Street Touring Hatchback (STH) discussion/setup

[xXDavidCXx]

Are you still running the 034 rear swaybar with the 650lb springs or did you also go back to the stock RSB?

Currently on the 034 rear bar on soft. If I go 750, I may go to the OEM rear bar.

This video shows the rear tire lift. Much less than a GS setup.

 

[Mini7]

Ok good. I wanted to check before getting 650 springs for the track. I believe Swift springs are 672 but I’m running 450 square, so the balance will be close to yours.

Where did you run your rear rebound? I’m assuming you haven’t revalved the rear shocks yet.

 

[JackRabbitSLIM]

This video shows the rear tire lift. Much less than a GS setup.

This looks like a lot of tire lift to me. It's not about the height of the tire lift, it's about the duration and frequency. This looks like you were lifting in slalom-ish stuff. You only want to be lifting the tires around the apex of a max lat G turn. If the tire is lifted all the way through the turn it's a problem to work on (in ST_ trim).

If you are having tire lift, adding more rear roll stiffness is not going to do anything except give you more tire lift and start lifting the tire earlier. Once the tire is in the air, the rear cannot transfer anymore weight and all the remaining transfer goes to the outside front. It doesn't matter if you have 400, 600, or 700# springs back there. I have been down that road and spent a lot of money making my car worse.

This is why I've been suggesting that you don't have a rear end problem, you have a front end problem...

I understand you were talking about going up in spring and down in bar, but what is the point? That bar change is going to change your roll stiffness (soften) way more than the spring change. I dare you to put the 650s on the front and the 750s on the rear and leave the rear bar.

 

[theDoktor]

This looks like a lot of tire lift to me. It's not about the height of the tire lift, it's about the duration and frequency. This looks like you were lifting in slalom-ish stuff. You only want to be lifting the tires around the apex of a max lat G turn. If the tire is lifted all the way through the turn it's a problem to work on (in ST_ trim).

If you are having tire lift, adding more rear roll stiffness is not going to do anything except give you more tire lift and start lifting the tire earlier. Once the tire is in the air, the rear cannot transfer anymore weight and all the remaining transfer goes to the outside front. It doesn't matter if you have 400, 600, or 700# springs back there. I have been down that road and spent a lot of money making my car worse.

This is why I've been suggesting that you don't have a rear end problem, you have a front end problem...

I understand you were talking about going up in spring and down in bar, but what is the point? That bar change is going to change your roll stiffness (soften) way more than the spring change. I dare you to put the 650s on the front and the 750s on the rear and leave the rear bar.

Conceptualizing what you are saying (& I tend to believe it's accurate) and applying it to a GS application, I'm even more convinced that going back to the OEM rear bar and installing a bigger front bar may be a solution to my rear tire lift problem. (I have a 26mm H&R bar ready to install and a 25.4 034 RSB in the soft position installed.) That's basically what everyone who was nationally-competitive was doing back when the Mk. I Rabbits, Sirocco's & GTI's were at the top of their respective classes, with the GTI being a case in point, being the only one with an OEM rear bar.
Thoughts?

 

[bfury5]

Conceptualizing what you are saying (& I tend to believe it's accurate) and applying it to a GS application, I'm even more convinced that going back to the OEM rear bar and installing a bigger front bar may be a solution to my rear tire lift problem. (I have a 26mm H&R bar ready to install and a 25.4 034 RSB in the soft position installed.) That's basically what everyone who was nationally-competitive was doing back when the Mk. I Rabbits, Sirocco's & GTI's were at the top of their respective classes, with the GTI being a case in point, being the only one with an OEM rear bar.
Thoughts?

Not sure if it plays into it a whole bunch, but a lot of the old FWD platforms were torsion beam rear suspensions, whereas most of the stuff today is independent and acts very different dynamically.

However, the Fiesta ST is torsion beam and most of those fast guys today are running with a stiff rear bar, so my point could be moot.

 

[bfury5]

Finished my setup changes today for my event tomorrow. Had an alignment done to set 1/16" total toe out (was 0 before) in the front, and swapped in new rear brake pads to help move the bias to the rear a bit after changing the front brakes a few weeks ago.

