Annoying sound from rear - possibly diff or wheel bearing?

[CJay]

I had clocked up about 200 miles in the FD this weekend when this annoying \'whirring\' noise kicks in from the rear (at least I think its coming from the rear, hard to be sure), its difficult to describe but the noise would change in pitch (but not amplitude) with speed, it sounds like the engine revs are 2k above what they should be reading, if you get my drift. I\'m guessing either wheel bearing or diff, but I can\'t be sure to be honest. I drove about 100 miles back home last night and the noise was getting worse towards the end of the journey, it also seems to be more pronouned when the car has been driven for a good lenght of time. Any ideas guys? Is there any sure fire way to isolate either the diff or whell bearing from the equation or is there something else that could be causing the noise?

Any help appreciated.

CJ

[OLSKOOLROTAR]

I\'d check the wheel bearings 1st mate, do all 4 wheels just to make sure, if its still there then have a look at your diff

forgot to say if you jack your wheels up off the ground and take them off, you can check the wheel bearings by turning them slowly look for any signs of sideways movement and any catching when you turn the disc\'s ( slowly turn them though, coz your looking for any signs of pitting etc inside the ball race), they might just need re greasing and tightening up.

Hope this helps

Jase

[CJay]

Cheers Jase.

Thing about the wheel bearing - it came on pretty suddenly (granted I was driving with the windows down for most the weekend and didn\'t hear the noise until I finally closed \'em up), in my experience, the droning will come on gradually. This is the reason I think it might be the diff. On that point, has anyone had any diff problems (standard diff) that resulted in it making a constant \'whirring\' noise (similar to an electric motor)?

CJ

[OLSKOOLROTAR]

Cheers Jase.

Thing about the wheel bearing - it came on pretty suddenly (granted I was driving with the windows down for most the weekend and didn\'t hear the noise until I finally closed \'em up), in my experience, the droning will come on gradually. This is the reason I think it might be the diff. On that point, has anyone had any diff problems (standard diff) that resulted in it making a constant \'whirring\' noise (similar to an electric motor)?

CJ

Okay no worries, you\'d be surprised how quick bearings  go though. I\'m not sure how much oil an FD diff holds so you might have to ring round a few of the vendors 1st, but you could always drop the oil out and put fresh oil in, you could be running low on oil. Worth checking the diff and around it for leaks could be your answer.

[McCARTHY]

check the rear toe arms the bushes go on these jack the car up and  just give them a shake push and a pull if they are gone they will knock

[CJay]

check the rear toe arms the bushes go on these jack the car up and  just give them a shake push and a pull if they are gone they will knock

I do notice a bit of knocking when slowing down \\ moving off in traffic but knackered bushes wouldn\'t cause the constant whirring noise, right?

CJ

[CJay]

I stuck the rear of the car up on axel stands this evening, theres no play in the wheels or noise from the wheel bearings or diff when the wheels are spun by hand. With regard to changing the oil in the diff, is the fill hole about half way up (just above the drain bolt) or is it further up the diff? 75W90 should do the job, right? (the local Halfords only had 80W90  :2Rolleyes

CJ

[CJay]

I changed the diff oil this evening, it had no impact on the noise. I noticed a piece of metal about 1.5mm sq. attached to the magnetic drain plug, is this something to be concerned about?

I made an attempt at recording the noise with an MP3 player, revs were at 3k max, check it out here (apologies for the bad quality):

http://www.fto-ireland.com/rx7/annoying_feckin_sound.zip (940kb)

Sound familiar to anyone?

CJ

[banned advertiser]

If you\'ve found metal in the diff its not sounding good.

[banned advertiser]

Sound clip dont sound good, but hard to tell.

[CJay]

Was up with my mechanic today, he\'s pretty sure the diff bearings are shot. He mentioned that it would probably be cheaper and easier to replece the diff rather than rebuild it, anyone have any comments on this? The next question is where do I get myself a bearing kit or second hand diff?

See pic below, it shows the small piece of metal that was stuck to the magnetic drain plug, there were also plenty of tiny metal fragments on the drain plug that you can just about make out:



Is it safe to drive the car when the diff is in this state (assuming I won\'t be driving hard)?

cJ

[mlautier]

Had a similar whirring noise when cruising slowly in fourth or  fifth gear .
Couldn\'t identify where the sound came from but when i came to replace the clutch my mech told me that the gearbox had no oil at all in it . The sound vanished after that so i guess that was the problem in mine.
Try to check it out . Might be same problem in yours