Conclusions from my last question seem to point to either the gearbox mount or the prop shaft bearings...I do have some more information now and a further question:

I took the car on a longer journey over the weekend (I only do about 10 miles a day normally!!!) and when properly warmed up the vibrations were no where near as bad as when cold/cool. They still continue when I take the car out of gear. Does this point more towards the rubber gearbox mount (someone suggested that when old and worn vibrations get less as the rubber gets warmer)? are there any particular visible signs that can be seen to determine the gear box mount?

Dave

Getting less vibration as it warms up does point to the box mount being suspect but also the centre bearing. It is not the bearing itself that usually fails, only that the rubber bellows affair that supports it which hardens and cracks at the top side and then sags the shaft down onto the bottom side of the mount.

 

I found this with mine. I should replace the gearbox mount as well but havnt got round to it. Instead I jacked the transmission up slightly and slipped some rubber pieces into the slot in the rubber mount to pack it slightly and counter the sag and lack of support.

 

Seems to have worked as there is no vibration on mine now.

 

Both components are implicated here as they allow the output shaft of the transmission to point down slightly and the centre bearing lets the middle of the shaft sag. All adds to vibration possibilities and ultimately ruined oil seals and damaged universal joints on the propshaft.

 

search will show you loads on this

Dave

 

Mine has the same symtoms you describe. I replaced the gearbox mount, but putting the old one side by side with the new one - the old one looked fine.

 

I still have the classic 30-50 mph vibrations, worse when cold, so I guess it must be the centre bearing, and I have heard that can be a b**ch of a job.

 

 

John

I spoke with a parts shop in Burton and they have had a number of ZX prop shafts in with worn bearings. They get them changed and the prop shaft balanced for about £150. If the centre bearing is worn (the guy told me that you will see movement in the centre mount without actually 'hitting' the rubber) they sell these separately. They seemed to think it was a fairly easy job...4 bolts for the back of the prop shaft and 2 holding the centre mount and bearings. We will see though.

 

If you want their number I will have to dig it out....otherwise its on Uxbridge Road in Burton upon Trent.

Dave,

 

I would be interested to talk to them. Are you saying that they sell a prop shaft with a new bearing for £150 ?

 

Apparently the prop shafts are a b**ger to separate. Also I understand the exhaust has to come off.

 

 

John

They recondition your prop shaft for £150 (includes the bearings and balancing)...takes about 3-4 days. If the centre bearing has gone (bearing with the rubber mount) then this is a separate item and can be bought from them...forgot to ask for the price on this one though. Not sure about dropping the exhaust as I haven't looked at it yet!!!

Centre bearing about £135-150 plus up to 3 hours labour to do the job if youve big zorsts that have to be dropped first.

Not too bad of a job for the DIYer. Me and me bro did it in about 6 hours - was first time, and just on axle stands, etc. The more room underneath the easier. We only had two axle stands, so at the gearbox end it was crooked neck, and little movement (just as well you don't need much ooomph at this end!) All the usual good practise applies...

 

1. Remove exhaust. We did it after the CAT, but may be easier from the manifold. After the CAT involves some tricky stuff with the CAT shields. Remember the be careful with these bolts - lots of penetrating oil, heat, etc.

 

2. Mark up all the relative positions between prop halves and rear axle.

 

3. Loosen the prop bolts joining the 2 halves while on the car. This is easier than off the car IMO. Undo the rear axle bolts (you might need a strong allen key!). You need the handbrake to be strong here (and I think we had the car in N)

 

4. Undo the centre bearing carrier bolts. We actually then broke the prop centre, and took the prop back half off first, and then withdrew the front half. It was easier to break the centre, and then get the rear out of the differential carrier.

 

5. Remove the stake from the centre bearing bolt, and put the "square" part of the bearing in a vise - it won't turn now. Remove the bolt, and withdraw the bearing using a puller. This bit was much easier than we thought it would be!!!

 

6. Reverse of all above.

 

The biggest b*tch was getting the exhaust back on again!!! Also helps if you've got a strong handbrake - mine is auto, but i DIDN'T rely on using the parking brake lock - don't want to break it!

 

My bro did the front gearbox mount - it was so quick I disn't have time to see what he actually did - I think its pretty easy though.

 

This cured the vibration problem. Now just need to get the wheels balance......:rolleyes:

 

HTH

 

StuartR