Do I really need a bumpsteer kit? - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 21 Old 03-09-2009, 02:24 PM Thread Starter
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Do I really need a bumpsteer kit?

Hi Guys,

Please help me decide if it's worth the PITA and added alignment time and expense to install a bump steer kit. Below is my combo and this is just a daily driver with frequent canyon runs for fun (1991 GT).

Stock K-member, arms, spindles....
JBA 600# Blue springs (sits low, but was missing the spring isolators which have been added now)
MM center drilled rack bushings
MM steering shaft
ProCi CC Plates (one long supplied spacer (15mm) underneath the plate, two short (10mm x2) spacers on top for the strut shaft - clears hood!)
Bilisteins (std) all around (These struts came with their own bolts, should I use them or stick with the OEM setup?)
Suspension Techniques front and rear swaybars (this might be overkill -any comments?)
The above also includes poly sway bar and end link bushings


Anyways....I have a BAER bumpsteer kit sitting around, but after reading about properly setting it up...I think I want to call it quits now. Will I regret this decision later? I am hoping the favored 90-93 outer tie rod will pick up the "slack" or is that wishful thinking?

Thanks in advance.

-Eric

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post #2 of 21 Old 03-09-2009, 03:01 PM
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Stock K, arms, and spindles? Stock balljoints, no X2s? Skip the bumpsteer kit IMHO.

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post #3 of 21 Old 03-09-2009, 03:27 PM Thread Starter
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Yup stock ball joints. Do you like those X2's? I keep reading conflicting reports about them. As a note, I do have SN-95 arms with uerathane bushings and X2's sitting in a box, but maybe I'll save that for a later date (or just not sign myself up for that kind of NVH harshness).

Thanks,

Eric
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post #4 of 21 Old 03-09-2009, 04:00 PM
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I liked the X2's, they were worth some time for me on course, but if you install them you will need a bumpsteer kit, properly adjusted.
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post #5 of 21 Old 03-10-2009, 02:17 PM
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Its not so much of a question should it be INSTALLED, but more of should it be ADJUSTED.

You can install C/C plates, now do you wish to "adjust" them?
Similar for bumpsteer, you can bolt on any part, its how you tweak it, will make a difference.


Was it worth the several hours to get within .020" on +/- 2" of travel...? YES (for me).

Darius Rudis

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post #6 of 21 Old 03-10-2009, 03:33 PM
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I can't answer for your current situation but I did switch to a bumpsteer kit when I went to the '96+ spindles and modified K-member. I was much happier with driving the car on the street afterwards. It was noticeably less darty.
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post #7 of 21 Old 03-10-2009, 04:59 PM Thread Starter
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I took a look at my used Baer kit, which didn't come with any extra shims other than what was already installed on the tapered stud. According from what I read on the boards is that with my fairly stock setup, I need to get the stud to sit as high as possible through the spindle. Fortunately, my used kit was set up that way...it has the .25 shim on the bottom and the .30 on top, which just covers the non threaded sections of the stud.

It's been an even 50/50 split from people advising on me to go for it or not to waste my time. I could just save these for my SVO which I know has a BS issue due to it's off-set rack bushings.

-Eric
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post #8 of 21 Old 03-10-2009, 05:19 PM
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Shim material could be made out of washers, a chunk of tubing or what have you to get the right stack height. Afterwards, you could get the exact length cut from, for instance, 0.120" or 0.188" wall tubing of the appropriate size so the bolt shank fits inside and you're good to go.

I can tell you how you might approach the problem but don't know if it is a problem in your situation.
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post #9 of 21 Old 03-10-2009, 09:36 PM
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The way my car drove and rode after steed did my bumpsteer kit and adjusted it was night and day. I would do it.

93gt vert 5 lug-cobra brakes steeda/mm susp. 306 tfs tw trk heats steeda 18 cam gt40-3550
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post #10 of 21 Old 03-10-2009, 10:31 PM
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A couple of observations...

Bumpsteer is really, REALLY sensitive to the front end's geometry and more importantly, tolerance stack-up.

The stiffer your suspension bushings, and the less compliance you have (from stiffer sidewalls, shorter sidewalls, stiff springs, sticky tires, etc...) the more affect bumpsteer will have. Severe bumpsteer in a factory setup with rick-hard street tires may not be noticeable at all. Slight bumpsteer in an AIX car with rod ends for bushings and race slicks may be very noticeable.

The factory design puts the null in the bumpsteer curve (the area of suspension travel where bumpsteer is the least,) at static ride height, That way, as the suspension cycles, it's moving through an area of minimal bumpsteer. If you do anything to change the static ride height (like lowering the car,) you will no longer be in that area of minimal bumpsteer.

So, if you're tightening up the suspension, or of you're moving away from factory ride height, you're going to increase the affects of bumpsteer. Will it be enough to be significant? No way really to tell without driving the car, unless you're moving a long, long way from the factory setup.

You've got the kit -- you're not going to hurt anything by installing it and adjusting it properly other than an afternoon of your time.


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post #11 of 21 Old 03-11-2009, 06:51 PM
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Quote:
Originally Posted by gt40mkII View Post
A couple of observations...

