BC Racing coilovers damping adjustment recommendations

S

sama156

Member
Getting our BC Racing coilovers fitted. I tried to search but could not really find advice on recommended damping adjustments. Somebody stated "16 clicks from hard front, 12 clicks rear". So a little harder setup rear.

Does this sound about right?

It is our family ride so I am looking for more control and accuracy than stock, but not overly hard...
 
Well preload is very important if your bc's have 0 preload you can adjust the fronts to 7-9 clicks and you will be fine, same with the rears you can adjust it too 4-8.
But if you have 5 or more preload then you want 10 clicks from hard for the front and for the rear same.
I noticed when 14 or more clicks from hard makes the ride bouncy, and same with rear (keep the rear lower than the front).
 
Just adjust them to your liking. It's very easy to do, especially on BCs. You can even adjust the rears without taking the wheel off.
 
AeroBFA said:
Just adjust them to your liking. It's very easy to do, especially on BCs. You can even adjust the rears without taking the wheel off.
Click to expand...

+1

I have had the BCs on two different FXs and the settings are slightly different for each chassis. The great thing is the ability to adjust so you've got your starting place.

Do you have RWD or AWD? If you have RWD, your car did not come with a rear factory sway bar and it is very easy to add. The combination of the rear sway bar and the coilovers along with some of the available chassis braces make a really positive improvement in the handling of the car.
 
Thanks for replies, I will play around with the settings. I was mostly curious about the fwd/rwd settings balance, seems that most set rear harder than front. Why is that?

Our car is a 2007 AWD.

As for lowering, we plan to drop it only by an inch or so. Is my wife's daily and she says that she prefers to rather drive an SUV than a coupe;) Interestingly the stock suspension seems to be clearly higher front than rear.
 
I do find it a bit weird to have the rears harder than the front. I actually have it the other way around. I have it harder in the front. That is also the consensus on the Lexus forum for my IS-F. I have BC coils on the Lexus too. I do find the ride to be pretty good with harder setting in the front. 0 being hard, 30 being soft. I currently have 15 front, 20 rear. I find this to be a good setting for every day driving. Not too harsh, not too soft. I have an AWD. Like others have said, play around with it. I suggest trying these 3 settings and make the detail adjustments based on your liking: 5 front & rear, 15 front & rear, 25 front & rear. Good luck.
 
I believe my fronts are around 8 from hard and rears are 10. Not 100% sure as I haven't changed them in forever but I thought I made the fronts a tad harder to prevent rubbing.
 
Just poking my head in to say Thanks for putting 'damping' and not 'dampening'. Pet pieve of mine... :smile (2):

Carry on
 
AeroBFA said:
Just adjust them to your liking. It's very easy to do, especially on BCs. You can even adjust the rears without taking the wheel off.
Click to expand...

I never got around playing with these as some other projects got first priority.

Ok, here is the noob question of the year, how do you do that? To get access to the rear adjustment, it seems to me that I would have to dismantle half of the trunk. I am obviously missing something crucial here.
 
Listen guys I'm having a real hard time getting my BC's dialed in. I got 10k springs on the front and 12k on the rears. I have 5mm preload front and back, I'm about 2 fingers from the top of tire to the fender. I just can't seem to get it right, the fronts even on the softest setting I can't move by pushing down on the front of the car, the rear is a different story, as I know the rears are soft anyway. What settings do you suggest? Also starting from hard to soft or soft to hard when giving the numbers. FYI, my rear tires are wide and the rims do not allow me to reach through them, so adjusting is a real pita! Have to lay on my back and reach up in there to get to the adjusters, extenders are on the way. I want a nice firm ride without looking like I'm bouncing all over like a ghetto rat! Please help!!
 
Thanks, but from all the research I've done the preload does nothing more than prevent the sspring from rattling around and making noise. I just need to know what settings you guys are at to kinda get an idea as basis to start. Also, a stupid question but how in the hell do you tell if it's the front or the back that is bouncing. What's the best way to determine if your to stiff or to soft. Is there a procedure to adjust the front then the back etc?
 
Renhalt said:
... from all the research I've done the preload does nothing more than prevent the sspring from rattling around and making noise...
Click to expand...
Not true. My understanding was that the spring is compressed, it becomes stiffer.
 
