Coilovers

[Trust33]

But you chose heavy spring rates, seems like the wrong trade off. Why? Because you can easily adjust the bar (antiroll) rates but you can't adjust the spring rates.

Cheers

Gary

i meant trade off for a thinner swaybar.

the shocks were on the car when i bought it ages ago. if i had thought into the future it would have paid for me to get new shocks rather than rebuild them. at least then i would have somthing worthy of aussie roads and be able to take to the track at the same time without the hassel of a rebuild at least once a year. yes thats right folks.

when it comes time that they do go again. i think thats what i will end up doing. buying new ones suited to our roads.

[Sydneykid]

My problem with using big anti roll bars is the amount of weight they transfer to the outside wheels in a corner. With a RWD car that may not be a crucial problem in the front but not so good for the rears, which afterall are also trying to lay down power as well as go round a corner.

So in theory I'd prefer heavier springs but not as high as Jap spec, together with a fair to large sized ARB in the front and a small or nonexistant one in the rear. As I said, theory, as a general approach to setting up a dual purpose road/track car, assuming whatever it takes would be spent on dampers.

Somethings to think about;

You would need to use twice the spring rate to achieve the same anti roll as a stabiliser bar. Why? Because the inside wheel goes down the same amount that the outside wheel goes up. So a stabiliser bar has twice the movement for the same amount of roll as a spring, hence twice the amount of resistence to roll. Only the outside spring resists the roll, the inside spring does nothing.

When you are not going around a corner, the stabiliser bar does nothing, so you get more traction from the softer spring rate.

Stabiliser bars are easily adjustable, spring rates are not. If, on any given day, you need more or less front or rear anti roll you can't easily, quickly or cheaply adjust it with springs. That's why (when the regs allow) race cars have driver adjustable stabiliser bars.

Diagonal weight transfer is best resisted with anti roll, not spring rate. Under corner exit acceleration the outside rear tyres take a large amount of weight transfer, this manifests itself as lift to the inside front tyre. Reducing inside front tyre grip means that the outsdie front tyre is carrying more of the cornering load than would eb the case if the diagonal weight transfer was a resisted by a stabiliser bar. Excessive outside tyre wear and inability to maintain consistent lap speed due to overheating are all systems.

Too little anti roll has side effects. One of which is the need to run excessive amounts of camber, front and/or rear. This reduces the contact patch of the tyre for straight line acceleration and braking.

Running an excessively high spring rate becuase of a lack of antir roll has a few more side effects. One of which is the need to run excessively high rebound damping in the shock absorber to control that higher spring rate. This means the shocks resists (slows down) the downwards movement of the suspension and makes it more difficult to keep the tyre in contact with the road surface. Skipping from small bump to small bump is not good for traction.

I have several more pages in me if necessary, if anyone remains unconvinced.

Cheers

Gary

[Roy]

I have to say that when i ran bigger swaybars with off the shelf whiteline springs and Bilsteins the thing was quite nice on skid pans and hill climbs and on slow to mid speed corners. Very comfortable on the street

At PI on the quicker stuff with the amount of speed you carry in corners meant there was too much pitch in the car when i was on / off the gas. (driving style maybe...but i need somehting to mask my bad driving )

You can see in the footage at PI that the big bars seem to unweight the inside tyre as well, as i wouldnt expect to be getting so easily sideways under power at 190km/h on the exit of turn 1 , Hay Shed etc. LOL, every track presents its own challenges to a car

Another problem was on big stops, the car had enough grip and braking capacity to almost do hand stands. So whether because i didnt have enough spring or bump in the shocks, the thing use to get way too much boogie on under brakes and was very unstable. Since going up in the spring rate its much nicer under brakes and i can brake much more confidently. The car is also a lot more stable in corners when i am adjusting my throttle position.

You can see HERE at around 50sec point just how unstable it was under brakes....a few laps later it had a big rear lock up and around i went into the tyres

So, i thought i would just add this as noone seems to have commented on how huge a difference suspension control makes to braking...something swaybars dont really help with...you need spring to keep the nose of the car off the ground. Swaybars go a long way but sooner or later you may find that you still need more spring to help in other areas, especially if you are running around tracks usign semi slicks and the extra grip they afford

[260DET]

Understand your points Gary, you explain them well, but isn't the weight transfer effect of ARB's the equivalent of increasing the spring rate on the outside wheels in a corner, so losing grip there anyway? I mean with a big front ARB and soft springs the outside front tyre will get a hell of a work out in a corner won't it, with the weight transfer effect plus wedge to the inside rear as well?

