Coilover set up ( opinions )

[Odin]

Right I thought seeing as I'v just bought a set of these and no doubt some of you lot will be doing the same. I will start a thread on susp set up's so that we can make the most out of this bit of kit .

I myself have no real idea about susp set ups . Hence this thread .

So for all you people in the know this is the place to show off your skills :idea: :arrow: .

I'd like idea's and opinions from everybody that thinks there can help please, THAT MEANS YOU JIM :lol: :lol: :lol: :lol: .


rob

 

[campbellju]

Lower it rice boy stylee as far as it will go. It looks cool and handles great.... NOT! :lol: :lol:

 

[Odin]

Lower it rice boy stylee as far as it will go. It looks cool and handles great.... NOT! :lol: :lol:

Whats this :?: :? , I was expecting at leat 10 pages :lol: :lol: :lol: :lol: .



rob

 

[CruiseGTi-R]

I have D2’s, been on for about 3 months, so also still learning.

I have to admit that I initially set the ride height by what looked right, using the bottom clamp so that the spring pre-load was unchanged from out-the-box (which stated that it was set for fast road use).

On their softest damper setting they are very hard, very good if you’re on smooth roads. However, I’m finding that if I hit a depression in the road the dampers work ok to take up the load of the car but as it rides out of the depression its followed by a too-violent spring rebound making the car skip and jump about. The ride over bumps does the same, manages to damp within reason but the rebound seems too harsh.

I’m going to wind off some spring pre-load to soften the reaction a bit (probably have to wind in some ride-height back in to compensate). Have yet to find out what this will do.

I have a feeling that most people who use coilovers always use the softest damper settings as they are inherently damped a bit too hard for general road use. You’re then left with only being able to wind off spring pre-load to take the edge off a bit as inevitably spring pre-load does contribute to damping too.

 

[Odin]

thanks mate that's very interesting, I'll proberly wind a bit off to start with then, and see how it goes from there 8) .



rob

 

[Fast Guy]

Do you have a lower brace fitted. My whiteline one is grounding out alot, even with the teins on medium. I keep raising the car a little at a time until it stops. :?

 

[Odin]

I'm going to try and set the hight with a 1.5" tyre to wing lip gap like i used to have, the bottom brace didn't ground out to much at that hight .


rob

 

[campbellju]

I thought I'd buck the trend and cut straight to the point for a change

Opinions first…. If you are on original struts designed for standard springs then you can't really lower the car more than an inch without risking terminal understeer. Our cars have about 4" of suspension travel so if you lower the car 50mm you only have 2" before you bounce off the bump stops or completely compress the spring. When this happens, your outside wheel suspension goes infinitely stiff and you lose all grip.

Coilovers mean you can lower the car whilst still maintaining good suspension travel, avoid bottoming etc and stopping the terminal understeer. Just because you can though doesn’t mean you should. The geometry on our cars’ were still designed with limited travel and past 3” (From experimentation) the lower arms go past horizontal, the geometry will start to get funky (technical phrase ) and it’ll understeer again.

I posted this on my experience with setting up the coilovers but its still a work in progress as I'm away from my pride and joy still:

http://bb.gtiroc.com/viewtopic.php?t=36437&highlight=ride+heighth+height

I’ve been doing a lot more research since then , the SCC magazine and SR20 Forum has a lot of good stuff. In short, the a55 up nose down stance seems to be the option as with a few tweaks, the suspension can be set to make the car oversteer at low speeds and understeer at high speeds. My current suspension setup is a compromise with a few bugs still but I’m on the right track.

Once your ride height is sorted, you’ll need to either corner weight the car or balance the side to side ride height. Ideally both but for me, I don’t have a set of auto scales and I do have a ruler. I may get it corner weighted too some time but I'm still fiddling too much. Corner weighting/ride height balancing should be Done with the equivalent weight of yourself in the car, you’ll be surprised at how much the geometry changes.

