When going over rough bits of road (which is everywhere in the UK lol) one of my coilovers rattles, sounds like a bag of small metal piece is being shaken lol. Very occasionally, that same coilover makes a loud knock when I break (I think its from there anyway).

Question is, could it be the spring tension slightly off? If so, how do I fix this? I've got instructions from when I bought the coilovers, but it's been translated into english so bad ....I can't understand it

Those are the type that I have:
http://www.bc-racing.co.uk/coilovers.asp

 

Check the exhaust.

I had exactly the same thing and I thought it was the coilovers. Jacked the car up and coudn't find anything wrong. Turned out to be the backbox had moved slightly over time with the harder ride. Removed it and refitted and 100% fixed. No noise at all

 

if its the rear near side then its common.

 

exhaust is fine mate. getting a new one next month though

it the rear off side

 

Had my bc's on a week or two now no noises at all yet (touch wood)
Check spring preload on nuisance side to see if any movement in it

 

Kris how do you check spring preload mate. I've heard someone mention something like this for a similar problem but didn't know what they were on about.

 

If you are looking at the coilover you will see 3 gold coloured locking collars.

The bottom one at closest to hub is for locking the coilover after setting your ride height.

the top two are used to pre tension the spring and to lock it.

Generally the springs are pretensioned around 6** mm i think , the spring will have some numbers on it , these are the spring dimensions and rate of spring , one number there will tell you the free length of the spring , so you basically slacken off the 2 collars then wind them up by hand till the free length of the spring is -6mm less.

Sometimes once the springs settle in , they can become loose in the seats, and you get a rattleing as the shock extends .

Best way to check yours is to jack up the car and try to give the spring a turn or move it around, if a spring is loose then just slacken the 2 collars and tighten it up to the required preload.

Lastly , what kind of top mounts are on the rears , as i think the early bc's had pillowball top mounts and they were pretty noisy, whereas the later spec bc's had o.e style rubber top mounts , i think this solved most of the noises.

Failing all this then Bren at Apex is the best man to speak to.

p.s dont quote me on the preload measurements, i think it may tell you in the manual you have for them.

 

OK Grant thanks. I think I might leave this to someone in the know lol. I've got a feeling I might mess this up. But the tip is appreciated and will be used. A mate of mine knows a bit more and should know what you're talking about once reading it. Thanks for all feebacks everyone

 

i think its spring length minus 3mm, quote below courtesy of bren@apex


Set spring preload to 3mm.

The spring length should be printed on the spring in the following format:

62.180.006

62 = spring id in mm
180 = spring length in mm
006 = spring rate in kg,mm

To set spring preload have a look to see what length your spring is. Then set spring preload via the spring platform so the total spring length with preload applied is 3mm less than the free printed spring length.

If the free printed spring length is 180mm then the spring should measure 177mm when installed with the correct preload.

 

ah thanks tubbytommy mate. I get the picture now cheers. this made more sense to me
I'll get on to this job tomorrow
thanks for all feedback everyone

 

I put 4mm of preload as bc say (thickness of big c spanner)

 

My offside front developed an occasional twang fron a slight spring movement so i put a bit more(c spanner thickness) preload on both fronts and been perfect since. now been on 3 years.

 

You think you life is difficult. Mine have the spring assisters on which is a nightmare to work out. You can put 20mm of preload on and still pull the spring off the top seat easily.

Still with long travel shocks and 6/5 I'd be on tippy toes without them. and no knocks either, but i do have the conical rear springs and O.E. style top mounts.

 

ScoobyVince

Assuming it's not too late, before you start playing with springs, etc, check the top mount.

Remove the rear seats and, with someone else driving, feel if the shock moves within the mount. ie the top of the shock is not fixed firmly to the body allowing movement.

My rear o/s mount failed within a short period of having BCs fitted last year and now I have the same problem with my front o/s mount.

 

I'll give that test a go gdavey thanks. there is no more knocking. just the clinging noise over bumps.

 

Well after reading this i have an issue,after jacking car up and removing wheel on o/s rear i can move the whole spring up by about a quarter of an inch !!!!!!! Aswell as turning the spring around by hand ! So i will have to reset the preloads on all i think as when going over bumps i get a compresion type noise and a very slight tap noise too,
Silly question but this wont affect geometry settings will it ? And is it same for fronts ?thanks

 

Any one had to adjust preload with this much play in it ?