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Rear upper control arms- Camber discussion

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#81
dstevens

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just for a note .05" (under 1/16 of a inch) deviation in anyone of the parts (subframe, A-arm upper, A-arm lower, rear upright, lower outer A-arm bolt) or a combination of them all adding up to .05 is .5 degree of camber. This is why mazda designed in the adjustable cam bolts. Since most want to work on the upper end of the scale of camber now we have cars that can give lots of rear camber and some that won't. The cam bolts our out of their nominal range of adjustment. It is simply manufacturing tolerance stack up of parts. 

 

I don't believe that a sheet metal part (subframe, a-arms) bent .05-.1 is at serious risk of failure. But thats just me. 

 

Indeed.   It's another case in SM of the competitiveness of the class surpassing production car tolerances.  The arms or the frames aren't going to fail with that bit of mods (though I doubt Mazda will get behind modding stock parts like that).  It's easy to model, plenty of tools readily available to do it.  There are plenty of street cars that old with damage to the parts 1/8" to 1/4" (or more)  that run 100k plus miles.  They aren't running the duty cycle a race car runs but this little bit of arm slot modding isn't going to impact the safety of the car.  There are good reasons to replace slightly damaged/bent parts but that has to do with performance, repeatability of settings and the ability to have a symmetrical setup.  Not my place to offer an opinion one way or the other but if the safety card is going to be played I think there should be some supporting engineering data.



#82
EMatoy

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I have a set of the AA sub frame checkers. I must not be smart enough to use them. I checked several that I own and could not conclude which sub frame was "bent" and the cause of only getting-3.1 on the left rear of my new car. Swapping parts I got a little more.

An upper control arm slot would easily and cheaply allow everyone to get what they feel they need. It also allows camber to be changed independently from toe. Saving a ton of time when you want to change ride height.

#83
38bfast

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In the outside chance that sloting was approved I would imagine it would be minimal. Say .125” (1/8) max. It would be easy to tech wit a set of calipers.

I just said outside chance and imagine.
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#84
Jamz14

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It also allows camber to be changed independently from toe. Saving a ton of time when you want to change ride height.


Best reason given yet for allowing. I am now all for allowing.
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#85
FTodaro

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Best reason given yet for allowing. I am now all for allowing.

I would not assume that the permitted method would be slotting. If the reason we were required to go with off-set bushings up front was because Mazda and/or SCCA did not want us modifying parts then its likely that we will need to use bushings in the rear, that means cost, work and no quick camber adjustments.


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#86
ccambern

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I find it ironic that the initial response was "no, because more camber won't make you faster." And now we've moved to, "no, because more camber will overload the rear suspension and cause failures." You can't have it both ways.

New rules aren't a bad thing if they address a known loophole and make it easier and cheaper for the little guy to bring his car into optimal range. That's why we allow fuel pressure regulators, slotted timing wheels, and offset bushings. In each case, a simple change made it easier to adjust the car while closing the loophole on an unteched item that was being modified.
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#87
EMatoy

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New rules aren't a bad thing if they address a known loophole and make it easier and cheaper for the little guy to bring his car into optimal range. That's why we allow fuel pressure regulators, slotted timing wheels, and offset bushings. In each case, a simple change made it easier to adjust the car while closing the loophole on an unteched item that was being modified.[/quote]

Exactly

#88
Todd Green

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Collectively we need to decide if ultimate speed is our primary concern? Or is it staying within the written rules? 

 

 

I'd also throw out there that camber isn't always about speed.  It also affects tire wear/longevity.  Not everyone can afford stickers every weekend and limiting camber can raise your tire budget (which is already one of the highest consumable costs for racing.)  (Not necessarily just talking about Dave's post, but also the propositions that the class limit camber and do camber testing in tech.  I'd be very much against that.)


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#89
Brandon

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I've heard there's a picture running around of the slotted arm from the Runoffs - has that been viewed here by anyone?

Can someone confirm it was a 'parallel to the centerline of the UCA' type of slotting?

My reason for asking is I believe it's a presumption that the slotting was for "more camber" when it could have been to achieve a target camber number while retaining enough suspension travel - aka not riding on the bumpstops.

 

Would slotting the UCA at an angle would give a slight ability to adjust for more camber while at a higher ride height?

 

I've heard lower is faster (less air under the car), lower gets you more camber, but the lower you get the closer to the stops you are statically leaving not enough travel before the infinite spring rate kicks in (slow hands need not apply).

 

I've commented "No" earlier in the thread but echoing other's comments about "not changing rules when hands are caught in the cookie jar" I feel is more than enough justification to not change the rules in any way (no slotting and no max camber).


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#90
Steve Scheifler

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...

