Chassis Stiffening importance...?

[sredish]

Running a base EB with some tuning and the suspension from a GT350, brakes also upgraded. Car is mostly a daily driver, not a dragger or a track queen although I intend it to be capable enough for occasional track use if desired.

My question is how important is stiffening of the chassis on this car and where specifically? It handles amazing with the suspension on it and I just don't want to put pressure and force on parts of the car that aren't ready for it and cause premature problems but I also don't want to spend money on parts that are unnecessary.

Suspension and tune went on at 2k miles and car has 45k on it now. The thing steers amazing and handles like a missile for sure.

Thanks.

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[Norm Peterson]

More positively locating the rear subframe would be the first thing to address.

If you do the strut tower brace, do it to make the car feel a little more solid, but don't expect the car's performance potential to improve (this chassis won't gain enough overall stiffness from this mod to matter, although your own part in the driving might benefit a little from the more solid feeling).

Don't bother with differential bushings unless you're going to drag race the car.


Norm

 

[Grintch]

Suspension and tune went on at 2k miles and car has 45k on it now. The thing steers amazing and handles like a missile for sure.

If you are happy with the handling, why do you want to mess with it?

From a numbers standpoint, adding braces never seems to make much performance difference. Yes, stiffer is better, but most stock chassis are MUCH stiffer than they were 20 years ago. And there are diminishing returns as you get stiffer. If your not racing the car, running very stiff suspension, and using slicks you probably don't need any additional bracing.

 

[shogun32]

Don't bother with differential bushings unless you're going to drag race the car.

but at least do the replacement bolts, or to be more precise the shims to fix the 2mm overside hole on the rear mounts.

 

[RRRob]

I have a base EB too. I added the strut tower brace and the brace that connects to the firewall.
the rear end felt like it was floating around. I just installed the Stop the Hop Starter kit on Saturday and WOW, so much better. I highly recommend the strut tower braces and the Stop the hop kit to get the chassis firmed up.

 

[shogun32]

If you are happy with the handling, why do you want to mess with it?

because he/you don't know what you don't know until you've tried a properly braced IRS. Same deal with suspension. The PP1 can't be really that bad, can they? If you don't know better (ie tasted actual GOOD suspension) you'd think PP1 was great even though as soon as you try the good stuff you will marvel at how shitty a job Ford did.

The S550 has a hinge in the back, like a Harley Davidson motorcycle. (ok, that's not fair the HD is infinitely worse) Nobody cares how good today's car is compared to 20 years ago. The S550 absolutely needs fixing and it is apparent and much appreciated just driving 2-lane roads at rational speeds.

 

[Norm Peterson]

If you are happy with the handling, why do you want to mess with it?

From a numbers standpoint, adding braces never seems to make much performance difference. Yes, stiffer is better, but most stock chassis are MUCH stiffer than they were 20 years ago. And there are diminishing returns as you get stiffer. If your not racing the car, running very stiff suspension, and using slicks you probably don't need any additional bracing.

Agreed.

The last couple of Mustang generations have been stiff enough that there isn't a whole lot of room for stiffness increases to improve the car's inherent performance limits. We're looking at less than a quarter of a degree of chassis twist at 1g cornering before any supplemental stiffening at all is added, which is little more than noise compared to street-ish suspension and tire flexibility effects. The same could not be said for the Fox (and its SN95 derivative) or the older generations.

Added bracing these days is really about improving composure for the driver and giving him a bit more confidence that the car really isn't a flexi-flyer or structurally a buzzy mess. This is what you're really getting, though it's impossible to objectively determine how much it's worth to any given individual.


Norm

 

[sredish]

well, i am happy with it but wouldn't mind discussing how the changes to the suspension could be adversely affecting other areas of the car or not. I was definitely going to throw on the strut brace and was considering the IRS rear subframe supports from Steeda.

What made me think about this was I was taking a hard sweeping on ramp pretty quick the other day and mid-turn hit an expansion joint where I could hear just the slightest change in wind noise in the passenger door which is very indicative of chassis flex. It was minimal but there's obviously more flex with this tight suspension.

