IRS and Front End Rise Question

[motorjock205]

I didn't install that firewall connector when I installed the brace and strut bar...I had no idea where it went or how to install it, but now that I have seen a post on how to install it, I will get it added sometime soon.

Well, went to install the firewall brace this weekend, and I must have thrown the darn thing away since I didn't know where it went, because now I can't find it anywhere! Damn...SMH...So, guess I will be looking for that part on line somewhere so I can install it now...Sometimes I could just kick myself...

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[accel]

OK, I am 61 years old and new to the IRS in the 15-18 Mustangs, but after doing a few updates on the wife's car this past weekend and taking the car out for a test drive, I am wondering how to keep the front end down at high speeds...I got the car up to about 150 MPH and the front end just felt very light and high up in the air...I know the IRS allows these things to squat more in the rear, but at high speed, a light front end kinda makes me nervous...Any help would be appreciated...I know you young guys can steer me straight on this. I will add that we just put new Cooper RS G3 235 18 tires on the car and I also replaced the brake pads...Car has just shy of 30K miles. I wouldn't think that the struts would be worn enough to let the front end go up so much, as they seem tight when I push on the fenders.

Might just be 15-17 cars having not enough down force at that much speed. Which is not a surprise looking at car's profile.

Still, I would not go for 18+ hood as I like 15-17 gt appearance more. And substantial hood in front of you is just part of the experience.

I've only driven the card up to 90mph though and did not have any weird experience with the hood.

I wish koni yellow sport shocks oferred height adjustability for mustang like they do to some other applications. You'd then be able to stay with stock springs and lower your front about an inch versus rear. That would just make it for more down force at high speeds.

Another option I saw people use for autocross- air dams - they block air from going under the car.

 

[Norm Peterson]

I wish koni yellow sport shocks oferred height adjustability for mustang like they do to some other applications.

Shocks and struts don't offer ride height adjustability unless they're coilovers (where the lower spring seat is on a screw thread).

You'd then be able to stay with stock springs and lower your front about an inch versus rear. That would just make it for more down force at high speeds.

Which also means that you're much more likely to hit the bump stops in normal driving. Even if you trimmed the stops slightly, the change in front aero (most likely just reduced front lift rather than actual downforce) on the same old spring rates will push the lowest points of actual suspension travel down further than what you're getting from the amount lowered alone.


Norm

 

[accel]

Shocks and struts don't offer ride height adjustability unless they're coilovers (where the lower spring seat is on a screw thread).

_Some_ koni yellow shocks (which I've actually dealt with in the past) have adjustable perch for a spring. So you can move it up or down. That's besides stiffness adjustability.

And those particular shocks are taking into account bump stop things. On my other car I switched from the setup you mention (with a screw thread) to just konis plus stock springs and couldn't be happier.

What I was saying - I wish such konis were available for our mustang. But they aren't.

 

[BmacIL]

Might just be 15-17 cars having not enough down force at that much speed. Which is not a surprise looking at car's profile.

Still, I would not go for 18+ hood as I like 15-17 gt appearance more. And substantial hood in front of you is just part of the experience.

I've only driven the card up to 90mph though and did not have any weird experience with the hood.

I wish koni yellow sport shocks oferred height adjustability for mustang like they do to some other applications. You'd then be able to stay with stock springs and lower your front about an inch versus rear. That would just make it for more down force at high speeds.

Another option I saw people use for autocross- air dams - they block air from going under the car.

Here you go:
http://www.ground-control-store.com/products/description.php/II=992/CA=2

 

[accel]

Here you go:
http://www.ground-control-store.com/products/description.php/II=992/CA=2

I've dealt with ground controls in the past and after some time preferred to go to height and stiffness adjustable konis plus stock springs.

those coilovers were clunky, setting them up correctly would require corner weighting, shock would've dust/moisture protection missing, etc etc.

 

[BmacIL]

I've dealt with ground controls in the past and after some time preferred to go to height and stiffness adjustable konis plus stock springs.

those coilovers were clunky, setting them up correctly would require corner weighting, shock would've dust/moisture protection missing, etc etc.

I mean getting the car setup correctly period requires corner-weighting. Anyone with non-height/preload adjustable suspension (like me) is 90% there at best, maybe a little more if you're lucky. There are other ways to get corner cross weights equal, though.

