Front left thudding sound

Cashy · Post by **Cashy** » Wed Jan 12, 2011 6:46 pm

Hi guys new to the forum and just wanting some advice. When i drive my 04 liberty (wagon) i seem to get a funny thud thud thud sound from the front passenger side... sounds like its coming from the tyre but not 100% sure. Just wondering if anyone has any ideas as to what it may be? oh it also only happens between speeds of say 40 to 60kmh.

Thanks for any replies!

Post by **TOONGA** » Wed Jan 12, 2011 7:02 pm

It could be a defect in the tyre, it could be something wrong with the CV shaft.

On a flat cement or bitumen surface, with your tyres chocked (not the one that will be jacked) and your car in neutral (engine off please) jack the tyre up that you think is making the noise and spin it slowly. looking for nails , bolts in fact anything that shouldn't be there.

TOONGA

bonzaman · Post by **bonzaman** » Wed Jan 12, 2011 7:30 pm

i've found flat spots on tyres causes thumping,also check inside edge of tyre for uneven wear.

Cashy · Post by **Cashy** » Thu Jan 13, 2011 5:51 am

Thanks guys will give it a check today. thanks for your help

YouTube · Post by **El_Freddo** » Thu Jan 13, 2011 9:20 pm

bonzaman wrote:i've found flat spots on tyres causes thumping,also check inside edge of tyre for uneven wear.

The flat spot was my thoughts too. Very hard to find at times. If you don't know the history of these tyres best to get them checked out at a trusted tyre store, ask them to check for roundness.

All it takes for a flat spot is one solid thump on the brakes that locks up the front end - usually in one of those quick reactions to avoid a collision. The reason why you'll hear the thumping between those speeds is because that's the speed that the skidding occured, thus the period of the speed range that you'll hear it.

A new tyre will sort out that problem, two would be best or retire this tyre to the spare's duties. Always best practise to replace front tyres together and rears together to keep each side at equal wear rates to the other front and rear.

I've also heard recently that if you have too much wear difference between the best tyre on the car and the worst you'll scrub out the centre diff before too long. Could be something worth investigating...

Cheers

Bennie

rebuilder · Post by **rebuilder** » Sat Jan 15, 2011 11:21 am

CVs worn or Hub Bearings completely shot.
most likely CVs tho, first place to start, if the rubber boot around the CV is broken, i guarantee you the CV joint itself is the issue, if not it still may be.

Jack up the wheel, and try wobble it (by grabbing the tob and bottom and trying to tilt it in and out) if ti wobbles, ur Bearings are shot.
If ur getting the thuds u talk about and its bearing related you'll see it in the free play in the wheel.

YouTube · Post by **El_Freddo** » Sun Jan 16, 2011 12:07 am

rebuilder wrote:CVs worn or Hub Bearings completely shot.
most likely CVs tho, first place to start, if the rubber boot around the CV is broken, i guarantee you the CV joint itself is the issue, if not it still may be.

Jack up the wheel, and try wobble it (by grabbing the tob and bottom and trying to tilt it in and out) if ti wobbles, ur Bearings are shot.
If ur getting the thuds u talk about and its bearing related you'll see it in the free play in the wheel.

Taking corners and hearing the noise I can see this/these being the issue but since its only at a certain speed and presuming at any angle of turning I'd be looking at tyres as the culprit as previously mentioned. Once they check out fine move on to the more "severe" items. I say severe as in the amount of work that's required to repair the worn part...

Cheers

Bennie

rebuilder · Post by **rebuilder** » Sun Jan 16, 2011 7:40 pm

so im learnign somethign here, are you saying that a flat spot from say, an emergency breaking situation) can cause enough of a problem to hear it on a stock wheel.
i would have thought flat spots only occur on soft compounds, usualy reserved for those situations like F1 hahah.
Thats insane hey, Cashy, if you find flat spots and they are the cause, tell me what tyres ur on, so that i never buy them!!
I woulda thought eggs and foreign matter would be the only out of round situation a road tyre could attain.

El freddo can u explain the science behind this quote, im intreagued.
All it takes for a flat spot is one solid thump on the brakes that locks up the front end - usually in one of those quick reactions to avoid a collision. The reason why you'll hear the thumping between those speeds is because that's the speed that the skidding occured, thus the period of the speed range that you'll hear it.

Why does it only come back at that speed, surely once you break, the tyre isnt doing any speed anymore, its at 0?
how does it work

YouTube · Post by **El_Freddo** » Mon Jan 17, 2011 3:13 pm

rebuilder wrote:El freddo can u explain the science behind this quote, im intreagued.
All it takes for a flat spot is one solid thump on the brakes that locks up the front end - usually in one of those quick reactions to avoid a collision. The reason why you'll hear the thumping between those speeds is because that's the speed that the skidding occured, thus the period of the speed range that you'll hear it.

Why does it only come back at that speed, surely once you break, the tyre isnt doing any speed anymore, its at 0?
how does it work

From what I know about it: Yes the wheel is doing 0 but the vehicle is still moving - this is effectively a locked up wheel in a slide and this is were the flat spot is being created. If you do a little half second lock I doubt you'll know about it later on. It can happen to ANY type of tyre if its locked up for long enough. The period and speed that the wheel is locked at will determine the severity of the thudding sound and also "sets" the speed that you will hear the thudding clearest. I think this has something to do with the shape of the tread, I believe that as a wheel increases speed the centre of the tread buldges outwards (hence why over inflated tyres wear in the centre the most) and this is what creates the slapping noise on the road - when the tread matches the shape of the flat surface its running on the noise is created.
If left because you decide to put up with it the tyre will wear out of shape and possibly create vibrations at speed.

I've not read up on this, I've experienced it! Two front tyres locked up to avoid a dickhead that stuffed up - I avoided a crash yet I paid the price for the other driver's mistake! Where's the Justice in that??

So to get a flat spot you need to lock up a tyre - enough to leave a black mark on the road (the mark that used to be a part of your tyre). If you look hard enough you might be able to find the flat spot on the tyre. You could try making a flat spot on your tyre(s) at your own risk on an old set of tyres and see what you come up with - but this is of course at your own risk!

Hope this gives you some idea as to how it can occur.

Cheers

Bennie

Post by **Alex** » Mon Jan 17, 2011 3:20 pm

his 04 lib will have ABS. The tyres wont lock up enough to cause a flat spot.

the best way to check the tyre for a flat spot is to swap it for the spare. If it goes away with the spare on, its obvious the wheel/tyre is fjucked.

alex

d_generate · Post by **d_generate** » Mon Jan 17, 2011 3:23 pm

Chuck your spare on and see if it goes away, then you'll know where to start looking.

rebuilder · Post by **rebuilder** » Mon Jan 17, 2011 4:11 pm

yeh i asumed the flat spot issue would be related to the billowing of the wheel outwards due to centrifual force (like watching a drag car move off from standstill u see the wheels go rounder like donuts).
Its amazing to think that this happens to a road car hey!
There must be alot of cars out there with noisy wheels like El_Freddo experienced.
I would have thought a flat spot allways makes a noise, just only when fast enough to mimmick the flintstones mobile!!! That must be incredibly annoying.