BC Racing coilover adjustment
 

For you guys with the BC coilovers, do you guys mess with the spring preload at all?

I ordered the extreme kit with the regular 10/8k spring rates and it is pretty stiff even after adjusting it

So far, I have only messed the the collar to adjust the height and put it to 10 clicks soft, but it is still riding pretty stiff. I was wondering if any of you guys messed with the spring preload it came with to make the ride a little smoother

Preload doesn't change stiffness. Technically if you only lowered with the spring collar, then you have little/no preload right now. How low are you? Maybe you're riding on the bumpstop? Maybe 10k/8k is still stiffer than what you want?

You need to adjust ride height by loosening the lower ring and spinning the threaded shock into the lower mount.

Preload should not be used to set height, and should be at about 3mm.

10k/8k, is the standard kit and shouldn't be too stiff, although it will wear-in a bit for the first few hundred miles and smooth out usually.

right now I have no gap with 19s, 245/35/19 and rears are 275/30/19

I haven't messed with the preload (top collar), just on the height adjustment (lower collar) but noticed that it rides pretty stiff even after a couple of weeks being driven on it

The car previous had Toms Advox coilover on it and it was really smooth. I was expecting that these were just a little stiffer. I assume that the bump stop was already removed as the car had coilover already on it and I just swaped them out for these BC ones

So I should not mess with preload at all to help soften the ride? What is the point of the preload then?

I will adjust the damper some more as I have home more clicks to go on the soft, but I don't think it will help out much

Thanks for the quick response and help

Did a quick search and found the Tom's spring rate: 7.7/5.7 (F/R). Those are some pretty soft spring rates, comparable to most lowering springs like the Tanabe NF and Eibach. There are guys with 8/6 spring rates on their BC and they seem to be happy. If the dampers are set to full soft and the ride is still unbearable for you, then order a set of 6kg/mm springs for the rear and move the current 8kg up front. The dampers should tolerate a 2kg/mm swing.

Like I said, preload does not affect stiffness at all. If it did, then the springs you have are not truly linear (read: crappy springs). Think of preload as a tool. It is used to combat against sagging by increasing the initial force provided when loading up the spring. If you have the same preload all around and you sit in the driver seat, your corner weight where you sit is higher, so naturally the spring gets compressed more (along with shortened shock travel). At this point, your shock displacement and damper force is slightly different. Increasing the preload allows you to raise the car back up to maintain similar shock performance all around. If your springs are good linear springs, then it wouldn't matter if one spring sees more preload than the other. On the streets, it wouldn't matter if each corner is off a bit, but it shouldn't change ride quality.

Been wondering what the spring rates were for the Toms, wasn't aware that they were so soft. That explains why the ride was really stiff.

I think I like it better with the 10/8k spring rates though, because with Toms, even though the ride was very smooth, the car bottom to much when on the freeways.

Wish Toms would make a kit or someone was able to rebuild Toms coilover other then them though. Such a waste of coilover after they are blown

Didn't really know what the preload did until now. Thats pretty cool actually.

Thanks for taking the time to explain that to me, especially so quick too

Correct, it's a compromise. You can't have a low soft riding car without rubbing. It all boils down to whether riding low is worth the loss in ride quality. Tom does rebuild coilovers, but shipping cost really kills it. I know a guy who is in touch with someone (in the US) that can rebuild most coilovers. He'll rebuild coils that most "JDM" companies refuse. Rebuilding coils isn't hard...it's tracking down the parts that makes it tough. When my coils go, I'm going to rebuild them, although at the rate I'm driving my car, I probably won't ever have to :woohoo:

Do NOT mess with the preload...leave it alone.

Not to go off topic here. But since the OP's question has pretty much been answered already. I want to ask a quick question suspension guru's. GSteq, PHML and Circuit.

I have BC racing coilovers 12k/10k spring rates and i ride around on full stiff. They're pretty stiff but not to the point i want them to be. Do you think the dampening could adjust to me buying 14k springs up front and putting the 12k in the rear? Or would it ride bad? Any negatives to this?

If the dampers were already matched for 12/10 spring rates, then 14/12 should be okay. Most dampers are able to accommodate +/- 2kg/mm change. It would be wise to increase damping force once you've added the new springs.

You got 10k/8k setup with only 10 clicks and you car has no wheel gap?? On 19's? Dang. Are you sure you don't bottom out?

I got 8k/6k setup at 24 clicks, no wheel gap, on 18's and I bottom out on dips.

TLcoats - Sent you a PM :)

My installer didn't adjust anything out of the box! What are the settings out of the box? I've driven about a 100 miles on them and beginning to think they are too stiff and bumpy!

I also am running 19's on 245/35's fronts and 275/30's rears!

What's your spring rate and what's your dampening?

I'm on 10/10k BC Racing "Extreme Drop" coilovers, put them on and did not adjust preload, just put the dampers to full soft and the car rides awesome.

Stiffer then stock but not noticeably harsh. I'm on 19x9 19x10 + 24 with 225/40 235/40 and tucks tire in the rear, no gap up front.