Horrific knocking noise - HELP!

[MTolman]

My new car has gotten ill, already!
I've only had it a week, 2003 Elise 111s

Need some advice or ideas on what it might be. Usually occurs when you set off, there is a deeply unnerving knocking sound coming from the front of the car. Feels massively like a flat tyre, with a constant bump, bump, bump sound and a knocking feeling in the steering wheel. - Its not the tyres - I've checked and checked again. The bump seems to be in sync with the speed - faster you go - the faster the bump gets. Finally at a random point, usually 3-4mins of driving it goes away?

My only thoughts it that it might be a wheel bearing, perhaps a slightly flattened edge on one of the ball bearings? It really is a strange one though. Definitely not coming form the engine.

Any advice/tips/ideas would be greatly appreciated.
Cheers

Mark

[TonyHetherington]

First question...have you had the wheels off recently for anything? Perhaps had new tyres fitted something like that?

Check the wheel nuts are done up to the correct torque (seriously, check this!)....77lbft is the correct setting.

[NWTony]

If this happens when you have the wheel on full lock it's nothing to be worried about! Check the clearances of your wheel arch lines but I believe they all "knock" a bit when the front wheels are fully turned. Mine does, my mates does as well. Only noticeable at slow manouvering speeds.

[LivinLaVidaLotus]

Or in new money, it's 105Nm on S2.

[MTolman]

No - Haven't taken the wheels off - and the knocking happens in straight lines and round bends! If anything, lots of cornering helps it to go away faster?

I'll be rushing out to check to torque after writing this - thanks for the tips though guys - I really appreciate the help.

[GreenV8S]

Does it happen if you roll the car by hand? If so you should be able to locate it if your glamorous assistant moves the car while you listen carefully by the wheel.

[Pesky]

Sounds like it may be the brake pads rattling. They expand with heat, so the rattle tends to go away. Pagids are particularly prone to this. Eliseparts sell "anti rattle" pads.

Try very gentle left foot braking, whilst still on the gas. If the noise dissappears, the above is the answer.

Edited by Pesky on Saturday 22 March 15:30

[subaqua]

I agree with Pesky... most likely cause is brake pad rattle in which case its nothing to worry about, although you can get the buffers to sort it out if it bothers you.

[MTolman]

I think you may have have cracked it! I checked the torque on the wheel nuts, was all fine. But brakes makes sense, especially as its an intermittent problem. Once I thought about it, only occurs after washing the car, or on a very wet day, and it only happens at the start of the journey.

Hopefully its nothing to worry about.

Thanks again for a great response.

Mark

[TonyHetherington]

MTolman said:

I think you may have have cracked it! I checked the torque on the wheel nuts, was all fine. But brakes makes sense, especially as its an intermittent problem. Once I thought about it, only occurs after washing the car, or on a very wet day, and it only happens at the start of the journey.

Ah excellent

(there's many noises and things that come from Elises; when I first got mine I was hearing every noise and thinking "what's that? is that a, no, it can't be, oh hang on there it is...uh oh" every time I drove it. Slowly you get used to the noises )

Enjoy!

[IanBowers]

Tyre blister; inside wall?

[SpeedYellow]

My money would be on a knackered anti roll bar bush...

[hueandcry71]

it may be your shoulder, mine has never been the same since driving a Lotus. It makes some beautiful clicking and cracking sounds caused through getting in and out. Come to think of it, it may even be your knees as mine also make funny noises since Lotus ownership.
Im looking forward to the free rocking chair and stenna stair lift that came with the Saab turning up to help ease my aches and pains and enhance my mobility !!

[MTolman]

Its back! With a vengence...

Not so sure it is the brakes anymore, theres such a pronounced bumping, both through the steering wheel, and the chassis. Feels like running over cats eyes. Its very intermittent too, and only ever at the start of a journey.

How do i check the roll bar bush?

[Porlock]

If its after washing and then the next drive i would go for the discs getting a coating of rust snagging the pads. When you wash the cars the discs soon go orange.

[DanCat]

I agree with Porlock about the corrosion, but in my experience (also a '03 111s) when the discs get wet and are then left, rust forms where the pads have been in contact with the disc and retained more moisture. Sometimes my rears seize on, especially after a salt coating.
When you next go to brake this rusted area causes a judder as it passes the pads again. This will go away after a few minutes after the disc has been cleaned by the pad.
Aside from removing the wheels and sanding the discs, theres not much you can do about it.

[S2john]

IanBowers said:

Tyre blister; inside wall?

I know it's already been said, but defo worth checking as it can easily go undetected
Had a similar sound on the rear of my Focus. You guessed, it was a bulge on one of the tyres. Replaced tyre no more problem.

[Grinnders]

Probably not loud enough to account for what your hearing, but recently I had a couple of new tyres put on the front of my car and they went tick tick tick.

Because I was literally driving away from the tyre centre it was easy to ascertain it was related to wheel revolution. Discovered that the clearance between the inside of the alloy and the brake caliper is so marginal that the balance weight was catching the caliper with every revolution.

Took it back straight away and got the weights relocated.

Just a lesson for others should they discover likewise with new front rubber.

[RobM77]

Warped brake disc banging into the pads? I suppose they could be seating back after a bit of driving. I've never had that problem, but it makes theoretical sense to me. I'll stand corrected if that's nonsense though. Try braking firmly as soon as you start off. If there's a vibration that's your culprit. Not an expensive one to fix.

[TonyHetherington]

MTolman said:

Its very intermittent too, and only ever at the start of a journey.

This bit's puzzling me. That suggests that it's something that warms up (for example) but I can't think what that would be?