Diff whine

[Saint]

I've just had my 1971 240z completely restored and took it for a test drive. While there are a few things that need attending to, the one that I'm not sure of is a consistent low level whine coming from, I believe, the diff of the car and at up to and over 90mph a vibration through the seat. I'm not sure if it should feel relative smooth at these speeds. Would this have anything to do with balance of driveshaft or maybe shafts to rear wheels, u-joints?

Any help would be appreciated as I haven't anything to compare with.

[24OZ]

Your welcome to come for a ride in my Z for comparison.

Its a 73, still have to restore it but I dont get any vibrations at all, but then again i havent taken it up to 90mph, you are a brave man or a man with better brakes then me .

[HS30-H]

Hi Saint,

90mph? Is this part of the break-in procedure for your rebuilt engine? I think you should be taking it a bit easier for the first few hundred miles at least...........

Pinning down the whine / vibration will be quite hard on a completely restored car that you never drove before the resto. - you do not know the history of some of the components that have not been replaced.

However, the low pitched whine is probably the diff. If it was the transmission you would be able to hear it more beside you rather than behind you - so where is it coming from? Since your car started life as an HLS30 you might very well still have a diff. ratio that does not suit your conversion to a 5-speed box. A 3.9 ratio would probably be better - so this might be a good chance to fit one. This should be easy to find here in the UK - but I have one that is a "known quantity" if you get stumped for one.

The vibration could be the propshaft or indeed any other rotating component, but the prop and driveshafts would be the most likely culprits seeing as your wheels and tyres are brand spanking new and have just been balanced..........

These cars are supposed to be smooth as anything when cruising in top gear - so there is definitely an issue with yours. However, after taking it completely apart and putting it back together you will have to expect some niggles like this. Don't get too upset, and it will all be sortable in the end.

Good luck,

Alan T.

[Saint]

Thanks guy's. The 90mph is not had to do when cruising the M25 and it was only for a moment downhill. I appreciate your comments about taking it easy and I am aware.

Thanks Alan for the offer on Diff. I'll see what Geoff has to say about things as he has a few more things to attend to and I know is probably aware that he will anyway. I already asked them to check the diff spec after my conversation with you at Goodwood. So I would assume that they know.

George thanks for your comforting comments on vibration at speed and yeah the brakes are great. Uprated at the front with 2 pot calipers. I'd love to take you up on the drive, thanks very much for the offer.

Perhaps you guys could e-mail your phone numbers etc so as we can catch up.

Cheers

Guy:D

[24OZ]

Guy, I've PM'd you, check your private messages.

I should be free the weekend of the 19th October, Alan if your around it would be great to meet you too. Fingers crossed the weather is on our side as I dont take her out when it rains.. the shock of water is too much for the old girl.