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Track Suspension...best Coil Over Kits!

mrtzila

By mrtzila,
in Motorsport Discussion & Builds

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sav man Grand Master

sav man

Posted
Posted
That's fair enough Snow, but I do assume that setting a car up for circuit as opposed to tarmac rally is quite different.

For instance, my car is quick with shit in it on the circuit, but I bet it aint quick with the same shit in it on a rally stage, but it sure was with the DMS in it. I'm glad you haven't asked me what spring rates I ran in the DMS at Targa. LOL

how is the best way to pick spring rates? we have run 310/210 on the gtr 07/08, dunno what was in it this year. and the car was very nice. but by the sounds of it you were running rocks in the much lighter car. is it just trial and error?

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Sydneykid Grand Master

Sydneykid

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how is the best way to pick spring rates? we have run 310/210 on the gtr 07/08, dunno what was in it this year. and the car was very nice. but by the sounds of it you were running rocks in the much lighter car. is it just trial and error?

For circuit racing I ask the tyre engineer what effective spring rates his tyre likes. After all that’s the point of contract with the road and optimising tyre traction is what it’s all about. In a RWD car I use that as my target front effective spring rate, then let the weight distribution of the car tell me what effective spring rate is needed in the rear. Note the term "effective spring rate" that is the actual spring rate divided by the movement ratio and then the leverage ratio. The tyre only feels the effective spring rate, it doesn't care what the actual spring rate is.

For a tarmac road event, using the same tyres, I would come down in spring rate in comparison to what I would run on the track as the average road surface tends not to be as well looked after as the track. Plus we have to be aware of the possibility of rain if its a long event like Targa Tas. Somewhere between 10% and 20% lower has worked for me in the past.

Cheers

Gary

mosoto Proficient

mosoto

Posted
Posted
The reason why helper springs are not used is simple cost, they can keep the cost down by leaving out the additional components.

By shortening the shock body you are reducing the droop travel of the suspension. A simple example of the effect of that, go over a bump of sufficient amplitude and the reduced travel means the wheel lifts off the ground after the bump. Obviously not an ideal situation on the road, but equally so on the track where I often see cars with too little droop actually lift both of the rear wheels off the track under brakes. Not a nice situation if you are trail braking on turn in, usually a spin is the result.

Just thought I'd re-itorate on this one as I didn't pick it up earlier. The PSS9/10 front coilovers don't have separate ride height and preload adjustment like the Ohlins DFV do, hence the DVF don't require the helper springs as they maintain full travel.

9krpm Mentor

9krpm

Posted
Posted

IF you guys don't mind, I'll throw in a slightly off topic question.

I have a 5-6 years old Bilstein coil over system for a mainly track car. Last time I took it out, I felt that it had a bit more body roll than usual but a lot of things were not perfect for racing either so it might not be the shocks.

How often do you need to reservice the shocks/spring?

What are the symptoms when the shocks goes off?

  • 2 weeks later...
phunky_monkey Grand Master

phunky_monkey

Posted
Posted

Just a bit of an update for anyone interested. I went for a ride in a friends Boxster S club car which had just been fitted up with Cargraphic fettled KW's (not sure of exactl model, but above the Clubsports and had remote reservoirs, circe 6-7k worth) and they rode really well. I was very impressed with them.

They seemed to control roll quite well considering stock swaybars, and the ride quality was better than my stock 06 STi. My mate was also really impressed with them on the track. Thought some people may be interested.

jonosx Apprentice

jonosx

Posted
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interestingly I think nfi does have a fi in this case!!! :) if he is who I think he is... possibly works somewhere on princes h'way.... starts with an "H" and ends with a "easmans"...

Haha...no that would be me...!

Yeah well I know one R33 GTR that has some MCA's in it and it's very average. It was used at Targa and had no end of problems as well. The guy who drove it there hated it and sold it straight afterwards and by all accounts the set-up on it is still shocking to this day.

I can't say for sure who was responsible for the settings in the car as it sits now, but if it came with Murrays recommended settings for that car for Targa and nothing has changed then I think you are going to have to spend some time finding what works for you (unless you either get lucky or else can pinch someone else's data who has the same basic car) if you go down that path.

I have no doubt Murray knows suspension as good as anyone out there - but that doesn't necessarily means he knows the atributes of all of the cars he builds suspension for and consequently the prefect settings. I know the suggested settings he discussed with me were along the lines I'd expect to see in an EVO which from my knowledge are usually fairly different to a GT-R - but he was the first person to admit that his suggestions were only a guess. So....

It may be that the shocks have bee adjusted by someone to less than optimium settings. Thats the thing with adjustables, people with little idea can easily turn a dial and throw a good setup out the window.

IF you guys don't mind, I'll throw in a slightly off topic question.

I have a 5-6 years old Bilstein coil over system for a mainly track car. Last time I took it out, I felt that it had a bit more body roll than usual but a lot of things were not perfect for racing either so it might not be the shocks.

How often do you need to reservice the shocks/spring?

What are the symptoms when the shocks goes off?

It would probably be beneficial to at least get them checked on the dyno. They could probably do with a freshen up after that many years.

Feel free to drop me an email if you have any other questions...

[email protected]

;)

  • 2 weeks later...
  • 2 weeks later...
phunky_monkey Grand Master

phunky_monkey

Posted
Posted

Haha here's hoping :P

If they perform anywhere near the set on my mates Boxster I will be over the moon, best body control and damping I've felt before. The way it took ripples was amazing so fingers corssed.

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