Intermittent vibration - o/s front

[edh]

Bit of a strange one this...

I get a vibration, felt through the body & steering wheel, which feels just like running over the anti-skid tarmeac they put before junctions.
It happens at speed - only occasionally. It's either through fast left hand bends, or sometimes after changing lanes on the motorway. It feels like you get it after you have loaded up the front o/s tyre.

I can't see any obvious signs of wear - the car was checked over by PH at the weekend & they didn't find anything. There's not all that much to check is there? - wheel bearing, suspension bushes, ARB bushes, track rod

I've just swapped wheels to see if it will make any difference.

Any suggestions? - I was wondering about the suspension top mount?

 

[tref]

Engine mount colapsed running on the steering shaft?

 

[Tam Lin]

Could it be a slight wheel rub during weight transfer?

 

[edh]

I'll have a look at the steering shaft today & see if there are any shiny areas - no other obvious signs of engine mount failure though...

Tam - I've swapped the wheels over now, so I'll see. I doubt it very much, becuase sometimes it persists on the straight. The vibration is felt/heard more through the shell than through the steering wheel

 

[Big Dave]

Could it be the exhaust rubbing somewhere.?? Maybee a mount snapped.??

 

[edh]

I hope ph would have spotted any exhaust issues when they fitted the Tial DPW last weekend

I'll have to get it up in the air & get the trays off at some point - won't happen before Silverstone though. I'll have to see how it feels through the complex after Copse (edited to replace RH bends with LH ones [])

 

[dann944]

engine mount broken??

or maybe a flat spot on that Tire, have you locked up recently?

 

[Indi9xx]

Check all 4 wheel bearings in detail and check the diff carrier bearings.

 

[Hilux]

I hope ph would have spotted any exhaust issues when they fitted the Tial DPW last weekend

Ahaaaaa.......................may seem obvious but was it there before this work took place?

 

[edh]

yes - it's been noticeable for a while. I pinpointed it a bit more clearly on a drive to Scotland & back the other week. As I've had a few rear suspension "issues" recently, I had't been too concerned about this minor vibration from the front - until now...

Had a look at the steering shaft from the top - no sign of the exhaust manifold touching it

 

[sawood12]

Have you driven your car in the rain recently? I notice that after I drive the car in the rain and then leave the car standing overnight I get some brake pad deposits adhering to the brake disks and this can cause an intermittent vibration for a time until I use the brakes enough to clean up the surface of the brake disk. Another good reason to stick with stock pads.

 

[edh]

I've got the wheels off to swap for tomorrow - I noticed a small bit of a mark on the springs - matches up with the tyre rim

there's a very small amount of scuffing on the tyre - this might be it

I had the alignment done a couple of months back & a bit more -ve on the fronts....

Going to see if I can wind a little bit of camber off.

 

[edh]

OK - that didn't help

But what did was putting on another set of wheels / tyres on the front - it seems to have solved the problem. I hope so....

 

[edh]

No progress - still intermittent vibrations. [] mainly through the floorpan/body, rather than wheel. Quite pronounced yesterday at Donington.

Apart from this, the car is driving beautifully. PH sportscars haven't found anything after a number of goes. We've changed both rear & OSF wheel bearings, rear shocks are new, front inner ARB bushes are new. There's no play in shocks, balljoints etc..

I re-read Jon's post above, suggesting diff carrier bearings - Simon at PH thought this would result in constant gearbox noise + noise on cornering. Apparently this car is fitted with an old style engine mount on the n/s, but I'm told it looks OK. That's probably the next thing to swap out.

Any more suggestions are welcome -PH are at a loss for anything else to try

 

[homesea]

This may sound odd but check the output shafts on the gearbox. Make sure they dont have loads of float.

 

[edh]

Output shafts? - do you mean from the diff to the CV's?

It's a very strange one this, because it feels like it's coming from the front, but I wouldn't rule out a problem at the rear.

 

[944 man]

Ed, considering the trouble that youre having and the expense that youve already gone to: can I suggest that you renew all of the consumable parts on the front of the car? This shouldnt cost too much: there should be a noticable benefit: and at the very least it will allow you to rule them out as potential sources? The strut mounts and ball joints arent cheap, so maybe a damned good inspection will suffice there: but the castor mounts and all other bushes, along with the steering rack mount rubbers and the TREs arent particularly expensive. Youll be able to thoroughly examine the condition of other parts whilst replacing the bushes too, the anti-roll bar surfaces for example. You can see an awful lot more when the parts are in your hand than you can with an inspection lamp on a lift...

Simon

 

[edh]

It could get very expensive if I start replacing everything on the car....

I'm inclined to discount front suspension / steering components on the basis that there's really no shake coming through the steering wheel. You can hear it, feel it through the seat and through the floorpan.

 

[944 man]

ORIGINAL: edh

I get a vibration, felt through the body & steering wheel, which feels just like running over the anti-skid tarmac they put before junctions.

This was the bit that caught me out... []

 

[edh]

as the problem has advanced, it's much more obvious through the shell - very noisy at Donington yesterday.

I looked at the engine this morning - it doesn't look like the mounts have collapsed (and I hope Simon would have spotted anything obvious) He has suggested replacing the n/s engine mount anyway, as it's an early (non-turbo) one.