Street Touring Hatchback (STH) discussion/setup

[Mini7]

Motion ratios and effective wheel rate factor into suspension frequency Calculations. Average lap speed plays into suspension frequency selected front to rear to keep suspension movement balanced and synchronized. The faster the average lap speed the higher the frequency required.

What I haven’t figured out, is what the ideal suspension displacement curve should look like for front and rear suspension frequency.
I went with 450lb springs front and rear for a suspension frequency of 1.75hz/1.81hz

 

[Mini7]

Why does no one on here get some fortune auto 510s? They're a really good coilover setup used on a lot of time attack cars and you can do custom spring rates and valve for it. They're ohlins money when you add swift springs but it sounds like you wont have to worry about being stuck with the spring rates these companies force you to use

Ohlins will revalve to accommodate any spring rate. When I go to stiffer springs, I will ask for full soft to equate to 14-15 clicks on the current rebound curve so I have more adjustment for the track.

I really like the Ohlins for a dual purpose car. They do a good job on the street and on the track. I keep forgetting to adjust back to my street setting. It’s only when I hit a rut or some bad tarmac that I realize I’m still running 5-clicks from hard and that I should back the shocks off a bit to soak up the bumps.

 

[xXDavidCXx]

Here are some of the other measurements I took for anyone interested in wheels rates. The swaybar rates are for the stock bars. The dimensions are probably similar on the aftermarket bars.
View attachment 180909

These are some calculation sheets I made for wheel rates, swaybar rate, weight transfer, etc. Use at your own risk.
GTI calculators

I would look at the wheel frequency instead of the wheel rate (you get frequency from wheel rate and a few other factors). For a suspension designed for racing on a 200TW tire, you'll want to be on the upper end of the "street" spectrum which is ~2hz in the front, and slightly higher (~2.2-2.3hz) in the back. From there you can fine tune based on feel. Working with the guy who built my suspension, that's how we decided on the initial spring rates.

Doing napkin math, assuming 100 front and 75 rear un-sprung weight, MR of 0.98F and 0.64R, and using my current corner weights yeilds 400F/550R spring rates to achieve 2.0/2.2 Hz

 

[bfury5]

Why does no one on here get some fortune auto 510s? They're a really good coilover setup used on a lot of time attack cars and you can do custom spring rates and valve for it. They're ohlins money when you add swift springs but it sounds like you wont have to worry about being stuck with the spring rates these companies force you to use

That's still a lot of coin to spend. Looks like you get discrete height adjustability which the Ohlins doesn't have, but the Ohlins also have their DFV tech which makes the coils downright amazing for just street driving. Don't get me wrong, there's certainly a bit of Ohlins tax to pay, but for most people the quality / ride / reputation is worth it. Lots of shops can do re-valves for Ohlins as well, some will even give you a free re-valve within the first year of your purchase. You definitely aren't "stuck", just take a bit more work after-the-fact.

 

[Gvazquez]

I didnt know ohlin let's you revalve like that. I know fortune auto has their version of DFV technology they use and they do come with camber plates stock. Idk just a thought as I'm looking at upgrade options. MCS would be my top pick but I'm upgrading platforms before I spend that kinda money

 

[bfury5]

Doing napkin math, assuming 100 front and 75 rear un-sprung weight, MR of 0.98F and 0.64R, and using my current corner weights yeilds 400F/550R spring rates to achieve 2.0/2.2 Hz

I wouldn't harp on the unsprung weights too much, when I was calculating mine I did a sensitivity study and +/- 25% of whatever weight I used (so say 100lb for front) would only change wheel freq by 0.015hz.

What were you using for corner weights? I definitely made some rough estimates for mine since it's never been on scales.

400 looks right for the front, my numbers agreed with that. For the rear, my math had the spring rate at closer to 650 but I was using .625MR based on my measurements. I ended up even higher in the rear at the advice of some seasoned FWD autocrossers to help with rotation. I'd say put the 500lb springs you have on now and see how it feels

 

[bfury5]

I didnt know ohlin let's you revalve like that. I know fortune auto has their version of DFV technology they use and they do come with camber plates stock. Idk just a thought as I'm looking at upgrade options. MCS would be my top pick but I'm upgrading platforms before I spend that kinda money

Ohlins per-se won't re-valve them for you (they'll sell them as a kit), but most of the shops that sell them will. Camber plates are a must have for this platform for most track driving, it's a shame Ohlins doesn't include them.

MCS are great, but that's even a step up from Ohlins and more than most people need.

 

[JackRabbitSLIM]

Why does no one on here get some fortune auto 510s? They're a really good coilover setup used on a lot of time attack cars and you can do custom spring rates and valve for it. They're ohlins money when you add swift springs but it sounds like you wont have to worry about being stuck with the spring rates these companies force you to use

These do have a lot that looks good on the spec sheet (I especially like the top hat), but anytime a damper boasts "simultaneous rebound and compression adjustment" it is the mark of a cheap damper. Most cheap dampers (Fortune, K-tuned, etc.) have the same internal parts that fail and give inconsistent damping curves.

