Fixing understeer and body roll

[FR500GT]

Always two sides to any coin.

I teach driving, and I sell parts. I see people with way too much crap on their cars trying to band-aid driving errors. On the other hand I see a lot of folks that are driving cars that are just not a whole lot of fun, so they force the issue and that creates bad habits too.

Someone mentioned my sway bars. I think they are the best for a number of reasons. Not the least of which is that both the front and rear are adjustable. I also was pretty picky about the sizing of the bars, and how they mount, and that they work with Fays2/Steeda type Watts links. And, they are both hollow (most rears are solid). I'm also pretty much one of the few folks that actually does handling type things, and I do complete setups... again a big reason BOTH are adjustable.

Whiz-bang fancy rear "links" are not functionally any better. They look cool, and I don't supply fancy aluminum ones, because I'm about function vs. form. BTW, they are only mounts, not links... the rear bar does not use any end-link at all.

As for never gonna beat an MX5. You'd be surprised what a well setup Mustang can do. And not for nothing I notice you have a Shelby GT, which has different swaybars and springs on it "stock" and is a much better balanced car than is a normal say 2007 GT.

My adjustable rear bar is $189.00. If you want fancy-shmancy aluminum "links" you can use them with my bar... But really why would you want a heavier bar that offers you no opportunity to do any tuning with?

Ill be giving you a call tommorow or wednesday Sam

 

[Norm Peterson]

like most Mustangs, has a problem with understeer. Coming from a 3 series BMW, it just doesn't handle the way I want it to. Obviously I realize it's a much heavier car with a solid axle, but I would like to address two things: body roll and understeer.

I currently have Vogtland springs with stock struts, BMR panhard bar, and upgraded front sway bar end links. My plan is to purchase Koni STR.Ts to keep the car stabilized and to cut down on body roll, and to purchase a BMR rear sway bar with billet end links to stiffen up the rear and cut down on the understeer.

Does this sound like a solid plan? My biggest reservation is with the BMR rear sway bar. It's quite pricey at $270 and I want to make sure it'll make a difference.

I doubt that you can completely duplicate the "feel" of an IRS with a stick axle, and you certainly can't by playing with roll stiffness balance alone. There's too much else going on, and it's entirely possible that lowering has increased the total amount of understeer even though you have increased your POTENTIAL lateral-g slightly.

Just the simple fact that both rear tires on the Mustang must toe together as the chassis rolls alone will make it feel different from any car in which the rear wheels can toe independently of one another. Yes, it may well feel a little "numb" to you coming from an IRS car, but that does not necessarily mean "bad" or "disadvantageous".

Predictability, especially with respect to what the end you don't have direct steering control over is up to, is a good thing. Having some little tail end wiggle suddenly grab your attention is not, even when you're 99-44/100% sure that it'll stay stuck down.

I'm curious as to what makes you think that your 2009 or older Mustang has too much "body roll"? I've never noticed that about my '08 even when the suspension was 100% as delivered.

I guess I should have clarified...I'm not a road racer so this is for street driving mostly.

It sounds like transient handling feel may be more what you're trying to fix, and in this case I suggest the Koni yellows (once they become available again). A little more rear bar may help, but too much might be . . . too much if you're still on the 34mm OE front bar. You may want to play with front and rear tire pressures being not all the same (hey, it's free if you've got your own pump and this may be all you need - try 34f/30r if you don't ever carry much back seat or trunk load). Maybe even alignment specs (do you know where they are at now?).


Do you really need any less roll than this ↓↓↓ (Sam's bars, mid front, full firm rear, Koni yellows +1 turn front, +1/2 turn rear. And STOCK springs)? Note the apparent RF tire load and the LR tire distortion. 255/45's on 18 x 9.5" wheels.

Yes, it pushes a little at autocross (the last RWD auto-X for me was a few years ago so I know I need the driver mod). But on the street it's fine, and there even are a few situations where too much enthusiasm in 3rd gear at very modest speeds will loosen the tail more than either necessary or desired.


Norm

 

[ModMe]

I am coming from an '01 Bullitt with hotchkis sways and the factory Tokico's and lowering springs. When I installed the rear sway it felt pretty good. The front bar made it entirey too bouncy. I plan to upgrade my current 07 GT suspension with a strano rear bar. It already has lowering springs on factory struts. I don't want to mess with the front too much from past experience so I will probably just add chassis bracing to see how that works. Any suggestions? I want a really nice ride, but tighten up the chassis at high speeds.

 

[Norm Peterson]

Koni yellows. Too bouncy and wanting to "tighten the chassis up at high speeds" is a shock/strut issue.


Norm

 

[ModMe]

Just bought some Tokico Blues from a guy on this forum. See how they work, then the rear bar if more is desired.

 

[Gray Ghost GT]

..its never gonna be an mx5 or that sorts, so be nice to her, and she'll treat you right on the track

I don't know about that.... Here is a video of my naturally aspirated GT with the "right" suspension upgrades going turn for turn with a Supercharged Lotus Exige in the advanced/solo group on the VIR full course, and I had no problems with the Miata MX5. Mike

 

[Swoope]

nothing more fun that to get a point by from a tuned and driven well miata.

but only if it is during a very twisty section!

beers

 

[Gray Ghost GT]

nothing more fun that to get a point by from a tuned and driven well miata.

but only if it is during a very twisty section!

beers

Absolutely!

 

[pcdrj]

I guess I should have clarified...I'm not a road racer so this is for street driving mostly.

If you're not tracking the car, I would stay away from too much camber. I run between -2/-2.25 but it gets annoying on the back roads in PA. Rutted roads tend to yank your steering around a bit which exaggerates the lack of steering precision in the Mustang.

 

[NickS]

Like mentioned, sways, springs, and adjustable shocks/struts and you'll be more than happy with how it handles. Even with its solid axle.

Agreed. Those vogtland springs or whatever are near as soft as stockers. I'd invest in some FRPP K springs or H&R Race with Koni yellows.