Anyway what I'm going to try is to run springs that are liveable with on the road and then use ARB's to tune the suspension so it handles on the track. The dampers are custom three way jobs valved for R tyres and the spring rate range that will be tried eg 3-400lb wheel rate at the front, less at the back. What Roy says above is relevant as well eg a front ARB does nothing to control dive under brakes.

[Kaido_RR]

i through i add something into the equation again.

had my R33 with the tein RS (10/10) at a mc tuning day on monday, and had the suspension workshop guys come down and have a drive of the car.

He found the front to be good, with very good turn in but he felt the rear spring rate was alittle to big and made the rear more tail happy and very easy to get it side ways, But having said that he also made comment that with a better tyre (softer compound tyre) it would also improve the rear end grip.

My experience on the day was that on the small skid pad with the cone setup the car was very tail happy (but this may also be due to my driving style as atm i use the car more for drift events then grip), Also the car was very controllable even with the rear end hanging out it was easy to control and if i adjusted my driving style, i found i could keep the car gripping then sliding.

On the long track, the car handle wonderful, i didn't find it that tail happy, i was able to put the power down and drive a grip style with racing line and the car handled it great

just to note i had both the damper and rebound set on the softest setting and didnt play around with it as their wasn't enough time, also my tyres have less than 50% left on them and are Potenza G3, i will be looking to upgrade to Potenza RE01R next or AD07 or 6 to help to improve the grip.

I hope to take the car to some hill climb events so i will also update on how the car went.

But for the moment i am going to keep the spring rate, as i am very happy with the results

Michael

Edited January 9, 2008 by [Michael]

[dangerous_daveo]

Can't you get anti lift and anti dive kits tho?

I'm not saying that the soft spring rates were right, but arent there other options? Or don't these exist for skylines?

[Sydneykid]

I have to say that when i ran bigger swaybars with off the shelf whiteline springs and Bilsteins the thing was quite nice on skid pans and hill climbs and on slow to mid speed corners. Very comfortable on the street

At PI on the quicker stuff with the amount of speed you carry in corners meant there was too much pitch in the car when i was on / off the gas. (driving style maybe...but i need somehting to mask my bad driving )

You can see in the footage at PI that the big bars seem to unweight the inside tyre as well, as i wouldnt expect to be getting so easily sideways under power at 190km/h on the exit of turn 1 , Hay Shed etc. LOL, every track presents its own challenges to a car

Another problem was on big stops, the car had enough grip and braking capacity to almost do hand stands. So whether because i didnt have enough spring or bump in the shocks, the thing use to get way too much boogie on under brakes and was very unstable. Since going up in the spring rate its much nicer under brakes and i can brake much more confidently. The car is also a lot more stable in corners when i am adjusting my throttle position.

You can see HERE at around 50sec point just how unstable it was under brakes....a few laps later it had a big rear lock up and around i went into the tyres

So, i thought i would just add this as noone seems to have commented on how huge a difference suspension control makes to braking...something swaybars dont really help with...you need spring to keep the nose of the car off the ground. Swaybars go a long way but sooner or later you may find that you still need more spring to help in other areas, especially if you are running around tracks usign semi slicks and the extra grip they afford

For the benfit of the guys that didn't see the original posts when you asked this question.

I would suggest building some anti dive into the front geometry, which is rather simple to do if you have garage fabrication skills. Make some spacers for the front radius rod mounts and space them down from the subframe. We use 3 mm and 5 mm alloy, stacked to achieve the amount of anti dive we require. Some tracks need more than others of course.

Since braking is a low velocity action, you would also be much better off with more bump valving than heavier springs. That way you only have the heavier compression damping when you need it (under brakes) and not when you don't need it for traction in corners over the ripples and bumps.

There is always more grip available with softer spring rates than there is with excessive spring rates. A recent example, last Tuesday we were at Oran Park testing for the 12 Hour (not a Skyline). For a number of reasons, we are using Jap Spec N1 double adjustable dampers so I ordered them with the SOFTEST spring rate available. Just in case, I brought along 3 sets of locally sourced spring rates, being 10%, 20% and 30% softer. The car was over a second faster on the softest of my choices than it was with the softest rate availabe from Japan. These days Oran Park is rather bumpy, and with the Jap spring rates I just couldn't get enough stiffness out of it even on zero bump setting. With the softest spring rate I could actuallly use the bump valving adjustment to fine tune the handling.