400 looks right for the front, my numbers agreed with that. For the rear, my math had the spring rate at closer to 650 but I was using .625MR based on my measurements. I ended up even higher in the rear at the advice of some seasoned FWD autocrossers to help with rotation.

I bet you're on the right track, how is your rotation? Especially mid corner with a tiny bit of throttle lift?
I found these (Vorshlag MCS) a while back when I was looking for coilover options with interchangeable type springs, not the fat progressive style that I have on the rear. Notice the spring rates on the competition package (scroll all the way down). If I were doing a clean slate build, I'd probably start in that 600F/900R area. Ride frequencies around 2.5hz.
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In my experience driving ST cars on the road, as long as the suspension has enough travel to not bottom out, the damper has a much more significant impact on the ride than the spring rate. My STX Integra had 1200F/950R (not struts) and the ride was great because I had dampers (Koni 3011) that were valved for all that spring.

 

[bfury5]

These do have a lot that looks good on the spec sheet (I especially like the top hat), but anytime a damper boasts "simultaneous rebound and compression adjustment" it is the mark of a cheap damper. Most cheap dampers (Fortune, K-tuned, etc.) have the same internal parts that fail and give inconsistent damping curves.


I bet you're on the right track, how is your rotation? Especially mid corner with a tiny bit of throttle lift?
I found these (Vorshlag MCS) a while back when I was looking for coilover options with interchangeable type springs, not the fat progressive style that I have on the rear. Notice the spring rates on the competition package (scroll all the way down). If I were doing a clean slate build, I'd probably start in that 600F/900R area. Ride frequencies around 2.5hz.

In my experience driving ST cars on the road, as long as the suspension has enough travel to not bottom out, the damper has a much more significant impact on the ride than the spring rate. My STX Integra had 1200F/950R (not struts) and the ride was great because I had dampers (Koni 3011) that were valved for all that spring.

There's an Audi TT that runs STH around the country, I know he's running the MCS setup. Seems solid, if not extremely pricey.
(I actually just checked, this post from Vorshlag was for that STH Audi)

My rotation has been pretty good so far, great on brakes but could be a little better at lift-off. Part of that is my driving and understanding the setup vs stock, and I'm not quite there yet. My coils have linear hyperco springs so they're interchangeable like the MCS you have listed above.

My dampers appear to be valved very well for the springs I have. On the road, aside from nasty expansion joints or the obvious hole my car rides great. I wouldn't hesitate to add spring front or rear. Next autox I'm planning to check front travel and see if that's an issue. If it is, I'll step up both front and rear. If not, likely just rear.

 

[xXDavidCXx]

I wouldn't harp on the unsprung weights too much, when I was calculating mine I did a sensitivity study and +/- 25% of whatever weight I used (so say 100lb for front) would only change wheel freq by 0.015hz.

What were you using for corner weights? I definitely made some rough estimates for mine since it's never been on scales.

400 looks right for the front, my numbers agreed with that. For the rear, my math had the spring rate at closer to 650 but I was using .625MR based on my measurements. I ended up even higher in the rear at the advice of some seasoned FWD autocrossers to help with rotation. I'd say put the 500lb springs you have on now and see how it feels

1060/1011
660/614

 

[Autobahn]

Ohlins per-se won't re-valve them for you (they'll sell them as a kit), but most of the shops that sell them will. Camber plates are a must have for this platform for most track driving, it's a shame Ohlins doesn't include them.

MCS are great, but that's even a step up from Ohlins and more than most people need.

Still don’t get while Ohlins doesn’t offer a camber plate for a complete package.

 

[Autobahn]

Personal preference - I prefer KW Clubsports, they offer killer camber plates and tuning on their 5 post chassis dyno along with Nurburgring testing for real world application. That seems like a lot value for the cost

 

[xXDavidCXx]

Personal preference - I prefer KW Clubsports, they offer killer camber plates and tuning on their 5 post chassis dyno along with Nurburgring testing for real world application. That seems like a lot value for the cost

I chose the Ohlins over the KW V3 specifically for the DFV feature. Comfort is more important for me, and stability over bumps whilst autocrossing is good too.

 

[bfury5]

Personal preference - I prefer KW Clubsports, they offer killer camber plates and tuning on their 5 post chassis dyno along with Nurburgring testing for real world application. That seems like a lot value for the cost

I toyed with the idea of the clubsports too, but just like the Ohlins the decision was primarily price driven. 3k for the Clubsports is on par with some of the other high end kits, and definitely a good value if that's where people want to play

 

[Autobahn]

I chose the Ohlins over the KW V3 specifically for the DFV feature. Comfort is more important for me, and stability over bumps whilst autocrossing is good too.

Awesome choice no question, I’d say the Clubsports are more in-line with Ohlins compared to v3. Also just to note, Clubsports feature a twin valve technology to keep the wheel planted when experiencing high impact such as hammering over the curbs