School me on bumpsteer

[BluePonyGT]

First, it's a 2017 GT and it's a non-PP car from the factory (which has caused its own challenges).

Second, in my quest to get this car to handle better in corners I've gotten to this suspension upgrade plan (all Steeda):
* Progressive springs front and rear
* Adjustable pro action shocks and struts
* sway bars front and back
* Adjustable sway bar ends front and back
* Rear: vertical links, adjustable toe links
* Yet more IRS stiffening: bushings and bracket

I have this weekend carved out to start on all of this.

Yes, I'm obviously changing the geometry of the front with the progressive springs and struts. As advertised this is going to drop the front a little over an inch. Yes, I'm going to increase bumpsteer by doing this.

So I've seen bumpsteer come up and did some digging, but I've been hearing that it's a concern for cars that have been lowered a LOT (eg 2+ inches).

With this front combo what am I likely to experience if I leave the steering nuckles as-is (stock)? Am I kidding myself and am already in this territory and should be addressing bumpsteer now? Is the increase in bumpsteer going to be so much that I would be wise to just address this now rather than waiting until later?

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[SteedaTech]

First, it's a 2017 GT and it's a non-PP car from the factory (which has caused its own challenges).

Second, in my quest to get this car to handle better in corners I've gotten to this suspension upgrade plan (all Steeda):
* Progressive springs front and rear
* Adjustable pro action shocks and struts
* sway bars front and back
* Adjustable sway bar ends front and back
* Rear: vertical links, adjustable toe links
* Yet more IRS stiffening: bushings and bracket

I have this weekend carved out to start on all of this.

Yes, I'm obviously changing the geometry of the front with the progressive springs and struts. As advertised this is going to drop the front a little over an inch. Yes, I'm going to increase bumpsteer by doing this.

So I've seen bumpsteer come up and did some digging, but I've been hearing that it's a concern for cars that have been lowered a LOT (eg 2+ inches).

With this front combo what am I likely to experience if I leave the steering nuckles as-is (stock)? Am I kidding myself and am already in this territory and should be addressing bumpsteer now? Is the increase in bumpsteer going to be so much that I would be wise to just address this now rather than waiting until later?

You will be just fine with your build listed above. If you go with the extended ball joint to improve your front roll center later then do the bumpsteer with that upgrade.
Steeda Tech

 

[BluePonyGT]

You will be just fine with your build listed above. If you go with the extended ball joint to improve your front roll center later then do the bumpsteer with that upgrade.
Steeda Tech

Yeah that was my feeling earlier this morning.

Then I had another cup of coffee and started thinking about it again.

Bottom line is I need to see how the car handles after I do this. Most likely I'll jump on it if I don't like the additional bumpsteer, but was REALLY curious if anyone else went through this and either decided to let it be (and why) or go with the upgrade (and why)...

 

[Roadway 5.0]

Yeah that was my feeling earlier this morning.

Then I had another cup of coffee and started thinking about it again.
Bottom line is I need to see how the car handles after I do this. Most likely I'll jump on it if I don't like the additional bumpsteer, but was REALLY curious if anyone else went through this and either decided to let it be (and why) or go with the upgrade (and why)...

I went a year or two lowered on Ultralites (1.1”F drop) with no significant issues, however installing the roll-center correction/bump steer kit about a year ago has been one of the best mods yet. The kit really changed the car’s handling dynamics for the better.

 

[BluePonyGT]

I went a year or two lowered on Ultralites (1.1”F drop) with no significant issues, however installing the roll-center correction/bump steer kit about a year ago has been one of the best mods yet. The kit really changed the car’s handling dynamics for the better.

That's good feedback.

So this is going to boil down to how the steering feels post upgrades, then I'll go from there.

 

[fatbillybob]

You will be just fine with your build listed above. If you go with the extended ball joint to improve your front roll center later then do the bumpsteer with that upgrade.
Steeda Tech

SteedaTech,

Can you comment on our experiences?

First a knowledgeable member ( Bmcil) here reported that when he did the package of steeda bumpsteer tierod ends with the enxtended ball joint arms that the track width was reduced enough to see less static negative camber.

I did not measure to note changes myself but I also think I have Bmcil's same issue. I installed MCS Dampers on Vorschlag plates and was unable to achieve more than -2.5 degrees of camber. Vorschlag says I lost 1/2 degree of negative range. That forced me to use yet a thicker spacer to use the spindle bolt adjusting trick to get back to -3 for my S550 racecar on 315-35-18 tires.

Is this a known issue with your bumpsteer/extended ball joint set-up?