My rule is simple, I specify the softest spring rate that I can and then use the other tools at my disposal (anti roll bars, shock valving, anti dive and anti squat geometry etc etc). If I run out of other tools, then I reluctantly reach for a higher spring rate. So higher spring rates are not the first thing I reach for, they are the last.

Cheers

Gary

[Sydneykid]

i through i add something into the equation again.

had my R33 with the tein RS (10/10) at a mc tuning day on monday, and had the suspension workshop guys come down and have a drive of the car.

He found the front to be good, with very good turn in but he felt the rear spring rate was alittle to big and made the rear more tail happy and very easy to get it side ways, But having said that he also made comment that with a better tyre (softer compound tyre) it would also improve the rear end grip.

My experience on the day was that on the small skid pad with the cone setup the car was very tail happy (but this may also be due to my driving style as atm i use the car more for drift events then grip), Also the car was very controllable even with the rear end hanging out it was easy to control and if i adjusted my driving style, i found i could keep the car gripping then sliding.

On the long track, the car handle wonderful, i didn't find it that tail happy, i was able to put the power down and drive a grip style with racing line and the car handled it great

just to note i had both the damper and rebound set on the softest setting and didnt play around with it as their wasn't enough time, also my tyres have less than 50% left on them and are Potenza G3, i will be looking to upgrade to Potenza RE01R next or AD07 or 6 to help to improve the grip.

I hope to take the car to some hill climb events so i will also update on how the car went.

But for the moment i am going to keep the spring rate, as i am very happy with the results

Michael

Precisley what I was saying, with adjustable stabiliser bars you could have tuned the handling for the short AND the long track. You are stuck with the spring rate, no adjustment there.

Cheers

gary

[Simonster]

Diagonal weight transfer is best resisted with anti roll, not spring rate. Under corner exit acceleration the outside rear tyres take a large amount of weight transfer, this manifests itself as lift to the inside front tyre. Reducing inside front tyre grip means that the outsdie front tyre is carrying more of the cornering load than would eb the case if the diagonal weight transfer was a resisted by a stabiliser bar. Excessive outside tyre wear and inability to maintain consistent lap speed due to overheating are all systems.

Too little anti roll has side effects. One of which is the need to run excessive amounts of camber, front and/or rear. This reduces the contact patch of the tyre for straight line acceleration and braking.

As always, Gary, very informative and educational, sory to jack the post but to consolidate my understanding of the above, would i be correct in say that i have too little anti roll bar in the attached photo as i am picking up the inside front tyre at turn one @QR??

If that is true, then my current front 28mm anti roll bar on the softest of 3 settings and rear 21mm on hardest of 2 need to go up in size? Or do i have a roll centre problem keeping in mind the spring rates are 7kg/mm front and 4kg rears?

Cheers

Simon

http://s51.photobucket.com/albums/f377/jun...nt=IMG_0889.jpg

[djr81]

For my ten cents worth - you are running mismatched front to rear spring rates. For my Gt-R I have 5kg front 4kg rear with a 22dia front & 24 dia rear sway bars. You are much stiffer on the front & softer on the rear both in spring & in sway bars- hence the car will pick up its inside front tyre.

So you need to bring the spring rates closer together & then fatten the rear sway bar. Also (again spring rate dependent) the front bar is pretty fat relative to most offerings although at 7kg/mm it is much more liveable than if the car was (for example) running a 5kg/mm spring. Whether you do this by just adjusting one end of the car or not depends on how high you like your rates.

Edited January 11, 2008 by djr81

[Ride417]

Well... I didn't quite understand everything that has been said and it took me 2 or so read of everything everyone has posted to make some sense of what I am doing (kinda) and I think I got myself in the shits and didn't use my money well. My car had stock suspension, shocks, blah, blah, blah, and I noticed the back was rolling around like a fat kid on sugar. Recently, my rear shocks shat itself so I went into CarToys in SA to get some new coilover kits similar to my brothers which were HSD. Instead I was recoommended the Greddy Damper Kit Type S-Niss Ecr33 Gtst which had 32 point adjustments and a electronic control system so I could adjust it in the car. Fancy? Yes. Worth it? I have no freakin idea. Got too excited I suppose but now I think I just spent $2,600 inclu. installation then another $500-$600 on the control system which is coming in next week just for kicks and I have no idea if it is going to make driving easier for me... I can feel for the car and say what I like and don't like about the handling. But I have no idea how it all works and decided to learn the expensive way.

