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Re: What causes front tires to turn outwards during wheelie [Re: TheOtherDodge] #1689642
10/24/14 08:01 PM
10/24/14 08:01 PM
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Sweden
Mopar Guy Offline
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I have done alot of work on race track cars and bump steering on those cars and beleve me when i say you dont whant to mess whit that if you dont know what your doing becas it can end up realy bad if you dont know what your doing to the front geometry !

Re: What causes front tires to turn outwards during wheelie [Re: Guitar Jones] #1689643
10/25/14 09:47 AM
10/25/14 09:47 AM
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Man,I am old school,forgot that the new trucks are rack and pinion.SORRY

Re: What causes front tires to turn outwards during wheelie [Re: 540DUSTER] #1689644
10/25/14 01:21 PM
10/25/14 01:21 PM
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TheOtherDodge Offline OP
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Guitar Jones: Yes, it is toeing out. But to be 100% sure what is going on, I will have to go out and study exactly what is going on.

Re: What causes front tires to turn outwards during wheelie [Re: TheOtherDodge] #1689645
10/25/14 02:22 PM
10/25/14 02:22 PM
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dvw Offline
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Simple explanation. Go to the tech archives here, click on suspension, read bulletin 15. Doesn't matter if it's R&P or conventional steering, geometry needs to be correct. On R&P the inner socket joint can be considered the inner tie rod end. The wobble shown on Tig's car is not caused by bump steer. Many different theory's. Mine is the front track is narrower with the suspension in jounce. When the car comes down there is pressure trying to push the tires outward to reestablish normal track width. This pressure causes the wobble phenomenon. Not just Mopars, it happens on a lot of cars. Mines done it when the compression on the shocks was set very loose, tightening it seemed to correct the issue. For what it's worth mine has had the toe pattern corrected to zero through it's entire travel.
Doug

Re: What causes front tires to turn outwards during wheelie [Re: Guitar Jones] #1689646
10/25/14 02:34 PM
10/25/14 02:34 PM
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Milwaukee WI
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Quote:

Quote:

Thanks Guys! let me rephrase...I knew it was bump steer, but I wasn't 100% sure what caused it. I see now from the replies.

Do you think going to a drop spindle would put the geometry of the suspension in better shape and eliminate or drastically reduce bump steer?




No, the issue is the difference in pivot points of the control arms and inner tie rods. Drop spindles aren't going to change that.




Actually drop spindles will most likely fix it.
The problem with lowering with the springs, is the control arms are not in their factory designed working area. Because the upper control arm is normally positioned with the upper pivots much higher than the upper ball joint, the control arm is normally angled down. The way you've lowered the truck, the control arm is sitting more level than it should be. This makes the upper arm effectively longer. I'm sure to have it aligned, they needed a lot more shims than normal. So, if the arm is in a position where at normal(modified) ride height, it is in it's widest part of the travel arc. That means any travel in the suspension will pull in the upper part of the spindle, and make it toe out.
This is all just a guess though. I haven't looked under a Dakota for years, just my best "off the cuff" guess.
Put the geometry back to stock, and get the stance with drop spindles.


"use it 'till it breaks, replace as needed"
Re: What causes front tires to turn outwards during wheelie [Re: TRENDZ] #1689647
10/26/14 08:16 AM
10/26/14 08:16 AM
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north of coder
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if the suspension is in perfect alignment geometry wise, and the bump steer is zero or close to zero, it appears to me it would almost have to be flex some where. tierod ends or sleves, or ???

Re: What causes front tires to turn outwards during wheelie [Re: moparx] #1689648
10/26/14 12:21 PM
10/26/14 12:21 PM
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Eighty Four, PA
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Usually it has nothing to do with bump steer.When the suspension is unloaded under acceleration the movement of the suspension in relation to the fixed point of the steering componants can effect the position of the wheels.Look to the Ackermen geometry of your suspension/steering relationship for your issue.

Re: What causes front tires to turn outwards during wheelie [Re: B G Racing] #1689649
10/26/14 06:22 PM
10/26/14 06:22 PM
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Cincinnati OH
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Re: What causes front tires to turn outwards during wheelie [Re: B G Racing] #1689650
10/26/14 07:06 PM
10/26/14 07:06 PM
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Quote:

Usually it has nothing to do with bump steer.When the suspension is unloaded under acceleration the movement of the suspension in relation to the fixed point of the steering componants can effect the position of the wheels.Look to the Ackermen geometry of your suspension/steering relationship for your issue.