 

I've commented "No" earlier in the thread but echoing other's comments about "not changing rules when hands are caught in the cookie jar" I feel is more than enough justification to not change the rules in any way (no slotting and no max camber).

 

So I guess that means you would like to remove the adjustable timing wheel from your car, and the fuel pressure regulator, and upper-inner front control arm bushings, and throw away the head that won't pass pre-2014 rules, and probably more that I can't think of at the moment.  Right?  By all means, you first.  And your other questions seem to suggest that your vote on this is not influenced by any technical knowledge of your own, correct?  If your mind is made up, why do you even care about the rest?


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#91
Walter Vetter

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Mr. Scheifler, I'd vote for returning to the original SM rules circa 2002.
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#92
Dave D.

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 I'd vote for returning to the original SM rules circa 2002.

But wasn't there a lot more cheating going on back then? Sunbelt engines that idles like ProStock drag cars, clocked ECUs, bent parts,hot fuel,etc....



#93
Walter Vetter

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Because there was a lot less tech then. I think we're better at knowing what to look for.
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#94
Tim Wright

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But wasn't there a lot more cheating going on back then? Sunbelt engines that idles like ProStock drag cars, clocked ECUs, bent parts,hot fuel,etc....

Nitrous in the roll cage ;)



#95
Brandon

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So I guess that means you would like to remove the adjustable timing wheel from your car, and the fuel pressure regulator, and upper-inner front control arm bushings, and throw away the head that won't pass pre-2014 rules, and probably more that I can't think of at the moment.  Right?  By all means, you first.  And your other questions seem to suggest that your vote on this is not influenced by any technical knowledge of your own, correct?  If your mind is made up, why do you even care about the rest?

 

Steve,

I'll ignore the attempt at putting words in my mouth, you know that's not what I was writing/implying/anything.

 

Again, as someone else on the thread has noted, there has been a significant increase in the amount of tech being performed at events now and that's what caught a lot of the earlier items which rules were modified to accommodate. I'm not going to split hairs between the earlier items and today's UCAs, but to note these rules were changed because there was no viable method of regularly confirming compliance with the specific hard parts.

ECUs were being flashed and that cannot be easily teched == slotted timing wheel and FPR.

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

Heads were being modified == stated absolutes for machine work were implemented.

 

See the difference?

 

Slotted UCAs are easily teched and a blatant cheat for correcting "something" that may be wrong with a car yet everyone here is speculating on why (more camber? higher ride height with more camber?). So suggesting a rule change to accommodate it is not only the wrong path but an entirely different one with respect to the earlier changes. If you are unable to attain a particular number with your platform, it's not the rules that need to be changed but parts on the car.

Please don't assume anything about my technical knowledge or whether that influences my opinion on the matter. I compete in this class just like (nearly) everyone else who's posted in this thread, ergo my opinion is as pertinent as yours or anyone else's. To attempt to diminish or reduce its influence or relevance is not in the spirit of the sport.

 

Regards,

Brandon


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#96
Steve Scheifler

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Brandon, we can agree that all participants should have equal opportunity to voice an opinion, regardless of where they run in the field or how pretty their car is, or how much of the work they do themselves. But surely we can also agree that when engaged in public debate where our opinions and reasoning influence others, it is also valid to question the experience and knowledge behind those opinions. No? Without straying too far from the topic, we all know that the internet is an incredible resource for information on almost any topic, but..., well, you know. So yes I was a bit snarky in my delivery and I apologize for that, but I think the points were valid. Conspicuous slots in the arm aren’t the only way to increase camber, some already weld over the hole and re-drill. Sure you can pull it and measure that, but there will be others. Somewhere I have a picture of a 1.6 up in the air with the diff out and a porta-power between the lower arm mount points, one side high up at the cross member and the other lower. Want to guess what I was doing? I was fixing the damn thing in the one weekend between Autobahn where someone dive-bombed me and bent the shit out of it, and our next race. That’s when I first ponied up for a brand new one to get a bunch of reference measurements, which didn’t work so well either.

I certainly haven’t worked on as many of these cars as the pro shops so I won’t be insulted if someone gives less weight to my opinion than to theirs. On the other hand, I’ve done all the work myself rather than paying employees to do it for me and factoring those costs into where the time is spent, and I don’t have an endless source of spares that allow me to just swap and move on without wasting time on the details. So maybe my personal hands-on experience is worth a little something when combined with the “volume experience“ of others. Being the internet and not really knowing much about most people here, when someone states a firm opinion while referencing only what “I’ve heard” from others on the subject, I think it is reasonable to challenge the basis of their opinion. I should have done so with less of an edge.

And even IF it were 100% techable, we all know that applies to a tiny number up front. Why should someone a few rows back be at a disadvantage to the person alongside who doesn’t even need to be as bold as Danny because he has never had anything teched and probably never will?

