Lowering springs and roll center bump steer kits.

[Veteran]

Can those that have lowered their suspension comment on whether it is necessary to i stall a roll center / bump steer kit.
I seldom see mention of above, yet occasionally someone will say how it “fixed” his bad steering / bump steer.
surely all cars will react the same and if so we would all need a bump steer kit.
please advise.

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[Norm Peterson]

Any necessity for correcting bumpsteer would depend on whether you notice it. Which is to some degree an individual thing, though the more you lower the front suspension the more likely it will be that you would notice it.

If you find yourself having to saw the steering wheel back and forth to steer a constant radius through a curve in sync with gentle heaves in the road, that'll be bumpsteer. General skittishness or tramlining on truck tire rutted pavement is not.

Correctly setting bumpsteer correction is a somewhat involved procedure, and I'm not at all convinced that places outside of shops with race car alignment experience are really equipped to do this. Personally, I'd choose less lowering instead of more and then driving it to see if it's a problem. There isn't a whole lot of sense "fixing" something that isn't a problem, and it can always be done as a separate mod if it turns out to be one.


Norm

 

[Veteran]

Any necessity for correcting bumpsteer would depend on whether you notice it. Which is to some degree an individual thing, though the more you lower the front suspension the more likely it will be that you would notice it

If you find yourself having to saw the steering wheel back and forth to steer a constant radius through a curve in sync with gentle heaves in the road, that'll be bumpsteer. General skittishness or tramlining on truck tire rutted pavement is not.

Correctly setting bumpsteer correction is a somewhat involved procedure, and I'm not at all convinced that places outside of shops with race car alignment experience are really equipped to do this. Personally, I'd choose less lowering instead of more and then driving it to see if it's a problem. There isn't a whole lot of sense "fixing" something that isn't a problem, and it can always be done as a separate mod if it turns out to be one.


Norm

Thanks . I think you answered it.
I will be dropping 3/4 inch in front, which is about minimal drop.
wont order that kit for now.
if I feel something odd then I will reconsider.

 

[Roadway 5.0]

My front is lowered 1.2” inches-ish. The roll-center correction / bump steer kit absolutely fixed my sloppy steering. It was all about the height correction—I had no issues with bump steer.

 

[Veteran]

My front is lowered 1.2” inches-ish. The roll-center correction / bump steer kit absolutely fixed my sloppy steering. It was all about the height correction—I had no issues with bump steer.

Hi, could you elaborate how your steering changed ? Less turn in ? Vague when going straight ? I will look fo symptoms on mine when done.
One thing I must add, I am a sucker for ultra sharp steering response. For me it’s a must. My 20 GT PP1 with magnaride is acceptable at best. I would hardly call it sharp. If anything I would like to find a way to sharpen it up. Will start with some toe Adj.

 

[Vicr]

First of all my Mustang is not a daily driver and never will be. I have the money and wanted the car set up for the track. After having the lowering springs, caster/camber plates and Koni yellows (adjustable) installed I drove it for a few months and although there was no very undesirable steering issues there were some issues that high speeds and sharp heavy cornering might be amplified. At that point I brought it in to my speed shop, which does prep and build racing cars, for the bumpsteer kit as well as other chassis mods and then had a full alignment performed which accounted for my weight, driving style, driving use and tire compound. I am extremely happy with steering response and handling.

 

[Veteran]

First of all my Mustang is not a daily driver and never will be. I have the money and wanted the car set up for the track. After having the lowering springs, caster/camber plates and Koni yellows (adjustable) installed I drove it for a few months and although there was no very undesirable steering issues there were some issues that high speeds and sharp heavy cornering might be amplified. At that point I brought it in to my speed shop, which does prep and build racing cars, for the bumpsteer kit as well as other chassis mods and then had a full alignment performed which accounted for my weight, driving style, driving use and tire compound. I am extremely happy with steering response and handling.

Thank you for the thorough explanation.

 

[Norm Peterson]

Notes concerning any roll center correction mod - the more you lower the front suspension the more you're likely to benefit from this mod. But if you do, that pretty much locks you into doing the bumpsteer correction.

The bumpsteer mod is basically 'downstream' of the roll center mod, so for mild amounts of lowering you might still do the bumpsteer mod without that necessitating the roll center mod.


