Suspension stroke

[DaveB 20]

For everyone who has adjustable coilovers on the gt86, how much suspensions stroke do yo have? Out of the box my bc coilovers have a few extra inches of spare travel so I was going to lengthen the spring stroke. And before I ruin the handling I thought if anyone else had done this I should find out. Cheers

[Lauren 2259]

If you have coilovers that are adjustable on the length of the dampers case, then you don't lose damper travel by lowering the car. You maintain the whole length of the damper stroke. My Teins are like this, not sure about BC's. 

 

The finite length of your stroke is dependent upon the stroke of the damper.

[DaveB 20]

Yes strut extends at bottom to control ride height. Is it better to have longer spring and more suspension travel, Lauren?

[Lauren 2259]

A longer spring will not change the amount of suspension travel as it will be pre-loaded and thus not as long when on the car. Suspension travel is determined by damper stroke length which is a set amount. 

[Sonic 4]

long stroke suspension is generally a good idea

as anything that allows the tyre to stay in contact with the road better will find more grip than if the suspension bottoms out and allows the wheel to lift

[Deacon 1357]

Doesn't necessarily have to be a particularly long stroke though - the piston design plays a big part in how well the suspension responds to the bumps.

[DaveB 20]

Still confused, i'm thinking if I lengthen the spring Ill have to add some ride height to balance it up. Don't know whether to keen it the same and safe or completely cock up the handling on my car!

[Guest]

I'll try and explain this so you understand Dave..

Imagine for a minute, you have coil overs without the adjustable uprights, i.e. only one threaded ring and locking ring. To lower the car, you would wind the ring down the strut. This will basically put the top of the damper casing closer to the top mount and bump stop. So, you have a lowered car, but reduced suspension travel. BUT, remember one thing, wherever you set the spring seating ring the spring will always assume the same length with the weight of the car on it.

Now, you have adjustable spring seats and adjustable uprights/hubs. Theye are made in this way so you can adjust the preload on the spring. There will be a recommended preload with your coilovers, I remember seeing a BC video on YouTube showing how to do this very adjustmant. So, you can imagine you put a little compression in the spring before loading it with the weight of the car, but remember, as long as you add less preload than the cars weight, the spring will always assume the same length under the cars weight.

If you take away the preload and wind the strut into the upright/hub, then you will effectivly lengthen your overall travel by pulling the strut body away from the bump stop, however, the spring will fall out of its seat every time you take the weight off it, which is very dangerous in my opinion.

Unfortunately these cars have limited rear suspension travel, lowering just compounds the issue. this is whay I am turreting my shock mounts, which basically entails lifting the mount in relation to the rest of the car. A VERY serious mod that should only be contemplated by a complete nutcase!!  

[Ade 517]

Nig there are top mounts you can buy state side to lower the car a bit. They are not cheap though and given your engineering skills I will looks forward tp see the finished parts! :-)

oh they are solid metal with pillow ball too so ride confort will be affected.

[Guest]

Nig there are top mounts you can buy state side to lower the car a bit. They are not cheap though and given your engineering skills I will looks forward tp see the finished parts! :-)

oh they are solid metal with pillow ball too so ride confort will be affected.

I just checked those out. They're made by Raceseng in the U.S. They only increase the shock stroke, which will be great for a road biased car. I am going for the full Turret option, lifting the whole platform up.

[Ade 517]

ah right I was thinking of the cas cam plates anyway 0 whcih dont lower anything!. Those rear ones can fit aftermarket coilovers though. That's particularly useful to add stroke to coilovers that adjust height by adding preload. If you use tein, HKS, Ohlin ect.. where ride hight is adjustable independantly of pre load they arnt worth it.

[Guest]

ah right I was thinking of the cas cam plates anyway 0 whcih dont lower anything!. Those rear ones can fit aftermarket coilovers though. That's particularly useful to add stroke to coilovers that adjust height by adding preload. If you use tein, HKS, Ohlin ect.. where ride hight is adjustable independantly of pre load they arnt worth it.

I think you'll find the type of coil over with adjustable preload is the only type with height adjustment independent of the preload? Simple coil overs which use one spring platform to adjust height don't have adjustable pre-load.

[Ade 517]

Well yes something like the KW3, you basically wind up the spring (add preload) to lower the ride height. Not ideal as you lose droop travel. If you want truely adjustable preload, without affecting ride hieght you need to be able to adjust the position of the mounting point like the HKS, ohlins or Tein to name a few.

[Guest]

Well yes something like the KW3, you basically wind up the spring (add preload) to lower the ride height. Not ideal as you lose droop travel. If you want truely adjustable preload, without affecting ride hieght you need to be able to adjust the position of the mounting point like the HKS, ohlins or Tein to name a few.

No, you are not adding preload, you are merely lifting or lowering the car with the adjustable spring seat.

[Ade 517]

If you were adjusting the top and bottom seat together that would be correct ....but the KV3s/RCE Tarmacs you are adjusting only the lower spring seat. I.e you are compressing the spring more to lower it; adding preload.

 

Its not ideal....

[Guest]

If you were adjusting the top and bottom seat together that would be correct ....but the KV3s/RCE Tarmacs you are adjusting only the lower spring seat. I.e you are compressing the spring more to lower it; adding preload.

 

Its not ideal....

I give up!!

You move the spring seat down to lower the car, and up to raise it. The car determines the spring compression by its weight. There is no preload adjustment!!!.

On coil overs such as Ohlins, the spring seat is turned up into the spring to set the preload at full extension.

[Ade 517]

Sorry, I meant move the lower seat down to lower the car. My mistake there.

 

I am often wrong so here is a diagram to show what I mean by adusting preload to change the ride hight (but losing or gaining droop travel):

 

8mm vs 58mm droop travel

 

Am I doing something wrong?

 

 

[Guest]

Your error is that you are imagining the top mount is fixed. The difference is indeed 50mm, but your description of "preload" is incorrect as you are just lifting the top seat higher when the spring is pushed upwards. So, the car will sit 50mm higher.

 

Of course, if you extend the shocker to its limit on extension, you can preload the spring as much as you like, but why on earth would you do that?? You will lift the car higher and increase bump travel, but you will lose all rebound.

[Ade 517]

With the RCEs and KW V3s the top mount and bottom mount is fixed?

 

All you have is the bottom spring seat?

 

Instrcution here:

http://www.racecompengineering.com/index.php/settings-instructions

 

 

 

[Guest]

Now I really do give up.

 

Please put your theory into practice, let me know what happens..

[Ade 517]

I give up too. Case closed.