1.7 TD steering knock

[Bob Dodds]

I keep getting an odd knock from the wheels/steering, not regular but usually on a corner. Last week decided to replace all the regular culprits so have done the following on both sides because if I was going this far then do the lot. So wishbones, CV joints, wheel bearings, drop links, track rod ends then tracking set up correctly. The springs, shock absorbers, discs & pads had been done previously. Front end is noticiably better but knock is still there and I'm running out of ideas. Any suggestions?

[Cavalier342]

Is the knock felt through the steering wheel, kind of feeling like you ran over a pebble on the road? I had the same on my old 92 LS, it was something to do with the rack itself, it was on it's way out I think. With mine, it was almost always at low speeds, and when feeding the steering wheel back to center position during a turn. It wasn't a loud knock but it was there, only happened occasionally.

[Bob Dodds]

No, not felt through steering but seems to RHS low down but that could be me. When the garage did the tracking he thought engine mount but checked that and seems OK.

[Robsey]

I would guess that it is the strut top mounts...
My car knocked on low speed uneven surfaces.
My top mounts were barely attached as the struts had cracked and stretched the hole through the mounting cup type thingy.

[Bob Dodds]

That's worth a look as it sounds similar and must be the only part not replaced. I didn't consider them as the knock seemed low down. I'll check next week, too much else on at the moment.

[Robsey]

If it is low down, it is usually -
1 - a snapped drop link (pendulum)
2 - worn anti roll bar bush.

Some form or linkage or bush that has failed allowing excess wishbone movement and metal to metal contact.

But if it is not clearly defined where it is - then the top mounts are worth a good look.

Anything else would give vague steering.
Worn track rod end, worn steering arm rubbers, worn steering rack.

If it was engine mounts, then I would think that knocking would be easily achieved by pulsing the engine revs.
You should also see your gear stick kicking / twitching back and forth as the engine rocks back and forth.
The more the mount wear, the more the engine movement and associated gear stick movement.

[cavalier1990]

Hi Bob

Have a look at gap between top strut plate and strut tower under bonnet. If it's more than about 3 or 4 mm then the top rubber doughnut mount is likely shot. I replaced mine and have pics old and new on my thread in projects for my 1.8 cav. The old gap was about 8 mm. The metal was all cracked too.

Also check anti roll bushes, the inner ones for play.

[Bob Dodds]

Well changed both top strut bearings and rubbers yesterday. One bearing was actually upside down. Drove it to garage for tracking check, knock is still there and now out of ideas. Cars MOT is Monday afternoon so hopefully it will fail on problem. Never thought I would say that!

[Bob Dodds]

Well car now has new MOT (failed on exhaust, easily sorted). MOT mechanic actually heard knock driving into garage but found nothing wrong apart from exhaust and he was looking for it. Car drives great apart from this random knock usually on a corner and sounds to be low down RHS. Anyone any suggestions?

[T1BBST3R]

How tight are the shock absorber 'ring nuts'? If the nock happened just after changing something, that's usually the culprit. They are supposed to be 220nm, that's doing them up in a vice with a large stilson & hammering tight. I only say this as that happened to me, I put in some shocks, tightened the nut in 1/4 turn thinking it was tight enough and got a loud nocking sound going down the road. Only other thing that jumps to mind is a worn bush on a wishbone but that would only happen while breaking, are they in really tight.

[Bob Dodds]

As in top of post. New wishbones, track rod ends, cv joints, wheel bearings, drop links, top steering rubber bushes and top bearings. Shock absorbers and springs were new when I got the car and knock has only been the last few months. I was there when the MOT mechanic was testing everything looking for play and he couldn't find anything. When the knock started I got together the bits to do everything because I only wanted to do the job once. The only thing not changed are the torsion bar rubbers as checked and no wear. I've got a very nice tight front end with an occaional annoying knock.

[Cavalier342]

Stupid thought, but check your spare wheel well, take the spare out and see if any tools or metal objects are laying on the floor. I've had it once before, sometimes sounds can be deceiving as to where they are coming from.

[Robsey]

Okay - super random...

It isn't the exhaust support bracket off the rear of the engine block is it?

That has a rubber grommet affair in it.
Maybe the rubber has crushed or split allowing the support strap to jiggle about on the mounting bolt.

Not sure how the TD exhaust is mounted, but I know the multi-point injection engines have the mounting that I describe.

Or perhaps the front silencer pipe / box is hitting the underside of the floor pan.
(Weak hanger rubber).

[cavalier1990]

I had the same thing on my cavy 1.8. I eventually found that it was the back bush on the new arm I fitted. The bush had spaces on each side through the middle, I think this is for a different model perhaps the 1.4 or 1.6 not sure. When I looked at my old arm the bush was totally solid throughout.

The bush was flexing and letting the edge of the arm rattle off the subframe, although it was hard to replicate while lying under the car. Changed arm to another new one I had with solid bush and it was fine.

[Bob Dodds]

Well I finally found the cause of the knock. It was the RHS wishbone rear bolt. I noticed although it was in tight, the flat on the bolt head was not hard against the frame. Found a washer to fit the bolt and then tightened up again. No knock for a week now, I don't understand why but its a relief to be rid of something that been bugging me for ages.

[Mk3alan]

I guess the bolt was too long and bottomed out? Glad you got there!

Alan