ST165 Recommended Spring Rates

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ST165 Recommended Spring Rates

Postby GT4_DRED » Tue Apr 16, 2013 5:58 pm

I'm putting together a custom setup for the 165 using eibach adjustable collar/sleeves and Hypercoil or Carrera springs. I remember reading a post on here waaaay back in the day, where a member (I think it was Robert Pina) did the original GC setup and thought the rates were a bit conservative. With that said I'm trying to get a ballpark on a street/track-day spring rate that might be a good start. I'm currently running Koni adjustables, so I should be able to dial the shock in a bit to match.
What are the you collar/spring guys running?

TIA
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'00 SC300 - "The long way home" daily driver
'88 ST165 - project "Rahtid"
'88 ST165 - Project "Supah Cyat"
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'93 Corrado SLC - "Purple Haze"
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Re: ST165 Recommended Spring Rates

Postby alltrac101 » Tue Apr 16, 2013 7:18 pm

Karl, scale the car 1st, that will get you a better idea on spring rates. I don' remember if the rebound is adjustable on those Koni
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Re: ST165 Recommended Spring Rates

Postby brutekiller787 » Tue Apr 16, 2013 9:52 pm

I like my 8kg/mm ones, but i have yet to scale the car to see if i cant change things up a little.
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Re: ST165 Recommended Spring Rates

Postby MrMcQuacker » Wed Apr 17, 2013 1:47 am

This is actually perfect, I am also going to the eibach springs/Koni or KYB struts. I am to also interested in knowing what rates to put. I know for the most part I will be hauling some weight, due to full car loads every now and then and full gas/ some heavy driving.
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Re: ST165 Recommended Spring Rates

Postby binkie » Wed Apr 17, 2013 3:44 pm

Hey Guys,

Been a while since I have checked in. This is one of my favourite subjects, so I'll help out.

I performed a KYB adjustable shock conversion on my ST165. Used front struts cartridges in all four corners. I got help selecting springs from guys in the local rally club who built their cars about the same time as me. I believe my springs ate 350 lb/in X 12" front, 225 lb/in X 10" rear.

Now, back in the old GT4 Onelist days, David C. posted an email that he got from Bruce Neale at TTE, the post was dated March 1999:

"Our spring and damper specs for ST165GroupA are probably not relevent as we used very progressive springs at that time and the damper rates relate only to the springs we used. I can give you the base spring and damper settings for ST185, which used linear springs. These are relevent to our rally cars weighing around 1200 KG, but would not be suitable for road use, as they would be too hard:

Gravel front: 75Nm spring, 400-220 damper
Gravel rear: 40Nm spring, 260-240 damper

Tarmac front: 80Nm spring, 430-200 damper
Tarmac rear: 75 Nm spring, 280-220 damper."


I believe that the above units are in fact supposed to be N/mm, and the above email has typo. This would put a gravel set at 425lb/in, 225lb/in. This is extremely close to my set up (350/225 from memory). My springs are stiff, even though my car is likely around 3000 lbs (stripped with roll cage). Keep in mind, my springs are already 2-3 times stock rates. If you are building a true stage car with anticipated air time, you would want to kick it up a notch. Dampers play a huge roll in rally, and my KYB shocks would have nothing on what real rally teams use.

There is some leeway here. I changed the fronts from 250 to 350, and did not notice much difference. Unless you are doing severe racing, and have access to lab type testing and datalogging, once you get into these ranges, you will not notice much difference in spring changes. I would budget on changing one set, either front or rear, after the fact to try and fit your driving needs. IE, too much understeer-maybe soften front or stiffen back...too much over steer-maybe soften rear or stiffen front. It is really hard to gauge this without access to legal test area (race track, parking lot, etc).

I noticed Bilstein has started selling dampers ready for customization. You would need to weld on tabs and custom machine the tops. The info is all on line.

I have a pair of used Eibach 12"L, 2.5ID, 250lb/in springs. If someone wants them, make me an offer. I am in Edmonton. I can get them to Vancouver as well.

Good Luck.

Marc
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Re: ST165 Recommended Spring Rates

Postby GT4_DRED » Mon Apr 29, 2013 8:32 pm

alltrac101 wrote:Karl, scale the car 1st, that will get you a better idea on spring rates. I don' remember if the rebound is adjustable on those Koni


Pat, I'll be doing a track day at road atlanta in a few weeks, so hopefully I'll get it corner weighted while I'm there. The Koni are not rebound adjustable, but I'm considering going with a set of MR2 bilsteins on all four corners. Their valving allows for a pretty wide range of rates and they can be re-valved for pretty cheap as well. I've got them on the SC300 with carrera springs and love them! I've moved the battery and I'm in the process of installing swaybars as well, so I'm guessing all of that will affect the choice of rates. BTW, do you still have the FIC, I may be interested in picking it up for the SC.

binkie wrote:Hey Guys,

Been a while since I have checked in. This is one of my favourite subjects, so I'll help out.
I performed a KYB adjustable shock conversion on my ST165. Used front struts cartridges in all four corners. I got help selecting springs from guys in the local rally club who built their cars about the same time as me. I believe my springs ate 350 lb/in X 12" front, 225 lb/in X 10" rear.
Marc


Thanks for the info Marc. 350 lb/in front, 225 lb/in rear seem like a mild street setup? I'm running 500 fr / 250 re on my sc300, granted she's a bit heavy, but she feels similar to a 911t with those rates.
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'00 SC300 - "The long way home" daily driver
'88 ST165 - project "Rahtid"
'88 ST165 - Project "Supah Cyat"
'91 MR2
'93 Corrado SLC - "Purple Haze"
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Re: ST165 Recommended Spring Rates

Postby strangel » Mon May 13, 2013 12:15 am

I have a ST165 Gravel Rally car, which weighs in at about 1200kg.
It runs 340lb/in linear springs in the front, and progressive rears. Rear rates are from 100lb @ 2" to ~210lb @ 6".
Struts are 50mm TRD Bilsteins.
The whole setup is OLD (at least 15 years) but in perfect condition.
To be honest, it rides like a skateboard, but I'm unlikely to get anything better or as reliable for less than $10k.

Cheers,
Leigh
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