Bumpsteer is really, REALLY sensitive to the front end's geometry and more importantly, tolerance stack-up.

The stiffer your suspension bushings, and the less compliance you have (from stiffer sidewalls, shorter sidewalls, stiff springs, sticky tires, etc...) the more affect bumpsteer will have. Severe bumpsteer in a factory setup with rick-hard street tires may not be noticeable at all. Slight bumpsteer in an AIX car with rod ends for bushings and race slicks may be very noticeable.

The factory design puts the null in the bumpsteer curve (the area of suspension travel where bumpsteer is the least,) at static ride height, That way, as the suspension cycles, it's moving through an area of minimal bumpsteer. If you do anything to change the static ride height (like lowering the car,) you will no longer be in that area of minimal bumpsteer.

So, if you're tightening up the suspension, or of you're moving away from factory ride height, you're going to increase the affects of bumpsteer. Will it be enough to be significant? No way really to tell without driving the car, unless you're moving a long, long way from the factory setup.

You've got the kit -- you're not going to hurt anything by installing it and adjusting it properly other than an afternoon of your time.

Steeda bump steered my car and did an excellent job. One observation i have is my car has always ran 245/40/17 street tires, now i just put on a set of hoosier r6 slicks and decieded to try the 225/40/17s up front over the 245's and i notice a huge increase in bumpsteer. I assume it is both the reduced height of the tire and the fact they are slicks. Correct?

93gt vert 5 lug-cobra brakes steeda/mm susp. 306 tfs tw trk heats steeda 18 cam gt40-3550
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post #12 of 21 Old 03-11-2009, 07:29 PM
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What did they get your bumpsteer down to and at how many inches of travel?
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post #13 of 21 Old 03-11-2009, 08:09 PM
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I have the sheet somewhere. Il have to find it. But the car drives better then ever.

93gt vert 5 lug-cobra brakes steeda/mm susp. 306 tfs tw trk heats steeda 18 cam gt40-3550
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post #14 of 21 Old 03-11-2009, 08:15 PM
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Quote:
Originally Posted by foxbody302 View Post
Steeda bump steered my car and did an excellent job. One observation i have is my car has always ran 245/40/17 street tires, now i just put on a set of hoosier r6 slicks and decieded to try the 225/40/17s up front over the 245's and i notice a huge increase in bumpsteer. I assume it is both the reduced height of the tire and the fact they are slicks. Correct?
I think you're confusing bumpsteer with tramlining. Two completely different things, but yes, the shorter, stiffer sidewall will contribute to it.
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post #15 of 21 Old 03-11-2009, 08:16 PM
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Tire and wheel size has no effect on bumpsteer.

You are probably feeling increased camber thrust from the Hoosiers and maybe some steering torque from a higher scrub radius from the different offset wheels.

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post #16 of 21 Old 03-11-2009, 08:34 PM
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Quote:
Originally Posted by MFE View Post
I think you're confusing bumpsteer with tramlining. Two completely different things, but yes, the shorter, stiffer sidewall will contribute to it.
Excuse my ignorance, but I thought they were the same thing. If following the imperfections of the road isn't bumpsteer, what is?
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post #17 of 21 Old 03-11-2009, 09:32 PM
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post #18 of 21 Old 03-11-2009, 10:21 PM
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Quote:
Originally Posted by Jack Hidley View Post
Tire and wheel size has no effect on bumpsteer.

You are probably feeling increased camber thrust from the Hoosiers and maybe some steering torque from a higher scrub radius from the different offset wheels.
Yeah im no expert in that field but the car rides/drives way worse with the slicks on.

93gt vert 5 lug-cobra brakes steeda/mm susp. 306 tfs tw trk heats steeda 18 cam gt40-3550
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post #19 of 21 Old 03-11-2009, 10:41 PM
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Jack covered Bumpsteer, "tramlining" is following ruts in the pavement, as if the car were a train on rails, or as the europeans would say, on a "tram", hence the word. http://www.tirerack.com/tires/tirete...jsp?techid=47&
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post #20 of 21 Old 03-12-2009, 01:45 PM
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My car was downright SCARY after I went 5-lug, the tie rod angle was terrible and the car would jump violently and tramline terribly, the car just wasn't fun to drive.

I bought the bumpsteer kit from MM and installed it with all of the spacers on top of the new tie rod end. I didn't even measure it, because even if I did I don't have enough range of adjustment to get it where it needs to be due to the tapered and not bolt-on kit I used. Just doing this made a HUGE difference, car is so tame on the roads now and predictable.

FWIW, I am planning a MM K-member and reaming out my spindles for the bolt-on bumpsteer kit, so I didn't worry too much about just bolting it on and not adjusting it properly.

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331, AFR 185, FTI cam, 90mm LMAF/30 lb, TFS-R intake, BBK LT's, X-pipe, Spintech mufflers
Suspension:MM: TA, PHB, Rear LCA's, C/C Plates, H&R Race Springs, Bilstein HD's, SFC's, Moser 28 splines, 3.73's, Cobra brakes,10th Anniv. Cobra wheels
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post #21 of 21 Old 03-13-2009, 03:11 AM Thread Starter
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I guess I'll make it easy on myself and just stick with the stock tie rods.

-Eric
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