Knock When Braking

[frodo]

Just noticed this today. Driving along slowly and I put my foot on the brake I get a small 'knock' sound. Sounds like its from the front.

Brakes work fine, but there's this little knock. Only does it once as I apply the brakes, but seems to be doing it every time I brake. Its not loud, and I wouldn't hear it if I had music playing, or was going at any speed.

But I'd like to know what it is, so I can fix it.

I imagine its the pad knocking against the disk, or caliper.

[Gedrick]

I imagine its the pad knocking against the disk, or caliper.

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Thats what I would put it down to.

[mikeb]

Could it be a worn suspension bush making a noise as the weight transfers forwards?

[celica dave]

could also be anti rollbar bushes?

[frodo]

Ah. Now I can get a slight knock if I am at a standstill and rock the steering wheel from side to side a little bit.

[daktari]

Probably a bush somewhere.... Worse case scenario..... Check the steering rack to bulkhead mounts. They`ve been known to part company. :(

[frodo]

Thanks. I'll have a look at the weekend and see if I can see whats what

[frodo]

Jacked the car up and had a good look. Can't find anything loose, so can't get the sound by pulling or tugging anything, and yet the sound is still there. I had a good listen and feel whilst getting someone else to play with the steering wheel. Definitely coming from the wheel/steering area, but I just cannot work out which part is the culprit.

Its not bad, and I have to have the stereo off and be going slowly, and listening carefully to hear it, but I know its there, so would like to know what the problem is.

[daktari]

Could be the lower arm ball joint.. You`ll need to jack the car up again and support it on stands so the wheel is about an inch or so clear of the ground. Get a longish lever/prybar and try and lift the wheel. If you can manage to get your hand round the back of the wheel at the same time you`ll feel any play in the joint. Or get someone to lift while you look/feel.

[frodo]

Jacked it up again, and my next door neighbour had a look at it (he's a mechanic). Got it to knock by moving the steering wheel side to side a little, with the engine off. No sound with the engine going. Seems there is a little bit of play in the drivers side of the steering rack.

Brake noise could be the ball joint, or more likely to be a pad, as the pads were changed in the last few weeks.

Anyway. Nothing serious, and nothing expensive.

[daktari]

Jacked it up again, and my next door neighbour had a look at it (he's a mechanic). Got it to knock by moving the steering wheel side to side a little, with the engine off. No sound with the engine going. Seems there is a little bit of play in the drivers side of the steering rack.

Brake noise could be the ball joint, or more likely to be a pad, as the pads were changed in the last few weeks.

Anyway. Nothing serious, and nothing expensive.

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Makes a change for a Toyota.

[frodo]

Yeah. Thats true.

I could get a complete steering rack from Fennies for £80, which I thought was reasonable. Fitting it could be time consuming though.

Ball joint woudn't be expensive - I could probably get one of those from TCB, and that is easy to fit.

[mikeb]

Did you check the steering rack to bulkhead mounts, as suggested by dak?

[frodo]

I didn't, but I guess my neighbour did. It all seemed fairly solid in there, and the knock is so slight, and disappears if the engine is running, ie the power steering is up and running.

[sotal]

Just a random thought but what's the level on your power steering fluid??

My uncle had a volvo estate which made a knocking noise as you describe and it turned out to be the level of fluid. It was about half way between min and max. When he filled it up to the top it dissapeared.

[frodo]

Been there, checked that.

The level is spot on. Bit weird, but it is slight, so I'm not worried.

Hoping to sell the car in the next few weeks anyway, but I didn't really want to sell the car with a problem, but I guess most cars that are being sold have some sort of problem, even if its slight.

[frodo]

Sorted :D

Pulled the pads out from the side that was knocking. Cleaned off the caliper, liberally coated the edges with copper grease, and refitted the pads.

Just been out for a test, and all is well. The knocking has gone.

I fitted new pads a few weeks ago, and obviously hadn't cleaned and lubricated the surfaces enough.

Thats me a happy boy

[daktari]

Sorted  :D

Pulled the pads out from the side that was knocking. Cleaned off the caliper, liberally coated the edges with copper grease, and refitted the pads.

Just been out for a test, and all is well. The knocking has gone.

I fitted new pads a few weeks ago, and obviously hadn't cleaned and lubricated the surfaces enough.

Thats me a happy boy 

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Glad it was a cheap and easy fix.