Hopefully it won't cost as much to get repaired if it is stuffed.

    I'll hop under it and have a look see if anything is out of whack and post a few pictures of the underside to see if anyone else can spot anything if I can't.

    Man, shes an unfriendly beast in FWD mode. Whole reason I went the 6 in the first place was because it had a rear diff

  9. #9
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    Quote Originally Posted by GreenMountainGoat View Post
    Thanks for the early morning response! I like the dedication to the forum

    Is the magnetic clutch itself in the diff or inside the transfer case up front?

    I did a scan with my obd tool last night after the light showed up but no error codes came up. I should probably note that the 4WD light was only flashing for about 10 seconds before stopping, but would start flashing again every time I gave it a bit of power. From how she was driving though, it definitely felt like she was in front wheel drive mode

    This might be a dumb question, but what exactly would I be looking for on a visual inspection? Shearing, breakages, oil leaks etc??

    Thanks,

    -Pete
    i would get your 4WD solenoid in your diff checked out because if its stuffed the 4wd light will only come on while accelerating because it engages only under acceleration that would be the no.1 suspect i think mazda here we come
    next the mag clutch
    05 VR 6 MPS LUXURY - WHATS STOCK????
    Winner of Most modified @ Smokeys car meet
    UP an coming events: Winton Track day 17th December

    Remember pay by the 16th of November and get free lunch and drinks on day
    Next install: New Head, ARP Studs, Upgraded VVT, BSD, Mazdaspeed Coil Cover, Injector seals + studs

  10. Default

    Update!

    I got under the car to have a look and lo and behold it looks like I have snapped the left axle. Notice in the photos, the sleeve in the left hand axle is all twisted and I am able to shake the axle loose. In the right hand side axle, the sleeve is not twisted and I can't make the axle budge from its location.

    To all you seasoned pro's. does this look like a broken axle, and has anyone else experienced this? Does anyone have a ballpark idea as to how much it might cost to fix this?

    Here are the pics:

    Left hand side axle, twisted inside the sleeve and loose from the diff
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    Right hand side axle. Sleeve is not twisted and the axle is not loose from the diff
    Click image for larger version. 

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    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  11. #11
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    Pull the boot back and have a look! Should be able to see damage and feel crunchies in the grease!

  12. Default

    Yeah just had a look. Its looking pretty sad at the moment. Loose with plenty of crunchies

    Are the rear axles difficult/expensive to replace in these cars? My mates VS Commodore had a snapped axle a while back and it only cost him a couple hundred to fix. Difference is, those cars were made for serviceability...

    I have just wired up the rear diff disengage switch to the handbrake switch so I can have it permanently off until I get it fixed, but one thing I'm worried about is, could there be a chance under free-wheeling that the axle might fall apart and fall out from under the car while I am driving?

  13. #13
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    I prob wouldn't drive it to much, the wheels are still driving shaft so things can still get worse!

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    dont go to mazda go to the driveshaft shop and get 500hp ones for $1200 roughly a set instead of mazdas $800 - 1000 for one

    The Driveshaft Shop | Mazdaspeed 6 - Mazda - Import Axles they have a aussie branch to just email them

  15. Default

    Can anyone recommend any good mechanics that have worked on their cars in the Melbourne area?

    I am thinking that if it does turn out cheaper to buy the 500Hp axles from the US and have them installed, then while they are under there, might as well get them to install the CP-e diff mount and rear sway bar.

    Can anyone recommend good suppliers for these parts and reputable mechanics that'll do a good job without ripping me off?

  16. #16

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    Quote Originally Posted by Axspeed6 View Post
    i would get your 4WD solenoid in your diff checked out because if its stuffed the 4wd light will only come on while accelerating because it engages only under acceleration
    Thought I should clarify here. The AWD is active all the time. Coasting down hill, going in reverse, the diff coupling is always receiving a square-wave signal from the 4wd control module (ie the rear wheels are engaged) whenever the car is in motion. However the system is intelligent enough to disconnect the rear wheels when you are parking (low speed with high steering angle) to prevent the AWD tendency for drive-line binding. And as we all know it also disconnects when the hand brake is pulled.

    As for the broken axle, the photos show a stock standard 6MPS LR axle failure. It's actually the CV cage that fails, not the axle itself. This is why the HD axles from the states come with massive CVs.

    I wouldn't drive the car at all with a broken axle. At the very least you're likely to tear the CV boot and get sticky black grease everywhere, at worst you risk doing more mechanical damage.

    Gone to Volvo


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    i should of said fully engages under acceleration

  18. #18

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    Quote Originally Posted by Axspeed6 View Post
    i should of said fully engages under acceleration
    Not trying to be smart, it's just that many journalists created confusion about the 6MPS AWD system by copying the first published review which incorrectly described it as 'AWD on demand' leading many to believe it normally operates as FWD, which of course is not the case.

    Gone to Volvo


  19. #19
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    yes its in operation all the time i know but the level of torque output through the diff varies depending on two things, this is only if DSC/traction control is on, if its on the the 4WD control computer will adjust the torque out put to the rear and power to the engine via the throttle thats why its electronic to control understeer or oversteer esp noticed during hard or wet weather cornering (this is in the workshop manual) and depending on surface traction, if dsc is off its on 100% all the time
    Last edited by Axspeed6; 19-08-2012 at 04:41 PM.

  20. Default

    Thanks guys. Lets not turn this into a debate about how the AWD does or doesn't work

    The disengage switch works a treat for keeping all the torque to the front wheels and not driving the rear wheels. The car still drives like normal, just no power to the back. It seems as though the arm is stable enough where it is to not destroy itself without being driven (because it seems to rotate as one unit when I had the car up on 4 stands and not one bit inside spinning faster than another).

    I wont be driving it around unless its an absolute emergency, but it shouldn't get any worse from how I've seen it behaving.

    Theres a place in Melbourne that works on RX-7's and RX-8's called ProMaz, and given that the cars rear drive train is out of the RX-8 I figured they may be well equipped to do the replacement when I get a new axle.

    Does anyone else have any recommendations for a reputable place in Melbourne that has had prior experience with MPS's or perhaps other AWD systems such as EVO's and WRX's?

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