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How Do I Tell What My Spring Rates Are?

Sydneykid
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  • 2 weeks later...
driftmeister Community Regular

driftmeister

Posted
Posted

Hi SK

I really appreciate your great feedback on this thread.

Sorry to bring slightly out of topic, wonder does R34 GTR Vspec original

shock & spring fit well on ER34 GTT 2 door? I wish to get it more sporty for spirited driving than stock setup without sacrificing comfort. Got a good price for it from buddy.

The spec are :

Stock R34 V-spec suspension:

Spring rate: F 4.0 kgf/mm. R 5.0 kgf/mm.

Shock compression rate: F 110 kgf. R 77 kgf.

Shock decompression rate: F 267 kgf. R 125 kgf.

Appreciate ur advice. Cheers!

Sydneykid Grand Master

Sydneykid

Posted
  • Author
Posted
Hey SK,

Can i please get the rates for these specs in KG/MM preferably.

OD: 86mm

# Coils: 9.125

Coil Diameter: 12mm

Im expecting it to be 8kg/mm or so.

Thanks,

Neil

Hi Neil, 390 lbs / inch or 7kg/mm

:) cheers :P

Sydneykid Grand Master

Sydneykid

Posted
  • Author
Posted
Hi SK

I really appreciate your great feedback on this thread.

Sorry to bring slightly out of topic, wonder does R34 GTR Vspec original

shock & spring fit well on ER34 GTT 2 door? I wish to get it more sporty for spirited driving than stock setup without sacrificing comfort. Got a good price for it from buddy.

The spec are :

Stock R34 V-spec suspension:

Spring rate: F 4.0 kgf/mm. R 5.0 kgf/mm.

Shock compression rate: F 110 kgf. R 77 kgf.

Shock decompression rate: F 267 kgf. R 125 kgf.

Appreciate ur advice. Cheers!

GTR's being 4wd are very differeent to GTST's and GTT's being 2wd.

Two things seem to be common, firstly GTR's don't suffer from excessive power oversteer at the same power level anywhere near as much as GTST/GTT's do. Secondly GTR's understeer because of their extreme front weight bias.

Keeping that in mind, the Japanese suspension designers use higher comparative rear spring rates in GTRs. Remember they don't have the history of upgrading stabiliser bars, so they try and fix the understeer with spring rates. Plus they can't increase the front spring rate too much as it will reintroduce the understeer problem.

As to be expected that is the problem in this case, with the rear spring rate at 5kg/mm (280 lbs / inch). That is way too high for decent traction for a 2WD. As an attempt to get over the harsh ride problem that such high rear spring rates introduce, they run rather soft bump damping in the rear shocks (77 kgf).

The front spring rate at 4 kg/mm (225 lbs per inch) is more like what you would run in the rear of a 2wd. As an attempt to control the roll problem that such low (compared to the rear) front spring rates introduce, they run rather high caparitive rebound damping in the front shocks (267 kgf). This couples the stabiliser bar (side to side) and helps with the roll.

In summary, front spring too soft and rear spring too hard for a 2wd. The spring configuration is different front to rear, so you can't simply swap the springs, plus the shock valving wouldn't match anyway.

Hope that was of some help

:) cheers :P

  • 3 weeks later...
Sydneykid Grand Master

Sydneykid

Posted
  • Author
Posted
front:

id- 98mm, 66mm

dia- 12mm

#coils- 7 3/4

rear:

id- 88mm, 77mm

dia- 11mm

#coils- 8 1/3

cheers sk, great thread!

Sorry for the delay, I have been away from my engineering computer for a week.

Fronts are 235 lbs per inch (4.2 kg/mm)

Rears are 155 lbs per inch (2.75 kg/mm)

:D cheers :D

Sydneykid Grand Master

Sydneykid

Posted
  • Author
Posted
Fronts

Coil ID = 99mm / 69mm

Wire OD = 15 mm

# of Coils = 6.5 turns

= kg?

Thanks a heap

let me know soon

Sorry for the delay, I have been away from my engineering computer for a week.

Big ones, 630 lbs per inch (11.2 kg/mm)

:D cheers :D

  • 3 weeks later...
tridentt150v Grand Master

tridentt150v

Posted
Posted

Front:

14.1 so 14mm thickness without the powdercoat?

Base 100mm

Top 120-125mm couldn't get any more accurate than that [still on car]

7.5 number of coils.

Back:

14.0mm again.

Base 100mm

Top 120-125mm

7.7 number of coils.

Total length 280mm, with a 47mm preload spring included at back and same at front with 37mm preload.

ie main coil is 233mm long.

Tein HA's if that helps.

It rides very firm.

I was looking to put the back on the front and get softer back ones, but that isn't going to work.......damn.

I'd like to consider your Bilstein group buy, are they any softer than the Teins I have? And will the car sit at the same height, the Bilsteins are 350mm long vs 280mm for the Teins. Does this mean car will be higher???

Sydneykid Grand Master

Sydneykid

Posted
  • Author
Posted
Front:

14.1 so 14mm thickness without the powdercoat?

Base 100mm

Top 120-125mm couldn't get any more accurate than that [still on car]

7.5 number of coils.

Back:

14.0mm again.

Base 100mm

Top 120-125mm

7.7 number of coils.

Total length 280mm, with a 47mm preload spring included at back and same at front with 37mm preload.

ie main coil is 233mm long.

Tein HA's if that helps.

It rides very firm.

I was looking to put the back on the front and get softer back ones, but that isn't going to work.......damn.

I'd like to consider your Bilstein group buy, are they any softer than the Teins I have? And will the car sit at the same height, the Bilsteins are 350mm long vs 280mm for the Teins. Does this mean car will be higher???

Sorry for the delay, been very busy, just got home form Oran Park.

The fronts are 430 lbs per inch (7.6 kg /mm)

The rears are 415 lbs per inch (7.4 kg /mm)

I have no doubt it would ride very firm, that is almosy triple the standard spring rates. The Group buy Whiteline springs are 20-25% increase on the standard rates.

The Bilsteins with the Whiteline springs will give heights from 365 mm to 325 mm, centre of wheel to guard, depending on whihc groove you put the circlips in. Compare that with the heights you have now.

:D cheers :nyaanyaa:

  • 2 weeks later...
Sydneykid Grand Master

Sydneykid

Posted
  • Author
Posted
sk, can you please work out these spring rates for me:

12mm dia

130mm internal dia

5.5 turns

cheers

Wow 130 mm ID, that's a big one. What is it out of? A WRX perhaps?

It's a softy, 115 lbs per inch (2 kg/mm)

Cheers

Gary

  • 3 weeks later...
d1a31 Collaborator

d1a31

Posted
Posted

Hey sydneykid im getting new coilovers for my cefiro soon but would like to know what rates i have at the moment, these are the coilovers that it arrived in oz with, measurements are

front

coil OD - 85mm top and bottom

wire OD - 12mm

No of coils - 7.9

rear

coil OD - 85mm top and bottom

wire OD - 11mm

No of coils - 7.25

measurements taken on the car without verniers so may be a bit rough, thanks heaps

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