Horrible understeer

K4fxd

Well-Known Member
Joined
Apr 2, 2020
Threads
64
Messages
5,802
Reaction score
3,552
Location
NKY
First Name
Dan
Vehicle(s)
2017 gt, 2002 FXDWG, 2008 C6,
OK, now that I have 99% of my suspension mods done, Steeda stop the hop, knuckle bearings, 200/800 springs, good struts and shocks, all the normal upgrades. It plows like a Mack truck, even with 295/35 19 R7's square

I read a lot where people recommend larger front sway bars?? Wouldn't this make it understeer more????

So what should I do to balance the car out. HPDE type events, no competition other than me against me per lap.

Thanks

 

WildHorse

N/A or GO HOME
Joined
Jun 28, 2017
Threads
189
Messages
7,046
Reaction score
4,975
Location
HomeWorld: CLASSIFIED
Website
www.instagram.com
First Name
ⓇⒾⒸⓀⓎ ⓈⓅⒶⓃⒾⓈⒽ
Vehicle(s)
'17 S550
Vehicle Showcase
1
OP
OP
K4fxd

K4fxd

Well-Known Member
Joined
Apr 2, 2020
Threads
64
Messages
5,802
Reaction score
3,552
Location
NKY
First Name
Dan
Vehicle(s)
2017 gt, 2002 FXDWG, 2008 C6,

NightmareMoon

Well-Known Member
Joined
Nov 22, 2015
Threads
38
Messages
4,400
Reaction score
2,936
Location
Austin
Vehicle(s)
2016 Mustang GT PP
Vehicle Showcase
1
OK, now that I have 99% of my suspension mods done, Steeda stop the hop, knuckle bearings, 200/800 springs, good struts and shocks, all the normal upgrades. It plows like a Mack truck, even with 295/35 19 R7's square

I read a lot where people recommend larger front sway bars?? Wouldn't this make it understeer more????

So what should I do to balance the car out. HPDE type events, no competition other than me against me per lap.

Thanks
Larger front swaybars alone will generally make it understter more, yes, but together with rear swaybars you may have enough adjustment to dial it.

Are your shocks adjustable? What camber front/rear? What phase of the corner is it understeering?
 
OP
OP
K4fxd

K4fxd

Well-Known Member
Joined
Apr 2, 2020
Threads
64
Messages
5,802
Reaction score
3,552
Location
NKY
First Name
Dan
Vehicle(s)
2017 gt, 2002 FXDWG, 2008 C6,
Shocks are not adjustable. Bilstein B6's. I have camber plates and last time out used -2.5 front and -2 rear.

Mostly mid corner unless I come in hot then it plows on entry. I can get throttle oversteer.
 


thompsje

Well-Known Member
Joined
Feb 18, 2021
Threads
4
Messages
112
Reaction score
144
Location
MA
First Name
Jeff
Vehicle(s)
2018 Mustang GT Premium
Front x-brace? IMO, anything you do with the front suspension needs a solid platform to work from. The front end is pretty floppy without the extra bracing, especially if it's not a PP car.
 
OP
OP
K4fxd

K4fxd

Well-Known Member
Joined
Apr 2, 2020
Threads
64
Messages
5,802
Reaction score
3,552
Location
NKY
First Name
Dan
Vehicle(s)
2017 gt, 2002 FXDWG, 2008 C6,
Front x-brace? IMO,
Yes all braces are on, like I said in the first post, all parts are installed, Top braces, bottom braces, cowl extension, IRS braces ect.... now need to fine tune. It understeers, I want it to be more balanced.

It has the stock sways but it does have steeda end links.
 
OP
OP
K4fxd

K4fxd

Well-Known Member
Joined
Apr 2, 2020
Threads
64
Messages
5,802
Reaction score
3,552
Location
NKY
First Name
Dan
Vehicle(s)
2017 gt, 2002 FXDWG, 2008 C6,
@WildHorse

Seriously dude if you can't help, your smart ass comments are not welcome.

Yes, I can slow down and it will not understeer, I can also stab the throttle and then it oversteers.

So in your infinite wisdom should I slow down or should I stab the throttle?

I'd rather tighten the front or loosen the rear so the car is balanced.
 

AvalancheSVT

Well-Known Member
Joined
May 20, 2022
Threads
6
Messages
333
Reaction score
306
Location
houston, tx
First Name
Douglas
Vehicle(s)
1997 SVT Cobra
1. what is your front camber set to?
2. what size is your front swaybar?
3. what size is your rear swaybar?
4. do you have adjustable swaybar end links?
5. do you have adjustable coilovers/shocks?

here's the basic idea: body roll is grip if you can stand it. when the front and rear aren't balanced you get wacky stuff like understeer or oversteer.

so like think rock crawlers, why do they need supension movement? to grab stuff.
well when you make things super stiff that front end can be less grabby in relation to the rear and make it feel like it has more understeer.

the issue could be that you've got the rear super dialed and the front just needs to be tweaked a bit.
 
