Curing Bumpsteer?
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DarkBuddha
Founding Member
I eventually plan to go with one from Pro-motorsports (https://www.pro-motorsports.com/store/products.asp?id=8). Kinda pricey, but I know those guys know their stuff and I've already got their negative wedge kit.
Hope this helps...
Hope this helps...
BobV
20+ Year Stangneter 
There's really only 2 that I know of - the Pro-Motorsports (mentioned above), and the Baer Trackers. I prefer the Baer setup, because they are adjustable to cure varying degrees of bumpsteer. The pro-motorsports is "one size fits all", and may actually change the curve too much on some cars. TCP used to sell one - it was the Baer kit re-labeled. 
Hack
15 Year Member
I'm curious, why do you have bump steer? Did you replace the steering with a rack and pinion unit? How new/old are your suspension components?
I realize that the suspension geometry is different in different years of Mustangs. Is bump steer a persistent problem with the earlier models?
I just finished replacing my front suspension components on my '70 vert, and there's not the smallest hint of bump steer. I have manual steering. I did a 2" Shelby drop, with wedges/shims to prevent upper ball joint bind. The car is aligned to the recommended Shelby dimensions that I've seen published. I have new front shocks. They're just the stock replacements. Nothing special, milodyne (sp?) bushings.
Sorry for the slight thread hijack, but those darn bump steer correctors just cost so much. I'd hate to see someone buy them unless they were absolutely necessary.
Then again, I'm really cheap.
I had to make my own wedge shims because I couldn't see paying so much for those either.
I realize that the suspension geometry is different in different years of Mustangs. Is bump steer a persistent problem with the earlier models?
I just finished replacing my front suspension components on my '70 vert, and there's not the smallest hint of bump steer. I have manual steering. I did a 2" Shelby drop, with wedges/shims to prevent upper ball joint bind. The car is aligned to the recommended Shelby dimensions that I've seen published. I have new front shocks. They're just the stock replacements. Nothing special, milodyne (sp?) bushings.
Sorry for the slight thread hijack, but those darn bump steer correctors just cost so much. I'd hate to see someone buy them unless they were absolutely necessary.
Then again, I'm really cheap.
I had to make my own wedge shims because I couldn't see paying so much for those either.thanks all.
I don't know if I have bumpsteer yet, because I haven't had everything realigned (other than an "eyeball & tape measure" job by me) since I installed my GAT 1" drop/620# coils (from which I cut 3/4 coil), 4.5 leaf mideye rears, Global West Neg Roll UCAs, Baer 4 wheel discs, front & rear swaybars, and GAT "Make it New" steering rebuild kit.
Even without a true alignment, teh handling difference is unbelievable....although I've only tested it on some twisties near my house to avoid excessive tire wear.
From what I read, modifications like mine are supposed to make bumpsteer more severe, so I wanted to have some ideas in advance in case I have problems after everythign is aligned.
I read somewhere that the ProM bumpsteer kit should only be used with ProM's neg wedge kit. Anyone know about this (to save me a phone call to ProM)? Also, does anyone know how much teh Baer Trackers cost?
I don't know if I have bumpsteer yet, because I haven't had everything realigned (other than an "eyeball & tape measure" job by me) since I installed my GAT 1" drop/620# coils (from which I cut 3/4 coil), 4.5 leaf mideye rears, Global West Neg Roll UCAs, Baer 4 wheel discs, front & rear swaybars, and GAT "Make it New" steering rebuild kit.
Even without a true alignment, teh handling difference is unbelievable....although I've only tested it on some twisties near my house to avoid excessive tire wear.
From what I read, modifications like mine are supposed to make bumpsteer more severe, so I wanted to have some ideas in advance in case I have problems after everythign is aligned.
I read somewhere that the ProM bumpsteer kit should only be used with ProM's neg wedge kit. Anyone know about this (to save me a phone call to ProM)? Also, does anyone know how much teh Baer Trackers cost?