 

[SteedaTech]

Steeda has been providing extended ball joints since the Fox body days. Furthermore, Ford saw great advantage and incorporated them in their purpose built S197 race mustangs. The improvement in front roll center correction out ways the slight track and camber changes. With that being said most people will be running camber plates ,wheel spacers and different offset wheels to make up the difference. If you need more than 2.5 degrees camber simply enlarge the upper strut hole and you get well over 3 degrees of camber.
One last note, Steeda does not recommend camber bolts or modifying the spindle for additional camber if you will be on tracking or road racing your Mustang

Thank you,
Steeda Tech

 

[fatbillybob]

Steeda has been providing extended ball joints since the Fox body days. Furthermore, Ford saw great advantage and incorporated them in their purpose built S197 race mustangs. The improvement in front roll center correction out ways the slight track and camber changes. With that being said most people will be running camber plates ,wheel spacers and different offset wheels to make up the difference. If you need more than 2.5 degrees camber simply enlarge the upper strut hole and you get well over 3 degrees of camber.
One last note, Steeda does not recommend camber bolts or modifying the spindle for additional camber if you will be on tracking or road racing your Mustang

Thank you,
Steeda Tech

I'm new to mustangs and macpherson struts. I think the spacers and wheel offsets only allow one to use wider tires to clear the strut body. It does nothing for the camber unless one is adjusting at the spindle to strut connection (camber bolts, and the spacers/offsets help gain clearance so this spindle angle change can be made) but that change messes with scrub radius so not a desirable way to gain camber.

Enlarging the strut tower hole only allows more camber if the shock hits the side of the hole. People after more camber enlarge these holes to not only prevent the shock from hitting but also so shocks can be adjusted and to read/adjust the camber plate.

I'm at the limit of the vorschlag camber plates when running the Steeda bumpsteer links/extended ball joins. I want to keep the advantages of the Steeda bumpsteer/extended ball joint. Are there other manufactuer's camber plates with more adjustment range?

 

[SteedaTech]

The Steeda camber plates to the best of my knowledge offer the most negative camber on the market.
We can get well over 3 degrees of neg camber on the front when you enlarge the strut opening like you displayed.
Steeda Tech

 

[shogun32]

when you enlarge the strut opening like you displayed.

I wonder why I don't see people just notch the hole instead of cutting out the entire circle. Is it that difficult to cut?

And here I thought 'bump steer' could be solved with tighter seatbelts - your passenger bumped you, you steered.
/joke

I have the roll-correcting arms without BS kit and thought it handled quite well. The BS kit is now installed so we'll see what new feel it imparts.

 

[fatbillybob]

The Steeda camber plates to the best of my knowledge offer the most negative camber on the market.
We can get well over 3 degrees of neg camber on the front when you enlarge the strut opening like you displayed.
Steeda Tech

Thanks! I will look into Steeda Plates.

I wonder why I don't see people just notch the hole instead of cutting out the entire circle. Is it that difficult to cut?

I have the roll-correcting arms without BS kit and thought it handled quite well. The BS kit is now installed so we'll see what new feel it imparts.

My picture shows the jig to cut the circle with a plain hole saw. It is easy. The reason for not slotting it is because racers don't set it and forget it. We might play with camber for a specific track. With a slot we can adjust the camber but have to measure it at the wheel. That is an iterative process. If you cut a circle and your plates have lines on is like the vorschlag plates you can preset and measure at different lines for your setup and know if say I back out 2 lines I'm -1 degree etc. It makes for faster trackside adjustments with a known expected result. I never understood why some plates have no lines? If you have plate with no lines you can scribe them or just use a center punch and match know positions and make dots.

 

[fatbillybob]

Has anyone actually bumpsteered their car? It is a pain to do taking the coils off is a job in itself because the strut has to come off. I should have done it when I installed my MCS coils but was too anxious to install and go drive. I'm partial to stupid simple methods so I don't own a bumpsteer gauge. I use my laser level and a mirror and do it like I did here when trying to see if it was worth bumpsteering the rear of my lowered corvette racecar that had an elegant rear suspension design that was infinately tuneable.

https://www.corvetteforum.com/forums/autocrossing-and-roadracing/4210524-bumpsteer-measured.html

 

[Grintch]

It is good to minimize or eliminate, but I think it is a bit of an overrated worry.

I used to have a Lotus 7 replica with what my race mechanic described as a "scary" amount of bumpsteer. And I was still able to set a lap record for my class at my home track that held up for 5 years. Now the steering feel wasn't great, but it didn't seem to be a big performance degradation.

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