Droaning noise at 70 - ideas?

gturner008

Well-Known Forum User
Finally have the 240z on the road. All the jobs getting sorted. New shocks all round have made a huge difference. Good tune up and other bits complete.

I've notice that when I get to around 70mph in 5th I get quite a load droaning noise coming into the car. When I put in the clutch it goes away. I rev to 4k rpm, with clutch in, no droaning. Clutch out again and the noise comes back. 60mph, fine. Press on and get to 85mph, noise mostly gone. Put into 4th, noise still there - but not quite as loud.

I'm guessing, but feels like something is out of balance in the drive train. Any thoughts or ideas? Cheers. Gary
 

MaximG

Well-Known Forum User
Hi Gary,

It sounds like the same issue I had with my original box. After replacing it and subsequently dismantling the old one it turned out to be a bearing issue. Prop and drive shaft imbalance usually causes vibration which you can pretty much feel through the car.

Regards,

Mike
 
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gturner008

Well-Known Forum User
Thanks Mike. The box has been out, along with diff and other bits and pieces. I have a specialist in Coventry who will get the prop and mechanicals tested and sorted. I'm pretty hopeful this will sort it out. Will let you know. Gary
 

davezeds

New Forum User
Prop out of balance will be indicated by your interior mirror shaking like cray. Sounds like a bearing.
 

gturner008

Well-Known Forum User
Could be, yes. It's there in 5th gear, but also in 4th gear, but not as bad. Different shafts? Or do you mean the main bearing as it joins the prop shaft? Is there a way of testing? (Other than take off the prop and test that independently...)
 

MaximG

Well-Known Forum User
Could be, yes. It's there in 5th gear, but also in 4th gear, but not as bad. Different shafts? Or do you mean the main bearing as it joins the prop shaft? Is there a way of testing? (Other than take off the prop and test that independently...)

It's one of the bearings inside to box, exactly the same symptoms as I had.
 

MaximG

Well-Known Forum User
I was quite lucky in that I was able to replace the box with a reconditioned one. The Bearings may still be available from Nissan, however any decent gearbox rebuilding would probably be able to replace them. At the end of the day Nissan didn't make bearings they got them in. I did find a very good online provider which I used to replace the bearing in the steering rack so anythings do able.

Mike
 

gturner008

Well-Known Forum User
Thanks Mike. I think the evidence points to gearbox bearing. The noise stops when I put the clutch in. If it was prop imbalance it should stay - with clutch in or out. At 70 with load, probably is a main gearbox bearing - triggered by some prop imbalance.
 

gturner008

Well-Known Forum User
I'd like to keep this gearbox. Hopefully it is just a prop balance and a refurb of a bearing or two. It's not a bug deal. A spring job I think.
Next up is a bare metal respray. Good news is that the car is straight and free of any corrosion.
 

jonbills

Membership Secretary
Site Administrator
I'd like to keep this gearbox. Hopefully it is just a prop balance and a refurb of a bearing or two. It's not a bug deal. A spring job I think.
Next up is a bare metal respray. Good news is that the car is straight and free of any corrosion.

Which gearbox do you have? I have a reconditioned early 240 3 piece box I picked up a few years ago that I'm not going to use.
 

gturner008

Well-Known Forum User
Thanks Jon, its a 5 speed early car - HS000596 chassis number - RHD sold into Australia.

Does this sound like it might work? Cheers Gary
 

RIDDLER

Well-Known Forum User
Found this on the internet on a Z problems site. Don't know if it has any relevance:

GROWLING FROM REAR AROUND 70 MPH
This is usually due to a worn out rear joint on the driveshaft. Go under and twist the driveshaft joint where it bolts to the differential. There should be no slight clicking or play, but after 30+ years it's gotta go sometime. Unfortunately, the joints on 280Z/ZX driveshafts aren't replaceable. Nissan made them cheaply by stamping the joints in, so there's no way to remove and replace the circips and joints. The junkyard is a good place to get a replacement but you're still stuck with a very used part.
 

jonbills

Membership Secretary
Site Administrator
Thanks Jon, its a 5 speed early car - HS000596 chassis number - RHD sold into Australia.

Does this sound like it might work? Cheers Gary
not sure I'm afraid, I don't know enough :-( someone might be along who knows the dates/numbers.
empirical approach would be to get under the car and look - is the 'box in 2 or 3 sections?

I'll take a pic of mine over the weekend!
 
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