Jim

 

[zia]

have set mine up so ride height is slightly lower at the front, and have set the rear damper's to setting stiffer than front,enabling the rear tyre's to stay more firmer when cornoring. the front camber i,ve played between positive 1.5 deg. (was getting alot of tyre squeal and have now set it to negative 1.5 deg. with the combination anti lift the wheel angle does look a bit different :lol: .at the moment seem ok but true test will occur on sunday....

zia

 

[campbellju]

Edited as just seen some infor on the D2's

On their softest damper setting they are very hard, very good if you’re on smooth roads. However, I’m finding that if I hit a depression in the road the dampers work ok to take up the load of the car but as it rides out of the depression its followed by a too-violent spring rebound making the car skip and jump about. The ride over bumps does the same, manages to damp within reason but the rebound seems too harsh.

I’m going to wind off some spring pre-load to soften the reaction a bit (probably have to wind in some ride-height back in to compensate). Have yet to find out what this will do.

I have a feeling that most people who use coilovers always use the softest damper settings as they are inherently damped a bit too hard for general road use. You’re then left with only being able to wind off spring pre-load to take the edge off a bit as inevitably spring pre-load does contribute to damping too.

We'd best explain a few things fella

They call it fast road use setting as it saves them winding the spring up and speeds up manufatcure. Most people don't adjust or even attempt to try from this so you're ahead of the game already.

Spring pre-load is there to stop spring sag at full extension and has very little to do with the handling. If your springs sag or droop they will fail an MOT. On the D2, suspension travel and ride height can be setup seperately. Pre-load is normally around 5-10Kg of static force and keeps the main spring inplace. When you compare this to the main spring that needs around 150kg to move an inch, the more the suspension moves the less effect it has. If the car rolls 1" over, it needs 160Kg with the spring preload rather than the 150Kg normally. Tein's don't have sperate adjustability and at full drop the spring can rattle around a bitand at max ride height the springs have less travel.
The main springs on all the coilovers I know are linear so to compress it 1" might take 150Kg, to compress it another 1", it will still take another 150Kg. Tis is another common misconception and it means you are able to adjust ride height without changing the spring rate. Springs are not perfect though and though the first inch might be 150Kg, the next might be 160Kg etc. This effects comfort more than handling as said previously.


Your D2's use a combined bound and rebound adjustment. Don't be afraid to play with the dampers a little. Depending on the road/conditions, sometimes more is less and at other times vice versa in terms of following the road AND comfort.

BTW, spring pre-load does not contribute to damping, the clue is in the question Coilovers are designed for tuning ride height but if you've not tried it yet. Give yourself an hour and prepare to get a few blisters.

Jim

 

[campbellju]

What you up to Zia?

 

[zia]

not alot mate just going around silverstone for track session.nice good speed cornor's :lol: .
would love to try sprint course's but car isn,t mapped 100% yet.

zia

 

[campbellju]

Roughly roughly that's the setup I'm after. Would be interested to know how even your front tyre wear is at that level of camber.

Good luck on Sunday.

 

[Odin]

I'v had my fronts set to -1.5 for about 2 to 3 months now with no sign of any extra ware .


And thanks for the info Jim I knew you wouldn't let me down :lol: :lol: .


rob

 

[CruiseGTi-R]

Edited as just seen some infor on the D2's

We'd best explain a few things fella

They call it fast road use setting as it saves them winding the spring up and speeds up manufatcure. Most people don't adjust or even attempt to try from this so you're ahead of the game already.

Spring pre-load is there to stop spring sag at full extension and has very little to do with the handling. If your springs sag or droop they will fail an MOT. On the D2, suspension travel and ride height can be setup seperately. Pre-load is normally around 5-10Kg of static force and keeps the main spring inplace. When you compare this to the main spring that needs around 150kg to move an inch, the more the suspension moves the less effect it has. If the car rolls 1" over, it needs 160Kg with the spring preload rather than the 150Kg normally. Tein's don't have sperate adjustability and at full drop the spring can rattle around a bitand at max ride height the springs have less travel.
The main springs on all the coilovers I know are linear so to compress it 1" might take 150Kg, to compress it another 1", it will still take another 150Kg. Tis is another common misconception and it means you are able to adjust ride height without changing the spring rate. Springs are not perfect though and though the first inch might be 150Kg, the next might be 160Kg etc. This effects comfort more than handling as said previously.


Your D2's use a combined bound and rebound adjustment. Don't be afraid to play with the dampers a little. Depending on the road/conditions, sometimes more is less and at other times vice versa in terms of following the road AND comfort.

