Now the zeds back on the road i'm gradually sorting out the niggles, one thing that is really annoying is this vibration that comes on from around 20mph - 40mph then lessens, its quite bad as you can feel it through the seat.

 

Many thread searches would lead me to believe its either the autobox rear mount or prop shaft centre bearing or both, its a 1990 J spec TT auto, if i take it to my usual spanner monkey will they be able to tell which it is by looking at either of them?

 

I'm not too bothered about flash upgrade parts like one piece props or nismo mounts, as i don't plan to keep the car for ever would stock nissan parts suffice?

Your right it is propbably one or the other, or both, a Nismo rear mount is cheaper than the stock item and one piece prop is only about £50 more than just the bearing which is why most people go that route, it is easy to tell if the bearing has gone, rear mount harder to tell from just looking.

Your right it is propbably one or the other, or both, a Nismo rear mount is cheaper than the stock item and one piece prop is only about £50 more than just the bearing which is why most people go that route, it is easy to tell if the bearing has gone, rear mount harder to tell from just looking.

 

how do you tell the prop bearing has gone by looking at it?

In most cases the rubber surrounding it will break up, I have a picture somewhere of mine where it had broken up completely and you can feel the play by hand, also the Nismo rear gearbox mounting is actually designed for the 240SX and some say should not be used on the 300ZX as it makes the gearbox sit 2mm higher although I and many others have it fitted without issue.

 

Picture of typical bearing found on the net.

Where are theres parts available from?

Gearbox mount can sag as well adding to the problem. The propshaft centre bearing can be temporarily padded using strips of 5mm ish thick rubber or polythene to pack it up. Same with the autobox mount. You have to gently jack up the shaft near to the centre bearing so that you can see a gap in the cracked up bellows effort as the bearing lifts up. It is riding on the bones of its ar5e so to speak and out of line. You pack a couple of 5 mm thick ish strips in there and let the jack down. Result the shaft is now centred better and vibration should be gone until your new part arrives. The strips eventually work their way out of place tho.