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> Question 911 front strut steering knuckle, bump steer
Krieger
post Feb 3 2009, 09:40 PM
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I know there are shops out there that raise the spindle on bilstein struts then heat and bend the steering knuckle down to help with bump steer. I plan on lowering the front suspension about 1.5" by using the adjuster. I have boge struts and want to know if anyone has done just the heating and bending of the steering knuckle, does it work to counteract bump steer, is it hard to do acurately?
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J P Stein
post Feb 3 2009, 10:01 PM
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ERP tie rod extensions are the way I went. Bending is the steering arm is iffy.
It must be done right. A guy with a hammer & torch is gonna have broblems making both sides the same.


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J P Stein
post Feb 3 2009, 10:04 PM
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Oops, not my car. Too dirty. (IMG:style_emoticons/default/biggrin.gif)
This is


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Krieger
post Feb 3 2009, 11:27 PM
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Did you use rack spacers too?
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brant
post Feb 3 2009, 11:31 PM
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I don't think you would need the lowered struts OR the tie rod extensions for only 1.5 inches over stock...
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charliew
post Feb 4 2009, 12:29 AM
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Those extensions put a lot of twist motion on the spindle arms. I can't believe that is a good solution. The fact that these cars are light helps. If these were off road vehicles that would never work. The fatter the tire the more strain on the steering parts.
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ArtechnikA
post Feb 4 2009, 04:31 AM
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QUOTE(brant @ Feb 4 2009, 12:31 AM) *

I don't think you would need the lowered struts OR the tie rod extensions for only 1.5 inches over stock...

(IMG:style_emoticons/default/agree.gif) The standard 10mm rack spacer is fine for moderate lowering on a street car.

Raising the spindle is basically done to recover suspension travel and damper range.

If you think about it, you can only raise the spindle about 19mm anyway unless you are running monster-truck size wheels... (19mm is the max for a 15"...)
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Eric_Shea
post Feb 4 2009, 10:19 AM
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Anyone know the pitch on those M10x22's for the rack? 1.5?
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Wes V
post Feb 4 2009, 10:53 AM
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QUOTE(Eric_Shea @ Feb 4 2009, 08:19 AM) *

Anyone know the pitch on those M10x22's for the rack? 1.5?



1.5 is correct.

Wes
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Eric_Shea
post Feb 4 2009, 11:27 AM
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Thanks.

I'm ordering spacers from McMaster in 4.5mm chunks. My spindles are raised by 18mm so 4 out to do it. That and some M10x40's.

Am I missing something with this whacky geometric logic? I'm thinking it keeps the t-rods parallel to the ground this way. (IMG:style_emoticons/default/confused24.gif)
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SirAndy
post Feb 4 2009, 12:05 PM
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QUOTE(Eric_Shea @ Feb 4 2009, 09:27 AM) *

I'm thinking it keeps the t-rods parallel to the ground this way. (IMG:style_emoticons/default/confused24.gif)


Actually, if you're talking about bump steer, it's more important to get the tie rods parallel to the a-arms.

With the car on the ground, your a-arms should be close to parallel to the ground, but bump steer is really when the a-arms and tie rods are not in the same plane ...
(IMG:style_emoticons/default/bye1.gif) Andy
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ArtechnikA
post Feb 4 2009, 01:01 PM
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QUOTE(Eric_Shea @ Feb 4 2009, 12:27 PM) *

Am I missing something with this whacky geometric logic?

The reason the standard spacers are 10mm is that that's all the room you have to raise the rack before it hits the body...
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J P Stein
post Feb 4 2009, 01:38 PM
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I have taken the time to measure how much suspension compression ....at the strut...is taking place up front. I made decisions based on that and how far I could lower the car....keeping off the bump stops is gud, IMO.
Raising the spindles gave me another 3/4 inch of shock travel and allows me to lower the car that much more.

How ya'll deal with bump steer is your problem. I showed you my method.
Show me your method to do it better on your car and I'll listen.

Yes, I have rack spacers also.

I've been running the extensions for 2-3 seasons on an AX venue that is rougher than a cob.....using 9.5 inch Hoosier slicks. Don't plan to go off road, tho.
There's "believe" & then there's experience.
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zig-n-zag
post Feb 4 2009, 01:53 PM
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Its not my thread, but thanks to all for sharing, I find it helpful.
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brant
post Feb 4 2009, 02:21 PM
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Eric,

the above is correct
there is only a limited amount of room for a spacer until things touch
you can't double that, or run much more than the standard kit provides.

I suppose every chassis could be slightly different
we were able to add a few flat washers to the "spacer kit"
but not many.

b
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Eric_Shea
post Feb 4 2009, 03:37 PM
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I was wondering about that... well, I'll get 35mm bolts and use 2 spacers per side.

Maybe this is the real answer... I'll talk to Chuck about it.

http://www.elephantracing.com/suspension/b...11bumpsteer.htm
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Krieger
post Feb 4 2009, 08:27 PM
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Thanks for the feedback.
QUOTE
Actually, if you're talking about bump steer, it's more important to get the tie rods parallel to the a-arms.

So this is the key? I have my car up and I will assemble the front suspension without the torsion bars, but with rack spacers and turbo tie rods, elephant bushings. I will jack up the front a arm until it is level or slightly down and see what that tie rod looks like in relation to the a arm. I will also look at it throughout the range of motion. I will post some pictures and see what I've got. Maybe this weekend. Still no ideas on bending that knuckle down?
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Eric_Shea
post Feb 4 2009, 10:13 PM
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QUOTE
Actually, if you're talking about bump steer, it's more important to get the tie rods parallel to the a-arms.


I've got a factory manual that shows otherwise... Section W, W4, Fig. 5. They show the tie-rod in an absolute parallel with the ground. Basically stating:

The distance to the center of the wheel (dead center on the dust cover) minus 108mm +/- 5mm (or 126 for me?) should equal dead center on the rear of the torsion bar.

Tell me more... I want to set the ride height and get this resolved before I get it aligned (which it needs badly) (IMG:style_emoticons/default/confused24.gif)
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SirAndy
post Feb 4 2009, 10:19 PM
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QUOTE(Eric_Shea @ Feb 4 2009, 08:13 PM) *

They show the tie-rod in an absolute parallel with the ground.

And where is the A-Arm in that picture?

Parallel with the ground?
(IMG:style_emoticons/default/shades.gif) Andy
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Eric_Shea
post Feb 4 2009, 10:21 PM
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QUOTE
And where is the A-Arm in that picture?

Parallel with the ground?


No Sir. Looks to be angled at about a 15 degree downward angle sloping toward the wheel.
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