Street Touring Hatchback (STH) discussion/setup

[xXDavidCXx]

I would have as well, but only one shop had a set in stock, and it wasn't a shop that did shock servicing.

As a matter of fact, today I ran the rears at full stiff, and could have used more rebound.

Going to set the rear toe to zero before the next event. If I can't get more rear rotation, I may have to increase the rear spring rate.

 

[bfury5]

As a matter of fact, today I ran the rears at full stiff, and could have used more rebound.

Going to set the rear toe to zero before the next event. If I can't get more rear rotation, I may have to increase the rear spring rate.

Toe should definitely help, I know you mentioned it prior but how toe-in are you now? Rear spring would probably have a much greater effect. Does Ohins give any guidance as to what spring increase the valving can handle?

 

[GTIfan99]

As a matter of fact, today I ran the rears at full stiff, and could have used more rebound.

Going to set the rear toe to zero before the next event. If I can't get more rear rotation, I may have to increase the rear spring rate.

I'm not seeing a lot of rotation still. I'm pushing in steady state corners, but get good rotation in transitions. You look tight everywhere.

 

[xXDavidCXx]

Toe should definitely help, I know you mentioned it prior but how toe-in are you now? Rear spring would probably have a much greater effect. Does Ohins give any guidance as to what spring increase the valving can handle?

I think current toe in is 0.1 per side. Ohlin documentation that came with the shocks didn't mention anything about changing rates. I'm sure 25-50 in/lb change would be fine.

 

[xXDavidCXx]

I'm not seeing a lot of rotation still. I'm pushing in steady state corners, but get good rotation in transitions. You look tight everywhere.

My steady state is much better, but I get punished for over-driving, so I've had to be more careful with turn-in speeds to keep from scrubbing the front tires.

 

[Mini7]

I think current toe in is 0.1 per side. Ohlin documentation that came with the shocks didn't mention anything about changing rates. I'm sure 25-50 in/lb change would be fine.

I’m on 8k/450lb springs front and rear without a revalve.

 

[bfury5]

My steady state is much better, but I get punished for over-driving, so I've had to be more careful with turn-in speeds to keep from scrubbing the front tires.

I struggle with this too. The increase in camber I dialed it made me *too* confident in the front end. Been struggling with either too much entry speed, or over-braking and then being slower than desired. Just need to get the front end figured out

I think current toe in is 0.1 per side. Ohlin documentation that came with the shocks didn't mention anything about changing rates. I'm sure 25-50 in/lb change would be fine.

In the rear I'd say 100 lb/in would be the smallest step I'd make. Due to the motion ratio, a 100 lb/in increase would only increase effective wheelrate by ~40lb

 

[Navi]

I’m on 8k/450lb springs front and rear without a revalve.

you wild, boy

 

[xXDavidCXx]

In the rear I'd say 100 lb/in would be the smallest step I'd make. Due to the motion ratio, a 100 lb/in increase would only increase effective wheelrate by ~40lb

Forgot about that, good point.

 

[xXDavidCXx]

I’m on 8k/450lb springs front and rear without a revalve.

On Bilsteins?

 

[Navi]

On Bilsteins?

ohlins mt21 w/ 8k swift springs

 

[greekspec2]

So I actually called these guys specifically about re-valving the B14 kit and they said they wouldn't. Something about those kits Bilstein doesn't want people messing with so they won't sell the parts. At least that's what I was told, circa November 2019.

thats odd they done it in the past there is a shop in North Carolina that is one of the largest Bilstein parts dist they will do it I'm sure

 

[JackRabbitSLIM]

My steady state is much better, but I get punished for over-driving, so I've had to be more careful with turn-in speeds to keep from scrubbing the front tires.

Definitely check your shock travel, you probably need close to 2" considering your corner weights and your spring rates. Hitting the bumpstops is a huge problem and easy to solve. If you are tight at corner entry, you are transferring your weight too quickly to the front, either by shocking the tire when hitting the bumpstop or because your rear inside lifts too early (different subject). Try raising the car a good bit (maybe .75") or cut your bumpstops down to see what happens. The suspension is there for a reason, let it work for you. It has to be allowed to move. Think about your experience in the GS car...

The case and point for all this is that you ran out of rear bar stiffness and rear shock adjustment and still nothing much happened You said the it got a little better, but the car is still tight and the video shows it being tight. So look at your evidence: the car is tight and your bar and shock adjustments don't fix it. Why? Because the front is not happy.

 

[xXDavidCXx]

Definitely check your shock travel, you probably need close to 2" considering your corner weights and your spring rates. Hitting the bumpstops is a huge problem and easy to solve. If you are tight at corner entry, you are transferring your weight too quickly to the front, either by shocking the tire when hitting the bumpstop or because your rear inside lifts too early (different subject). Try raising the car a good bit (maybe .75") or cut your bumpstops down to see what happens. The suspension is there for a reason, let it work for you. It has to be allowed to move. Think about your experience in the GS car...

The case and point for all this is that you ran out of rear bar stiffness and rear shock adjustment and still nothing much happened You said the it got a little better, but the car is still tight and the video shows it being tight. So look at your evidence: the car is tight and your bar and shock adjustments don't fix it. Why? Because the front is not happy.

1. I'm unlikely to raise the car above the OEM ride height, which is what adding 3/4 of an inch in ride height would do, and I'm at the Ohlin recommended ride height. Additionally, I can't raise the ride height without affecting spring pre-load, so that effect needs to be considered.

1.5 Unable to measure shock travel with the inverted nature of the shock, and the tight space in the wheel well to access the shock body, and the dust boot is in the way.

2. I can't cut the front bump stops, they are internal to the insert because of their inverted nature. I'm not going to disassemble the shock for this. Also, if the rear bump-stops are any indication, the fronts may not be that long to begin with.

3. Can you explain what you mean by "tight" at corner entry?

I don't dissagre with the front's not being happy (enough) but two things have made it better. The bar change, and new tires gave more front grip, and less overdriving into the corner is helping. But your analysis is true. Not much to try for rear rotation except to raise the rear spring rate, revalve the rear shocks for more rebound, lower the front spring rate, and/or toe zero or out.

I have 500 in/lb springs on-hand and I have free alignments for life, so those are the most likely COAs for now.

 

[xXDavidCXx]

Also, I'm considering more front camber from a revised Ground Control top mount.

https://hinzmotorsport.com/products/ground-control-camber-plates?variant=31599346581527

Buuuut, my tire temps from this weekend don't support more camber.

At the test and tune, and at the points event, whichever front tire did the most work, i.e. the preponderance of the turns in one direction, the center of that tire was consistently the hottest.

I was running 34 PSI front, and based on shoulder wear, I didn't want to go any lower.

Also, the tire gauge I use, reads 1.5-3 psi lower than the gauge mounted in-line with my air tank.

So, here is another possibility.

Not enough front camber and fears of roll over damage to the outside edge of the tire, caused me to over pressurize (because of a pressure calibration issue) the front tires causing higher center temps resulting in less front grip.