Opentracker
20+ Year Stangneter
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The only kits I see at the track are the Baer kits. We use 'em and they work great. I don't like that Pro Mo deal. I see no reason why a bump steer kit would have anything to do with the angle of the upper ball joint. Someone is trying to sell more parts.
John
John
Hack
15 Year Member
I totally agree with gathering as much info as possible. 
I like to do that too. I looked at your list and it doesn't look to me like you changed spindles? Or was that part of the Baer kit? I'm no expert, but I would think that if the "arms" of the spindles that connect to the tie rod ends change length, I can see where that might introduce bump steer.
Hard to be sure until you get the alignment, unless there's someone here who has done the exact same changes.
I like to do that too. I looked at your list and it doesn't look to me like you changed spindles? Or was that part of the Baer kit? I'm no expert, but I would think that if the "arms" of the spindles that connect to the tie rod ends change length, I can see where that might introduce bump steer.Hard to be sure until you get the alignment, unless there's someone here who has done the exact same changes.
DarkBuddha
Founding Member
Now, not that I'm disagreeing with your statement, but where does Pro-motorsports state that their bump steer kit has "anything to do with the angle of the upper ball joint"? The only thing I found readily was:Opentracker said:
A bold statement for sure, but it doesn't say that the bump steer kit is required or needed because of ball joint angle. I think many folks will recognize that lowering the upper arm can lower the car, which can cause bump steer issues.Pro-Motorsports Engineering said:
Baer is good stuff, and I'm sure their kit would work too. My one thought is that Baer's kit is a generic design, and Pro-motorsports kit was specifically designed for vintage Mustangs.
HistoricMustang
Active Member
I do not use any of the aftermarket suspension stuff for reasons explained a bunch of times and created a lot of arguments.
The performance of my car at the track speaks for itself.
To have fun in the early models you do not need to spend all the big bucks. Put those suspension dollars into other performance items and have fun.
HistoricMustang
www.historicmustang.com
The performance of my car at the track speaks for itself.
To have fun in the early models you do not need to spend all the big bucks. Put those suspension dollars into other performance items and have fun.
HistoricMustang
www.historicmustang.com
HistoricMustang said:
And the Amish still drive horse wagons because they are the high point of transportation evolution?...
Anyway...Historic typically doesn't need the bumpsteer kits because most of the time he's on a smooooth race track..the rest of us who drive mostly on the street would like not to have our steering angle wigging out on us as we drive a little spiritedly around town.
One thing to look out for is not having the center link actually centered, it'll amplify the problem. The idea is to have the tie rod link and lower arm parallel with close to the same arc lengths and pivot points. If you lower the car much, typcially the tie rod is pointing up at the spindle end, and it's made worse by the r&p units that move the inner pivots out further, shortening the arc length.
blah, blah...all that to say I'd buy the pro-m setup, it's simpler...but probably made more for the stock steering setup w/lowered ride height.
chepsk8
Founding Member
I too have good experience with bump steer issues! When I converted my car to Rack & Pinion, I had severe issues with big bumps, dips, and everyday road irregularities not found on race tracks. I used the BAER-Tracker to get the tie rod geometry to line up correctly, and made street driving fun again!
I did an article in Hemmings Mustang Magazine about a year ago on bump-steer, and the installation of the kit. Lot's of good info!
Most Vintage racers do use the Bump-Steer kit, including a few I know, as the original steering oes induce bump-steer under full suspension travel. It can be clearly seen in many pics of cars cornering.
Historic, I am envious of your table-top smooth surfaces!
I did an article in Hemmings Mustang Magazine about a year ago on bump-steer, and the installation of the kit. Lot's of good info!
Most Vintage racers do use the Bump-Steer kit, including a few I know, as the original steering oes induce bump-steer under full suspension travel. It can be clearly seen in many pics of cars cornering.
Historic, I am envious of your table-top smooth surfaces!