I've got a bunch of things I'm going to try tomorrow between damper, tire pressure, and sway bar settings to see how the front end reacts if the toe change alone doesn't give me the turn-in that I'm looking for.

 

[theDoktor]

Finished my setup changes today for my event tomorrow. Had an alignment done to set 1/16" total toe out (was 0 before) in the front, and swapped in new rear brake pads to help move the bias to the rear a bit after changing the front brakes a few weeks ago.

I've got a bunch of things I'm going to try tomorrow between damper, tire pressure, and sway bar settings to see how the front end reacts if the toe change alone doesn't give me the turn-in that I'm looking for.

Try to get those pads bedded-in first. Hope you have a successful testing day.

 

[theDoktor]

Not sure if it plays into it a whole bunch, but a lot of the old FWD platforms were torsion beam rear suspensions, whereas most of the stuff today is independent and acts very different dynamically.

However, the Fiesta ST is torsion beam and most of those fast guys today are running with a stiff rear bar, so my point could be moot.

Any observations on rear wheel lift for the Fiesta ST fast guys?

 

[JackRabbitSLIM]

Conceptualizing what you are saying (& I tend to believe it's accurate) and applying it to a GS application, I'm even more convinced that going back to the OEM rear bar and installing a bigger front bar may be a solution to my rear tire lift problem. (I have a 26mm H&R bar ready to install and a 25.4 034 RSB in the soft position installed.) That's basically what everyone who was nationally-competitive was doing back when the Mk. I Rabbits, Sirocco's & GTI's were at the top of their respective classes, with the GTI being a case in point, being the only one with an OEM rear bar.
Thoughts?

It's hard to say, I've wondered about a front bar setup in Street too. It would really come down to how the diff reacts to the front swaybar, and if the OE rear bar is enough to get the wheel off the ground. You want the rear inside off the ground, but only to a point. Street is about finding the best trade-off though in GS.

As an anecdote, I have driven a GS Civic with the rear bar disconnected (accident) and the main issue was that the car drove as if it had an open diff (the rear bar helps keep the front planted). The Civics have a helical limited slip which becomes open as the inside tires is unloaded. I think the GTI diff is not a helical type which could mean it doesn't rely on torque from the driveshafts to create lock, so I'm not sure how it would react.

 

[JackRabbitSLIM]

They have lots of wheel lift. I've tried to convince Piehl to try a front bar setup on his HS car just to see what happens. Fiestas have an open diff though...

 

[theDoktor]

It's hard to say, I've wondered about a front bar setup in Street too. It would really come down to how the diff reacts to the front swaybar, and if the OE rear bar is enough to get the wheel off the ground. You want the rear inside off the ground, but only to a point. Street is about finding the best trade-off though in GS.

As an anecdote, I have driven a GS Civic with the rear bar disconnected (accident) and the main issue was that the car drove as if it had an open diff. The Civics have a helical limited slip which becomes open as the inside tires is unloaded. I think the GTI diff is not a helical type which could mean it doesn't rely on torque from the driveshafts to create lock, so I'm not sure how it would react.

Thanks for the good feedback. Looks like I may have to just do it & see what happens. I'm definitely ready to try something different. Having top 3 National class competition locally gives me a good reference point.

 

[JackRabbitSLIM]

Thanks for the good feedback. Looks like I may have to just do it & see what happens. I'm definitely ready to try something different. Having top 3 National class competition locally gives me a good reference point.

I almost co-drove with David at nationals last year. In hindsight, I definitely should have.

 

[theDoktor]

I started autocrossing with his dad in the mid-late 70's. Pre-Covid, we'd frequently socialize together with parents & kids. Mike is no slouch behind the wheel either. Went to my first Nationals with Mike.

 

[bfury5]

Finished morning runs, and I can definitely say that toe out in the front was the right call. The car bites much harder now on initial turn-in, even with just 1/16" total toe out.

 

[pseudorealityx]

That's basically what everyone who was nationally-competitive was doing back when the Mk. I Rabbits, Sirocco's & GTI's were at the top of their respective classes, with the GTI being a case in point, being the only one with an OEM rear bar.
Thoughts?

It's also during a time when you were not allowed to change the rear bar in stock classes. The argument on the front bar was that more front roll stiffness would offset the limited camber available on most cars.