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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Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
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Quote:
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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.
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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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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
5.7L Hemi, 6spd
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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.
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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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Joined: Mar 2006
Posts: 9,910 Eighty Four, PA
B G Racing
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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.
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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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Joined: Feb 2003
Posts: 4,953 Houston, Texas
TheOtherDodge
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Just a bump on this to see if there are any "easier" solutions to this after 7 years! 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.
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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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Joined: Jan 2003
Posts: 2,981 A shed in England
Tig
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Just a bump on this to see if there are any "easier" solutions to this after 7 years! 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
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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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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Joined: Jan 2003
Posts: 19,537 Las Vegas
Al_Alguire
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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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Joined: Feb 2003
Posts: 4,953 Houston, Texas
TheOtherDodge
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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 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.
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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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Joined: Mar 2006
Posts: 9,973 MI, usa
dvw
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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
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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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Posts: 4,953 Houston, Texas
TheOtherDodge
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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.
Last edited by TheOtherDodge; 01/01/22 10:53 AM.
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