Car shaking between 45 and 55mph but not wheel balance

mgoodlad · Unread post by **mgoodlad** » 20 Aug 2006, 11:17

Hi - just getting all my problems solved today hopefully (see my other posts on oil on coolant and engine check light).

Car is a 1998 806 1.9 SLDT with 97,000 miles. The car has started to shake between 45 and 55 mph. It is the whole car which shakes and not detectable in the steering - so I had assummed it was the balance of the rear wheels. These have been balanced twice now and it makes no difference.

The other interesting thing is that the car only shakes when you are accelerating - the minute you take your foot off the pedal the shaking stops immediately...and if you then try to accelerate again the shaking returns. So that seems to point to not being the wheel balance as the shaking would remain while the wheel was turning at that speed.

So could it be a driveshaft or engine mount or something? How can I check for faults there?

One related problem I had was a new tyre fitted by a garage and the nuts weren't tightened properly and with my wife driving she kept on going until the wheel was nearly off (!!) Don't know if that could have somehow damaged something? It was a rear wheel.

Once again any help much appreciated.
Michael

1998/R 806 1.9 SLDT 97,000 miles
1996/N 106 1.5d 123,000 miles

Adstar · Unread post by **Adstar** » 22 Aug 2006, 10:17

If the wheel was pratically off, could the hub assembly have been either damaged or pulled out of place? Have you checked all 4 tyres for 'roundness'. My Girl Friends Fiesta developed an unbelievable shake which turned out to be a small 'bubble' in the tyre (caused by the bands breaking after hitting a speed bump FAR too fast!)

Not sure abotu it happening only under acceleration. This woudl hint at drive shaft or possibly bearings. I will be interested to see what other ideas are put forward.

Decca · Unread post by **Decca** » 23 Aug 2006, 12:00

My first thought was what Adstar alluded to. a Tyre/s out of round, could be caused by damage such as hitting something or flat spotted due to heavy braking.

Could be a rear tyre if more noticeable under accelaration as weight is forced back (opposite to weight going forward when braking). Swap tyres front to rear to start the process of elimination

Is problem worse when tyres are cold, first thing in morning?
Is wheel alignment ok? steering wheel in correct position when car is travelling straight on a level road?

Decca

jgra1 · Unread post by **jgra1** » 23 Aug 2006, 22:52

hi had this with flatmates ZX, took ages to pin it down. In the end advice from the board saved us..

on her car it was related to a certain torque band, and most prominent in 3 4 5th gears as 1st and 2nd 'powered past it' etc..

Driveshaft inner joint was destroyed.,. tried engine mounts / new tyres etc to no avail...

john

dancingdog777 · Unread post by **dancingdog777** » 27 Aug 2006, 20:38

Check the engine mountings would be my first guess. Accelerating would show this symptom since releasing the accelerator pedal (in a diesel) makes the engine try to return to tickover.

Decca · Unread post by **Decca** » 01 Sep 2006, 10:20

First thing to check is ... does the vibration occurr irrespective of engine revs.
try 50mph in different gears.
This will show if fault is in the engine or drivetrain

Decca

fastandfurryous · Unread post by **fastandfurryous** » 02 Sep 2006, 11:43

I will bet good money that this is a knackered driveshaft tri-axe (inner) joint.

get under the car, and then try to "lift" the shaft (radial movement rather than axial) while it's in position. Any movement at all indicates it's knackered.