Ive got the omnipower full street coilovers on my car and ever since I got them Ive heard loud thuds coming from the rear. Everything is tightened down and i even sent them back to omni to inspect. im still hearing the noise. its annoying as hell and one reason why i might be switching to a different suspension.

However, i was just wondering if anyone has been able to remedy this problem. i know ive read other people having the same problem.

 

How long have you had them on there for? Been making this noise? Could just be them settling in.

 

had them on since last winter/spring

 

Oh damn...that could be a problem then

 

did you preload them?

 

lol even preloaded they can clunk. THe problem isn't exactly with the coilovers I have noticed, but instead with the lack of a bushing for the upper shock mounting plate.

The upper plate on the rear is just that big metal circle.

If you think about it, since it is only mounted with two nuts, it can rock side to side parallel with those two nuts.

Since there is no rubber bushing or plastic bushings between the plating and the shock, it clunks slightly. I had this same issue. I don't think there is anything you can do about it.

If you really notice it that much I guess you could try putting a rubber circle peice between the shock upper plate and the chassis.

 

What is preloading?

 

thats exactly what i was thinking, however, i was thinking about adding 2 more bolts to hold it better. take the spring/shock off, drill a whole through the mount and then through the body of the car and put 2 bolts in there... is that something i should consider or forget about it?

 

you can try that. I never thought about it. I don't know about drilled two new holes into each of your shock towers however. Thats kind of a permanent modification

 

Tech Tip 5 - Spring Preload - second of 3 on the subject of Springs
Spring preload is normally adjustable by the spring preload collar, on rear shocks or via the topcap adjuster on forks. These adjusters compress the spring and should be used to fine tune the correct amount of sag. Turning the spring preload collar to compress the spring will decrease the amount of sag & vice versa. They will increase or decrease the hardness of the suspension but should be used with care or damage can occur. To little preload & the spring will rattle & possibly damage surrounding components, to much & it's liable to snap.

On front forks turning the adjusters will usually increase or decrease the amount of spring preload by between 5-10mm or 0.2-0.4". So if you had a 60lb springrate (see tech tip 4 below) you would increase the initial force required to compress the fork by 12-24 lbs & similarly the ending spring rate would increase by the same amount. This may seem like a large increase & therefore many people think adjusting the preload will make a huge difference but in reality it doesn't. So if the fork was a 5" travel model the ending springrate would increase from 300lbs to 312lbs or 324lbs this as you can see is only a 4-8% increase. If however you were to go to the next springrate, say 70 lbs, you get an increase of 14% & the ending rate would be 350lbs or with preload 364 to 378lbs.

On rear shocks the spring preload collar is infinitely adjustable (with a little help from some pipegrips!) so in theory you could get the ending rate you want. The only problem here is the limited space for the spring. As you screw the preload collar down to compress the spring the gaps between the coils become smaller. These gaps must add up in total to a value higher than that of the shock stroke. Ideally they should be 10% greater otherwise premature failure of the spring will occur. This is why all coil over shocks have a maximum amount of allowable preload. This amount is usually between 3-8 turns & is counted from the moment the spring collar contacts the spring & begins to compress it.

As most suspension is supplied for Joe Average who is 170lbs or 70kg you will usually need to take different springs if you are more than 10% ether side (assuming the manufactures called the springrate right in the first place!) if you want the ultimate ride.
http://www.tftunedshox.com/techtips.htm

there's a basic idea....