And even if you dismiss ALL of that, this just plain ticks me off:

“If you are unable to attain a particular number with your platform, it's not the rules that need to be changed but parts on the car.”

Not to put words in your mouth but someone could interpret that as “If you can’t afford new parts and the labor and time after some idiot hit you, get a better job or find a different hobby.” Not exactly within the spirit of the club. This isn’t like a fresh engine or two sets of tires every weekend, there are cheap and easy ways to ensure that more people can get “enough” camber even if something is just a bit tweaked or simply not optimal right from the factory.

What it really sounds like to ME is that you are simply fed up with the cheats and taking it out on the wrong guys.
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#97
BNaumann

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Somewhere I have a picture of a 1.6 up in the air with the diff out and a porta-power between the lower arm mount points, one side high up at the cross member and the other lower. Want to guess what I was doing?


Cheating! 😀

#98
Brandon

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I'm sorry Steve, but that reasoning just doesn't hold water.

If you've been hit, you've been hit. It's not the equipment rules that need to change, so you can fix your car cheaper, but to correct the behavior and change those rules. But that's a topic for another thread and I don't want to debate it here.

 

Yes it's an inevitability with this class that contact will happen but if you're so far out of spec after an impact you're replacing control arms, there's always a high likelihood of other things being bent besides just the CAs and you should be considering the subframe for replacement as well. To your example with the porta-power: if you already had the differential out, you're only 14 nuts/bolts & a brake line away from swapping in a spare subframe. You're running in this class and don't have a spare subframe?

 

I'll be blunt: I can pick up used full rear suspension bits for less than $100 (control arms and subframe), whether those have been in an accident or not is a chance you take in using these but it's not like you're spending $560 for a single set of new CAs only (ignoring the $500+ new subframe cost). You could potentially afford to buy five sets of those used suspension pieces and mix/match to finally find something that works.

Yes it's the same as the parts binning that was done before the head rules.

Yes it's the same as the parts binning that was done before the FPR/CAS rules.

Yes it's the same as the parts binning that was done before the offset bushings.

This is a production car class and there will always be variance in the tolerances of parts and using "parts binning" as a justification to allow a non-stock part is not valid.

 

Ergo, the need for a slotted UCA allowance in the rules is not supportable on all accounts.

 

If you can't deem it worthy to spend $100 to fix a bent car then I don't know how to help you any further. I've replaced controls arms many times, and only recently had to replace my subframe after 8 years of driving the car, and not once has this process resulted in my setup guy being unable to get the settings he wants to see. Which I believe are approximately -3.5* or so on each side (static with me in the car).

 

And for the record, I do all my own mechanical work short of setup, rebuilding of large components (engine, trans, diff), bodywork (paint), or welding so presuming I'm a moneyed player in this game and use a shop for everything, I am not. This position is not something I'm taking to make it more difficult for folks "like you" (as you assert) because I am a guy "like you" doing all my own work when it comes to this except setup. Hell, I don't even have a lift and do all of this on my back with jackstands for chrissakes!

 

As I've stated before, if anyone has specific, articulable, and sharable knowledge of the slotting on Steyn's UCAs were solely to gain more static negative camber, it would be good for everyone to know it as that seems to be the crux of this entire debate. The presumption that "MOAR KAMBAR" is the salve for what ails us is what's triggering this debate, for which I'm not entirely supportive of being accurate.

 

I stand by my position the slotting was not solely for "more negative camber" but a combination of that and ride height.


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#99
davew

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As much as I hate to say it, I agree with Brandon. If you can not make your car as fast as desired through legal methods, you should not be allowed to do something illegal to get what you want.

 

To take this to an extreme would be to allow a worn out, low powered engine to increase compression ratio because it is cheaper to mill the head than buy a pro engine. I wanted to say "add a turbo" but thought that was over the top.

 

As mentioned previously, I have a set of jigs to measure all 8 control arms and the rear uprights. I have my fab guy working on a resale version of my "made from scrap metal" jigs. Hopefully we will have them designed this week and ready for sale in a couple weeks. My guess (purely a guess) is a retail price of $250 for the 5 piece set.

 

Dave


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#100
OrangeCrush86

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I'm more or less new to SM, and this might be a dumb question... but is it possible to just include approved slotted control arms with the suspension kits every SM will already have (like the Bilstien coil overs)? Then you don't need to deal with Mazda not allowing modified parts and people can run whatever camber they want.

 

What I say doesn't really matter here, but of the current options I read about, I would rather have a max camber rule that would stop people from hunting for parts. To ease enforcement an "official" measurement tool would be defined that all SM racers could also purchase so they have a clear expectation of what the tech shed would measure.

 

Buying a bunch of factory subframes to get over -3.1 isn't in the spirit of spec racing in my opinion.






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