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Rear upper control arms- Camber discussion

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#121
Tom Sager

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A 0.5 degree increase in camber only requires a change in length of 0.0769 inches of a suspension component that holds the wheel at a desired angle.

There are many ways to change the length. It could be an obvious slot as reported to have been done by Danny. You could also adjust many different parts of the sub frame, the knuckle or lower control arm.

Currently there are not any dimensions on these parts in the rules so you have to compare the part in question to a new one. Sure a slot is obvious- but will you visually see 0.0769 inches on a sub frame when compared to a new one? Would you see a 0.5 degree bend in a knuckle? Who actually has a new subframe (with a part number and in a factory bag) at a race to compare it to? How do you prove it was not tweaked due to contact? If the cam adjustment slots are worn and the upper control arm mounting bolt hole are worn how do you prove it was modified not wear from someone driving with the bolts lose when it was a street car for 200,000 miles? So now you might say publish dimensions and measure. What are the tolerances on each part? How precise can you measure a sub frame? Is the gain some want smaller than the tolerance stack up and measurement error?

Point is if you are cleaver and want to cheat on camber you can- this is not new. There are many ways it can't be measured and proven Danny simply brought it to everyone's attention. Why not take the cheat away, level the playing field, reduce cost and time spent? A 0.100 inch slot is almost free takes just a few minutes and removed any advantage (real or perceived). This is what my letter will ask for.

Some very good points but I don't like the slotting method as the bolt will probably move in the hole under racing stress unless it's bushed somehow. 


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#122
FTodaro

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 A 0.100 inch slot is almost free takes just a few minutes and removed any advantage (real or perceived). This is what my letter will ask for.

Many of the posts assume that if a rule adjustment is made that it will be with a slotted control arm as opposed to offset bushings. I think Mr. Wheeler made a good point that historically, you should expect off set bushings not a slot. A slot modification, while easy may be counter to what Mazda would approve. The use of offset bushings, will move the inboard side top of the control arm closer to the sub frame. I have not looked at it but it already is a tight fit in there, It may be difficult to move the control arm in that far.


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#123
BNaumann

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Many of the posts assume that if a rule adjustment is made that it will be with a slotted control arm as opposed to offset bushings. I think Mr. Wheeler made a good point that historically, you should expect off set bushings not a slot. A slot modification, while easy may be counter to what Mazda would approve. The use of offset bushings, will move the inboard side top of the control arm closer to the sub frame. I have not looked at it but it already is a tight fit in there, It may be difficult to move the control arm in that far.


Well my knee-jerk response is to put a single bushing in the knuckle (where apparently there is enough clearance to slot the arm) rather than two in the arm, but then I realized that would open up the kinematic can o' worms again.

#124
SaulSpeedwell

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1) allow -4 degrees +

2) we need better hubs

3) we need subframe gussets

4) we should be allowed to suare the back up with the fronts...

5) we need new rear hub flanges

6) we need rear subframe gussets

 

then where?

Sounds like you need RA-1s ...  :)


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#125
EMatoy

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Some very good points but I don't like the slotting method as the bolt will probably move in the hole under racing stress unless it's bushed somehow.


The clamp force of the bolt would be sufficient to keep parts from moving. I am willing to test and prove this at mid Ohio this weekend. Stop by and we can discuss the results.

#126
Steve Scheifler

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The clamp force of the bolt would be sufficient to keep parts from moving. I am willing to test and prove this at mid Ohio this weekend. Stop by and we can discuss the results.


Agreed. We already rely on it being enough to prevent rotation of the arm around the bolt which would change preload on the bushing and change cross weight. That’s why we tighten everything down with the car loaded, to lock all those points in place with no torsional load on the bushings at rest, and we expect them to stay there.
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#127
EMatoy

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Agreed. We already rely on it being enough to prevent rotation of the arm around the bolt which would change preload on the bushing and change cross weight. That’s why we tighten everything down with the car loaded, to lock all those points in place with no torsional load on the bushings at rest, and we expect them to stay there.

Exactly

#128
Jim Drago

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How about we just do away with offset bushings at the front and leave front and rear alone? :) That way both sides will be the same :)


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#129
Tom Hampton

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How about we just do away with offset bushings at the front and leave front and rear alone? :)


You can't take something away once its been given! Everyone knows this. 

