I have a 93 UK manual TT. Currently at speeds over 30 the car vibrates (peeking between 40 and 50). I have had the tyre balance checked. I have replaced one of the rear steering rack arms but the garage tells me that the other has play in it. Could this cause the excessive vibration? What other things can cause vibration? (I believe it is coming from the back as the vibration does not seem to be concentrated through the steering wheel).

 

Thanks for any help

A lot of people seem to suffer from worn propshaft centre support bearings. 'fuzzy rear view mirror' is the usual symptom.

 

The repair kit is about £250 I believe.

 

HTH

 

RobH

Yep - the prop shaft centre bearing support sounds like the most obvious choice. See if it still happens if you take the car out of gear.

 

Russ.

It does still happen when I take it out of gear. What would this show? I assume that the prop shaft is still rotating wether it is in gear or out?

 

Cheers

Dave

You *should* get less load on the bearing when the drive is disengaged - here's where I got my info from (as well as Jeff TT) -

 

courtesy of Nico...

 

 

Things to check for vibrations.

 

Road Test stuff.

Check Location of vibrations.

 

If you feel it thru the Steering wheel, signs point to wheels or Front steering rack. See below

 

If the vibrations are felt more thru the seat in a left and right sorta way then back wheels are a good possibility, Check for Toe end Wear and other signs of tracking problem on the tyres as below. Also check for play in the bearings and the Track End Rods of the HICAS and the rack itself, (I.e Check for signs of lateral play when focing the wheel in and out from its axle)

 

Check the Props shaft "tunnel" i.e the raised section behind the gear stick and hand break. If you feel distinct vibrations from there (may be a good idea to have someone else drive) it is a drive line problem see below. You can also try depressing the clutch while the vibrations can be felt if they lessn or appear to change frequency - this all depends on your feel for the vibrations speed and road you are on, some people notice absolutly no difference when they do this. But in theory there should be as the load on the bearing is lessend when drive is disenguaged.

 

Exterior / Mechanical Checks

 

Wheels :

Balance,

Check for damaged rims.

Tracking - Proper 4 wheel allignment is need on tt's or it will not be correct.

 

Prop Shaft balance.

Measure run out with a Micrometer or similar instrument.

Check the Transmission mount.

Check the Center Shaft bearing.

Chance are if the vibrations are coming from the shaft then it will be one of the above,

 

 

How can I check for play in the prop shaft bearings? is it visually noticable?

Never done it myself, Dave - Sorry.

Russ.

If vibration starts bad when cold, but gets less as the car is driven then this points to propshaft centre bearing or rear gearbox mount (or both!). As the rubber warms up, it gets more pliable and the vibrations get smaller.

 

HTH

 

StuartR

...do the rear gearbox mount first as it's most likly the culprit - and it's cheaper...

 

About £55 for the gearbox mount and £150 for the centre bearing.

 

Gearbox mount replacement is a couple of spanners, centre bearing is a couple of spammers and a puller - and remove the exhaust system cat back.

 

good luck.

 

Jack

Jack,

 

I have an entire prop and almost brand new centre bearing for sale in the "for sale" section. £70!