Track Going Gtrs

[JDSracing]

I'm at the point where I have enough money to get some coilovers for the GTR in preparation for superlap now.

What do you guys run in terms of Spring Rates on your GTRs? I'm asking in here and not the suspension area because I'm not really concerned about street handling as such and don't feel like being recommended "Super Streets".

My two main choices at the moment are Greddy Type S coilovers or Cusco Zero 2's. Both are about the same cost ($1700), both are height and damper adjustable but they come with fixed spring rates.

The Greddy Type S's run 8kg front, 6kg rear but are a "progressive spring", whereas the Cusco's are 12kg front, 10kg rear.

Assuming I want it setup with track, not street in mind, am I better to go with the stiffer option?

Thanks,

Matt

[swanny180]

What sort of tyres will you be using?

Im assuming some kind of semi given you are competing in super lap?

I think (don't quote me on this) that you can typically run spring rates a little higher when running on a semi as opposed to a street tyre (and likewise a bit stiffer again with a full slick)

[Merli]

Interested as well.

For those who will be willing to help, they will probably need to know whether or not you will have a roll cage, and whether it is welded in or bolted in?

[Hi Octane Racing]

All depend son how much you want to spend on it. Personally would go for Bilsteins or Ohlins but as I said all depends on funds.

[JDSracing]

RT615s are the plan at the moment!

6 point cage, full SK kit bar coilovers.

Thanks for the help, I am leaning towards the stiffer setup at the moment, as I think running at stock weight the 8 fronts 6 rears will be a bit too soft.

Bilsteins or Ohlins are out of the question money wise!

[djr81]

RT615s are the plan at the moment!

Thanks for the help, I am leaning towards the stiffer setup at the moment, as I think running at stock weight the 8 fronts 6 rears will be a bit too soft.

Ok a few things:

1. Using RT615's is like trying to get a bit pregnant. Either buy some proper R compounds or don't. Re55's are the most popular on GT-R's due to their grip & pricing in the appropriate sizes.

2. Don't forget to include sway bars & a camber/castor fit in amongst the springs.

3. 8/6 is more than stiff enough. 12/10 is plain silly.

[Hi Octane Racing]

You will notice that all real high performing japanese suspension use rather high spring rates due to a number of reasons:

1. their tracks are perfectly smooth

2. they dont touch the ripple strips

3. the mega high performing cars dont use anti roll bars they purely run of spring rates.

On our tracks 12/10 would be almost to stiff i think. How much are you looking to spend? Only around the $2000 mark?

Edited April 7, 2008 by Hi Octane Racing

[Merli]

3. 8/6 is more than stiff enough. 12/10 is plain silly.

Really? What are you basing this on?

I know some of the spring rates that some of the racing GTRs (without naming any of the race teams) that we all know and love, and they are running MUCH stiffer than 8/6. Much much much stiffer.

I'm no suspension guru (as far from it as possible), but I have a feeling that it really depends on the quality of the shock absorber, and its ability to handle the rebound stroke of the stiffer spring rates? I've been for a ride in some GTRs with RIDICULOUS spring rates, and they felt perfectly fine, even over corrugated iron tarmac. On the other hand, I have also been in some GTRs running slighty softer spring rates on a popular green japanese coilover brand that was rough as guts.

Again, if any REAL suspension gurus wish to tell me I'm full of sh1t, please feel free

[djr81]

Really? What are you basing this on?

I know some of the spring rates that some of the racing GTRs (without naming any of the race teams) that we all know and love, and they are running MUCH stiffer than 8/6. Much much much stiffer.

I'm no suspension guru (as far from it as possible), but I have a feeling that it really depends on the quality of the shock absorber, and its ability to handle the rebound stroke of the stiffer spring rates? I've been for a ride in some GTRs with RIDICULOUS spring rates, and they felt perfectly fine, even over corrugated iron tarmac. On the other hand, I have also been in some GTRs running slighty softer spring rates on a popular green japanese coilover brand that was rough as guts.

Again, if any REAL suspension gurus wish to tell me I'm full of sh1t, please feel free

I am basing it on the spring rates I run in my GT-R.

Some people prefer harder spings, some softer. It depends on what track you run on also. As an example Phillip Island would be different to say Winton.