I am a bit off the point but what am I expecting out of this kit if anyone has any experience with Greddy and will it stop my back rolling around like "a fat kid on sugar"?

[Kaido_RR]

Precisley what I was saying, with adjustable stabiliser bars you could have tuned the handling for the short AND the long track. You are stuck with the spring rate, no adjustment there.

Cheers

gary

im happy with my results so far, i have had yet to fine tune my setup, but i most likly wont be doing that as the car well be seeing more drift action this year then grip events, and i have already tested it at a full-day drift practices and the car is setup perfect for drifting, if i move into grip i will address my issue, and will consider dropping the rear spring rate to a 6 or 8 BUT i personally feel that will be my last opinion as my tyre rs are build for the 10/10 spring rate, and i don't think tein got it wrong lol....

tyre grip will be the first thing i look at for a grip event.

also their is nothing wrong with running non-unadjustable swat bars

[salad]

For my ten cents worth - you are running mismatched front to rear spring rates. For my Gt-R I have 5kg front 4kg rear with a 22dia front & 24 dia rear sway bars. You are much stiffer on the front & softer on the rear both in spring & in sway bars- hence the car will pick up its inside front tyre.

So you need to bring the spring rates closer together & then fatten the rear sway bar. Also (again spring rate dependent) the front bar is pretty fat relative to most offerings although at 7kg/mm it is much more liveable than if the car was (for example) running a 5kg/mm spring. Whether you do this by just adjusting one end of the car or not depends on how high you like your rates.

You're forgetting motion ratios. S13s have the ARBs attach to the LCA, and skylines have the ARB connect directly to the upright, giving a motion ratio of close to 1. S13 is much smaller, somwhere between 0.3-0.5. Similar thing, but not as extreme with springs. I do still think there is a mismatch, but maybe not to the extent that it seems just by looking and comparing with skyline numbers.

[Simonster]

You're forgetting motion ratios. S13s have the ARBs attach to the LCA, and skylines have the ARB connect directly to the upright, giving a motion ratio of close to 1. S13 is much smaller, somwhere between 0.3-0.5. Similar thing, but not as extreme with springs. I do still think there is a mismatch, but maybe not to the extent that it seems just by looking and comparing with skyline numbers.

Thanks for the replies guys,

Suspension stuff certainly is interesting and frustrating to learn, but that's what makes it exciting.

Gary said in a pm to me some time ago, that the front tyres were "seeing" a spring rate of around 5.7kg which was ok for the tyres i was using. For those that want to know, the S13 has a 0.9 to 1 movement and leverage ratio.

I was more concerned with getting the anti roll bars correct.

Cheers

[mystery_kid]

it all really comes down to if you're a soft cock or not

whoever mentioned 4/3 way earlier on in the thread is one

if you can put up with a stiff ride (which i thought that was the point of doing coil overs) then go for it

[djr81]

it all really comes down to if you're a soft cock or not

whoever mentioned 4/3 way earlier on in the thread is one

if you can put up with a stiff ride (which i thought that was the point of doing coil overs) then go for it

Please don't take this as a criticism, but that is so wrong as to be laughable.

If you need teeth jarringly hard suspension to prove to your mates how tough you are - well that simply shows how ignorant they must be.

The point of upgrading the suspension on a car is to make it ride/handle/grip better. Unfortunately to a large extent you can only have two of those three options.

With regard to the Silvia shown inthe photo a few things a obvious:

1. The car looks to have insufficient roll stiffness.

2. It looks to be falling over its rear suspension.

Which means:

3. You need to address the rear springs & sway bar stiffness first, but only if you are happy with the front spring rate.

[1400r]

Ueo said it best

"softer spring rates are better for covering up mistakes"

I'd take a wild guess that drift,street and track require different tweaking to get the "best" setup anyway

[mystery_kid]

it's simple do you care more about handling, or more about your comfy ride to work

buy a cima or a celsior or something if you want comfort

[BHDave]

Hooray for school holidays!

[mystery_kid]

sorry mate i'm going to be here long after school holidays are over