Norm

 

[Roadway 5.0]

Hi, could you elaborate how your steering changed ? Less turn in ? Vague when going straight ? I will look fo symptoms on mine when done.
One thing I must add, I am a sucker for ultra sharp steering response. For me it’s a must. My 20 GT PP1 with magnaride is acceptable at best. I would hardly call it sharp. If anything I would like to find a way to sharpen it up. Will start with some toe Adj.

You’re right on track looking to adjust your alignment; for sure the most cost effective way to dial-in steering preferences.

When I lowered my car, the on-center feel and initial response dwindled. I am hypersensitive to this, as a note. The kit remedied these issues 100%. This, paired with PS4S tires and a precision alignment, have the car responding to millimeter movements in the steering wheel.

Next up, I’m going to try and tune the yaw sensation with my adjustable anti-roll bars and experimenting with springs.

 

[Veteran]

You’re right on track looking to adjust your alignment; for sure the most cost effective way to dial-in steering preferences.

When I lowered my car, the on-center feel and initial response dwindled. I am hypersensitive to this, as a note. The kit remedied these issues 100%. This, paired with PS4S tires and a precision alignment, have the car responding to millimeter movements in the steering wheel.

Next up, I’m going to try and tune the yaw sensation with my adjustable anti-roll bars and experimenting with springs.

Thanks for reply. i See you’re into driving some of the best roads. I have same affliction. Flowing mountain passes being better than a track in many respects.
The Roll center kit , which I did a lot of googling on brings back the steering into spec from manufacturer.
I’m wondering what would be effect of adding a roll center kit when not really needed ?
Will it perhaps sharpen up the steering to Over sensitive levels ?

 

[Roadway 5.0]

Thanks for reply. i See you’re into driving some of the best roads. I have same affliction. Flowing mountain passes being better than a track in many respects.
The Roll center kit , which I did a lot of googling on brings back the steering into spec from manufacturer.
I’m wondering what would be effect of adding a roll center kit when not really needed ?
Will it perhaps sharpen up the steering to Over sensitive levels ?

I can’t speak technically on what would happen if you installed the kit on an OEM car, but I can’t imagine it would be a good thing.

And yes indeed, I love a good road. Twisty and scenic at a reasonable pace keeps my world going. Glad to hear you share the passion.

 

[Norm Peterson]

I’m wondering what would be effect of adding a roll center kit when not really needed ?
Will it perhaps sharpen up the steering to Over sensitive levels ?

Hard to say, as several things are affected. Some static in nature (think midcorner in a sweeper), some dynamic (cornering transients).

Higher geometric roll center (a little less roll with a bigger dose of instantaneous lateral load transfer . . . and a car that takes slightly bigger stiffness changes to effect the same amount of handling balance tuning).

Shorter front view swing arm (more rapid camber gain, probably a good thing).

There's probably other things.


Norm

 

[jt021119]

First of all my Mustang is not a daily driver and never will be. I have the money and wanted the car set up for the track. After having the lowering springs, caster/camber plates and Koni yellows (adjustable) installed I drove it for a few months and although there was no very undesirable steering issues there were some issues that high speeds and sharp heavy cornering might be amplified. At that point I brought it in to my speed shop, which does prep and build racing cars, for the bumpsteer kit as well as other chassis mods and then had a full alignment performed which accounted for my weight, driving style, driving use and tire compound. I am extremely happy with steering response and handling.

Which plates and springs did you pair up with those Konis? Thanks!

 

[Vicr]

It's in my signature but, Eibach Sportlines and Maximum Motorsports plates.

 

[Dave2013M3]

My Ford Racing Y springs only lowered the car just under .875" and I don't notice any bumpsteer. That being said I found the Mustangs front end to be adequate but nothing near the sharpness my E92 M3 had (which this car is legendary for). I don't know if this has anything to do with the EPAS vs. the older hydraulic steering of the E92 as Ford normally does EPAS pretty good. The EPAS on my 2014 FiST was unbelievably good.

On the other hand the way the rear end tracks and grips compared to the E92 is quite a bit better than the BMW with the Ford Racing Track kit.

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