BTW, spring pre-load does not contribute to damping, the clue is in the question Coilovers are designed for tuning ride height but if you've not tried it yet. Give yourself an hour and prepare to get a few blisters.

Jim

When I say spring pre-load I think I mean the rebound rate of the spring.

Am I right in that winding off the spring load (as long as I keep some pre-load in to stop the spring actually being able to slop around) I can adjust the rebound rate of the coilover?

You mention rebound damping, something I hadn't thought of. So its possible that if I wind in a bit more damping I might, by compromising a bit of ride comfort, be able to calm down the rebound rate of the coilover?

I can’t get my head round the springs not contributing to damping though. It might be that I’m thinking more about ride comfort than actual damping. I always thought that suspension was essentially always a compromise as a stiff damping rate could never be accompanied by a soft rebound rate (actually monster trucks have exactly this, but they use Nitrogen and special reservoir rebound tanks :shock: ).

If a damper is compressed by 1 inch going over a bump, then the spring will also be compressed. The spring cannot help but provide a reaction of its associated stiffness (say 150kg) as the damper goes through its stroke and compresses, even before it has a chance to force the damper back up and complete the rebound. Surely it provides 150kg/inch of damping too? Maybe its such a small proportion compared to the damping that its ignored?

It feels in my car like at slow speeds the stiffer springs cause the awful ride as the ‘hits’ on the coilover aren’t enough to overcome the load in the stiff spring to get the damper working.

I’ll be fettling spring rates this weekend me thinks….

 

[campbellju]

I think you're there ot there abouts with what you are saying but a quick bit of terminology as you're confusing me :shock:

Springs control movement, dampers control rate of movement. Springs don't dampen anything.

Both can control roll, ride comfort and handling.

When a spring is designed its dynamic performance is defined dependant on spring length, width, thickness and number of coils. The rest is dependant on the damper.

Monster trucks like normal trucks/coaches etc might use Air suspension that is whole differnet kettle of fish. I don't think you'll find any springs

At the moment you're talking about comfort. If you put your dampers on the lowest setting then for slow speed driving you won't be able to improve your comfort.

A little trick I've used in the past is to up the damping more than you'd think. At low speeds its even worse with pot holes etc but at high speeds, the wheels (+60mph) seem to skip over pot holes rather than crashing through them. This is a fine balance though and one easy to get wrong, hit a pothole, put too much strain on your dampers and you'll blow a valve.

TBH, I think the spring rate on your springs are just too high for our poor roads. The Teins come with springs 4kg/mm front and 3Kg/mm rear, your D2's according to the website are 7Kg/mm front and 5Kg/mm rear. IMO, this is the top limit of acceptable for street use and are proberbly why you're finding the ride so uncomfortable.

The ride height is irrelevant for sltraight line comfort. Remove as much pre-load as you safely can and turn the dampers right down and that is about as good a "low speed" ride comfort as you're going to get.

You could change your D2 springs to 5kg/mm front and 3.5Kg/mm rear as an option but I don't know how much that would cost.

You could also fit a softer seat or drive on better roads :shock: :lol:

Cheers,
Jim

 

[Odin]

I think you can pick up new springs for about $50 a pair , I seem to remember reading somewhere .



rob

 

[Odin]

Well I started fitting my new K-Sport coilovers last night .

What I'v found so far as I'v only got as far as fitting the fronts and trying to set them up :shock: , Is that there bl00dy hard work to get right .

The topmounts are a very tight fit and we may need to make the big hole at the top bigger to get the right camber adjustment :roll: .

Setting the ride hight is a lot of trial and error as you think you'ev made a big adjustment in shock length but you haven't , I'v now set the spring platforms and am playing around with the hub hight at the moment.

At the moment the car is just sitting far to low for my likeing, But I'v got 4 or 5 hours later today to try and get it right.

rob

 

[gavmc18]

cool rob let us know how you get on will be doing the same once my d2's arrive

gav

 

[campbellju]

Good to hear how you're getting on Rob. I didn't realy think you needed my help

I'm still struggling to get past a deg of camber with the ride height set at 325 on the front too