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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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 Posted: Thu Jul 03, 2003 4:49 pm Post subject: Bump Steer |
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In the Tech Section there is an area describing how to make a bump steer kit ... I'm wondering if anyone has done this? .. and if they have .. I would like to see pictures of what has to be done.
Min |
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turbobob9242
Joined: 08 Feb 2003
Posts: 138
Location: Hinckely Ohio
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| Posted: Mon Jul 07, 2003 10:01 am Post subject: RE Bump steer kit |
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I was owndering the same thing!!
In my case, I can't get the damn steering lined up at all.
I had everything apart for repair and cleaning.
I made up a reinforced cross member and my rack is about 1 inch lower on the cross member. Now I can't get the tires lined up.
One wheel is straight the other turned in about 2 inches!
If I used this bump steer idea I could lengthen effective length of the steering arms.
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Bob Ward
80 9214 turbo, w 5.3 LS V8 |
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Tue Jul 08, 2003 5:18 pm Post subject: |
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| Quote: | Making a bump-steer kit for our cars is really easy...make a 6061 (aluminum) sleeve 1.125 OD (outer diameter)...about 6 inches long...drill and tap one end for rack thread (14mm I think) and other end for a 5/8 heim joint (aka rod end, available at most motorsports supply houses for $10-20))....then you drill out the taper in the steering arm of the upright (where the ball joint previously went through) to accomodate a 5/8 bolt....you can then shim the rod end up or down (using washers on the 5/8" bolt between the rod end and the steering arm) to tune the toe change out of the suspension...the tuning is a time consuming nuisance, but yields HUGE improvements in turn-in and mid-corner balance.
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that whole thing is sort of vague ... I'd do it instantly if i didn't have to drill out the rod end of the steering arm (meaning you can't revert back if it doesn't work properly) ... I have a few questions about it as well .. like .. do you have to do it to both sides? (logically I would think you would.) .... I would love some clarifications of this procedure.
Min |
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leadfoot
Joined: 11 Dec 2002
Posts: 2222
Location: gOLD cOAST Australia
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| Posted: Thu Jul 10, 2003 8:35 pm Post subject: |
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i wrote an explanation on this board under post camber box...
basically allows camber adjustment without affecting toe...
will send you an email with the picture can you put the picture up on the post for me.. i dont know if the picture i sent got through to jesse
leadfoot |
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leadfoot
Joined: 11 Dec 2002
Posts: 2222
Location: gOLD cOAST Australia
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| Posted: Thu Jul 10, 2003 8:36 pm Post subject: |
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i wrote an explanation on this board under post camber box...
basically allows camber adjustment without affecting toe...
will send you an email with the picture can you put the picture up on the post for me.. i dont know if the picture i sent got through to jesse
leadfoot
oops need you email though... |
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morghen
Joined: 21 Jan 2005
Posts: 8889
Location: Romania
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| Posted: Sat Aug 18, 2007 10:05 pm Post subject: |
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ok so i've got a nasty bump steer on my CGT project car. It is a bit lowered and i'm using 17" wheels...the steering wheel goes left right left left right like crazy when i go over bumps...i know that porsche corrected this with the 931...but how?
I've read that this problem occurs when tie rods are paralel to the steering rack and it gets worse when the car is lowered.
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Sat Aug 18, 2007 11:35 pm Post subject: |
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A more recent and informative thread on the topic - http://www.924board.org/viewtopic.php?t=21774
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"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11724
Location: PacNW
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| Posted: Sun Aug 19, 2007 3:20 am Post subject: |
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Two things. . .you can revert back. If you hog out the hole in the steering knuckle it can be repaired by welding.
Second, I have a pair of steering knuckles with spacers that I might be willing to sell. You would then need a threaded Heim joint to replace your TREs.
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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!tom
Joined: 28 Aug 2006
Posts: 1934
Location: Victoria, BC Canada
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| Posted: Sun Aug 19, 2007 3:51 am Post subject: |
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| morghen wrote: | | the steering wheel goes left right left left right like crazy when i go over bumps |
That's not bump steer.
That problem can be corrected by changing the offset of your wheels.
Bump steer is when the toe of the wheel changes during suspension travel.
Another remedy to your problem would be a steering damper.
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78 924 NA
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Sun Aug 19, 2007 5:03 am Post subject: |
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| Rasta Monsta wrote: | | Two things. . .you can revert back. If you hog out the hole in the steering knuckle it can be repaired by welding. |
welding? .... on critical suspension components? .... also keeping in mind that Tie rod ends have a specific taper to the hole, how exactly do you plan on putting that back in if the knuckle gets hogged out?
Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11724
Location: PacNW
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| Posted: Sun Aug 19, 2007 5:11 am Post subject: |
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According to a racing supply house I spoke to here in Portland, material can be added back to the hole and the taper re-created via machining. He wanted $40 each to do this to the knuckles in the photos above, and spoke of it as if it were no big deal.
And if you look carefully at your suspension, I bet you can find a bead or two. . .
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Sun Aug 19, 2007 5:38 am Post subject: |
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| Rasta Monsta wrote: | | According to a racing supply house I spoke to here in Portland, material can be added back to the hole and the taper re-created via machining. He wanted $40 each to do this to the knuckles in the photos above, and spoke of it as if it were no big deal. |
Wow, I'm not seeing how that could be 'no big deal' ..... for safety and longevity reasons, I think stressing the metal with various types of heat based work on something you rely on that heavily may be a bad plan.
| Rasta Monsta wrote: | | And if you look carefully at your suspension, I bet you can find a bead or two. . . |
I ment to say critical steering components.
Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Sun Aug 19, 2007 5:41 am Post subject: |
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if welding on steering components is ok with you, why bother dealing with bump steer in this fashion at all? ..... you can just heat up the steering knuckle arm, and bend it down/up (which is a techique described in 'how to make your car handle' by fred puhn, but i believe he also mentions having the parts heat treated again after this work to prevent catastrophic failure. But I'd have to go look it up again, its been awhile since i read that book)
Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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morghen
Joined: 21 Jan 2005
Posts: 8889
Location: Romania
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| Posted: Sun Aug 19, 2007 7:12 am Post subject: |
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i'm never going to mod the steering system...i'm not afraid to say it...i'm too chickenshit to do it....+ if the authorities find out i'm facing big time jail. 
i am only interested if i can use 931 parts to get rid of the bump steer...i've noticed that the 931 deals way better with the bumps...but then again the 931 has factory 15" wheels not 17". Anyonke know more about the improvements that porsche made on the 931 in this matter ?
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924guy
Joined: 29 Dec 2003
Posts: 2088
Location: Port St. Lucie, FL
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| Posted: Sun Aug 19, 2007 9:54 am Post subject: |
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IRRC i have a print article someplace with instructions on how to build a dampner type bumper steer device, that involves no modification of existing parts, its a bolt on.. ill try and find the article...but no guarantees...
it was similar in concept to this atv kit.. http://www.danacreechracing.com/categories/products/product-120.html
correction, had an article, cant find it in my notes...sorry..
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Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
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