2014 rules package; the National Director's cut

Questions and answers about CMC and NASA rules

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cozog
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Postby cozog » Wed Nov 20, 2013 1:51 pm

Glenn wrote:
RCR#10, 3 in favor, 5 against: Personally I think the idea of allowing aftermarket rear upper links makes sense for the Fords. We’re fighting both parts availability and ripped up pickup points, both of which can be helped with aftermarket arms of a specified length and with spherical bearing/rod ends instead of rubber or urethane. Opinions differed though, and for now I am happy to go with the majority.


I would like to see a responce from those who voted no to this and explain why. I'm getting emails from my guys and I voted yes. So I can't answer as to why it wasn't passed other than "it didn't get enough votes.."

Alot of the failure in the upper mounts (the ones we passed the repair kit for) is related to the twist placed on the mount due to the bind of the rubber bushing. The more you deviate from straight, the more resistance the bushing provides. I rodend here would allow movement w/ no twist type bind on the mount.


OK, I'll bite.

Not being a Ford expert, I based my no vote on cost, common sense physics and info from a Ford expert. If a beefier arm is allowed, the failure point is now the body/mounting point/sheetmetal. Carrying a spare arm in the trailer is a much easier/cheaper fix on race weekend if one fails. Having to weld up/repair the torn body mount will probably end your weekend. Not to mention the additional time/money required to repair it. and there's no guarantee that the aftermarket arm won't break either.

The Ford expert I heard from said this:
===================
1. Like it or not, control arms (front and rear) are consumable items. Certainly not like brake pads, but they are an item to inspect regularly, and replace when they show significant signs of wear.

2. On a Ford, from my own experience, for the rear uppers, you do NOT want an aftermarket, super strong arm when using the standard, factory 4 link setup. Some flex is needed.

3. Going to a different, stronger, aftermarket control arm WILL effect handling.

4. From my own experience - I never went to a poor mans 3 link as I felt the trade-offs were too much. A Mustang wasn't designed to operate that way, so it does indeed impart a tremendous amount of stress on ONE suspension point when it should be two. Additionally, it's a CHOICE to run a PM3L, so the racer has to accept the consequences of that choice. I ran the standard 4 link for eleven years, and replaced my rear uppers 3 times in that period. When they got worn (bushings worn out, elongated mounting holes, etc), they got replaced. At a cost of approximately $40, per set. I always bought decent used arms with used bushings to keep the compliance in the rear.
===============

Based on the above info, cost consideration and common sense physics, I voted no.
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Postby Glenn » Wed Nov 20, 2013 2:09 pm

The stronger arm is not the goal but rather an arm with a non-binding bushing. It isn't the arm that fails but rather the body mount and that can't be fixed easily.
It you have a rubber bushing in the arm and deflect that arm side to side, that twist load is transmitted to the mount and results in the mount failing. If there was a bearing there, the twist load goes away.
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Postby Glenn » Wed Nov 20, 2013 2:11 pm

Remember, we approved the mount repair kit because we have seen plenty of issues there.
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Postby ShadowBolt » Wed Nov 20, 2013 2:39 pm

The new stock upper rears are over $200.00 per set now. I think there is only one company producing the stock type unit. I went away from the PM3L this year. The car is way different and has to be driven different than with the PM3L but I like it way better. I don't know how long I will get out of the uppers now running the four link but running the PM3L I would go through a stock upper in two weekends.


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Postby suck fumes » Wed Nov 20, 2013 2:57 pm

Keep in mind that if you run a spherical upper and lower arms you will have to run a Panhard bar to keep the axle from shifting side to side. So that is another added cost. Plus the Panhard bar will bind once it reaches a certain point of flex. So in reality you are just chasing your tail and not fixing the problem.
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Postby cozog » Wed Nov 20, 2013 3:27 pm

Glenn wrote:The stronger arm is not the goal but rather an arm with a non-binding bushing. It isn't the arm that fails but rather the body mount and that can't be fixed easily.
It you have a rubber bushing in the arm and deflect that arm side to side, that twist load is transmitted to the mount and results in the mount failing. If there was a bearing there, the twist load goes away.


Since bushings are free and your logic is centered on the non-binding bushing isn't this a better option than allowing beefy control arms?:
http://www.steeda.com/store/steeda-sphe ... stang.html

And along Aaron's line of thought, if the control arms are beefed up and the mounts are beefed up, where will that stress point move to? PH bar? Diff mounting? Now those need beefed up?

It seems to me that replacing a control arm is the least evil of the choices, and easiest to maintain (i.e. spare in the trailer).
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Postby suck fumes » Wed Nov 20, 2013 3:44 pm

I think the RCR intent was to allow sphericals on the body side of the upper control arm. The steeda ones are for the diff housing holes for the upper arm.
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Postby cozog » Wed Nov 20, 2013 4:01 pm

suck fumes wrote:I think the RCR intent was to allow sphericals on the body side of the upper control arm. The steeda ones are for the diff housing holes for the upper arm.


Gotcha. Thought those would be a solution.

I'm rethinking this. It still sounds like a bit of a rabbit hole, needing to beef up one part after another. But I understand that sometimes that's what's needed to go racing. I'm all for eliminating future maintenance and r/r costs.

I'm rethinking this...
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Postby cozog » Wed Nov 20, 2013 4:04 pm

ShadowBolt wrote:The new stock upper rears are over $200.00 per set now. I think there is only one company producing the stock type unit. I went away from the PM3L this year. The car is way different and has to be driven different than with the PM3L but I like it way better. I don't know how long I will get out of the uppers now running the four link but running the PM3L I would go through a stock upper in two weekends.


