Help me understand coilover preload

[10' Camaro SC]

I have BC BR coilovers. I want to make sure to get the preload correct and help understand the differences from zero preload, 5mm and 10mm for example.

Does more preload increase or decrease suspension travel?

Which preload setting gives u the best ride quality, least bounce?

Thanks

[FunkedOut]

Preload doesn't increase travel. It only decreases travel if the coils compress enough to touch each other before the suspension has a chance to travel its full throw.
Preload does increase the static rate. Sometimes used to set the ride height. Not sure about the BC's.

you're second question is really vehicle weight and coilover specific.
generally, bounce comes from the shock/strut being too soft to slow the force of the spring.

Example:
on rebound, allowing he spring to extend the shock/strut past (longer) it's ride hide. this is followed by the weight of the car's weight compressing the shock/strut past (shorter) it's ride height and the whole cycle repeats.

So, the valving in the shock/strut has to be strong enough to stop this oscillation.
The softest setting at which it does so, will be the softest ride (best ride quality).
The more you increase the preload, the higher you'll need to set the valving to eliminate the oscillation.

[VR Baron]

On my pedders supercars, and the XAs which are like the bc's they want 10mm preload in back. For me the front is 2-3mm only.but I have read in xa instructions 5mm also so not sure. I have read that yes less rear preload helps ride and helps get rid of bounce, some went 0 preload rear. Others say didnt help ride. Preload to is to hold spring in place when car is raised up and so it doesnt move around also. As to ride and boince alot of threads on bc's and pedders. For good ride seems 8/10 is about best you can do but still a bit soft and bouncy. I can adjust my bound and rebound so I can countrol it better. All good on smooth roads, and ripples or uneven surface and it moves more and ride isnt smooth. We have stiff spring rates and the ride wont be perfect, just more controlled

[10' Camaro SC]

I still have two problems:

1. small/fast bounce on some roads and coming to a stop at street lights. Reason why?
2. Lot of travel/bounce/car goes up & back down on large dips/bumps. Reason why?

I tried the following;

1. All kinds of dampening settings from soft to hard. It seems like towards the softer side is slightly better.
2. Preload - I just snugged the spring barely & also did it where I cant turn spring by hand, then added thickness of the wrench. Maybe I need to do somewhere in between the two?


I also have larger sway bars front & rear on middle hole. Can you have preload on the sway bar or will softer hole setting help?

Since these coilovers have a threaded body. Ride quality should change no matter how high or low you go right?

Any solutions?

Originally Posted by FunkedOut

Preload doesn't increase travel. It only decreases travel if the coils compress enough to touch each other before the suspension has a chance to travel its full throw.
Preload does increase the static rate. Sometimes used to set the ride height. Not sure about the BC's.

you're second question is really vehicle weight and coilover specific.
generally, bounce comes from the shock/strut being too soft to slow the force of the spring.

Example:
on rebound, allowing he spring to extend the shock/strut past (longer) it's ride hide. this is followed by the weight of the car's weight compressing the shock/strut past (shorter) it's ride height and the whole cycle repeats.

So, the valving in the shock/strut has to be strong enough to stop this oscillation.
The softest setting at which it does so, will be the softest ride (best ride quality).
The more you increase the preload, the higher you'll need to set the valving to eliminate the oscillation.

Originally Posted by VR Baron

On my pedders supercars, and the XAs which are like the bc's they want 10mm preload in back. For me the front is 2-3mm only.but I have read in xa instructions 5mm also so not sure. I have read that yes less rear preload helps ride and helps get rid of bounce, some went 0 preload rear. Others say didnt help ride. Preload to is to hold spring in place when car is raised up and so it doesnt move around also. As to ride and boince alot of threads on bc's and pedders. For good ride seems 8/10 is about best you can do but still a bit soft and bouncy. I can adjust my bound and rebound so I can countrol it better. All good on smooth roads, and ripples or uneven surface and it moves more and ride isnt smooth. We have stiff spring rates and the ride wont be perfect, just more controlled

[Stitch]

Originally Posted by 10' Camaro SC

Can you have preload on the sway bar or will softer hole setting help??

Load on the sway bars only happen when they are twisted (suspension travel differs from side-to-side), so in a static state, there shouldn't be preload on the sways.

[10' Camaro SC]

I have the following Installed;

• BMR front & rear sway bars @ middle hole setting
• BMR strut bar
• Prothane Radius bushings
• Prothane subframe bushings
• FE4 conversion
• BMR toe links & trailing arms
• BC coilovers w/ 12f & 10r dampening from full soft w/ 5mm preload.
• Nitto INVO 275/315 tire pressure @ 38psi cold

The ride quality is on the bouncey/stiff side. Low speed & stopping at street lights I'm getting tiny fast bounce, and going normal speed over dips/bumps the car jumps up and comes back down with a lot of travel and levels out. Sometimes feels like it might be more then 1 bonce sometimes. If I press on the car up & dn it's stiff but wiggles several times then stops.

Any settings or recommendations that I can try to have a better ride quality?

[FunkedOut]

try setting your rebound to full soft.
if that's not better, creep it up a couple of clicks at a time.

what spring rates do you have?

[10' Camaro SC]

Originally Posted by FunkedOut

try setting your rebound to full soft.
if that's not better, creep it up a couple of clicks at a time.

what spring rates do you have?

I have standard BC BR coilovers which are 8kg front & 10kg rear.

[FunkedOut]

Originally Posted by 10' Camaro SC

I have standard BC BR coilovers which are 8kg front & 10kg rear.

that's about 450lbs front and 560lbs rear.
Z/28 comes with 305lbs and 610lbs.

You might have too much rate up front.
You might try a 5kg (280lbs) or a 5.5kg (308lbs) spring up front?

[10' Camaro SC]

Originally Posted by FunkedOut

that's about 450lbs front and 560lbs rear.
Z/28 comes with 305lbs and 610lbs.

You might have too much rate up front.
You might try a 5kg (280lbs) or a 5.5kg (308lbs) spring up front?

I gotcha, unfortunately BC doesn't offer other spring rates for the front. Would stiff sway bars not help my situation?

[FunkedOut]

sway bars add to the wheel rate when the two sides are loaded unevenly, but not at all when both.
so either, they'll make things worse (stiffer), or do nothing at all.

are you limited to BC for spring source? are they a standard size, 2.25" or 2.5" diameter?
i'm about out of ideas.

[VR Baron]

Originally Posted by FunkedOut

sway bars add to the wheel rate when the two sides are loaded unevenly, but not at all when both.
so either, they'll make things worse (stiffer), or do nothing at all.

are you limited to BC for spring source? are they a standard size, 2.25" or 2.5" diameter?
i'm about out of ideas.

I thought they might have a 6 kg spring for the front but that's it. I have same rates in supercars. From a great source it isnt the springs, its the valving.