Ford drivers inside please.

[Glenn]

There is the GM cars too. If they do allow a TA for mustangs one day then they should also allow aftermarket ones for GMs

 

Disagree. Adding TAs to stangs only evens the playing field.

 

Assuming the field isn't level now.

If the TA's are allowed, a fixed pinion angle may be required. One that isn't provided by current Mustang TA manufactures. Changing pinion angle changes accell/decell grip. Allowing aftermarket Ford TA's will require the same for GM's. Also consider the issues w/ the GM's that do have it. Rear wheel hop limits the braking force allowed. The TA for GM's is also a stamped sheet metal part. Acts like a spring and is marginally up to street duty.

 

Back on topic (the comment above).

The playing field is leveled by various means.

Aero

F/R weight bias

Track width

wheel base

area under the curve (HP/TQ)

legal trans gear ratios

OEM suspension design

 

Change any one of those issues and the balance gets changed.

 

My guess is, allow TA's for Mustangs and the weights will be made pretty much the same for all platforms. GM's will get some track width back or Mustangs will have some taken away (Fords have been given a greater percent increase over OEM than GM's by a wide margin). If we take it away from Mustangs, who's wheels are now not legal?

 

So while allowing the TA's may have been the right call 3-4 years back, it was impossible to tell that from way back then. The path forward at the time each change was made was finding the lowest cost option that impacted the fewest people. Looking back we can always see what the correct answer was, it's the looking forward part us humans haven't figured out too well. so

 

So saying allowing TA's for Fords will level the playing field is not right. Most feel the performance envelope of all the cars is pretty damn tight right now.

 

Back on topic....

 

From all I have read in this thread, it seems the argument for TA on the Fords is simply for reliability and cutting costs of maintenance. Not leveling the playing field between platforms.

 

When I initially began planning to get into CMC, I wanted to run a Fox. I still do. I even PM'd and chatted with Michael Mosty about his car and wow....what a guy. Very welcoming and willing to help. Thank you Michael.

 

But I have to say from my standpoint, I really don't want those rear end problems everyone hear talks about. I don't like the sound of that. And I have since decided to go with the Fbody platform SIMPLY because of the RUCA problems with the Fords. If the rules were to change and allow TA on the Fords, I would change my mind back to a FOX in a heartbeat because I know those cars very well.

 

Please correct me if I'm wrong, but the arguement here is not about performance and lack of parity between platforms, but more about about reliability and overall cost of maintenance. The whole point of CMC is affordable muscle car racing right? If decisions could be made to lower costs and increase reliability, wouldn't we make them?

 

You are 100% correct and spot on w/ all points.

As I said earlier in this thread ..... The Directors always try and find the simple solution to the problem at hand that will affect the least number of drivers. Each solution was presented and thought it would solve the issue.

At one time only repairing a failed torque box was legal, then we allowed some welding prior to failure. Once we realized that wasn't stopping it, we allowed the battle box upgrade. It has only been a few short months since that was allowed. Not one single region has run 1/2 a season yet w/ that change. If more cars are seeing what Jerry see's, then my guess would be that allowing TA's would be better for all in the long run. This could also remove the need for the track width allowance and required fender mods. This could result in a major drop in costs to build a Fox. Only time will tell. So while most TA advocates in the earlier years of CMC wanted a TA for platform parity, the Directors felt that could be handled w/ weight and track width. It has worked very well thus far. Now we see a chassis failure concern, that may not be easily resolvable. The only fix may be a TA. Time will tell.

[aschroeder]

I'm not convinced the track width change made any significant difference in my pace. I have yet to reset a PB with the wide track configuration. I do (and did) have concerns about making severely difficult to reverse body modifications to my car that would be dropped in the foreseeable future.

 

To answer the original question, my fox has the factory 4-link and a homebrew PHB mated to a SN95 8.8 with MM adjustable RLCA's (the adjustment is disabled, although I supposed it can be reenabled now). Factory bushings on the RUCA.