OP
OP
K4fxd

K4fxd

Well-Known Member
Joined
Apr 2, 2020
Threads
64
Messages
5,802
Reaction score
3,552
Location
NKY
First Name
Dan
Vehicle(s)
2017 gt, 2002 FXDWG, 2008 C6,
1, -2.5
2, IDK stock base GT
3, IDK stock base GT
4, Yes
5, No

200/800 springs Steeda min drop
Bilstein B6's
-2.0 rear camber
 

Idaho2018GTPremium

Well-Known Member
Joined
Nov 20, 2018
Threads
19
Messages
1,340
Reaction score
1,078
Location
Idaho
Vehicle(s)
2021 Camaro ZL1 A10
You need more rear anti roll bar if you just have the base GT bars. For comparison, the PP1 package has an upsized rear bar only (I think it's like 1 mm bigger in diameter than a base GT), and the PP2 has a much stiffer rear bar than even the PP1. The PP2 has 12% stiffer front roll bars than a PP1, but 67% stiffer rear roll bars than a PP1.
 

Scootsmcgreggor

Well-Known Member
Joined
Oct 26, 2018
Threads
29
Messages
375
Reaction score
298
Location
CA
Vehicle(s)
2016 Ecoboost turned GT
And just to rule out an impact from aero do you have a wing and no splitter?

Also does it understeer in low speed, medium, and high speed corners? Or just some?

Assuming no aero imbalance your described setup should be pretty neutral, with one exception, your front camber. Hence why driving style is being mentioned. Not that you need to drive slower, but perhaps differently.

Have you tired trail braking? Also tried different turn in aggressiveness? For example this past track day I got rid of persistent mid corner understeer in a particular corner by trail braking and turning in sharper. Shifted weight forward to put more grip where it was lacking and pulled the tire under the car.

Grip is where the weight is. So if you’re under steering you need more front grip or less rear. Weight transfer is easiest to manipulate so ask yourself how can I transfer more weight up front with my driving style.

Camber: R7’s are a LOT of tire for the springs you have. Usually you’d be on coilovers with rates double what you have, and closer to triple up front. 500-600lbs springs with R7’s and minimal aero is not too much. And even with that much spring camber should be in the 3-4* range. So you need stop least that much since you will have considerably more body roll. You must be wearing the outside shoulders of the front tires quite quickly at 2.5* no?
 
Last edited:

Scootsmcgreggor

Well-Known Member
Joined
Oct 26, 2018
Threads
29
Messages
375
Reaction score
298
Location
CA
Vehicle(s)
2016 Ecoboost turned GT
You need more rear anti roll bar if you just have the base GT bars. For comparison, the PP1 package has an upsized rear bar only (I think it's like 1 mm bigger in diameter than a base GT), and the PP2 has a much stiffer rear bar than even the PP1. The PP2 has 12% stiffer front roll bars than a PP1, but 67% stiffer rear roll bars than a PP1.
Not necessarily. A number of fast guys on track have found that once you have the rest of the suspension set up right that the base GT bar is best. When you’re at the limit of the front of the car the pp or gt350 bars make for a loose rear end. My gt350r rear bar felt amazing on the street and when I was slower on track. Once my pace picked up it became very hard to drive. And I’m a former drifter. Went back to GT rear bar and balance was great. Others who are actually fast have confirmed this as well.
 
OP
OP
K4fxd

K4fxd

Well-Known Member
Joined
Apr 2, 2020
Threads
64
Messages
5,802
Reaction score
3,552
Location
NKY
First Name
Dan
Vehicle(s)
2017 gt, 2002 FXDWG, 2008 C6,
I get it "the nut behind the wheel".

I'm a very smooth driver was pro back in the late 1970's to early 80's. I'm sure I could learn tons more but at the edge this car understeers badly. I like a neutral car. At the edge I like all 4 tires sliding. I do know braking or throttle will upset this. I have the understeer with maintenance throttle.

The stiffer rear bar is what I was thinking about doing but everything I read says people increase the front. So I am ????

As far as body roll I think it is fine
 
OP
OP
K4fxd

K4fxd

Well-Known Member
Joined
Apr 2, 2020
Threads
64
Messages
5,802
Reaction score
3,552
Location
NKY
First Name
Dan
Vehicle(s)
2017 gt, 2002 FXDWG, 2008 C6,
Not necessarily. A number of fast guys on track have found that once you have the rest of the suspension set up right that the base GT bar is best.
I wish I paid more attention to the suspension guru's I was and am a motorhead.
 

 
104 - Cervini's Auto Designs - 1
Top