Scraping or Grinding Road Speed Related Noise

[ukkid35]

This has been getting progressively worse, I'd managed to convince myself it was the CATs vibrating against the chassis, but now they're gone it plainly isn't.

The noise gets worse after going over a bump, and also under hard cornering. I can't work out which end of the car it's coming from, I can't replicate the problem with the car on jack stands with the engine running and in gear.

I'm at a complete loss, and it is quite a disconcerting noise. I can't see any evidence of anything rubbing anywhere around the front or rear suspension. My only suspicion now is that there could be something rattling around next to the prop-shaft. But why can't I hear it with the car on jack stands?

Any thoughts? Anyone willing to come out in the car with me at Burghley House to help diagnose?

[camel_landy]

If you can't replicate when on stands, maybe it is coming from the front??

Could you have a bit of grit/stone stuck between the disk & pads/hub?? It's not uncommon to get it on a Landy and it'll make a horrible noise!

M

[ukkid35]

Thanks, I hadn't thought of that, but I've just bled the brakes and I should have noticed had there been debris in that area.

[billy no brakes]

ukkid35 said:

This has been getting progressively worse, I'd managed to convince myself it was the CATs vibrating against the chassis, but now they're gone it plainly isn't.

The noise gets worse after going over a bump, and also under hard cornering. I can't work out which end of the car it's coming from, I can't replicate the problem with the car on jack stands with the engine running and in gear.

I'm at a complete loss, and it is quite a disconcerting noise. I can't see any evidence of anything rubbing anywhere around the front or rear suspension. My only suspicion now is that there could be something rattling around next to the prop-shaft. But why can't I hear it with the car on jack stands?

Any thoughts? Anyone willing to come out in the car with me at Burghley House to help diagnose?

don't forget that going over bumps or around corners you cannot replicate when the car is on axle stands, it could be the exhaust just hitting the bodywork, which sounds more than likley

[ukkid35]

billy no brakes said:

it could be the exhaust just hitting the bodywork, which sounds more than likley

Blipping the throttle makes no difference at all, and I've just had the entire exhaust replaced and it is more thoroughly supported than ever before, so I don't think it's the exhaust any longer (even though I did originally).

[jeremyc]

Could it be a grumbling wheel bearing?

[V8 GRF]

Are the wheels and tyres standard sizes?

If not it could be tyres rubbing the bodywork or a wheel rim catching and rubbing on a suspension arm?

[ukkid35]

V8 GRF said:

Are the wheels and tyres standard sizes?

If not it could be tyres rubbing the bodywork or a wheel rim catching and rubbing on a suspension arm?

All standard sizes, and no visible evidence of rubbing.

[RAFsmoggy]

Is it possible to record the noise & stick it up here?

[TimJM]

I will be at Burghley and don't mind taking a listen on a drive. Sometimes having a passenger that can move round the car a little can help to pinpoint the location.

[Milky400]

uneven tire wear? had this on a Land Rover, and it was bloody noisey

[FarmyardPants]

The downpipes run very close to the chassis, if you get the noise under heavy cornering it could be that they are making contact. Check the gearbox and engine mounts are tight. You could perhaps smear something on the chassis edges and see if it appears on the exhaust. Mine does this from time to time and it sounds nasty. Usually when cornering hard one particular way. Andy at APM moves the gearbox on its mounts to get the downpipes more centred but there is only about 8mm of clearance on both sides on mine iirc.

[ukkid35]

FarmyardPants said:

Check the gearbox and engine mounts are tight.

Will do that, thanks.

[gruffalo]

ukkid35 said:

FarmyardPants said:

Check the gearbox and engine mounts are tight.

Will do that, thanks.

I had this, fast left hander and got a vibration and grinding noise through the car, getting back on the power would reduce it, shifted the engine over to the near side a couple of millimeteres and all was well.

[WhyTwo]

I have the same problem. It only happens occasionally and mostly when under braking, not even heavy braking, whilst turing left at the same time.

Jason at str8six diagnosed the manifolds rubbing on the chassis. Engine mounts were changed but it didn't resolve the issue. Next time it's into str8six they're going to look at it again. I think the suggestion from farmyardpants could be the answer

[ukkid35]

FarmyardPants said:

Check the gearbox and engine mounts are tight.

Gearbox mounts collapsed.







Reason being that the upper bolts seize before clamping on the gearbox bracket, so the mounts sheared and moved sideways, causing the engine/gearbox to drop by 1 1/2 inches.

Hopefully this will do the trick

http://www.ebay.co.uk/itm/360519537928

The TVR supplier prices are £12 to £16 plus shipping in comparison.

Edited by ukkid35 on Wednesday 9th April 06:57

[jamieduff1981]

That'll do it. It's always nice to positively identify something like this!

[FarmyardPants]