My M4 GTS build, GT3HNTR.

[JustAnothaM4]

I assume you need adjustable FLCAs, tie rods, and thrust arm to fit a 10.5 with a 305/35 up front? Offset is +16-20?

[Lienrocs]

Originally Posted by Project M4GTS

I assume you need adjustable FLCAs, tie rods, and thrust arm to fit a 10.5 with a 305/35 up front? Offset is +16-20?

All the control arms are spl but they are the stock length. The wheel is 10.5 et24 with no spacers (? I think. I have to double check, I've rebuilt them three times).

[0039]

Nice build!

I am doing the similar work on my GTS, would you mind sharing the spring length front and rear?

I know it's 900/800 however would really like to lower the GTS more than stock KW 3 ways.

I believe Ohlins TTX says 20mm more than KW 3 ways however I would like too make sure the spring length is supporting that as well, thanks

[Lienrocs]

Originally Posted by 0039

Nice build!

I am doing the similar work on my GTS, would you mind sharing the spring length front and rear?

I know it's 900/800 however would really like to lower the GTS more than stock KW 3 ways.

I believe Ohlins TTX says 20mm more than KW 3 ways however I would like too make sure the spring length is supporting that as well, thanks

I can give you my rates and lengths, I have to double check, but the TTX set up doesn't really work that way, especially in the front.

The height adjustment is done by moving the entire knuckle up and down on the damper body. The collars are only there to adjust preload on the main spring. To adjust the height you need to figure out what wheel/tire package you're going to run and what kind of ride height you need in the front. You also need to factor in the rake you need for your application. Once you figure out all that then you need to look to spring rates. Your spring length is going to be determined by how much bump and droop travel you need, not the ride height you want to run at.

Edit: If you look at the first picture in the thread you can see there's a space between the spacer and the bottom of damper (near the lower collar). That's because I was flying blind and needed to determine ride height and travel requirements before I could get spacers machined to set the ride height.

I added a picture of them off the car. You can see how the front dampers are just a long, non threaded body where it goes into the knuckle.

[Lienrocs]

Also, I've gone back to a divorced set up. I needed to take a little spring rate out of the back and if I'm not in using spring rates that require a c/o in the back I didn't see a benefit to keeping it a C/O. The rear is a 1200lb, 8 inch spring with a helper.

I went to a true C/O in the first place because finding a spring with the necessary length at a high rate was too hard during peak covid.

[Bobaeappa]

Originally Posted by Lienrocs

The GTS KW's work really well on track but are pretty harsh on the street after the Ohlins. The TTX rounds out bumps really well. It soaks up things that you think are going to upset the car which actually did upset the car with the KW's on. It's like the car is driving on carpet. They're just flat out incredible, especially considering the spring rates. The car had better compliance on both street and track compared to stock.

Could I pick your brain and ask what ttx springs your running ? I have recently gotten the ttx and was wondering if you went with the swift springs or just the ones psi provided ? The rears are 2.25 and 2.25 are hard to come by so any information would help thank you.

[Lienrocs]

Originally Posted by Bobaeappa

Could I pick your brain and ask what ttx springs your running ? I have recently gotten the ttx and was wondering if you went with the swift springs or just the ones psi provided ? The rears are 2.25 and 2.25 are hard to come by so any information would help thank you.

I was running 900 front and 1200 rears with helpers all around. The front helper wasn’t actually doing anything, it was always fully compressed so I either needed a shorter spring or eliminate the helper. When I was running a true coilover in the rear I was running 800 pound rears with helpers. I think swift vs eiback isn’t really relevant. They’re both very solid and I imagine if you were to throw a set of springs from either on a dyno theyd be near as makes no difference to one another. My two cents.

Edit, psi sent over some ridiculous spring combo. If I recall correctly it was a 500ish front and 1300 pound rear. I don’t know how they pick their rates but they didn’t work for me.

Second edit, make sure you either set aside a ton of time or a pile of cash to get the ride height set in the front. The collars are only preload adjusters, not ride height adjusters. The ride height with the psi kit is based on the spacers used to set the height in the knuckle.

[Bobaeappa]

Originally Posted by Lienrocs

I was running 900 front and 1200 rears with helpers all around. The front helper wasn’t actually doing anything, it was always fully compressed so I either needed a shorter spring or eliminate the helper. When I was running a true coilover in the rear I was running 800 pound rears with helpers. I think swift vs eiback isn’t really relevant. They’re both very solid and I imagine if you were to throw a set of springs from either on a dyno theyd be near as makes no difference to one another. My two cents.

Edit, psi sent over some ridiculous spring combo. If I recall correctly it was a 500ish front and 1300 pound rear. I don’t know how they pick their rates but they didn’t work for me.

Second edit, make sure you either set aside a ton of time or a pile of cash to get the ride height set in the front. The collars are only preload adjusters, not ride height adjusters. The ride height with the psi kit is based on the spacers used to set the height in the knuckle.

So this is gonna sound real dumb but when you say 900 front and 1200 back does that mean your adding two front spring rates together including helper or assist sping ? So when you say 900 it's 450 lbs each corner is that how your supposed to do the math or just the spring rate alone.

Sorry imma noob when it comes to this kind of coilovers

[Lienrocs]

Originally Posted by Bobaeappa

So this is gonna sound real dumb but when you say 900 front and 800 back does that mean your adding two front spring rates together including helper or assist sping ? So when you say 900 it's 450 lbs each corner is that how your supposed to do the math or just the spring rate alone.

Sorry imma noob when it comes to this kind of coilovers

No worries!
So there are three numbers on your springs you have. One is the length of the spring when it’s uncompressed, one is the diameter of the spring and the third is the length of the spring. Springs go per axle. So I was running 900 pound, 8 inch long springs up front at each corner (one spring per corner) with helper springs for each spring. In the back I was running an 800 pound spring at each corner with helper springs (true coilover). For a divorced set up you typically run a higher rate because the amount of leverage is changed when you move the position of the spring.

[Bobaeappa]

Originally Posted by Lienrocs

Also, I've gone back to a divorced set up. I needed to take a little spring rate out of the back and if I'm not in using spring rates that require a c/o in the back I didn't see a benefit to keeping it a C/O. The rear is a 1200lb, 8 inch spring with a helper.

I went to a true C/O in the first place because finding a spring with the necessary length at a high rate was too hard during peak covid.

Thank you so much to take the time to explain it, I really appreciate it !