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#1
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Bump Steer GM A-body
Working on trying to minimize my bump steer with mostly stock suspension components. I have about 0.240" of toe change in the full suspension travel on each side. Toes out on compression and toes in on extension. It appears I have to raise the outer tie rod end based on my measurements. All bump steer kits I can find seem to lower the tie rod, not raise it. Is the only solution to drill the steering arm out and use a bolt and locate a rod end/heim joint on the top of the steering arm rather than the bottom? I tried the Global west steering arms which lowers the tie rod about 5/8". They made my bump steer worse with about 0.5" of toe change.
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#2
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How much higher than stock do you need to raise the outer tie rod end? Up to 1/2", one of these ball joints might be useful.
https://howeracing.com/products/howe...777f6cc0&_ss=r |
#3
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Global west stuff is garbage?? I just bought a set of these and they show minimal variation in full movement on their website.
So they are misleading us? Just wondering what is different on your ride compared to what they show on their website? Mine is stock spindle with Global west uppers and lowers, so Modified I guess. How are you measuring the toe change?
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64 Lemans hardtop 4spd, buckets |
#4
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Wondering same. Springs removed?
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#5
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Springs and shocks are removed. Measuring bump steer with Longacre gauge with dial indicator.
Do not really want to revise spindle height with taller ball joints. Global West steering arms would likely work with aftermarket control arms and a lot of caster which would raise the steering arm up. I have to use stock upper and lower controls arms, and stock looking steering arms. Based on my measurements so far the tie rod has to be above the steering arm. |
#6
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Got ya
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#7
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That's how Global west shows it with there arms, but probably does have aftermarket uppers and lowers, and ya mine has 4.5 * Positive caster.
there Controls arms have 5* built in.
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64 Lemans hardtop 4spd, buckets |
#8
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I find it strange that a bolt on adjustable bump steer kit is not available for these A-bodys with stock suspension pieces.
Every kit I can find available lowers the outer tie rod and I need to do the opposite unless I am missing something. UMI does make a bolt through one that requires the steering arm to be drilled out for a 5/8 bolt. With this option I could put the tie rod on top. Global West steering arms if bent in the opposite direction would work too. I only have about 1.5 degrees of caster with the stock control arms. |
#9
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I believe you are right on the caster statement, Global west does say in their video that their arms would be a Great upgrade to the
upper and lower control arm replacement. Also they show Their control arms on the vehicle in testing video. Good luck with your venture and hopefully you find a fix for this. Let us know what you find please.
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64 Lemans hardtop 4spd, buckets |
#10
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#11
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Just curious, because I don’t know. Would billet aluminum be durable as a steering arm material? I don’t know what kind of load the arms can be subjected to. I would think some kind of steel (forged or otherwise) would be better. Of course that also depends on availability. Like the old saying ‘beggars can’t be choosers’. And maybe this is all a moot point. Like I said, just curious.
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#12
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Almost $400 to raise the tie rod end up 1/2"?
Here is a pic of the OEM arm in question. These are forged steel, so can be heated and bent up a bit and not lose Ackermann angle. Note the arm is slightly down to begin with, so rotating it up will not lose true length. Another option may be to cut the arm shown in red, bevel the edges and reweld with a MIG after reclocking it upward. |
#13
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Quote:
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64 Lemans hardtop 4spd, buckets |
The Following User Says Thank You to Lemans64 For This Useful Post: | ||
#14
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Why do you want to improve the bump steer? The why will help.
When you remove the springs & shocks, the suspension will travel more than when in use, keep in mind. Like, it will never reach total upward travel, the springs prevents that. So the amount of change would be less. "I have to use stock upper and lower controls arms, and stock looking steering arms." That kills a lot of options. And part of the reason I asked the 'why' question. From Global West' site on the steering arms: "The steering knuckle replaces the factory knuckle and corrects bump steer when performance suspension and alignment is being used with 4 to 6 degrees of positive caster. This much caster is only found in tubular control arms." Aside from grammar, they are meant to be used with GW control arms: 'performance suspension and alignment'. If you're in a class or competition that requires stock looking components, what are others in the class/competition using? If it's just personal preference, then you will have to go to non-stock appearing parts. .
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#15
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As HYWSTR455 suggets, that 1/4" of bump steer you have at full suspension articulation isn't a great indicator of what is happening when the vehicle is actually in motion and has it's springs and shocks installed. Depending on how the car is being used, you may only see about 4" of total travel at the wheel around the static ride height. That's where your measurements really need to take place.
What you're measuring is common for the GM SLA suspension system. In actually your measurements are pretty minimal compared to some reports I've read. Some people claim they've seen close to a full inch of toe out/in under bump/extension, especially on F-Bodies. You posted up some Chassis Works bits that may help, but there's another thing you can look at here. If you're only at about 1.5" of caster, adding more not only helps with negative camber gain with more steering angle, but will also reduce your bumpsteer as it raises the steering arm in relation to the lower control arm...the direction you believe you need to go. The way to achieve more positive caster from the stock control arm is through the use of an offset shaft cross-shaft. This will allow you to achieve much more positive caster in the system. THe offset shafts are going to be cheaper that the steering arms you found through Chassis Works and will start solving two issues inherent to the GM SLA, instead of just one. It's the route I would go first if you absolutely have to have stock control arms. Then, if you're still out a bit, you can still consider the steering arm.
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-Jason 1969 Pontiac Firebird |
#16
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Hi All,
Dedicated NHRA stock eliminator drag racing car. Have to use mostly stock parts in the class I am running. Had trouble with wheel shimmy this year after wheel stand. Looking at ways to try an correct and maybe pick up some et in the process. Have some ideas and new parts to try out. Thanks, Scott |
#17
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That makes sense. If the rules allow it, definitely run an offset cross shaft on the upper control arms. The added caster you'll be able to achieve should also help with straight line stability.
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-Jason 1969 Pontiac Firebird |
#18
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'Wheel shimmy' after a 'wheel stand' sounds like there's actual damage to the suspension, and that should be first on the list to correct.
.
__________________
. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
The Following User Says Thank You to HWYSTR455 For This Useful Post: | ||
#19
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just a minor detail...
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#20
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I run stock arms on my race car with offset top cross shafts that got me 3.5 degrees caster. I got the alignment at what I determined was ride height going down the track from video and the car goes straight. and is easy to drive. I don't pull 4' wheelies though.
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
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