I'll also just add, I'm not trying to irrationally gain some crazy performance increases, just wanting to increase the safety and reduce any unnecessary premature wear of other things.

 

[Vicr]

I have done all the frame stiffening that Steeda has to offer as well as steering and suspension mods as well as a full alignment after all the work was completed and I am very confident in the way the car handles at moderate and high speeds. These mods paired with excellent tires yields a truly pleasurable driving experience.

 

[Norm Peterson]

What made me think about this was I was taking a hard sweeping on ramp pretty quick the other day and mid-turn hit an expansion joint where I could hear just the slightest change in wind noise in the passenger door which is very indicative of chassis flex. It was minimal but there's obviously more flex with this tight suspension.

A strut tower brace isn't likely to change that. It's not improving chassis torsional stiffness locally to where the flex is showing up.


Norm

 

[spaz mk will]

As others have said, the front K braces are a great start. I immediately noticed a more solid feeling front end and less creaking from the dash. Strut tower bar is less noticeable subjectively. See here for the K braces

https://www.mustang6g.com/forums/th...extension-lower-k-brace-install-guide.100800/

I will also advocate for some reinforcement in the rear. There are multiple options. I am pleased with the BMR CB005. In either case, these types of braces do provide more confidence in the chassis under throttle during a turn/corner exit. You feel the car rotate directly and naturally, with less slop/movement in the rear. That added to my confidence in what the car was doing.

 

[Superspirit]

I'm running a stock gt. I've added steedas strut tower brace, g trac brace and the stop the hop starter kit. And it has definitely made a huge difference in the handling and flex.

 

[spaz mk will]

Depends on which one you do first. I did strut tower 1st, then k-member. I didn't feel the k-member in front ss much as I did the strut tower. It did let me know the back end needed to be locked down more.

Ha, I agree on the order mattering. I did the K braces first and it made me doubt the strut bar was worth the cost. Seems that either one in isolation does “enough” but together is the obvious “best” and why Ford uses them to begin with. That does make me feel a little better about the money spent adding the brace

 

[BimmerDriver]

If you are happy with the handling, why do you want to mess with it?

My thinking exactly.

You know, my car gains 5 horsepower every time I wash it, and I get more torque after an oil change.

A lot of the improvements realized after a modification are simply because you modified the car. It's not always better. Or maybe the car handles better after then new springs were installed because it then got a proper alignment. But most of it is the placebo effect. Yeah, I said it.

I"ve noticed that us Mustang owners are just crazy mod-happy. Even more so than BMW drivers. Not because the BMW is better, I wouldn't dare to presume that, although it's likely that Mustang owners have more money left over after purchase. There certainly are more options available for the S550 than say the F80 M3. Make of that what you will.

Yes, Ford cuts a lot of corners for cost, and engineers will often sacrifice performance for fuel economy or crash performance or (again) cost savings. But those guys know what they are doing. They've been refining this platform for over 55 years. It's pretty good.

Unless you are some kind of hard-core track fiend, the base car out of the box is really quite adequate for street driving. The GT and especially PP1 handle very well, but nearly every time you improve handling, you sacrifice comfort or ride. And sometimes you can improve raw lateral G numbers and reduce actual real world performance where you're not on a smooth race track.

Food for thought.

 

[shogun32]

They've been refining this platform for over 55 years. It's pretty good.

it took these "great engineers" 50 years to get a car that wasn't a total embarrassment, you mean.

The GT and especially PP1 handle very well

HA! I have basically no history in "sporty" cars save a Mazda Protege5 from years back. Within weeks of getting my PP1 I could readily identify handling problems and warts. I drove PP1 (and EB/PP) with Magneride and a GT350 also and they all were in need of fixing. Maybe it's my motorcycle background - cars just suck at performance and handling so it's more obvious to me than a person who only knows cars.

My '19 GTI Rabbit handled way better than the Mustang. No of course it didn't have the outright thrust or maybe even cornering traction on a skidpad but I could fling it confidently into apexes and drive it hard without a twinge of concern.

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