 

Clearly you are trying to pad your pockets by forcing everyone to buy "perfect parts" from you and get the "magic setups".   :devil:


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#130
Tom Sager

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Agreed. We already rely on it being enough to prevent rotation of the arm around the bolt which would change preload on the bushing and change cross weight. That’s why we tighten everything down with the car loaded, to lock all those points in place with no torsional load on the bushings at rest, and we expect them to stay there.

I'm familiar with that procedure and I'm also familiar with having to check and re-do it as stuff moves.  I think relying on pinch force for a sloppy hole is a bit of a barn job for a racing application. 


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#131
Jim Drago

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I'm familiar with that procedure and I'm also familiar with having to check and re-do it as stuff moves.  I think relying on pinch force for a sloppy hole is a bit of a barn job for a racing application. 

I would normally agree and  I disagree with this proposal.. But IMO the force will be pushing towards the slot not away from it and IMO it would never move. 


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#132
BNaumann

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How about we just do away with offset bushings at the front and leave front and rear alone? :)


Then I'm gonna start bending my shit.
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#133
Tom Hampton

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Then I'm gonna start bending my shit.


The "old ways" are best.


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#134
Tom Sager

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I would normally agree and  I disagree with this proposal.. But IMO the force will be pushing towards the slot not away from it and IMO it would never move. 

 

That's what we said when running Neon's years ago when they allowed us to slot the lower strut mounting holes for camber adjustment.  Any force upon it should have pushed in the camber gain or camber limit direction.  It was a frequent problem.  Granted that was a front heavy FWD car.  What I'm saying to those that want this change is to go for a better quality solution. 


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#135
Steve Scheifler

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I’m still trying to come up with something about these chick car grocery getters that isn’t “a bit of a barn job for a racing application“!

Seriously. No self respecting race car builder would use almost anything you can find on these cars, stock or otherwise. But let’s look for a moment at countless other classes, virtually all of them faster and with higher loads than SM. This kind of tiny modification wouldn’t even be a point of discussion let alone hand-wringing over who would approve or disapprove. Cripes, if I’m worried about it slipping I’ll add an outie star washer, or weld it up and drill a new one, or whatever. Do we really need our mommy to tell us how to do everything?
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#136
Tom Hampton

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Do we really need our mommy to tell us how to do everything?


hahahahahahaha....Does this really need an answer? Yes, of course. And you need to ask Dad for permission, too.
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#137
dc2696

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We race a Neon chumpcar with slotted struts for camber, they don't move if they're torqued properly. read: Miata alignment cam bolt tight

 

I don't see this being an issue


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#138
Todd Green

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Front spindles were being heated/bent and absent an easily measured dimension, could not be easily teched == offset bushings.

 

 

And what makes you think that people won't start bending rear spindles like the front or do otherwise equally hard to detect mods for the rear in tech?


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#139
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A 0.5 degree increase in camber only requires a change in length of 0.0769 inches of a suspension component that holds the wheel at a desired angle.

Move all existing NEW parts in the correct direction for maximum camber and one could legally get another .5 degree negative camber.


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#140
SaulSpeedwell

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I’m still trying to come up with something about these chick car grocery getters that isn’t “a bit of a barn job for a racing application“!

Seriously. No self respecting race car builder would use almost anything you can find on these cars, stock or otherwise. But let’s look for a moment at countless other classes, virtually all of them faster and with higher loads than SM. This kind of tiny modification wouldn’t even be a point of discussion let alone hand-wringing over who would approve or disapprove. Cripes, if I’m worried about it slipping I’ll add an outie star washer, or weld it up and drill a new one, or whatever. Do we really need our mommy to tell us how to do everything?

And yet, even once we drop these cars on the bumpstops and increase the scrub radius by 3X, and double the grip, and then race them wheel to wheel for YEARS ... they are still more reliable than anything Germany has made in decades. 

 

If 944Cup or SpecE30 or SpecE36 or Spec Boxster was a good idea, they would have SM sized, or even Formula Vee sized fields.  But nothing drops panties and impresses friends like demonstrating how much money you have to waste on superior German marketing :)


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