Coilover Custom Spring Rates

[Dubbs_RS]

Looking for some suspension expertise here... I am thinking about purchasing a set of BC Coilovers. A lot of vendors offer the option of custom spring rates. The standard BC Coilover spring rates for the Sonic are 6kg front/ 3kg rear.

I am curious on people's opinions of what optimal spring rates for the Sonic are. Would something like 10kg front/ 8kg rear work well on the Sonic? Or would that be too stiff? Please give me your suggestions on spring rates! I am willing to sacrifice comfort for better handling.

Thanks guys.

 

[laborsmith]

Since BC are the Chinese made version of Pedders XA coilovers, the following may apply: Now that the OPTIMA Ultimate Street Car Inviational is over we can give you more details about our Sonic setup. We tested so many combinations of coil springs we lost count. When we got close with coil rate we tuned with ride height. We wanted our Sonic to rotate in the turns based on speed or a trace of brake pedal pressure. The ideal coil combination turned out to be the 6kg coils that ship with the GMPP Xa coilover kit and rear 8kg160mm tall coils. Those stout and short rear coils were a bit tricky to fit.
Quote is from post #64 in JusticePete's Sonic LTZ build thread.


Laborsmith

 

[Luv2xlr8]

I can get you a set of BC springs new from their coil over suspension but I'm not sure which spring rate it is. They were sent out with 2 sets of springs when Modified mag did their build but I would need to ask if he knows which spring rate it is.

 

[mitdr774]

I looked into getting some coil overs and the changing springs, but you need to pay attention to the dampers. I kept finding 6kg/3kg sets with a damper good for a +/-2kg range. Last thing I want is a spring rate that is where I need it but a damper that cant control the motion of the vehicle.

 

[sx sonic]

I believe MPFab made a thread about this topic. Or maybe it was Preloader.

Try an advanced search for threads by those users and see what comes up.

 

[Dubbs_RS]

Hey guys, thanks for the responses.

Laborsmith, I think that is exactly what I needed. I was looking to see if anyone thought there might be any benefit to running stiffer springs, but if Pete spent the time investigating spring rates and determined that was the optimal setup, I don't want to try and reinvent the wheel and end up with something worse. I think I will try to aim for that.

Sx_sonic I saw that thread. I was mainly interested in people's opinions on going stiffer and if anyone thought there might be any benefit, but I think the info in that thread will be helpful in getting my springs setup.

Mitdr, what if you adjust both the spring rate and spring length (as suggested in the post Laborsmith quoted)? This way you have less spring travel, but you're still in the sweet spot for the dampers to work? Note: I know little about suspension, just tossing out thoughts...