Ackermann has little-to-nothing to do with the tires steering in heave or roll suspension movement. It is completely dependent on steering input and the knuckles turning relative to one-another.



If toe is changing during heave suspension cycling/unloading, it's bump steer.

If camber is changing, it is the built-in camber change in heave of the suspension.

It wouldn't be unlikely for it to be a combination of the two with given steering/suspension tolerances of these cars.

Re: What causes front tires to turn outwards during wheelie [Re: GoodysGotaCuda] #1689651
10/27/14 03:59 AM
10/27/14 03:59 AM
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" fixed Point of the steering componants". Maybe flexing steering box mounts, idle arm flexing or worn, rubber bushings on the strut rod (after seeing wheel stands the shimmy i see on landing is probably attributed to those too). Anycar with that many componants will have alot of slop when added up. IMO

Re: What causes front tires to turn outwards during wheelie [Re: GoodysGotaCuda] #1689652
10/27/14 08:33 AM
10/27/14 08:33 AM
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Eighty Four, PA
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Quote:

Quote:

Usually it has nothing to do with bump steer.When the suspension is unloaded under acceleration the movement of the suspension in relation to the fixed point of the steering componants can effect the position of the wheels.Look to the Ackermen geometry of your suspension/steering relationship for your issue.





Ackermann has little-to-nothing to do with the tires steering in heave or roll suspension movement. It is completely dependent on steering input and the knuckles turning relative to one-another.



If toe is changing during heave suspension cycling/unloading, it's bump steer.

If camber is changing, it is the built-in camber change in heave of the suspension.

It wouldn't be unlikely for it to be a combination of the two with given steering/suspension tolerances of these cars.




If the fixed steering componants (pitman arms,idler arms or rack) are too far forward or behind the attaching points at the wheel they will effect outward and inward movement of the tires.Cross travel like up and down travel must opperate in the same or similar plane.

Re: What causes front tires to turn outwards during wheelie [Re: B G Racing] #2999160
12/28/21 01:35 PM
12/28/21 01:35 PM
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Houston, Texas
TheOtherDodge Offline OP
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Just a bump on this to see if there are any "easier" solutions to this after 7 years! grin And to clarify, the concern is the wheels will "toe out" NOT change camber (at least drastically).

Last edited by TheOtherDodge; 12/28/21 01:36 PM.
Re: What causes front tires to turn outwards during wheelie [Re: TheOtherDodge] #2999228
12/28/21 04:48 PM
12/28/21 04:48 PM
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Originally Posted by TheOtherDodge
Just a bump on this to see if there are any "easier" solutions to this after 7 years! grin And to clarify, the concern is the wheels will "toe out" NOT change camber (at least drastically).


We've further improved things from the below video by limiting front end travel, We also found a steering joint which had some play in it. The reality is we are using a system beyond it's designed and expected use, the whole thing is just a compromise.
https://www.youtube.com/watch?v=D4B_QewPIhc


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Re: What causes front tires to turn outwards during wheelie [Re: Tig] #2999734
12/29/21 10:23 PM
12/29/21 10:23 PM
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Most every car that does this has toe change in and out. It’s not bump steer, it’s flex. Think about what’s happening as the front suspension drops during body rise. The control arms pivot down. This causes the front track width to narrow. You can measure it yourself with a tape measure. When the tires return to the ground they scrub as the track width returns to the original dimension. The rubber bushings flex. The idler arm pivot flexes. The steering box mount flexes. When this happens the distance between the outer tie rods changes. Loosen your idler arm pivot and move it up and down. Watch the toe. The more travel the suspension has, the greater the change in track width dimension. This is why limiting travel helps. Also stiffening the compression of the front shock helps. It slows the process of track change. Watch a rack and pinion car. They are far less likely to have this condition as the steering linkage is mounted very close to the chassis. Not cantilevered 7”-8” away from the mounting points. I have two friends with different style Camaro’s. A 69 and a 79. One has linkage in front of the spindle, one behind. Both have resorted to mounting steering stabilizers on the drag link to slow the process.
Doug

Re: What causes front tires to turn outwards during wheelie [Re: dvw] #2999923
12/30/21 01:35 PM
12/30/21 01:35 PM
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Las Vegas
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FWIW steering stabilizers aka "bump steer kits" are not that uncommon in SS racing with stock front ends. We have one on the Vette as we cannot make it happy any other way and we only have 1/8" of toe change through the entire range of movement of the front end. But it is a 100% stock parts front end steering box control arms and all. We have massaged mounting points a bit to aid in the toe issues.