I tend to think the same, but Josh at image racing said its only to keep the spring from moving around and the following is what shadow191 wrote in another thread:

The shock shouldn't be where you set the preload. On the front, the shock is used for height adjustment. You turn the threaded body up or down to adjust height. The 2 locking collars are for preload. On the rear, it's different. The spring isn't sitting on a threaded body so adjusting the locking collars will adjust preload and ride height. Adjusting the shock body on the rear will not change the ride height. It will adjust the limits or your travel, ie. mine are set so low that when I jack the car up, the wheel doesn't sag that much because I've topped out the shock and that prevents the spring bucket from coming any lower.

Best way to imagine it is this. On the front, if the spring was a solid 8" long pipe that did not move, you could still raise and lower the front end by turning the threaded shock body on which the spring sits. On the rear, if the spring was a solid 8" piece of metal that did not move, adjusting the shock body would not raise or lower the car since the spring isn't sitting on that shock body. Rear isn't a true coilover.

Don't sweat the preload too much. It will just minimize any clunking noises, but it doesn't really affect performance. Some of the hardcore stance guys remove their rear locking collars entirely on the G to get lower. The shock prevents the spring from falling out. On a previous car, I had Ground Control coilover sleeves. Since they just sat on a shock, i couldn't preload them, turning the collars affected ride height. Mine were set very low (so low that when I jacked the car up, there was about 4-5" of gap between the spring and top mount. I could remove them without a spring compressor. Other than some horrendous clunking noises on slow speed turns, no issues and I had those on for probably 50K miles.

Im so confused, if I were still in Florida I would just go to Josh's and have them set them up. Unfortunly I'm now in Lexington, ky and don't know of any reputable shops here with the knowledge to do it right!
 
Ummmm, spring preload does more than "just minimize any clucking noises".

Well, speaking from my personal experiences, went I preload the springs, I do feel the ride stiffen up and I do feel that the bounciness deminish when I preload the springs more.
 
BC Racing springs are linear, so increasing preload would not make them stiffer. You're only changing the weight point at which the spring starts to move. So if you have a 12kg/mm spring, it will normally take 12kg of force to move the spring 1mm if it is unloaded. At 5mm preload, it would take 60kg of force before the spring will compress. But once it starts compressing, the spring rate is the exact same. If you upped it to 10mm of preload, it would take 120kg of force before the spring started to move. But again, the spring rate remains the same once it starts moving. So if you're pushing down on the car, it may feel like the spring rate is higher, but in reality it's just because you're not pushing down with enough force to overcome preload.

Since our FX's are close to 4,000 lbs or roughly 1800kg, the car already sags and compresses the springs a good bit when on the ground. The car is compressing the springs way more than 5 or 10mm, so preload isn't really doing much other than keeping the springs from banging around. The car comes down with much more weight than a person can put down by just pushing. So even though the car may feel stiffer with more preload, it's really not.

On progressive springs, additional preload would move the travel deeper into the ramp up rate, so it would feel stiffer at first since by the time the spring engages, it's at a higher rate. But the maximum spring rate doesn't change, so if you were blowing through the travel, you still would blow through the travel. I can't think of any coilovers that run progressive springs though, by and large they are linear. Only time spring rate would increase would be if coils touch or "bind" at which point the spring rate for those coils goes infinite.

la_fx35 said:
Not true. My understanding was that the spring is compressed, it becomes stiffer.
Click to expand...
 
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In case you're looking for some pointers to adjust the rear coilovers:
1) Adjust the ride height with the spring mount.
2) Lift the knuckle enough with a jack to relief the tension on the shock so the shock body ring can be loosen easily.
3) Loosen the shock body ring and then adjust the shock body so that the spring just resting snugly not under compression on the spring bucket.
4) Tighten down the shock body ring to the lower shock cup. This is your 0 preload.
5) To do a 10mm preload, raise the shock body ring up 10mm from where the ring was seating.
6) Turn the shock body into the lower shock cup until the ring seat tightly onto the cup.
7) Go for a test drive and then adjust the dampening to your liking.
 
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