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Re: converting 70 Challenger to a rack and pinnion [Re: TC@HP2] #1266843
07/19/12 10:30 PM
07/19/12 10:30 PM
Joined: Jan 2004
Posts: 3,001
Coram, NY
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Joined: Jan 2004
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Coram, NY
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Base TVS w/new rear shackles from Summit (2559), then go over to firmfeel for shocks (400), 1.06 Tbars (325) , bigger tierod sleeves (225), sector support kit (135),stage whatever box (330), fast ratio idler and pitman (285).. still under 4300.






This also has the benefit that you don't shell out all the $$ at once. You can build the system over time. That can't be done with Alterk. i think Dan pointed that out too.




I'd also throw in that if you've added any goodies over the years, you don't have to toss them out. Maybe you plated your lower control arms? keep 'em! upgraded to poly bushings? keep 'em!

years ago, my power steering box was shot. I picked up a firm feel stage 2. I also added us cartool subframe connectors. Nice to know as I build my "tvs-like" suspension that I'm not tossing out parts that I paid good money for already.

Re: converting 70 Challenger to a rack and pinnion [Re: Rick_Ehrenberg] #1266844
07/25/12 03:29 AM
07/25/12 03:29 AM
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Posts: 185
east bay ca
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My 2¢...as published in Mopar Action:

I have found a couple consecutive negative remarks about RMS products published in recent issues of Mopar Action and I am seeking to understand why. This came as a surprise to me because I can find no negative data on any RMS product no matter where I look. Many builds, including my own, that are pursuing handling related performance upgrades often include RMS. A much smaller percentage use XV (due to cost and mods) and even less Magnum Force. Bill at RMS really seems to have his heart dedicated to building quality products capable of improving street and road race performance with more than 10 years of product application to support it. If you have experience with RMS quality problems, or data to support the “questionable” status, please share it with us enthusiasts seeking to get our Mopars onto the tracks. This way we can make the necessary improvements, mods etc. to appropriately benefit from these kinds of upgrades. There should not be fear, uncertainty and doubt between fellow enthusiasts. I understand how the RMS system distributes cornering forces on our car’s infrastructure differently from the T‑bar but is there data of failures resulting from this? I can’t find a single case of failure of any kind. If you know of any please share and help us understand what is “questionable” about these products. Maybe together we can make the perfect solution.
My ’71 Challenger is using XV in the rear and RMS in front with all XV bracing products including rad support, inner fender bracing and connectors.
Thank you for your help and expertise.
—Daniel Niclas, San Jose, CA