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Re: What causes front tires to turn outwards during wheelie [Re: dvw] #3000134
12/30/21 10:08 PM
12/30/21 10:08 PM
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TheOtherDodge Offline OP
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Originally Posted by dvw
Most every car that does this has toe change in and out. It’s not bump steer, it’s flex. Think about what’s happening as the front suspension drops during body rise. The control arms pivot down. This causes the front track width to narrow. You can measure it yourself with a tape measure. When the tires return to the ground they scrub as the track width returns to the original dimension. The rubber bushings flex. The idler arm pivot flexes. The steering box mount flexes. When this happens the distance between the outer tie rods changes. Loosen your idler arm pivot and move it up and down. Watch the toe. The more travel the suspension has, the greater the change in track width dimension. This is why limiting travel helps. Also stiffening the compression of the front shock helps. It slows the process of track change. Watch a rack and pinion car. They are far less likely to have this condition as the steering linkage is mounted very close to the chassis. Not cantilevered 7”-8” away from the mounting points. I have two friends with different style Camaro’s. A 69 and a 79. One has linkage in front of the spindle, one behind. Both have resorted to mounting steering stabilizers on the drag link to slow the process.
Doug


This is not what is going on with my truck (also has rack and pinion). My concern is the "immediate toe out" situation". Because I don't yank the tires but a few inches, I don't get the wobble. Maybe, that is why I don't experience that? Either way, I was wondering how to correct the "toe out" sensation.

Re: What causes front tires to turn outwards during wheelie [Re: TheOtherDodge] #3000350
12/31/21 04:00 PM
12/31/21 04:00 PM
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https://www.youtube.com/watch?v=bP4gi4jr9oU

This probably wont help but Herb talks about it here. Interesting video none the less.

Re: What causes front tires to turn outwards during wheelie [Re: TheOtherDodge] #3000418
12/31/21 06:57 PM
12/31/21 06:57 PM
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Originally Posted by TheOtherDodge


This is not what is going on with my truck (also has rack and pinion). My concern is the "immediate toe out" situation". Because I don't yank the tires but a few inches, I don't get the wobble. Maybe, that is why I don't experience that? Either way, I was wondering how to correct the "toe out" sensation.

So when the when the truck rises and the wheels drop (rebound) it toes out. When viewed from the front, the measurement between the rack inner socket joint and outer tie rod must be the same as the measurement between the lower control arm pivot and the lower ball joint. The measurement between the rack inner socket joint and the lower control arm pivot must match the measurement between the outer tie rod and lower ball joint. Thus forming a parallelogram. If any one of the 4 points mentioned is in the wrong spot, it will cause toe change throughout the travel range. The rack may be to high/low. The rack width to the inner sockets may be to narrow/wide. The outer tie rod attachment at the steering arm could be to far in/out, up/down.
Doug

Re: What causes front tires to turn outwards during wheelie [Re: dvw] #3000571
01/01/22 10:50 AM
01/01/22 10:50 AM
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[/quote]
So when the when the truck rises and the wheels drop (rebound) it toes out. When viewed from the front, the measurement between the rack inner socket joint and outer tie rod must be the same as the measurement between the lower control arm pivot and the lower ball joint. The measurement between the rack inner socket joint and the lower control arm pivot must match the measurement between the outer tie rod and lower ball joint. Thus forming a parallelogram. If any one of the 4 points mentioned is in the wrong spot, it will cause toe change throughout the travel range. The rack may be to high/low. The rack width to the inner sockets may be to narrow/wide. The outer tie rod attachment at the steering arm could be to far in/out, up/down.
Doug [/quote]

No, when the truck rises, it toes out. As it settles down, it returns to 0 toe. I attached a seq of pics of the truck sitting staged and immediately after the hit. This happens on both sides. When I just jack the front tires up to work on it, it does the same thing.

But I do understand what you are saying.

11.jpg
Last edited by TheOtherDodge; 01/01/22 10:53 AM.
Re: What causes front tires to turn outwards during wheelie [Re: TheOtherDodge] #3000578
01/01/22 11:26 AM
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We are talking the same scenario. Rebound is separation. Eyeball the locations mentioned.with that much toe change the offending spot should be easy to spot. Or post a picture.
Doug

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