Edited April 7, 2008 by djr81

[JDSracing]

You will notice that all real high performing japanese suspension use rather high spring rates due to a number of reasons:

1. their tracks are perfectly smooth

2. they dont touch the ripple strips

3. the mega high performing cars dont use anti roll bars they purely run of spring rates.

On our tracks 12/10 would be almost to stiff i think. How much are you looking to spend? Only around the $2000 mark?

That's the maximum yes, this is a very low budget car compared to a lot of what's running.

[Merli]

I am basing it on the spring rates I run in my GT-R.

But what you run in YOUR GTR is by no means an indication of what's best for a track-only GTR....... Is it?

[djr81]

But what you run in YOUR GTR is by no means an indication of what's best for a track-only GTR....... Is it?

Um, well I never claimed to be the font of all knowledge on the subject.

Just that the bloke asked what people were running.

So I thought I would share.

I'm sorry if I confused my opinion with one that had some validity.

But I have gone throught the exercise of setting my GT-R up to work on a track on R compounds.

Edited April 7, 2008 by djr81

[Merli]

Um, well I never claimed to be the font of all knowledge on the subject.

Just that the bloke asked what people were running.

So I thought I would share.

I'm sorry if I confused my opinion with one that had some validity.

Oh okay...

I wasn't having a go at you, I was genuinely interested, because I have heard SOOOOO many different ideas on what the ideal spring rates are.

It's hard to differentiate between personal "normal-person's", "tried one coilover and it seems to be good" opinion and informed, race-experience, "tried-all the different spring rates"-based opinion.

Suspension will make or break a track car, so along with the thread starter, I want to make sure I get all the right information

[JDSracing]

Oh okay...

I wasn't having a go at you, I was genuinely interested, because I have heard SOOOOO many different ideas on what the ideal spring rates are.

It's hard to differentiate between personal "normal-persons" opinion and informed, race-experience, "tried-all the different spring rates"-based opinion.

Suspension will make or break a track car, so along with the thread starter, I want to make sure I get all the right information

That my point exactly, and the reason I'm asking, there are good points backing both, hence why I'm looking to see what others run

I've already got the rest of the gear, camber, castor, cage, sway bars, bushings, subframe alignment kit. I just want to make sure I finish the package properly.

[Hi Octane Racing]

That's the maximum yes, this is a very low budget car compared to a lot of what's running.

For your application and as the car is only circuit use I would go the Cusco's. The spring rates may be high however they are adjustable so you will be able to soften it slightly if they are to stiff. For the money they would be the option of choice in my opinion. Otherwise keep saving till you reach $3900 for the Bilstein height & rate adjustable ones

[evil_weevil]

Ok a few things:

1. Using RT615's is like trying to get a bit pregnant. Either buy some proper R compounds or don't. Re55's are the most popular on GT-R's due to their grip & pricing in the appropriate sizes.

2. Don't forget to include sway bars & a camber/castor fit in amongst the springs.

3. 8/6 is more than stiff enough. 12/10 is plain silly.

Unfort for the clubman class for superlap, the RT615's are Matt's only option (or the 595RS's?)

[djr81]

Unfort for the clubman class for superlap, the RT615's are Matt's only option (or the 595RS's?)

Shame that.

Anyway the general trend is the more tyre grip you have the higher the spring & sway bar rates you need to run.

So if you are stuck being half pregnant IMHO that is more reason to run the lower rate spring.

[JDSracing]

Unfort for the clubman class for superlap, the RT615's are Matt's only option (or the 595RS's?)

Agreed, the rules chose the tyres

That being said though 12month old RT215s are the best tyres I've ever had on any of my cars so I don't know what I'm missing out on.

[Merli]

Agreed, the rules chose the tyres

That being said though 12month old RT215s are the best tyres I've ever had on any of my cars so I don't know what I'm missing out on.

Don't EVER try proper semi-slicks. Your wallet will hate you forever.

[WRRR]

Drop SK a PM he will give you the ins and outs.

Note though doing it properly is going to hurt the wallet.

I have gone as per djr81 with a bilstein coilover arrangement but for a 33 (not 32) with different shock valving and 5 front 4 rear Eibach springs. Desired handling is slightly more towards allrounder (road on street rubber and track on semis) but more F caster and more F and R camber than for a typical road set up.

Only just gone in but initial impressions are positive. drj81 has been progressively updating his for quite a while (how's the transfer case Richard??)