 

I have axled hopped the ever-loving-crap out of that axle when I lost a shock mount off the axle at Sonoma, I've broken a PHB axle mount, and I pretty routinely experiment with finding too much rear brake bias to give you an idea of the abuse I've put the car through. I've replaced the RUCA's once and it was more from the fear mongering and preventative maintenance view point than any discernable damage. I believe they had ever so slightly elongated bolt holes. The jury is out as far as I'm concerned, but when I broke the PHB, the balance of the car was disrupted, but not so bad that I don't think it could have been corrected with spring rate changes.

[trublu]

I haven't checked in on this thread for a week or so, man did it get off track...

 

I submitted the RCR to Glenn and Al to permit non stock uppers. It never mentioned or intended to create the impression that it was a precursor, to a torque arm.

 

Personally I would prefer to run sphericals at both ends of the arms. In my opinion the reason we have issues with damage or failure of torque boxes and control arms is due to the bushing material resisting change to its shape as the rear end articulates. The resultant forces are implied to the arms and torque boxes, causing wear over time or structural damage depending on the severity. Spherical bearings, already permitted by the rules, give a fixed center of rotation and do not imply the same forces back into the arms or boxes.

 

Also in my opinion, driving style is a significant factor. The RCR was never intended to delineate a good from bad driver nor will it fix one who isn't. Suck Fumes, using the stock 4 link, is clearly a good driver who is also very smooth with cornering inputs. Michael makes his fox do things most of us could only wish for using the poor mans 3 link. Jerry is also a good front running driver who has experimented with set ups and now uses the 4 link. All use the the right pedal to assist the steering wheel from time to time, some more than others.

 

So far as research goes, I did a lot of practical investigation and far less internet browsing to form my opinion. I encourage a day or so on your back under the rear end of the car. Remove the rear springs and spend some time with the trolley jack articulating the rear suspension through its full range of motions. Do this with the stock 4 link, then the poor mans 3 link, then combinations with panhard in/out and again with the various bushing styles available. Keep in mind the forces that would be acting on the car in a race situation as you go through the exercise. This is what influenced me to reinstate the 4 link, remove the panhard and submit an RCR to allow a stronger upper link to compliment the battle box RCR and my choice of bushing on the torque box end of the control arm.

 

To say the least I'm disappointed this thread got so far off track, personally attacking a guy I consider a friend. I'm even more disappointed the RCR looks like being denied. Tis what it is... Guess I'll start looking for a spherical to fit the other end of the stock arms once I spend another $500 on a pair of replacements. Thanks for the effort Glenn.

[Houstonnw]

 

Personally I would prefer to run sphericals at both ends of the arms. In my opinion the reason we have issues with damage or failure of torque boxes and control arms is due to the bushing material resisting chahnge to its shape as the rear end articulates.

 

 

I encourage a day or so on your back under the rear end of the car. Remove the rear springs and spend some time with the trolley jack articulating the rear suspension through its full range of motions. Do this with the stock 4 link,...

 

I thought one issue with the stock 4 link was that the upper arms essentially need to get longer and shorter as they move through their range of motion, which the big, soft stock bushings allow for. Are you sure that you can use spherical bushings on the uppers of a 4 link?

[suck fumes1548534743]

Using sphericals on both ends will not work cause even with a PHB the axle will still shift to much and cause a dangerous situation. People have already tried it.

[trublu]

I disagree and encourage you to gain your own understanding through the practical approach rather than third hand opinion as suggested previously. My investigation showed no binding of the rear suspension through the complete range of motion.

 

Again though, the choice of bearings is not what is being debated in this thread, it is the RCR to permit non stock arms. Bearing or bushing selection is already your choice.

[suck fumes1548534743]

Putting a car on jack stands is a lot different than "practically" driving it on track. Again, people have tried it here in Texas! And I'm not just talking about CMC.

