Noise from front suspension

[fife90]

I'm hearing a knocking from the front left suspension on my 1990 turbo (UK). It happens when driving over even the smallest defect in the road surface and can be very loud.

The mechanic who services the car has heard the noise on a test run but doesn't know where it's coming from and can't reproduce it while the car's on the ramp. He's ruled out the damper though....

Any suggestions as to what the problem might be?

Brian

[B16 RFF]

Is he an experienced Lotus mechanic? If not, then I would say dampers, despite what he says. If it's an internal fault, it will be very difficult to reproduce in the workshop.

PS Had a similar thing on my S3. Lotus agent mechanic (very helpful chap) took it for a test drive and pronounced it was the damper. Fairly common fault apparently.

>> Edited by B16 RFF on Monday 12th July 01:47

[wedg1e]

Oddly enough, I have a similar clonk from a similar place... and I recently rebuilt the front suspension!
I did however reuse the old dampers, which appeared to 'damp' when operated through their range of travel OFF the car; no leaks, no bent piston rods etc. BUT I know that doesn't guarantee them 100%.
Interestingly, if I go as passenger with someone else driving... no clonk.
I might try swapping the dampers and see if the clonk moves...

Ian

[B16 RFF]

wedg1e said:

Oddly enough, I have a similar clonk from a similar place... and I recently rebuilt the front suspension! I did however reuse the old dampers, which appeared to 'damp' when operated through their range of travel OFF the car; no leaks, no bent piston rods etc. BUT I know that doesn't guarantee them 100%. Interestingly, if I go as passenger with someone else driving... no clonk. I might try swapping the dampers and see if the clonk moves... Ian

So,could it be something moving under the passenger seat? Or the seat frame is loose? Or just the extra weight is changing the loadings on the damper?

>> Edited by B16 RFF on Monday 12th July 01:50

[wedg1e]

B16 RFF said:

wedg1e said: Oddly enough, I have a similar clonk from a similar place... and I recently rebuilt the front suspension! I did however reuse the old dampers, which appeared to 'damp' when operated through their range of travel OFF the car; no leaks, no bent piston rods etc. BUT I know that doesn't guarantee them 100%. Interestingly, if I go as passenger with someone else driving... no clonk. I might try swapping the dampers and see if the clonk moves... Ian So,could it be something moving under the passenger seat? Or the seat frame is loose? Or just the extra weight is changing the loadings on the damper? >> Edited by B16 RFF on Monday 12th July 01:50

OY! Are you calling me a fat bastrad?

No, it's not something INSIDE the car. If I'm solo or take Julie out, clonk. If she drives and I'm shotgun, no clonk. So yes, the extra weight may be loading the suspension in some way. I'm going to jack it up and see if anything is where it shouldn't be. At the mo, my favourite would be that the new polyurethane ARB end bushes have come adrift... cos they didn't seem all that secure when I fitted them.

Ian

[B16 RFF]

wedg1e said:

B16 RFF said: wedg1e said: Oddly enough, I have a similar clonk from a similar place... and I recently rebuilt the front suspension! I did however reuse the old dampers, which appeared to 'damp' when operated through their range of travel OFF the car; no leaks, no bent piston rods etc. BUT I know that doesn't guarantee them 100%. Interestingly, if I go as passenger with someone else driving... no clonk. I might try swapping the dampers and see if the clonk moves... Ian So,could it be something moving under the passenger seat? Or the seat frame is loose? Or just the extra weight is changing the loadings on the damper? >> Edited by B16 RFF on Monday 12th July 01:50 OY! Are you calling me a fat bastrad? No, it's not something INSIDE the car. If I'm solo or take Julie out, clonk. If she drives and I'm shotgun, no clonk. So yes, the extra weight may be loading the suspension in some way. I'm going to jack it up and see if anything is where it shouldn't be. At the mo, my favourite would be that the new polyurethane ARB end bushes have come adrift... cos they didn't seem all that secure when I fitted them. Ian

Shouldn't you be in bed by now? You grandads need your sleep you know.

>> Edited by B16 RFF on Monday 12th July 02:17

[wedg1e]

Well, I had a rummage under the car... and found nothing desperately wrong. The only thing that looks a bit suspect is the nearside spring is quite bowed and doesn't clear the damper by very much (spring is seated OK though). It may well be that under the right conditions, it's the coils hitting the damper that I can hear.
Will have to get the compressors out and rotate it...

Ian