I feel I am fairly mechanical minded, I’ve stripped engines and rebuilt them etc but one thing I have never understood is how springs and shocks each affect the ride stiffness of a car.

You get adjustable shocks like my TEIN flex were with a small allen key you can make the suspension firmer but also you get a different weighted spring i.e. my TEIN flex has 12kg springs which also affect the ride stiffness.

Can someone please explain the difference please?

Also if I increased my rear springs to 14kg spring how would that affect my car?

Thanks in advance.

Colin

 

the spring supports the weight of the car, the damper controls the reaction of the spring to compression and rebound events

I would recommend against going to an even stiffer spring...your springs are already quite stiff

If there is a certain handling trait you are trying to alleviate, best to list your exact setup, down to the tires, and do your best to describe what the car is doing that you dont like

 

Do some research on "Natural Spring Frequency" and the formulae which allow you to calculate it.

The softest spring that will do the job is always desired for rride comfort.

Another area to explore is that springs ratio should be just equal to body weight. [Some designers shift this ratio forward by 5%]............the problem is to design adequate road pitch control [on short wheelbase cars] at WHAT higway speed?

http://www.proshocks.com/calcs/imotion.htm
http://www.proshocks.com/calcs/anglefirst.htm
http://www.efunda.com/formulae/vibrations/sdof_cal.cfm
http://www.efunda.com/formulae/vibra...eg_vehicle.cfm

Necessary to add the tire sidewall stiffness to springs to arrive at final road to car stiffness, use this formula and ~~1500 pounds per inch for ~~tire.
2 springs in series result in a lower than lowest actual rate.
http://www.stockcarproducts.com/pstech7.htm


You might investigate ride frequency vs wheel hop frequency:
http://www.avpj18.dsl.pipex.com/docu...%20weights.xls

http://www.fromsteve.net/carstuff/su...ensionCalc.zip

 

What I am really looking for is to lower my car more than the springs that come with the flex kit allow at the rear. I have spoken to Tein and they can offer me a shorter spring but either 10kg or 14kg were the STD flex spring is 12kg.

I don't want to sacrifice suspension stroke so thought the harder one would be better but don't know how this would effect the car.

 

I would not recommend it at all without sending the units back to Tein for a full revalving

 

Why?

 

because your dampers are not valved for those springs

 

nice info, thanks.

 

Is it the spring rate or the length that is the problem?

 

the rate...you can compensate for the length

 

Can you get me a shorter spring with the same rate, doesn't need to be tein.

Thanks

 

Tein flex is valved to work with a spring rate range of + or - 2Kg, that much is true. In you case you can opt for a shorter Tein spring which can be ordered from any authorized Tein retailer that is willing to call tein to get a cost and model number on. If you are going this route do not go for the stiffer spring, IMO opt for the softer 10Kg rear spring.

However, I know of a free way to lower the rear of the car .8", might give you the lower rear drop your after at zero cost. Looking at the online instruction manuel from Tein, the rear spring setup reuses the oem upper spring seat. You can cut .8" off it's thickness and still have plenty of material left over for isolation, thats all their is to it.

Your desire for maintaining rear dampner piston stroke is well founded. The flex has adjustable dampner lengths, make certain that you can shorten them enough to cover whatever extra amount your going lower in the rear.

 

Does a softer spring on the rear not cause understeer?

How do i adjust the dampner lengh?

I may cut the spring seat, had heard of this before but i just didn't really want to cut things up but it may be my best option.

 

If you look at the height adjustment on the mono flex i feel that is much better and is quite different on the rear than the normal flex. This is the height i am looking to replicate.

I think i will go with cutting the rubber mount as 0.8" of a drop is more than enough looking for about 0.4-0.5 which will give the same rear height as the mono flex.

Have a quick question on strut length, how short should i make the struts?

Also can someone explain, "spring-preload". i'm not sure what is going on here when adjusting strut length.

Thanks