The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

Best known practice to correct front geometry?

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

218
369
Exp. Type
Time Attack
Exp. Level
5-10 Years
CA
I would like to get my front geometry and roll-center in line and make the car comply better with slicks.

I`ve been reading a lot and there is a ton of information. Lots of useful things, some outdated, some contradictory.
The goal is to find the best known/proven practices while keeping it somewhat simple and affordable, if possible.

Things like Boss a arms, BMR spherical arms and Kenny Brown "Super Grip" A arms, MM K member and bump steer kits come to mind.

Specs:
Splitter, Wing, Pirelli DH take-off slicks.
Vorshlag MCS TT1 coilover
Looking to upgrade springs to ~600/375.
LCA, full spherical rear accpet for dif.
Stock front arms and stock bushings.
 
Last edited:
1st thing, springs and shocks, for me it was the biggest bang for the buck!
I went with Kenny Brown JRZ shocks and springs but I Cortex also does a great job.
 

Grant 302

basic and well known psychic
It seems to me you already have most of the hardware to be able to adjust the front geometry however you want it. Ride height and camber control most of the properties regarding front end geometry.

Arms with tall ball joints and bumpsteer give you a bit more range to work with on the lowered end of things.

What (and why) are you trying to change from the current setup? What are the current front end settings?
 
218
369
Exp. Type
Time Attack
Exp. Level
5-10 Years
CA
@scmscout I took the coilover for granted. I got a set of Vorshlag MCS TT1. I updated my post now.

@Grant 302 Basically I just want to make to most out of what I got. My whole rear is spherical but my whole front is still stock and slicks work better with sphercials. I was looking to upgrade the A-Arms and allow for enough adjustability to correct the roll center as much as possible. The car will also be dropped about 0.5"-1" as it sits really high right now.
I`m running -3.7 front camber and still have a bit to go. I´ll max it out with the next alignment.
 

Grant 302

basic and well known psychic
By raising the connection to the knuckle, it 'allows' you to lower the car 1/2" and keep the geometry essentially the same. Mostly for the roll center properties, IMO.

When you lower the car, the roll center migrates lower much faster. Lowering the car 1/2" would move the roll center down just over 1" and increase the distance between the roll center and CG about 1/2". With the tall ball joint, the roll center would only move 1/2" down with the car and the lever arm to CG doesn't change.

There are other benefits like camber gain properties that are 'retained' with 1/2" lowering and the tall ball joint.

Negative static camber adjustment range increases a bit using the tall ball joint.

That's just scratching the surface of this topic, and I think most people have differing opinions on the matter.

I recommend the Howe units because they are rebuildable and seem more reliable for those who have used them.
 
218
369
Exp. Type
Time Attack
Exp. Level
5-10 Years
CA
By raising the connection to the knuckle, it 'allows' you to lower the car 1/2" and keep the geometry essentially the same. Mostly for the roll center properties, IMO.

When you lower the car, the roll center migrates lower much faster. Lowering the car 1/2" would move the roll center down just over 1" and increase the distance between the roll center and CG about 1/2". With the tall ball joint, the roll center would only move 1/2" down with the car and the lever arm to CG doesn't change.

Awesome, that is exactly the kind of info I am looking for.
Any opinion on bump steer kits?
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
With the tall ball joint / roll center correction, you shouldn't need camber to be set quite as far negative as you would without this correction - and this is with everything else kept the same (springs/lowering, bars/settings, dampers/settings).

Do experiment a bit with the camber settings.


Norm
 

Grant 302

basic and well known psychic
With the tall ball joint / roll center correction, you shouldn't need camber to be set quite as far negative as you would without this correction - and this is with everything else kept the same (springs/lowering, bars/settings, dampers/settings).

Do experiment a bit with the camber settings.


Norm

Agreed on the 'shouldn't need' qualification. Depends on the reference starting point. But on 315 DH slicks, and seeing some of Badger's videos...I think/suspect he might need the additional range. Especially on a short course like Streets.


How was the wear on the front last time out?
 

ArizonaBOSS

Because racecar.
Moderator
8,730
2,734
Arizona, USA

ArizonaBOSS

Because racecar.
Moderator
8,730
2,734
Arizona, USA
FWIW I will be converting to the CorteX SLA over the summer--so if people are lazy and in the market for used parts (control arms w/ welded collars, howe ball joints, strano front bar, JRi DA front struts w/ camber plates & slugs, etc), that stuff will be available for sale in the next 4-5 weeks from my car.
 
