Diff Whine

[peterjfox69]

Just had all my suspension bushes replaced with Poly bushes along with a load of other suspension work by a reputable Stag specialist.
My diff is now whining at around 40-60mph which it wasn't doing before. I'm presuming the Poly bushes are the cause of this?

[flying farmer]

If that is the diff noise that can be heard on the video rather than engine noise I reckon it is more likely to be bearing failure.

Diff whine tends to be an even sound whereas that one seems to be pulsating.

I had a very similar experience on my Stag about 8 years ago on a trip to the Isle of Wight, it was fine on the way down but with about a hundred miles to go on the return journey the diff got progressively noisier and it was a grumble rather than a whine.
I stripped the diff on my return to find the carrier bearing on the crownwheel side had an area about the size of my little finger nail that was suffering from surface disintegration, and the rollers were starting to pit as well.
Prompt attention meant it only needed a bearing set to mend it (still not cheap for genuine Timken bearings). Ignoring it would have caused rapid destruction of the whole diff as the fine flakes of bearing material make a very effective grinding paste!

I would suggest getting it looked at sooner rather than later as a good diff will still be silent even with poly bushes.

Neil

[peterjfox69]

Thanks for the reply Neil

[peterjfox69]

Just a thought,
by having polybushes fitted to the whole car on the advice of Stag specialists does that then open the door to endless bags of cash being lobbed into the said Stag as diff whine is caused by the said polybushes?
am I being taken for a bit of a ride here or are polybushes the way to go for a much better ride but because the diff is an old design it can’t handle the polybushes you have to suck it up and drop cash on a new recon diff with a modified crown/pinion?

[DJT]

Polybushes won't have caused problems with the diff. Some poly bushes are quite hard and they accentuate any existing diff noises through the chassis. Voided diff support poly bushes were developed to counter this problem. Only your supplier will know if they fitted solid or voided bushes.

[jbuckl]

They can transmit noise and vibration well.
They aren’t favoured by all.
won’t have been the cause of the diff issue, just an amplifier or transmitter instead of a damper / suppressor