Re: trailing arms: Goodmark vs. ECE vs. OEM
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The following excerpt is copied from the SA Design book on "Muscle Car Handling Upgrades: Rear Suspension Systems": Truck-Arm Suspensions The truck-arm design is another suspension that was never used by OEMs under any muscle car. It was used on many pickup trucks and Suburbans, from 1960 to 1972, hence the name “truck arm.” I mention this system because it has developed a small following in the ProTouring/G Machine segment in recent years. First adapted for use on racing cars by NASCAR legend Junior Johnson in the mid 1960s, it’s still used on every NASCAR Cup car today. The package consists of two very long arms with an I-beam cross section, rigidly attached to the axle with U-bolts and converging in plane view so they’re very close together at the frame mounting point. These arms are quite rigid longitudinally, but fairly flexible in torsion. This is no mistake! In order for the rear axle to articulate, the arms need to twist. This system is in bind whenever it moves, but the geometry and configuration of the arms makes this binding fairly linear. Mounting pads for a pair of coil springs sit on top of the arms just forward of the axle, and lateral axle restraint is almost always handled with a Panhard bar, although a Watts link would also work. Since this suspension is most often used on circle track cars that only turn left, the Panhard bar (usually called a track bar in NASCAR circles) can be used to induce jacking and tune the car’s behavior. This is perhaps the only application where a Panhard bar may be a better choice than a Watts link. About Us: Founded in 1993 CarTech, Inc has become one of the leading publishers of how-to automotive titles for the hardcore enthusiast. In 1995 CarTech purchased the S-A Design line of book from Larry Schreib and Larry Atherton who had published their first book in 1975 titled, The Chevrolet Racing Engine, by Bill Grumpy Jenkins. This single title gained wide recognition as “the bible” of high performance engine design and assembly. CarTech has continued to expand on this tradition and now has nearly 150 titles available for the enthusiast, in a wide variety of formats – from print to digital to video. Today, our publishing efforts include our traditional performance “S-A Design” titles along with race histories, biographies of industry icons; in addition to a number series that further assist readers with their projects. So, using a spherical joint in place of the front rubber bushing allows articulation w/o the instant bind . That being said, spherical joints only articulate so far before reaching their limits as well but that would be extreme articulation (think 4x4 trail climb territory). The factory arms flex is still better for the system in over-all function as designed but structurally stiffer square/round tube works & is more consistent within the range of motion allowed by a front joint that articulates. |
Re: trailing arms: Goodmark vs. ECE vs. OEM
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Re: trailing arms: Goodmark vs. ECE vs. OEM
Do we know there is no flex, sounds like twisting is the key word here, with tubular/boxed design or just less? Are NASCAR arms two pieces of light channel tacked together or are they tubular? I realize roundy round on a race track at 200 mph has different requirements. Very limited requirements compared to road driving.
All I am saying is are the ECE trailing arms really such a bad idea that there is some significant negative affect on performance? Are they really a bad idea? Something we wouldn't want? |
Re: trailing arms: Goodmark vs. ECE vs. OEM
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Are solid, tubular bars bad? Do they work? Yes. Are they a bad idea? If you know the OE arrangement was designed to achieve their articulation through torsional flex via the front rubber bushings & I-beam construction but delete both of those options from a replacement arm you either need another method that allows articulation or they will bind sooner than the OE stuff would. It's that simple. Will the 'Average Joe' that occasionally putts around town notice? Probably not. But, that does not make them better. |
Re: trailing arms: Goodmark vs. ECE vs. OEM
This is good conversation guys. Glad we can keep a good discourse on things unlike some other forums I've been on in the past where they tend to get ugly upon the first disagreement.
In any event, I think I'll be fine with the ECE/stock appearing arms. I'm not going to beat my truck, won't probably be hauling anything over 1000 lbs. They should be good. And while I think I could have gotten them when I first posted my question and even pulled the trigger on the CPP arms, the ECE arms are sadly no longer available. |
Re: trailing arms: Goodmark vs. ECE vs. OEM
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The weird thing is.... The title indicates 'Stock Type Rear Trailing Arms 6072STA-K' while the overview lists them as 'Control arm style: 'tubular/boxed'. One of the two is incorrect. The image displayed is OE/stock style arms. |
Re: trailing arms: Goodmark vs. ECE vs. OEM
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Re: trailing arms: Goodmark vs. ECE vs. OEM
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Thanks Scoti |
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