the_marky

Just wondering if anyone else has heard of this problem:

After long drives (maybe an hour plus), if I stop at traffic lights or whatever, I have this grinding sensation from the back of the car up to about 15-20km/h.

It's hard to describe, kind of like driving on rough gravel or cobblestones or like cogs slipping, that kind of feeling.

Have taken to mazda but they can't find anything - I guess because they don't drive it for an hour or more?

Anyone have any ideas, suggestions etc?

auzoom

How old is your car?

Other than that organise to have the car checked again and this time take the car for a long drive so its making the sound before you hand it over.

Cromax

It depends on what kind of grinding, but if your rear alignments out and you're running OEM tyres, you do get vibration through the rear of the car caused by cupping of the inside edge of the tyres.

Get your tyres rotated and see if it helps. The other thing I had done was they took the tyres off the rims and swapped them left to right.

erx8s

Differential could be playing up check your diff oil .

Also check your rear wheel bearings , if they are faulty they can cause grinding etc .

Cheers
Michael

the_marky

Thanks for the replies

Bought the car new Feb 06. They rotated my wheels at last service (30,000km), but this was happening before and since then.

I guess I'll take it in again warmed up and let them know they need to be ready when i arrive

Cromax

Do you get a vibration noise at highway speed as well?

takahashi

Hard to think what it was but my first thought was with Revolver - the diff. But not turning just stopping you get the noise... hmmmm.... Thinking the wheel hub/bearing thing

Ottog

Possibly a break pad problem (metal to metal) but then I would expect to hear it at pretty much any speed.

WhiteRain

Have u bumped any kerbs lately? Or any other significant impact to one of your rear wheels?

It could well be the early signs of a damaged rear wheel bearing. The sound you describe is definitely similar to a wheel bearing problem. Perhaps it disappears at about 20km an hour cos the damage/noise is so slight that the road noise and tyre roar takes over.

I doubt it would be the diff cos I was told that noise would be constantly there and just get louder and louder at high speeds.

Ask a reputable suspension shop to check your rear wheel bearings (someone who really knows what they're doing and has the patience to wait until the noise comes out). I don't think the Mazda dealership is the best place to go for noises like this.

Other potential problem could just be very uneven tyre wear caused by poor alignment/balance. Or just tyre noise in general...the stockies aren't exactly quiet.

Cromax

Think small and finish big.

The RE040 tyres tend to make a grinding noise at low speed when turning corners. It's quite disconcerting sometimes. I've got a grinding noise again now, but it's a lot quieter than what I had before when I had my tyres changed last time.

JAT1

i dont know if this would be anything like your issue but i had a problem with a piece of metal that hold the brake pads in rubing and making a grinding noise and could only be heard at low speed. I may have even been a pin or something but it was to do with something near the pads.

rotarenvy

when my car gets hot I get a rattle from under the car. I haven't tracked it down and neither has the service department. I'm guessing that it is in the power-plant frame.

the_marky

well it was finally time to take the car in for a service and i did as suggested (thanks!) - i made sure the car was nice and warmed up and asked them to come for a drive with me

well erx8s got it right - diff is stuffed was how the mechanic put it - they'll deliver a new one from melbourne

he wasn't sure if it was covered by warranty - is this right?

by the way i'm obviously pretty thick cause i never noticed that it only happened when i was turning

thanks to everyone again for their input and i'll let you know what happens

btw - the 40k service is $380 plus they wanna charge more for rotating tyres, wheel balance and several other things - does this sound normal?

auzoom

Assuming your car is still under warranty (Feb 06 so should be ok) I think they would have to prove neglect on your behalf. Has it been serviced by them the whole time? Have you missed a service?

Other than that I think you should be good. Ohh and dont let a car dealer do tyres. They are bad enough with engines...imagine what they can $%^&* up on your wheels and tyres.

mdr

Had the same issue with mine see thread.
https://www.rx8club.com/australia-new-zealand-forum-37/my-baby-back-purring-like-kitten-again-136197/
Replaced the dif and tranny oil and cleared right up.

the_marky

Thanks mdr - seems like the same problem

When i went in today they said they just replaced diff oil and not diff - told them that i've had the problem since beofre the car had 10k and reported the problem every time i went in - originally i had to drive it for about 2hrs+ before i got the problem

anyway he said try it out - so looks like i'm going for a nice long drive this weekend :-P

slash128

Hi... Did you ever get this resolved? I am having what I think is the same exact issue. Typical scenario goes like this. I drive a lot for work, like this week I had to drive out of town 4.5 hours one-way. Weather was warm, in the 80's. I tend to stop every couple hours to stretch, get a coffee/gas/etc.. During the highway driving things are fine. When I get off the highway, come to a stop at a sign or light, then start driving at surface street speeds I get a rumbling/grinding noise from the back end at take off. It only lasts for a few miles then goes away. I think maybe from cooling down? It is very frustrating because I too took it to Mazda, even after a long drive, but they are miles from the highway, so by the time I get there the noise is gone... Ugh!

I know it can't be tires because it happens with the original tires and two separate sets of snow tires. I was thinking wheel bearings but you said they mentioned the diff oil. Any word there?

the_marky

Bringing up an old thread ... haven't posted in ages.
I did finally get the issue resolved, and by mazda and under warranty.
The stupid thing is, I never made the connection that this happened when I was turning at low speed. The reason for this was that I was traveling up and down the coast a lot and that is when I always noticed it. In both directions, the first stop I came to was at a set of lights where I had to turn. I just didn't put 2 and 2 together :-P
Anyway, I took it in to demonstrate. Drove for ages with no problem. Then when doing a U turn it happened. The mechanic knew what it was straight away: "Your diff is stuffed"
They said they'd deal with it. Went to pick it up and they said they'd changed the diff oil. It was very dirty etc.
I asked why would it be dirty? Wouldn't it only be dirty if there was something wrong with the diff?
They told me to see how it goes. I rang back within a week and told them it was still happening. They replaced the diff.
Probably not the same problem that slash is having, but thought I should give some conclusion to the story. :-)
Moral of the story: Don't let them just replace the diff oil. It wouldn't be full of gunk if the diff was working ok.