 

[accel]

I mean getting the car setup correctly period requires corner-weighting. Anyone with non-height/preload adjustable suspension (like me) is 90% there at best, maybe a little more if you're lucky. There are other ways to get corner cross weights equal, though.

in general - yes. But those konis only had a couple fixed height positions. So you'd only need to decide that rear remains on stock height, but front goes on "low" and that was it. No corner weight necessary.

Motivation was different, but
that's what I actually did at my other car - lower front, but stock rear.

P.S. AND... if you get off the shelf ground controls you'd most likely end up replacing sway bars as they will not match spring rates anymore... so that was another reason to use height/stiffness adjustable konis and remain with overall stock suspension constraints if you liked it, which I did. And I'm ok with PP suspension of mustang as well.

 

[wanted33]

Jock, being our S550 is the my wife's car also, here's how I would fix the problem. I would tell her the front end of her car felt light at 150 miles per hour. She's kick me right in my arse, and take away the keys forever. Boom, problem solved.

 

[accel]

_Some_ koni yellow shocks (which I've actually dealt with in the past) have adjustable perch for a spring. So you can move it up or down. That's besides stiffness adjustability.

Checked koni website and looks like they do not have shock like this anymore at all. Completely discontinued.

The closest thing is Bilstein shock but they only offer these for 4wd vehicles.

https://www.bilstein.com/us/en/product/bilstein-b8-5100-ride-height-adjustable/

 

[99Zeus99]

My 2018 GT PP1 is solid at 140mph at 75-80 deg F. My strut tower brace has been removed to accommodate the Whipple supercharger. Haven't noticed any lateral issues.

 

[motorjock205]

Jock, being our S550 is the my wife's car also, here's how I would fix the problem. I would tell her the front end of her car felt light at 150 miles per hour. She's kick me right in my arse, and take away the keys forever. Boom, problem solved.

Nope, nope, nope!!!

 

[Roadway 5.0]

OK, I am 61 years old and new to the IRS in the 15-18 Mustangs, but after doing a few updates on the wife's car this past weekend and taking the car out for a test drive, I am wondering how to keep the front end down at high speeds...I got the car up to about 150 MPH and the front end just felt very light and high up in the air...I know the IRS allows these things to squat more in the rear, but at high speed, a light front end kinda makes me nervous...Any help would be appreciated...I know you young guys can steer me straight on this.

I cruise on the highways for hours at 120mph, and do the 150mph pulls every so often when I need the thrill (or an RS3 is approaching).

Anyway, here’s what I recommend:

1. The hood is a problem. I installed some weatherstripping to the tops of the headlights and the hood flutter/lift reduced quite a bit.

2. A splitter works! I put mine on for this summer’s driving season and really noticed a difference. The steering was heavier at speed.

3. Adding a bit of toe-in really helps stability. I chose to do 0.1 toe-in on each of the front wheels as opposed to the 0.00 to 0.06 many choose to run.

4. Springs and dampers made the most improvement of all, especially when cornering at these high speeds. Pick your poison; there are many options available to include minimum drop sets.

Btw, stay safe out there. Most public roads are not designed/maintained/inspected for high speed runs. You’ve obviously been successful at driving for 45 years or so, but I’ll launch the PSA anyhow.

 

[motorjock205]

I cruise on the highways for hours at 120mph, and do the 150mph pulls every so often when I need the thrill (or an RS3 is approaching).

Anyway, here’s what I recommend:

1. The hood is a problem. I installed some weatherstripping to the tops of the headlights and the hood flutter/lift reduced quite a bit.

2. A splitter works! I put mine on for this summer’s driving season and really noticed a difference. The steering was heavier at speed.

3. Adding a bit of toe-in really helps stability. I chose to do 0.1 toe-in on each of the front wheels as opposed to the 0.00 to 0.06 many choose to run.

4. Springs and dampers made the most improvement of all, especially when cornering at these high speeds. Pick your poison; there are many options available to include minimum drop sets.

Btw, stay safe out there. Most public roads are not designed/maintained/inspected for high speed runs. You’ve obviously been successful at driving for 45 years or so, but I’ll launch the PSA anyhow.

Can you attach a pic of your splitter that you added? Brand? Where purchased? Thanks!

 

[Roadway 5.0]

Can you attach a pic of your splitter that you added? Brand? Where purchased? Thanks!

It’s the Steeda splitter and I got it directly from them; super easy install btw. I’m pretty sure it only attaches to the Performance Pack factory splitter though; you may want to double check if you don’t have the PP.

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