[blk96gt]

As another data point, I took a look at Sam Crumpacker's car this weekend. He hasn't raced in a couple years, but he had raced for at least 2.5 years with the uppers that are still on the car. His passenger diff side bushing was pushed out just like mine was, and the sleeve was grinding against the inside of the arm. Sam and I both run the same set up (MM PHB, MM HD lower arms, H&R Super Race Springs). His bushing was in much worse shape than mine was, probably due to the length of time he had been driving with it pushed out.

[MHISSTC]

I thought one issue with the stock 4 link was that the upper arms essentially need to get longer and shorter as they move through their range of motion, which the big, soft stock bushings allow for. Are you sure that you can use spherical bushings on the uppers of a 4 link?

 

That is exactly my understanding also, along with the reason having all spherical bearings wasn't really a solution to alleviating the problem of bind inherent in the design.

[Dillon]

Would it be feasible to use a shock in place of a fixed arm? I'm surprised that none of the aftermarket companies have done this if so. I've been looking, but the trouble is, of course, finding one that would fit.

[suck fumes1548534743]

Motorcycle shock would prob work

[trublu]

Motorcycle shock would prob work

Yep if pinion angle was ignored.

[MHISSTC]

OK. We might have a solution for folks who are still running a whole OEM 4-link like we are. No panhard bar. Steeda Super Race (white) springs.

 

Back when they were still available (they aren't now, I checked) David Thede and I each bought a set of the Steeda Heavy-Duty Upper Rear Control Arms. One set was for his car, the other was for mine (which hasn't been completed yet). When we were building The Pumpkin, we had these arms OK'd for use in place of the OEM set because they are really just an OEM set of arms with the OEM rubber bushings and some very simple reinforcements added along with a lovely zinc dichromate plating. The reinforcements amount to a plate that bridges the gap in the stamped arm to stiffen them up along with a couple of washers tacked to each side of the bolt hole to reinforce that area.

 

Summit Racing has a picture of them even though they are no longer available, so you can see what a brand new set of arms looks like.

 

 

We have been super paranoid about these arms on The Pumpkin ever since this thread began and we started hearing horror stories of folks having their bushings, arms, and torque boxes torn apart.

 

To satisfy our own curiosity, we finally jacked the back of the car up and took a close look at the arms. They looked OK bolted into the car. But we wanted to be sure, so we pulled each of the two upper arms out of the car to give them a close inspection. GOOD NEWS. Other than being slightly polished where they were in contact with the rubber bushings, the bushings on both the chassis and axle side look brand new, and the arms, nuts, bolts and torque boxes look just as good as the day we installed them during one of our upgrade sessions about 6 years ago.

 

Instead of purchasing a new set of expensive OEM arms, aftermarket arms, or going with a completely different and more expensive setup that is going to need another period of testing and development, why don't some folks try modding a set of cheap ugly used, but still in good shape OEM arms with the modifications that Steeda did to the OEM arms when they were still available? Weld a plate across the arm to bridge the gap and stiffen them, and weld a couple of washers on either side of the arm to reinforce the area surrounding the bolt hole. This would be a cheap modification and does nothing to change the OEM mounting dimensions. I believe the rubber bushings are still available if you need those. I didn't check to make sure. We installed a new set of rubber bushing on the diff side to match the new ones in the arms when the arms were installed.

 

Below are the pictures of the arms and such that we took earlier today.

 

 

 

 

 

 

 

 

 

 

 

 

[Glenn]

Per the current rules, those are not CMC legal.

[MHISSTC]

When we were building The Pumpkin, we had these arms OK'd for use in place of the OEM set because they are really just an OEM set of arms with the OEM rubber bushings and some very simple reinforcements added along with a lovely zinc dichromate plating.

 

Glenn,

 

I think you totally missed the point of us posting this.

 

It was not to discuss the legality of our rear upper control arms. They were already approved, and no, I didn't save the email exchange from back then.

 

The point of us posting the pictures and story was to show what we think is a much simpler and cheaper solution to having a set of durable rear upper control arms that doesn't require the purchase of new and expensive OEM arms, aftermarket arms, or going full-bore with a change-over to a torque arm or any other odd or potentially more expensive and creative solutions.

