Knocking! Possible causes?? Please!

[Alex.J]

Hi all,

When I picked up the car I noticed a very faint knock!

Wasn't concerned as I was changing most if the suspension parts so pretty much knew it would be gone!

Well, it hasn't!

I'll describe the symptoms and see what you think..

Slight clunk on clutch depression when on load, slight clunk over big bumps under 5mph and when free wheeling with clutch in, loose vibration through pedal, like rough feedback, ideas?!

Could be driveshaft or wheel bearing related?!

I have changed camber bolts, arb drop links, front lca bushes, all engine mounts, gearbox fluid and engine oil and check all bolts are tight! Including wheels!

I have top mounts but the clunk and loose feeling doesn't tie in with this..

Thanks

 

[Sylar122]

Just a wild idea, but thrust bearing maybe??

 

[Alex.J]

What the devil is that and where?!

Gearbox?!

Thanks for the suggestion!

 

[coyote_dc5]

Agree with symptom 1 and 3 being clutch release bearing related which is a component which would be replaced with a clutch kit. The knock going over bumps sounds like top mount related

 

[Rom]

Thrust bearing is also called a release bearing, so yes, in the gearbox.
If its bad enough to feel, you should be able to hear it. Open the bonnet, have some one press and release the clutch while you listen by the box.

Knocking is most likely not related. Check drop link, top mounts, arb bushes. If its on bumps, rather than turning, or braking / accelerating, they are likely culprits. Over bottom arm bushes, engine / box mounts etc.

 

[coyote_dc5]

Not in gearbox but part of clutch. It pushes up against the pressure plate (fingers) on the clutch to release clutch plate off flywheel

 

[Rom]

Not in gearbox but part of clutch. It pushes up against the pressure plate (fingers) on the clutch to release clutch plate off flywheel

Sorry, i was being too simple. I meant as in it will sound like its in the gearbox. Technically, the bellhousing.

 

[Alex.J]

Thrust bearing is also called a release bearing, so yes, in the gearbox.
If its bad enough to feel, you should be able to hear it. Open the bonnet, have some one press and release the clutch while you listen by the box.

Knocking is most likely not related. Check drop link, top mounts, arb bushes. If its on bumps, rather than turning, or braking / accelerating, they are likely culprits. Over bottom arm bushes, engine / box mounts etc.

Replaced all you stated as mentioned in my OP!! If you change gear badly quick enough it clunks too..

Like a a double clunk, forwards back etc..

Thanks

Not in gearbox but part of clutch. It pushes up against the pressure plate (fingers) on the clutch to release clutch plate off flywheel

Agree with symptom 1 and 3 being clutch release bearing related which is a component which would be replaced with a clutch kit. The knock going over bumps sounds like top mount related

To me that's known as clutch release bearing, never heard of thrust in all 16cars I have had, that's why it threw me off slightly!

Thank you

 

[coyote_dc5]

Thrust bearing is American term I believe like hood/bonnet, header/manifold

 

[Rom]

Have you rechecked them all though ? Ive been amazed how many faulty parts ive fitted, or bolts that were a fraction too loose.

Try car running, handbrake on, then take up drive in first / reverse. This is leaning away from box, and checking mounts.But thats what happens under hard changes, the engine gets jolted around.

Is there any noise at standstill ? Pedal up or down.

 

[Sylar122]

Thrust bearing is American term I believe like hood/bonnet, header/manifold

My bad

 

[Alex.J]

Have you rechecked them all though ? Ive been amazed how many faulty parts ive fitted, or bolts that were a fraction too loose.

Try car running, handbrake on, then take up drive in first / reverse. This is leaning away from box, and checking mounts.But thats what happens under hard changes, the engine gets jolted around.

Is there any noise at standstill ? Pedal up or down.

well they were only changed on saturday and the sound hasnt gone, so it cant be anything i changed.. all bolts where tightened, torqued, double checked..

no noise at standstill at all, no depression noise either, hence i dont think its clutch/release bearing related more driveshaft/wheel bearing..

i just cant explain the clunk on bumps..

 

[Sylar122]

Pretty sure wheel bearings make more of a wooey noise at higher speeds when they are on their way out, never heard one clunk before. I recall my friends Astra a few years back making and clunk noise at low speeds. That turned out to be his driveshaft.


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[Rom]

Sorry, didn't realise you had changed them that recently!

There seems to be a few threads of noises lately that people can't suss out.

On bumps is usually something suspension related.

On gear change, acceleration, deceleration, it's usually lower arms or mounts.

Sorry can't be much more help.

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[Alex.J]

Pretty sure wheel bearings make more of a wooey noise at higher speeds when they are on their way out, never heard one clunk before. I recall my friends Astra a few years back making and clunk noise at low speeds. That turned out to be his driveshaft.


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Umm maybe be it the driveshaft then..

Thank you for your help!

Sorry, didn't realise you had changed them that recently!

There seems to be a few threads of noises lately that people can't suss out.

On bumps is usually something suspension related.

On gear change, acceleration, deceleration, it's usually lower arms or mounts.

Sorry can't be much more help.

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Dont worry at all, you have been of help and confirmed my original thoughts of possible cause..

Its an odd thing as suspension wise, it can only be lower ball joints and track rod ends( minus a shock itself as the springs are good)

Maybe the rack? but unlikely i guess...

Steering has no affect on the noise nor does loading up different wheels..

Guess its driveshaft related? not much else left ha!

Thanks for your help

 

[Rom]

Usually, driveshafts will click, pulling away on full lock is the usual complaint.

But anythings possible. So don't rule it out.

Noises like this can be a pain to trace. Something has to be worn, or have play. It's just tracing it.

Before now, I've had someone sat in engine bay, while I drive in the workshop listening for noises.

So can you replicate it at will?



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[Alex.J]

Usually, driveshafts will click, pulling away on full lock is the usual complaint.
But anythings possible. So don't rule it out.
Noises like this can be a pain to trace. Something has to be worn, or have play. It's just tracing it.
Before now, I've had someone sat in engine bay, while I drive in the workshop listening for noises.
So can you replicate it at will?
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Yeah it's easy to replicate!

Can do it on demand

 

[Rom]

Well that would be my plan of action. Assuming its at low enough speed, get someone to help out and sit in engine bay.

 

[Alex.J]

Changed to top mounts today!

It's tightened up the suspension lots and improved drive, the other tops where totally shot!

However, this bloody clunk/knock is still there!!

Argh!

 

[Phelpo711]

Did you get anywhere with this?

Also the term "thrust bearing" is correct - that's the job it does. It thrusts axial force unlike normal bearings with keep shafts etc running true - or rotational force.

Hope you got it sorted mate