Dan—
On a drag car, the RMS AlterKtion stuff is great—takes out lots of weight, makes more exhaust room. But there’s a laundry list of potential problems with using this on the street and/or road course. In no particular order...
> Heim joints—anybody’s heim joints—just do not last on the street. Even with added boots, they still don’t come anywhere close to OEM tie rod end durability. And, as an artifact of their construction, they are much more prone to total failure than an OEM tie rod end.
> The cantilevered outer tie rod end, spaced up with a stack of shims and spacers (for bumpsteer correction, no doubt out of necessity, because the rack could not be installed correctly due to interference, and a “generic” steering arm is used), is a scary potential catastrophic failure point. The loads on that bolt, should you be in a hard corner and hit a pothole, are astronomical. Some photos I have seen show the spacer tube welded to the steering arm, which may offer partial mitigation.
> The suspension (spring) loads are now taken by the front rails. They were, in the OEM Chrysler design, primarily, imparted to the torsion bar crossmember. On a drag car, where you’ll have a roll cage tube passing thru the firewall and tied into the top of what was the shock tower, the problem is pretty well mitigated. But on a street car, where you seldom see that, you’ll be inducing lots more chassis flex. Just hook up a small video camera and watch how the steering shaft telescopes over bumps. The Chrysler OEM system had a lightweight front structure with springs (T-bars) mounted low and rearward, damn near “Formula One” technology. Why give that up?
> The K-member is no longer a “K”, drastically reducing its ability to prevent the front rails from “parallelograming”. This would significantly reduce crashworthiness (especially in an offset frontal crash) as well as reducing overall chassis rigidity.
> I believe that the spindle diameter is smaller than stock. In 1973, Chrysler increased the spindle diameter as weight, tire size, wheel width, etc., were all increasing.
> The frame thru-bolts will crush the frame as the bolts are tightened. There should be tubes welded into the frame, EG: stock transmission crossmember, etc.
> Every pix I have seen shows brake hubs that have no way to pilot the wheel. ESPECIALLY road racing, hub‑centricity is paramount.
> There’s near-zero compliance—nothing to replace the OEM tension-strut bushing. Instantaneous impact loads are sky-high, exacerbating the above negatives. And the effective footprint of the LCA, which, in the OEM design, included that tension strut, is greatly reduced (nearly 50%) in the RMS design, further reducing its ability to safely handle impacts.
> The steering column’s pot coupling is eliminated. The pot coupling is what compensates for chassis flex; deleting it means that one of two things will occur over time/abuse: Either the nylon shear pin on ’67-up non-E-bodies will break, or the upper column bearing will fail (possible on any Mopar).
> You’ll note that there is not one weld in the factory suspension components. By design. That’s not to necessarily say that welds are always bad, but, if they can be avoided, you’ve eliminated one area where, unless each weld is X-rayed, you just don’t know what to expect over the long term.
Mr. Reilly has always thought I’ve had it in for him. That’s simply not true, I think he has designed a very good drag-race suspension conversion. It’s just when you take a drag race front end, sell it for street use, with nothing even close to factory durability and stress testing, that I worry. Lack of reported or known failures isn’t proof of anything: Space shuttles made many flights “before,” the Silver Bridge carried tens of millions of cars safely, then one day it simply vanished into the Ohio River, killing hundreds, to cite just two well-known examples. When a fleet of test cars have spent 250,000 miles each being hammered at a PG, then get back to me. This applies to the competitor’s products as well. If I didn’t point these things out, I’d be complacent. Reilly, in fact, does point this out, go read the disclaimer that is in the RMS documentation:
“....By purchasing this product, the buyer/end user assumes all risks associated with its use and agrees to having the proper skills for it’s [sic] installation. Reilly MotorSports Inc. and its suppliers will not be held responsible, liable or accountable for any injury, damage, loss, penalties, or fines that occur from using this product in any manner.”
For my dime, upgrades to the basic T-bar system are the way to go. Firm Feel, XV’s level one, and even Hotchkis have parts and packages that get the job done, although Hotchkis’ swapping (giving up) brake anti-dive* for more camber gain doesn’t thrill me either. If you’re building a straight-line-only drag car, your opinion may vary.
Guys often confuse “race” parts with “durability.” Often the opposite is true. EG: Aluminum con rods and rocker arms, “race” axle shafts and gears, tiny radiators and fans, super high-lift cams, and many more. A lot of guys, of course, do get by with race parts on the street. How? Simple: The car sees 10 cruise-ins or 300 miles a year, smooth roads, 40 MPH, etc.
If I don’t take care to see that there’s some kind of disclaimer in articles featuring cars with these suspension conversions, we could be seen (legally) as endorsing them—which we are not.
To boil this down: Again, I’m sure the RMS setup has good geometry (even has anti-dive) and drives just fine. On a drag car, the extra header and oil pan real estate, and reduced weight, would be the hot ticket. It is the specter of sudden, catastrophic failure in “real street” use that worries me.

*—See p. 35 for more on this. {Aug 201 issue}

Rick





What about the XV system? it looks different than the RMS system. It looks more sturdy and like it could be worth the extra 2k it cost. It doesnt look like it puts stress on any of the front end. What do you guys think?

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