First thiing, find out if you have a bump-steer problem. Set your car up on level spot and measure the amount of toe change you experience as your suspension travels up and down. Removing your springs and setting up some kind of measuring device would be nessasary. The Pro-motorsports bump kit is one size fits all, the baer trackers need to be dialed in to get rid of the bumpsteer. You will need to add or remove spacers tell you get the least amount of bumpsteer. Here is a pic of my setup for reference
Make sure all your suspension parts are in good condition, worn out bushing especially strut rod bushings can look like a bumsteer issue..
Make sure all your suspension parts are in good condition, worn out bushing especially strut rod bushings can look like a bumsteer issue..
Opentracker
20+ Year Stangneter
- Feb 4, 2004
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The question was:
Just giving my opinion on the question.
My wifes car with a bump steer kit, lower arm with a spherical bearing inside pivot and a screw in ball joint, full length brace and the Pro-Mo vario camber kit,Street or Track strutts, roller idle arm and brake coolers. Damn I need to get to work on my car.
John
DarkBuddha
Founding Member
Got it!Opentracker said:
A questions for anyone with experience with the Baer kit... Pro-m claims quickened steering, does the Baer kit do the same thing? If it's cheaper (and it was the last time I checked), and it'll do the same thing, it sounds like a good choice to me.
BTW, Opentracker, your work is badass! I'm totally impressed with the thoughtfulness and budget oriented nature of your mods. Really excellent.
Hack
15 Year Member
Yes, just bolting some non-adjustable parts on can't eliminate bump steer for every set up. If you end up with bump steer that you want to fix, go with something adjustable. Also, it seems to me that the aftermarket R&P units are the common culprit. I've lowered my car quite a bit, and I'm sure my original front springs are sagging, and I don't have any bump steer that I've noticed. I think that's probably why Historic doesn't have a problem, more so than smooth tracks. Historic hasn't put a R&P unit on his car. Tracks aren't all that smooth.Billgear said:
I would probably look for a shop that has all the gear to precisely adjust bump steer out, rather than buying it. Unless you are going to have several different project cars/suspension set ups.
BobV
20+ Year Stangneter
Agree 100% with Billgear's comment about "find out if you need a kit first".
The way you find out is to measure and chart toe at 1" height intervals... Anyone who says their car doesn't have bumpsteer has probably never measured theirs. It's not at all uncommon to find 3/8" or more of toe change with stock parts! A lowered car or car with a spindle change WILL have even more.
Yes, upgraded suspension parts aren't "required" to "have fun". But neither are 4-barrel carbs, headers, or any other "upgraded" parts.
BTW, the "other" way to adjust out bumpsteer is heating/rebending the steering arms. It's "no cost", but very expensive if done incorrectly.
The way you find out is to measure and chart toe at 1" height intervals... Anyone who says their car doesn't have bumpsteer has probably never measured theirs. It's not at all uncommon to find 3/8" or more of toe change with stock parts! A lowered car or car with a spindle change WILL have even more.
Yes, upgraded suspension parts aren't "required" to "have fun". But neither are 4-barrel carbs, headers, or any other "upgraded" parts.
BTW, the "other" way to adjust out bumpsteer is heating/rebending the steering arms. It's "no cost", but very expensive if done incorrectly.
thanks for all the excellent points, everyone!
FYI: I don't know if I have bumpsteer yet, but because I've done a lot of suspension work, I want to know what my options are IN ADVANCE in case I end up having a bumpsteer problem after everything is aligned.
And BTW, in my original post, I said that I'd heard somewhere that the ProM bumpsteer kit can only be used with their neg wedge kit....
Coincidentally, I just got my ProM Eccentric Eliminators, and right there in the box was a Dr. Gas/ProM catalog advertising their parts, and it also says that their bumpsteer kit should only be used with their neg wedge kit. ????
FYI: I don't know if I have bumpsteer yet, but because I've done a lot of suspension work, I want to know what my options are IN ADVANCE in case I end up having a bumpsteer problem after everything is aligned.
And BTW, in my original post, I said that I'd heard somewhere that the ProM bumpsteer kit can only be used with their neg wedge kit....