I don't think many go beyond Howe ball joints/bump steer kits because messing with everything up front is a bit of a pain. I probably could have done it cheaper/easier.

I have:
  • stock 2011 LCAs with Howe ball joints and prothane bushings
  • MM K-member
  • steeda bump steer kit
  • m-3200-epas steering rack
Right height is ~13.5" (don't quote me on that) from hub to top of fender FWIW. I'm very very lazy, so I eyeballed the bump steer kit and it feels stable jumping rumble strips and in transitions. Don't think I have a wild toe curve.

Things I could have done easier:
  • Get ready to go front (Boss 302S or similar) LCAs. I wasn't equipped to weld on the balljoint collar and remove stock bushings. Took some buddy visits
  • Get a cheap 2013-2014 steering rack rather than the stupid expensive Ford Racing one to avoid the unhappy 2011 steering rack with stiffer LCA bushings
  • Assemble LCAs and steering rack on the floor. Unbolt the old setup, install the new (good opportunity for headers).

To the point Norm raised, I have camber at a max of 2.5º and I still get more inner tire wear on the front. My guess is it's because I turn like a wuss. I want more camber to fit 335s up front, but that'll likely worsen inner tire wear. Still working on the wuss part.

I'm trying to do what Drew is doing but cheaper (and less cool). I keep asking MM to produce and sell their SLA upper control arms to go with their K member. Their prototype used the stock spindle and LCA, so shouldn't need any changes for brakes. Hopefully a little less static camber, more inboard room for big tires (335s fingers crossed), and a great camber curve.

I don't come close to matching your times at SoW and BWRP 13CW, so all this to say that the setup exists but I'm not going fast on it.
 
218
369
Exp. Type
Time Attack
Exp. Level
5-10 Years
CA
I don't think many go beyond Howe ball joints/bump steer kits because messing with everything up front is a bit of a pain. I probably could have done it cheaper/easier.

I have:
  • stock 2011 LCAs with Howe ball joints and prothane bushings
  • MM K-member
  • steeda bump steer kit
  • m-3200-epas steering rack
Right height is ~13.5" (don't quote me on that) from hub to top of fender FWIW. I'm very very lazy, so I eyeballed the bump steer kit and it feels stable jumping rumble strips and in transitions. Don't think I have a wild toe curve.

Things I could have done easier:
  • Get ready to go front (Boss 302S or similar) LCAs. I wasn't equipped to weld on the balljoint collar and remove stock bushings. Took some buddy visits
  • Get a cheap 2013-2014 steering rack rather than the stupid expensive Ford Racing one to avoid the unhappy 2011 steering rack with stiffer LCA bushings
  • Assemble LCAs and steering rack on the floor. Unbolt the old setup, install the new (good opportunity for headers).

To the point Norm raised, I have camber at a max of 2.5º and I still get more inner tire wear on the front. My guess is it's because I turn like a wuss. I want more camber to fit 335s up front, but that'll likely worsen inner tire wear. Still working on the wuss part.

I'm trying to do what Drew is doing but cheaper (and less cool). I keep asking MM to produce and sell their SLA upper control arms to go with their K member. Their prototype used the stock spindle and LCA, so shouldn't need any changes for brakes. Hopefully a little less static camber, more inboard room for big tires (335s fingers crossed), and a great camber curve.

I don't come close to matching your times at SoW and BWRP 13CW, so all this to say that the setup exists but I'm not going fast on it.

What exactly does the MM K-member do? I know it`s more adjustable, but its also a hefty item to get and a lot of work to get it mounted.

I`m at -3.7 front camber right now and it`s not enough. I guess I can max it out at -4 to -4.5

Yea, the steering rack. I´m still curious how the 13 and the ford racing rack compare. @ArizonaBOSS, do you have any insight on that?
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
I`m at -3.7 front camber right now and it`s not enough. I guess I can max it out at -4 to -4.5
Wider front wheels might soften the need for that much negative camber and keep you from compromising front tire braking any more than necessary. For 315/680's, I'm thinking 11.5", or better yet, 12".

A head-on picture of lateral tire distortion may be showing the outboard shoulders rolling under with min-recommended 11's.


Norm
 

TMO Supporting Vendors

Top