Diff, gearbox Or driveshafts?

[TLicense]

All,

 

I think I've knackered something.

Basically as you all know, I have an auto diff, with a manual box.

I was doing a high speed run on the private test track a week or so ago, showing 170 on the clock, when there was quite a loud bang acompanied with a whining noise coming from the back of the car. Obviously, after a little rectal pinch, awaiting the wheels to lock, I realised apart from the noise all was well, so slowed to a halt.

On a cursory external inspection all appeared well, and as it should.

I then drove home from the test track at normal legal speeds.

Then over the weekend, and another visit to the track, I ramped up to "higher speeds" and about 130 on the clock the whining noise started to come in again.

It really does sound like it's coming from the rear of the car, but can't see what. It isn't a tapping noise, but like a constant whine, loud enough to be loud over the engine noise at high revs. It is associated with speed not revs, and will occur in both 5th and 6th gear.

Have I gone past the accepted max speed for the auto diff and knackered it? (Not likely I think as I'm sure some of the "big guys" have pushed them much further. Has my "frigging the gearing" possibly caused it to fail? What would fail on the diff if it did go? How could I test it?

Any other ideas would be greatly appreciated.

 

Regards

 

Tony

[Matt Harwood]

How's the oil level in the diff?

 

I wouldn't have thought it's anything to do with the maximum speed the diff is capable of though. - More likely that a bearing has just decided to give up/wearing out...

 

Edited to add, I know of several auto's that have exceeded that speed without problem.

[dk_supra]

Tony,

 

the easiest thing to do is:

 

1. jack the car up and drain the diff fluid. If particles are coming out, you need a diff, the torsen is in other words toast. (Oh by the way this is very unusual but hey it happens, and I have a diff here if you are interested from a EU spec Supra Auto.)

2. Grap the Driveshaft and check if it has play, try to twist on opposite direction, put one of your buddies to twist clockwise and you twist counterclockwise to see if there is a play. If there is then the driveshaft gone, pretty unlikely too. (I have an auto driveshaft as well, if you need one.)

3. Tranny, drain it and unbolt the pan and check for parts on the mesh screen, (if you find any this thing is gone, we got an auto here with 70k klm., good one)

4. Drive axle (I never broke one, but oh well I guess it might happen, do the twist again and check the joint that way, we got those too in stock, just in case).

 

Let me know via email if you want.

 

[email protected]

 

Later

Dimitri

[TLicense]

My thoughts exactly.

 

I've not checked the diff fluid, but will have a look.

 

The problem is, obviously because this only happens at speed, it's a pain to see/hear what's actually going on.

If it is a bearing or something that's gone up the swanny, what's the prescription? Replace the diff? If so would it be worth my while upgrading to the TRD unit?

 

So many questions - sorry

 

regards

[TLicense]

Originally posted by dk_supra

Let me know via email if you want.

 

[email protected]

 

Later

Dimitri

 

Dimitri,

 

Thanks for your help, just the sort of thing I was looking for

I guess your not aware that I've converted my car to a 6 speed.

I'm pretty sure that the gearbox is not the problem, in fact I'm definate, as the noise is coming from another area, and is too loud to be a noise travelling if you see what I mean, ie I would definitely hear it coming from the tranny area.

 

I'm going to go outside now and perform the checks you mentioned. I'll keep you posted.

 

Many thanks

 

Tony

[Matt Harwood]

Diff bearings are replacable. My old auto had a whiney diff, that had the bearings replaced.

[heckler]

I'm pretty sure that the gearbox is not the problem, in fact I'm definate,

 

Not that i'm trying to be a Pain in the arse but...

 

My dad had a automatic granada and developed a vibration from the rear end (ooer) and speed, all signs and symptoms pointed at a bearing, drive shafts, diffs, bearings were replaced fault was still there... anyway as it turned out it was the gearbox.

 

now, i know this will be no use what so ever to you.

[dk_supra]

Tony,

 

since your baby is a 6 speed, it's very unlikely to blow the tranny, unless of course the driving skills of you or the previous owner are questionable. If we eliminate this idea, then basically what's left is

 

1. Differential

2. Driveshaft, Unless you have twisted the front shaft from good traction, this thing usually is bullet proof.

3. Driveaxle, Highly unlikely, they are good for many many miles

4. Wheel Bearings, they can go bad if the wheel offset is wrong

 

If it's No.1 then just swap it with the TRD and some new side bearings and you are set.

 

Cheers.

Dimitri

[Guest Terry S]

Hey Dimitri how's it going, thought you'd fallen off the face of the plant after leaving DE.

 

I will drop you an e-mail. Still building mad Supras??

[TLicense]

Originally posted by dk_supra

Tony,

 

since your baby is a 6 speed, it's very unlikely to blow the tranny, unless of course the driving skills of you or the previous owner are questionable. If we eliminate this idea, then basically what's left is

 

1. Differential

2. Driveshaft, Unless you have twisted the front shaft from good traction, this thing usually is bullet proof.

3. Driveaxle, Highly unlikely, they are good for many many miles

4. Wheel Bearings, they can go bad if the wheel offset is wrong

 

If it's No.1 then just swap it with the TRD and some new side bearings and you are set.

 

Cheers.

Dimitri

 

Ahhh see now that makes me think maybe wheel bearing, as I know my wheels are nothing like what they should be in terms of width, so probably offset too. What would be the correct way to check for a worn wheel bearing?

Thanks for all your help so far

 

Regards

 

Tony

[dk_supra]

Jack the car up from behind (from the pumpkin) and with the handbrake loose, check the rear wheels, Check the freeplay of the wheels on the x and y axis, meaning hold it left and right and try to wobble it, and then up and down. If they have any freeplay and the nuts are tight on the wheel then the bearing of that wheel is gone. Telling you in advance that I have a MKIV with 800rwhp and stock wheels and 200000klm so far and no wheel bearing problems at all.

But I changed the diff bearing when I swapped the TRD diff inside at about 160000klm and the bearings showed some wear and tear.

 

L8ter,

 

Dimitri