Coincidentally, I just got my ProM Eccentric Eliminators, and right there in the box was a Dr. Gas/ProM catalog advertising their parts, and it also says that their bumpsteer kit should only be used with their neg wedge kit. ????
bump steer
There are some other issues that can imitate true bump steer: drum brake fade, incorrect caster, incorrect toe-in, worn parts, tires.
Here is another point, starting on the (1967 I think) models, Ford began making the camber adjustable at the LCA inner mounting point using a larger hole in the frame with an adjustable, eccentric bolt inside a channel bracket. So when we all do our UCA drops and other mods, we go and get an alignment and nine times out of ten this LCA eccentric bolt has to be turned, changing LCA mounting points either inboard (decreasing camber) or outboard (increasing camber). And a lot of times they aren't adjusted equally on both sides of the car either (lazy alignment guy).
Now.... the center link on our cars has two stamped and drilled, non-adjustable holes for the inner tie rod mounting points. This means that the measurement between the inner tie rod pivot points has stayed the same, but the measurement between the LCA pivot pints has changed and guess what happens? BUMP STEER. Adjusting the tie rods at their threaded sleeve does nothing except change toe-in. To minimze the affects of bump steer (ackerman angle), the inner tie rod mounting point measuremet (center link)has to be kept as close as possible to the LCA mounting points measurement. And it also helps to have the lower arms level with the center link and parallel to the road, at ride height.
What they did with the Trans Am bosses was they removed the stock eccentric bolt set-up, welded the appropriate size washers in the LCA mounting holes and in doing this they equalized the distances for the LCA points and center link points. I am not sure how they adjusted for camber, probably by using shims at the UCA shock tower bolts.
There are some other issues that can imitate true bump steer: drum brake fade, incorrect caster, incorrect toe-in, worn parts, tires.
Here is another point, starting on the (1967 I think) models, Ford began making the camber adjustable at the LCA inner mounting point using a larger hole in the frame with an adjustable, eccentric bolt inside a channel bracket. So when we all do our UCA drops and other mods, we go and get an alignment and nine times out of ten this LCA eccentric bolt has to be turned, changing LCA mounting points either inboard (decreasing camber) or outboard (increasing camber). And a lot of times they aren't adjusted equally on both sides of the car either (lazy alignment guy).
Now.... the center link on our cars has two stamped and drilled, non-adjustable holes for the inner tie rod mounting points. This means that the measurement between the inner tie rod pivot points has stayed the same, but the measurement between the LCA pivot pints has changed and guess what happens? BUMP STEER. Adjusting the tie rods at their threaded sleeve does nothing except change toe-in. To minimze the affects of bump steer (ackerman angle), the inner tie rod mounting point measuremet (center link)has to be kept as close as possible to the LCA mounting points measurement. And it also helps to have the lower arms level with the center link and parallel to the road, at ride height.
What they did with the Trans Am bosses was they removed the stock eccentric bolt set-up, welded the appropriate size washers in the LCA mounting holes and in doing this they equalized the distances for the LCA points and center link points. I am not sure how they adjusted for camber, probably by using shims at the UCA shock tower bolts.
thanks, Streetmod.
I'm going to install LCA Eccentric Eliminators before I have it aligned, so hopefully that will force my camber adjustments to be precise. I actually wasn't going to do the eliminators yet because I didn't really understand what they did, or whether or not I'd need them, but after adjusting my LCAs about 20 times and seeing how much slop is in the eccentrics, I was able to see the obvious benefit of eliminating them.
Right now my LCAs are almost parallel to the ground.
I'm going to install LCA Eccentric Eliminators before I have it aligned, so hopefully that will force my camber adjustments to be precise. I actually wasn't going to do the eliminators yet because I didn't really understand what they did, or whether or not I'd need them, but after adjusting my LCAs about 20 times and seeing how much slop is in the eccentrics, I was able to see the obvious benefit of eliminating them.
Right now my LCAs are almost parallel to the ground.
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