ayellows2k

Hi guys, I finished putting my front control arms in today with new compliance and front lower bushings. I also loosened every bushing bolt/nut, jacked up each corner to ride height which i measured before and torqued everything to spec.

Now my front is sitting about .5 inches lower then it did before and it's too low. The back has also lowered a little bit. I had a shop install bilstein pss9's on my car about 4 years ago and I don't think they preloaded anything.

Could preloading the suspension bushings now cause this drop?

Apex1.0

Yes!

First the term preloading can be confusing. Bottom line is at static ride height, the suspension bushings should have no rotational tension on them. So when you say your are preloading, you may likely be unloading the bushings. Think of these bushings like a torsion bar or rotational spring. After being torqued, once they are rotated in either direction they will provide progressive resistance until failure (usually tearing).

In your situation: At stock ride height say 14.25" from hub to fender, there is zero tension on the suspension bushings from the factory. Once you lowered your static ride height via coilovers to say 13.25", you effectively loaded the front bushings 1" of travel. The bushings are now providing a supplemental spring rate. The fix is to loosen the bushings at ride height and re-torque. This unloads them and removes the supplemental spring rate. This is perfectly fine, and what you want. To get you ride height back, you need to add some preload to your coil springs. This will restore the total initial wheel rate.

ayellows2k

Ok great to hear. I'll just raise the car back up to the height it was at before I preloaded everything.

Car Analogy

This is called clocking the bushings. Preloading is something entirely different.

Apparently, the morons that installed your coilovers never clocked the control arms. This is why you need to learn to diy. Most shops suck.

ayellows2k

I know, I hate taking my cars to shops. I try to diy as much as I can. At the time, I wasn't confident installing coilovers.

I have a question. I clocked the bushings at the ride height the car was sitting at by jacking up each control arm. Now my car is lower all around. If I raise the car back up to that certain ride height I clocked the bushings at by moving the spring perch up, I don't have to re-clock the bushings right?

Car Analogy

Every time you change ride height, you should reclock bushings. Otherwise they are adding an unwanted, and possibly inconsistent, extra spring in one direction, and a negative spring in the other.

When you are going to adjust ride height, FIRST loosen all the bushing mounting bolts, upper CA, lower CA, lower shock mount, at all four corners. THEN adjust ride height, knowing the bushings are getting in the way of how you have it sitting.

Once you like how its sitting. Then tighten each corner, clocking it (weighting it). Now clocking won't change how you set ride height.

ayellows2k

Ok thanks for the info. Very helpful