DSPBMW
New Member
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| 10 Apr 2012 09:08 AM |
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I understand the rules and why they are in place in regards to original attachment points.
My question is does anyone see a problem with allowing the slotting of original attachment points if these are done for alignment purposes only?
Naturally questions like this come up, and a person has a specific car in mind. This is another example. However, I'm not sure I see a problem with other cars being able to use a similar allowance. Maybe the "alignment purposes only" would be able to eliminate any tortured interpretations.
This specific example includes slotting subframe holes (trailing arm mounting points) and welding on a slotted tab, and installing eccentric bolts to achieve alignment settings.
In this instance I would be happy enough with using them ONLY to reach factory alignment specifications.
In this example there is an eccentric bushing available that is garbage, difficult to adjust, and doesn't hold alignment. Not really an option. |
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snaponbob
Veteran Member
Posts:2830
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| 10 Apr 2012 09:18 AM |
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Not loving those rear control arm gizmos, huh? Sure can't tighten the outside pivot on E30s with an open end wrench, and no room for a box end. However, how will slotting help if the bolts can't be tightened enough? |
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| Bob Buxbaum
STX E36 328
KC Region |
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DSPBMW
New Member
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| 10 Apr 2012 04:02 PM |
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snaponbob wrote:
Not loving those rear control arm gizmos, huh? Sure can't tighten the outside pivot on E30s with an open end wrench, and no room for a box end. However, how will slotting help if the bolts can't be tightened enough?
Once the hole is slotted you can install an eccentric bolt that holds much better than the eccentric bushings. The hole slotting only affords adjustment. Eccentrics must be installed to actually adjust anything. |
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boxboy
Advanced Member
Posts:512
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| 11 Apr 2012 12:48 AM |
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Not sure I get exactly what you are describing, but if the resultant position was achievable through factory adjustment I think you'd be ok.
-Andy M. |
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DSPBMW
New Member
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| 11 Apr 2012 07:28 AM |
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boxboy wrote:
Not sure I get exactly what you are describing, but if the resultant position was achievable through factory adjustment I think you'd be ok.
-Andy M.
I'll post a picture later today.
The problem is the factory doesn't have an adjustment. It does have a spec however. These could be used just to get back to factory spec. |
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DSPBMW
New Member
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| 11 Apr 2012 09:13 AM |
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This is a picture of the slotted mounting point with the slotted, brackets welded in place. And the BMW bolt/eccentric in place. |
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cpyanowski
New Member
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| 11 Apr 2012 09:15 AM |
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I have the same rear suspension on my 300ZX and my opinion has been what you are trying to do is not legal. In SM suspension components are unrestricted as long as they use the original attachment points. By slotting the crossmember you are moving the attachment point. The legal way to change camber would be by eccentric bushings or by modifying or making custom control arms.
Chuck P. |
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DSPBMW
New Member
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| 11 Apr 2012 09:27 AM |
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cpyanowski wrote:
I have the same rear suspension on my 300ZX and my opinion has been what you are trying to do is not legal. In SM suspension components are unrestricted as long as they use the original attachment points. By slotting the crossmember you are moving the attachment point. The legal way to change camber would be by eccentric bushings or by modifying or making custom control arms.
Chuck P.
I agree with you, this wouldn't be legal now. My question is should it be?
In my opinion, if wording includes "slotting of holes to attain factory alignment specifications", there shouldn't be gray area available for tortured interpretations. You are right a custom arm could be built to solve the issue, but as classes allow more and more modifications, it seems silly to me to force custom designed and built parts to attain something as simple as alignment adjustment. |
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PMcCartin
New Member
Posts:76
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| 11 Apr 2012 07:36 PM |
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cpyanowski wrote:
I have the same rear suspension on my 300ZX and my opinion has been what you are trying to do is not legal. In SM suspension components are unrestricted as long as they use the original attachment points. By slotting the crossmember you are moving the attachment point. The legal way to change camber would be by eccentric bushings or by modifying or making custom control arms.
Chuck P.
That seems like a tortured interpretation to deny the mod.
The Miata is from the factory with what the OP is trying to do. Does that mean a change in alignment causes it to be illegal? IMHO, the "suspension mounting point" is the box structure the the arm and bolt attach to. As long as that's in the OE place on the subframe. The mounting point hasn't moved. |
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DSPBMW
New Member
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| 12 Apr 2012 08:40 AM |
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PMcCartin wrote:
cpyanowski wrote:
I have the same rear suspension on my 300ZX and my opinion has been what you are trying to do is not legal. In SM suspension components are unrestricted as long as they use the original attachment points. By slotting the crossmember you are moving the attachment point. The legal way to change camber would be by eccentric bushings or by modifying or making custom control arms.
Chuck P.
That seems like a tortured interpretation to deny the mod.
The Miata is from the factory with what the OP is trying to do. Does that mean a change in alignment causes it to be illegal? IMHO, the "suspension mounting point" is the box structure the the arm and bolt attach to. As long as that's in the OE place on the subframe. The mounting point hasn't moved.
The real question is, is this something that should be allowed?
Suspension mounting points may be slotted for the purposes of alignment adjustments.This allowance does not allow for repositioning of suspension parts other than incidental in the adjustment of camber and toe.
Sound OK? Any issues with this? |
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JBrettHowell
New Member
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| 12 Apr 2012 10:49 AM |
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I think such a statement would be in direct conflict with this:
"Any minor modification, intended to allow or facilitate any allowed modification, is permitted as long as it does not provide any intrinsic performance benefit in and of itself, does not provide a weight reduction of more than 1 lb, and is not explicitly prohibited elsewhere within these rules.
This rule is intended to allow minor notching, bending, clearancing, grinding; the drilling of holes; affixing, relocating, or strengthening of brackets; removal of small parts, and similar operations performed in order to facilitate the installation of allowed parts or modifications. Minor strengthening, without relocation, of original chassis/suspension pickup points is allowed. Examples include welding washers restricting control arm mounting bolt movement, local reinforcement of control arm chassis mounts, etc."
Since this rule seems to specifically make the mod you are proposing illegal, I think some serious thought needs to be given to how the rule change should be worded. |
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msimanyi
Basic Member
Posts:262
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| 30 Apr 2012 02:17 PM |
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DSPBMW - I think you should write in to the SEB. It's possible they'll decide what you want to do is legal right now and will issue a clarification stating such, or it's possible that such an allowance may be put out for proposal if they think the idea has merit.
I would be reluctant to support the generic allowance you proposed, but I do think that if you were merely using the allowance to achieve alignment settings achievable with eccentric bushings on a rear trailing arm suspension, it has some merit from the perspective of lowering costs for competitors working with that type of setup, while allowing them some of the flexibility that others with A arm and multilink suspensions already have. (I write that noting the failure rate and cost of eccentric urethane bushings in a trailing arm setup, the inability to use solid materials in an eccentric bushing in that setup and the significant expense of custom trailing arms.)
Mike
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Marshall Grice
Basic Member
Posts:299
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| 30 Apr 2012 05:39 PM |
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Does 15.1.F not provide coverage for what you're trying to do?
Quote:
On all forms of suspension, camber/caster adjustment within factory
specifications may be achieved by the use of shims or eccentric
bushings. The intent of this allowance is to permit cars to be restored
to within factory-allowed specification ranges, not to provide an additional
method beyond those permitted in Section 15.8 to obtain
alignment settings beyond the factory specifications. |
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