Rebuilding strut/shock dampers to be firmer than spring rates?

[fooddude]

I have a couple questions about rebuilding/revalving dampers to be an overall firmer setup, specifically for track/HPDE/autox.

Let's say I got Tarmac springs (5kg all around) and a set of Bilstein B8s. Now, let's say after 1-3 years of use and wear and tear, that I want to rebuild them with a stiffer firmer setup for track.

Approximately how much firmer can you have it revalved and still work with the 5kg springs? ...maybe emulating something like the firmest setting of let's say a 16way adjustable coilover.

Can it be valved 2-3kg firmer than the Tarmac 5kg springs to emulate something like a firm coilover? I'd like to emulate maybe a 7kg or 8kg from a Tarmac/B8 setup.

I believe this is possible...and I've read people have done/thought of doing similar things with stock springs for stock-class auto cross (since you're not allowed to change springs, but you're allowed to change dampers).

What exactly would you ask the damper rebuilder to do so?

I know rebuilding costs+tarmacs+b8s would cost more than viable and similarly priced coilover options...but that wasn't the question(I just said this cuz I'm sure someone will reply "why not just buy coilovers?")... It'll be a while anyways before the B8s get worn and need rebuilding or me wanting to go firmer. Basically, just asking to know the future capabilities and versatility of a Tarmac/B8 combo.

Thx

[Racecomp Engineering]

I'll have a good post here as soon as I finish this burrito.

- Andy

[gramicci101]

Originally Posted by Racecomp Engineering

I'll have a good post here as soon as I finish this burrito.

- Andy

This man has his priorities in order and he's not afraid to stick to them. I applaud you, sir. Well done.

[Racecomp Engineering]

It was pretty fantastic. Ain't no way I was gonna type a well thought out response with one hand on my space phone and another stuffing my face full of delicious burrito!

Okay. First, remember that springs and dampers are different things that have different jobs. You don't exactly measure a damper's stiffness in just kg. Generally dampers are there to damp the spring, not add additional spring rate.

You can crank up the valving and the car will feel stiffer. Stock class autocrossers do this sometimes...the car reacts very quickly and might feel good in transitions but it has it's drawbacks (beyond just a rougher ride). Too much rebound on a soft spring can cause the car to jack down, meaning it doesn't extend back up quick enough after a bump so the next bump you hit, you're still compressed. And then say hello to your bumpstops. Too much compression can make the car crashy and harsh over bumps, or very jittery.

All that said, there is still a lot you can accomplish with a revalve. The Bilstein Sports are an off the shelf damper designed for an FR-S/BRZ with lowering springs. That's great, but there is a little fine-tuning you can do to match them more precisely and more specifically to the RCE Tarmac springs. It will feel very good off the shelf though. Dialing in the rebound and compression will give you just a little more control. You can also increase the gas pressure even more, which adds a lifting force to the car and can be very helpful.

Think about it in terms of matching the springs rather than adding to them. We want to control the chassis (sprung weight) and the wheel/tire (unsprung weight) with the shock and spring. Your 5k springs will always be 5k. But you can improve what the shocks do with them and it can be a pretty big difference.

The one advantage of the Koni Yellows is the adjustability. It is pretty nice because you dial them in a little bit to your choice of spring, although you are still limited. I still lean towards Bilsteins because I think the base valving is slightly better and the gas pressure is awesome. Both good though. A revalved Bilstein matched to your springs is best IMO.

Who knows, in 3 years we could have our own Bilstein fixed perch strut with our own valving for our springs, so you could just talk to us when that day comes.

- Andy

[gramicci101]

Originally Posted by Racecomp Engineering

It was pretty fantastic. Ain't no way I was gonna type a well thought out response with one hand on my space phone and another stuffing my face full of delicious burrito!

I completely understand. I'm the same way with good Thai curry.

Originally Posted by Racecomp Engineering

Who knows, in 3 years we could have our own Bilstein fixed perch strut with our own valving for our springs, so you could just talk to us when that day comes.

- Andy

Aww...

[Racecomp Engineering]

Originally Posted by gramicci101

I completely understand. I'm the same way with good Thai curry.

Ditto.

Originally Posted by gramicci101

Aww...

It's just one of those things...gotta be patient.

On the plus side, a WRX with our custom revalved Bilsteins and RCE Yellows just passed 100k miles on the set-up and is still going strong! Pretty awesome.

- Andy

[Racecomp Engineering]

One other thing, you don't NEED to revalve the Bilstein sports. They'll work great off the shelf. You just get a little "more" with the revalve.

- Andy

[gramicci101]

Why would he run revalved Bilsteins with yellows instead of Tarmacs?

[Racecomp Engineering]

Originally Posted by gramicci101

Why would he run revalved Bilsteins with yellows instead of Tarmacs?

That's just for the WRX...our Yellows for 3rd gen WRX were specifically designed for our custom Bilsteins and are our firmer spring for that car. Our other springs for that car are softer. Kind of backwards compared to our BRZ line up but it happened that way because we held off making springs for the WRX until our Bilsteins were ready.

- Andy

[gramicci101]

Oh, that makes sense. Thanks.

[fooddude]

Just finished my night jog, read the replies... and now it's time to murder this western bacon cheeseburger.

Nice one with the burrito and thai curry. Sounded delicious and made me more hunger. What kinda burrito? I dig carnitas and al pastor.