 

Tell us instead if you think this is a better solution or not.

[suck fumes1548534743]

Wouldn't the extra stiffness add more strain on the bushing itself causing it to push out faster??

[BADVENM]

Like MHISSTC said, the bushings look in excellent shape. We've had those arms in there since at least 2009 and possibly 2008. It was only in 2013 (I think) where we started hearing the grinding noise. Could have been due to the track width adjustments we made and/or me driving the car harder then in previous years.

 

I think we're gonna try and put a keyfob camera near the control arm that is giving us the grinding noises that we're hearing under certain conditions for right hand turns. We're hoping it will shed some light into whats going on.

[MHISSTC]

Wouldn't the extra stiffness add more strain on the bushing itself causing it to push out faster??

 

I'm not sure, but I don't think so. I'll try to explain why.

 

Putting OEM upper control arms into race duty is overstressing the design by adding more power, more grip, and more braking. And with more strength already added to other areas in the rear suspension system, it appears the rear upper arms are now the weak link in the system. The only thing we may not be providing more of is additional articulation of the rear suspension system. That is likely a good thing.

 

For example, I know from driving them both and looking at video and pictures of both cars that I produce much less rear suspension articulation and side-to-side axle movement in The Pumpkin (higher HP, higher speeds, heavier braking, heavier 8.8 trac-loc rear, lower ride height, stiffer springs, beefy rear sway bar, stiffer upper rear control arms, stiffer lower rear control arms with less compliant bushings, lighter car), than I can produce with my stock '83 Capri V6 (low HP, lower speeds, lighter braking, lighter 7.5 open diff rear, stock ride height, limp springs, stamped steel upper and lower control arms with all rubber bushings, no rear sway bar, heavier car). I'm much more concerned about blowing a rear suspension bushing in my daily driver Capri when I take it to the track then I am blowing one in The Pumpkin because of all the twisting and moving around the rear axle does in the Capri.

 

I can't prove it yet, but my hunch is the modified OEM uppers we are using are stiffer and therefore twist and deflect much less than the un-modified OEM uppers and are helping to extend bushing life by maintaining the vector of bushing deflection within it's design tolerances when used within a complete OEM 4-link suspension system that hasn't been modified into a PM3L and also hasn't had the deflection vectors modified by adding a panhard bar. By staying within the design parameters as far as the direction of forces is concerned, even with the likelihood that those forces are greater, I think the bushings are still allowed to deflect as they've been designed to do (although to a somewhat greater degree), but are much less likely to be twisted, contorted, and torn out of their shells.

 

Something else got us thinking when we were taking pictures of our rear upper control arms and when we were putting them back in. Are folks properly torquing the bolts when they are installing their suspension pieces? I have a factory service manual I use to look up all of the torque values when we install any parts. I can see how either under or over torquing these bolts could lead to additional wear and tear or a premature failure of the mounting locations and bushings.

 

We plan on placing several small cameras in various locations under the car at a future event to look at the suspension pieces in use. We still need to track down a noise we have in hard right hand turns when the suspension is under full compression. It sounds like tire tread in a wheel well or a u-joint making contact with a bolt on a driveshaft loop (both of which we've had before), but we have zero signs of rubbing or contact anywhere under the car. We've even had the diff cover off and there are zero signs of problems in there. I'm hoping we can locate the source of this noise by using the cameras. We may also gain some insight as to why our suspension parts are remaining intact after years of use while other's are failing very quickly.

[trublu]

So the RCR was to allow non stock arms. This thread has taken it through a progressive discussion which included torque arm versus four link, spherical bearings versus rubber bushings and now looks like it'll take a track toward modified stock arms versus stock arms. At least we are getting closer to the RCR topic.

 

Isn't a modified stock arm still just a non stock arm? So if this was either deemed a solution in the past or could be considered one now shouldn't the RCR be approved and let the driver choose which route to take?

 

For some folks welding might not be desirable or within their skillset.