JJ


This is disturbing to hear. I hadn't heard that the control arms weren't avail or in short supply. Who is the only mfr that's left?
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Postby soundguydave » Wed Nov 20, 2013 4:11 pm

The physics of the stock 4-link just flat suck. It works fine in pure longitudinal axis motion (acccel/brake), but quite literally the instant you put the car in roll, the upper arms are in bind. This puts tearing stresses into the bushing material as well as the mount. Going to a higher-durometer bushing (poly) only exacerbates the problem, and while sphericals would help, the real problem is with the stamped sheetmetal arms themselves, as well as the geometry of the design. Junkyard parts are a minimum of 10 years old at this point. That means a decade or longer worth of exposure to heat, ozone, salt, etc. that in my mind make dumpster-diving a non-starter. None of the pure aftermarket arms are legal, and AFAIK, the only source for OE upper arms is Maximum Motorsports, with prices WELL north of $200 per set.

If aftermarket arms were to be allowed, I don't think "where will the stresses go?" is a valid argument, now that the WR torque boxes are legal. It won't be through the PHB, and I seriously doubt that the cast-iron axle mounts will become the weak link.

It still cracks me up that we're allowing seven layers of band-aid to correct an OE design flaw, with potential costs skyrocketing (spherical bearings, torque boxes, consumable hard-parts, panhard to locate the rear if you run sphericals) while we treat symptoms, but not the underlying disease. There IS a simple, cost-effective (relative to the "fix" catalog) solution, a torque-arm, but we won't even consider it.

There is a reason they call it "quadra-bind," after all.
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Postby suck fumes » Wed Nov 20, 2013 4:14 pm

I run the 4 link and it works perfect for me. If the 4 link sucked that bad then ford wouldn't have invested a ton of money in development into it and wouldn't have left it on 3 generations of mustangs. It works great if you have the car setup correctly!
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Postby soundguydave » Wed Nov 20, 2013 4:15 pm

cozog wrote:
ShadowBolt wrote:The new stock upper rears are over $200.00 per set now. I think there is only one company producing the stock type unit. I went away from the PM3L this year. The car is way different and has to be driven different than with the PM3L but I like it way better. I don't know how long I will get out of the uppers now running the four link but running the PM3L I would go through a stock upper in two weekends.


JJ


This is disturbing to hear. I hadn't heard that the control arms weren't avail or in short supply. Who is the only mfr that's left?


AFAIK, there IS no current mfgr. Max Motorsports bought all the back stock when Ford disco'd them from the dealer parts supply chain. Not available through Ford Racing, either. At least, that's my undertstanding.
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Postby Glenn » Wed Nov 20, 2013 4:22 pm

cozog wrote:
Glenn wrote:The stronger arm is not the goal but rather an arm with a non-binding bushing. It isn't the arm that fails but rather the body mount and that can't be fixed easily.
It you have a rubber bushing in the arm and deflect that arm side to side, that twist load is transmitted to the mount and results in the mount failing. If there was a bearing there, the twist load goes away.


Since bushings are free and your logic is centered on the non-binding bushing isn't this a better option than allowing beefy control arms?:
http://www.steeda.com/store/steeda-sphe ... stang.html

And along Aaron's line of thought, if the control arms are beefed up and the mounts are beefed up, where will that stress point move to? PH bar? Diff mounting? Now those need beefed up?

It seems to me that replacing a control arm is the least evil of the choices, and easiest to maintain (i.e. spare in the trailer).


You keep focusing on the beefing up and that is not the goal. I focusing on the reduction of twist the chassis mounts see. Nothing else.
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Postby soundguydave » Wed Nov 20, 2013 4:25 pm

suck fumes wrote:I run the 4 link and it works perfect for me. If the 4 link sucked that bad then ford wouldn't have invested a ton of money in development into it and wouldn't have left it on 3 generations of mustangs. It works great if you have the car setup correctly!


Oh, it does work well, if you're out getting groceries or hitting the dragstrip. Throwing it into a corner is another matter. We get grinding noises in left turns (no witness marks mrom tire contact), and short of throwing new arms at it repeatedly, it stll comes down to roll-induced bind. Using bushing torsional deflection is just not the right way to locate an axle laterally.

As for Ford leaving the design alone, yes, they did, but I would bet BIG money that it was a cost-based decision, and not performance-driven. 90% of the people that buy Mustangs don't race them. And 90% of those that do, don't turn in their chosen form of motorsport.
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Postby cozog » Wed Nov 20, 2013 4:34 pm

Glenn wrote:
cozog wrote:
Glenn wrote:The stronger arm is not the goal but rather an arm with a non-binding bushing. It isn't the arm that fails but rather the body mount and that can't be fixed easily.
It you have a rubber bushing in the arm and deflect that arm side to side, that twist load is transmitted to the mount and results in the mount failing. If there was a bearing there, the twist load goes away.


Since bushings are free and your logic is centered on the non-binding bushing isn't this a better option than allowing beefy control arms?:
http://www.steeda.com/store/steeda-sphe ... stang.html

And along Aaron's line of thought, if the control arms are beefed up and the mounts are beefed up, where will that stress point move to? PH bar? Diff mounting? Now those need beefed up?

It seems to me that replacing a control arm is the least evil of the choices, and easiest to maintain (i.e. spare in the trailer).


You keep focusing on the beefing up and that is not the goal. I focusing on the reduction of twist the chassis mounts see. Nothing else.


check ur email.
Todd Johnston, #59


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