Coilover problem

[Phelan]

Diamondback,

 

Static sag is the difference of the length of the spring (or how much the spring has compress) due to the weight of the car. Normally the manufacturer will have their recommendation for the static sag base on the model of your car.

 

Get this wrong, and no matter how much you adjust your damping (rebound or compression), you will never get to enjoy the full benefits of using coilovers.

 

A lot of people mistook static sag with preload.

 

Maybe some of our more knowledgable members here can explain in detail.

 

I pick up on tuning suspensions when i was bike racing in my younger days.

Edited November 2, 2008 by Phelan

[BMW320i]

Hmmm, i'm running on fully adjustable coilovers for my GT. 7kg springs in front and 3.5kg springs at the back. Springs are single rated.

 

Are you using progressive springs?

 

Did the original workshop calulated the static sag of the springs when they installed the coilovers? If they did, your coilvers should not be bottoming out.

 

Another option is to play around with the preload and compression, if your coilovers are adjustable but i wouldn't recommended this if you are a beginner.

 

Just out of curiosity, what coilovers are you using and what can you adjust ?

[Pandaeyes]

I'm using BC. My rear shocks r only 1 month old. As for static sag, I'm not too sure. The usual advise was to just adjust to 2 fingers. Do wheel alignment and off we go from the workshop.

 

My family is complaining alot in the rear. I set the rear to very comfort... 5 clicks out of 32. The ride is very uncomfortable. My car is still going INTO pot holes, rocking every time it goes over a hump/bump. I did 16 clicks before but it became bouncy.

 

I'm making a decision to change back to stock shocks for rear. My front coilovers are ok.

 

Pls advise. I'm still a green horn for suspension. I fear for safety most.

[Phelan]

Ohlins Road & Track coilovers. Fully adjustable for preload, rebound and compression

[Phelan]

When you mention 2 fingers, i presume that you are adjusting the preload of the coilovers. This will in turn affects the height of the car's rear. This has nothing to do with static sag.

 

Static sag is related to the weight rating of the springs chosen for your coilovers. Let say the manufacturer recommends a static sag of 40mm for your car base on their coilover design, then the workshop needs to choose the correct spring rating (in kg) that will give you this 40mm static sag when the coilovers are fixed to your car. This is important as static sag will influence the amount of suspension travel that your car has. Of course adjusting your damping to compensate for a lack of static sag will help a bit but there is only so much you can adjust before you encounter other problems...such as the "bouncy" feeling that you are getting.

 

When you adjusted the rear dampers, are you adjusting the rebound or compression? "Bouncy" feeling means you need more rebound damping.

 

Hope this information helps. Anyway, you should go to a reputable workshop to help you with this problem.

[Pandaeyes]

The only thing I can adjust is the damper level 32 clicks right and left. Is there anything else to adjust?

 

What I do not understand is that if the whole set is for the car, why is there still so much of trouble? Shouldn't the manufacturer take into consideration all that you have just said?

 

I did mine at R**eT**h. I think I should meet you up soon to understand my issue better. I really hope not to spend any more money on this.

 

Or you have any workshop to recommend to solve this issue? Stamford/Autobacs???

Edited November 2, 2008 by Pandaeyes

[BMW320i]

Flag L series ?

[Boyboy]

i feel that certain workshops will just fit and do only a basic adjustment for non-sports cars (if they even bother for sports cars)

 

i have no idea of what static sag. just fit, adjust height and damping and off i went.

 

but not sure whether i got lucky or because i take humps very slowly. so far no issues besides the usual loss of comfort coilovers have. i'm also using BC coils adjustable for "hardness" and height only

 

this "hardness", i'm not sure if it's compression or rebound damping. but it just feels harder overall when i adjust it

 

anyway, since u are quite knowledgeable, what is the interval i should send my coilovers for servicing?

 

i think mine have had about 50k on them so far and they still feel ok.

[Pandaeyes]

How do your friends or family feel about the rear seats? Bouncy?

 

I sat at the rear today and I asked my friend to drive. I did feel that my stomach vibrating cuz I have a tummy. Other than that, I find it not bad. So I really don't understand when full load sits behind, the feeling seems so different and heavy. When hit hump or bump, like will hear 'bomp bomp' and the rear passengers will hop upwards and down again. IS IT NORMAL?

[Diamondback]

Diamondback,

 

Static sag is the difference of the length of the spring (or how much the spring has compress) due to the weight of the car. Normally the manufacturer will have their recommendation for the static sag base on the model of your car.

 

Get this wrong, and no matter how much you adjust your damping (rebound or compression), you will never get to enjoy the full benefits of using coilovers.

 

A lot of people mistook static sag with preload.

 

Maybe some of our more knowledgable members here can explain in detail.

 

I pick up on tuning suspensions when i was bike racing in my younger days.

 

Thanks pal... very chim thou...

 

how do i check if the static sag is correct?

 

and also can you further enlighten me on rebound and compression?

[Boyboy]

it's stiff but not bouncy. like no suspension

 

a bump is just that, a bump. no bouncy. when u say bouncy i suppose that after the bump is passed the suspension still ocscillate once or twice?

 

no seasick feeling in my car though it's not at all comfortable

[Pandaeyes]

Hi,

 

Just went to check my absorbers. They are fine. No bang sound now. I tuned it to softest to see how the car performs. Still harder than stock.

 

But one thing common, regardless whether I tuned it to hardest or softest, the rear always seems to have 'up and down' feeling. It has always been bouncing up and down with pple sitting behind. So how to solve this problem?

 

Is it the spring or absorber problem? The springs are prgressive (tighter at the ends and looser in the middle section) 4kg.