Suspension Guru's - Need help on Sway Bar/Endlink Preload Question...

[Alan l.]

Hi all,

I just got back from my shop that installed a set of springs on my brand new Bmw. Everything was installed while the car was on a lift...

Car looks great and seems to handle much tighter than before but i am noticing a slight rattle/clunk coming from the front of the car after the install. Doesn't make any noises while the car is stationary and turning the wheel left to right. It only makes the noise if i hit a sharp bump going over potholes. On larger bumps that is more gradual the car doesn't make any noise even with more suspension compression. Only on sharp bumps. Sounds like something is loose up front.

I am suspecting it has to do with the swaybar/endlink preload causing the clunks but I am getting conflicting information on the web about this. I've read where it is not possible to preload or zero out load using the OEM endlinks but i've also read where people eliminated suspension noise by doing so using oem endlinks.

Then i am also getting a mix bag where most will tell you you want zero preload on your sway bars by tightening everything while the car is on ramps (my springs were installed on a lift) but have also seen cases where zero preload can cause clunks since there is no tension on the sway bar at all unless you are turning. I've seen this happen on my 335 where i installed a set of adjustable endlinks up front and at zero preload (car was on ramps) if i just banged on the sway bar with my hand you get a nasty resonating vibration/sound. Once i added a little preload by adjusting the endlink if i banged on the sway bar again it felt completely solid.

If anyone has any ideas about this please let me know. I plan on rechecking everything under my car this weekend while it is on ramps and I want to make sure i do it right first time around instead of chasing this for who know how long. I can't stand a car that clunks let alone a brand new car!

Thanks,
Alan

[Richbot]

I can't think of a way you would change the preload with oem endlinks unless you had ride height adjustment collars.

I have the Turner endlinks with my RDSport front bar, and adjusted the length with the car on the ground to eliminate preload. There is significant preload in thar bar from the factory for some reason, probably because they use one endlink part number for a ride height tolerance that is +- 10mm side to side. It might also help with noise slightly, but noise by itself isn't bad. Swaybar bind can cause all kinds of handling weirdness

[TXmtrhed]

If you think that the bar is bound up at the bushings couldn't you zero out the preload by putting the car on ramps and loosening the bushing-to-subframe bolts and letting the bar rotate? Or am I not visualizing this correctly?

[bigjae1976]

Originally Posted by TXmtrhed

If you think that the bar is bound up at the bushings couldn't you zero out the preload by putting the car on ramps and loosening the bushing-to-subframe bolts and letting the bar rotate? Or am I not visualizing this correctly?

You could but it would be easier to just leave the lower ball joint nut loose, drop the car and then tighten. You just reach behind the wheel.

[RickyBobby]

Sounds like installation error to me. Take it back to the shop and have them check all the bolts. You can't mess up swaybar pre-load from a spring install using stock end links. It's probably a loose not on the end link.

[rzm3]

If something sounds loose, check all the nuts and bolts. Don't worry about sway bar preload when you've only put in a set of lowering springs.

[IMG]

Disconnect both your front sway bar links and take the car for a ride and see if the noise is still there !
If it is,then its not your sway bar links !
Also sway bar bushings might be done.