Truck Armed 57 Project

[F1 Speed]

Looks like a really killer 57 Chevy project is nearing completion at Metal Works Performance Engineering (http://www.metalworksperformance.com/_57chevy_jr_.cfm) . Super nice detail work on the chassis and suspension. I got super excited when I saw how the custom Truck Arm suspension turned out. I had the opportunity to see this car in the mock up stage and the attention to detail is incredable.

Kip has a couple of other versions of this Truck Arm set-up that are almost complete. The A-Body version is really trick! I'll try to keep you guys updated as to whats in store for the next version as the A-Body testing and development continues.

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More here (http://www.metalworksperformance.com/_57chevy_jr_.cfm)

[93Polo]

Good looking work

How much does the A-body set up run? Could you buy just the panhard rod?

[wally8]

That's really nice workmanship but it appears they missed the fact that a truck arm should not be torsionally rigid if you want it to work properly. That's more like a swing arm rear suspension and not a good one at that.

If handling is your game, that's going to suck. It will look great at the shows though. It's as nice looking as anything I've seen. Very cool from that perspective.

Wally

[TonyL]

looks like that front swingarm connector may have a spherical bearing in it. In that case it might be ok.

[F1 Speed]

Swing arm suspension? Nope. Torsionally ridgid? Not even close. This thing articulates like no other set-up I've seen before. Is it a full on race suspension? No, but it flat out smokes any leaf spring, 4 link or 4 bar that I have ever seen. What your looking at is the same basic set-up that GM designed over 30 years ago. It's also the same design that all the Nextel Cup and Bush stock cars have been using for years. Are there other rear suspension designs that work better? Sure there are, but in my opinion for the performance, cost and packaging involved this set-up fits nicely in the middle of them all.
I find it intriguing that a 30 year old design can be utilized effectivly with with todays technology and parts. I guess thats why the NASCAR boys have stuck with it for so many years on the oval and road race tracks. Basic design, cost effective and packages well to go along with the performance. I'm in, especially now that I have experienced the performance of this set-up first hand.
I would love to hear your opinions or see the expresions on your faces after you have gone for a ride in a properly set-up truck armed car.

[sinned]

It's also the same design that all the Nextel Cup and Bush stock cars have been using for years. I find it intriguing that a 30 year old design can be utilized effectivly with with todays technology and parts. I guess thats why the NASCAR boys have stuck with it for so many years on the oval and road race tracks. Actually the Nascar boys are stuck with because the guys that write the rules for Nascar say they MUST run it. Given the choice they would almost all run a 3-link.



Any reason with all the mods done to this chassis he went with a rear steer?

[Mean 69]

That is a really pretty show car chassis, but I'll have to agree, I don't dig the truck arm approach as it seems to be applied to this example. Truck arms can be pretty effective, but it is no question that the NASCAR guys use it as a mandate rather than choice.

Now, a few weeks back there was a not-so-nice thread regarding a SUPPLIER that defended his product without a whole bunch of technical analysis, of course that is being kind. So, knowing that some of the other folks on here know pretty well how the truck arm setup works, with specific emphasis on bind, can you please explain, specifically, how a ladder type tubular construction of the arms themselves would be superior to the traditional I beam construction used in all truck arms setups both commercially avaliable, as well as those used in NASCAR? Free body diagrams welcome.

Those of you that know the answer, please don't shout it out, we are trying to have the suppliers answer the questions, specifically, at a higher standard than that of our ordinary members.

Regardless, damn nice craftsmanship. If the rest of the car looks this good, it'll be a really nice ride.
Mark

[F1 Speed]

First off I am not the vendor or supplier for this set-up I just happened to be in the right place at the right time when this project was nearing completion. I thought it would be something cool for everyone to check out so I asked Kip if he would mind if I threw a few pics up for everyone to check out. As I stated earler I was just giving my own opinion as to how I veiw this set-up through actual real world seat of the pants experience. As far as suspension bind goes, I didn't see or feel it but then again I am no suspension expert but I do know how a properly set-up suspension should feel and react. It's not the best suspension available I admit but for me it flat out works with no bind. Once again I'm no expert but I have rode in a lot of cars both for the street and semi competition. A race car driver probably would not be happy with this set-up if he were given a wide open and unlimited choice.

[Travis B]

I talked to metal works last night for awhile on the phone seemed to be very knowlegable on the truck arm set up....I told him about the posts here and at lateral-g.net! He wasn't at liberty to say alot because they are not releasing anything for awhile......

[wally8]

F1 Speed,

You were right in posting that it was something cool to look at. Where you went wrong was saying it was better than any other suspension you've ever seen, saying uninformed things about NASCAR usage and casting aspersions that people don't know what a "properly setup car feels like".

I've got 250+ pit passes worth of racing experience with literally thousands of laps of suspension tuning and I'm definitely not the smartest guy on this board. I've also toured every Cup shop in the state of NC and have seen everything behind the scenes of Hendricks Motorsports, so I seen me a few Cup cars as well (notice I'm using the lingua franca here for added effect :-)).

I also know that "seat of the pants" isn't worth any more than what comes out of the orifice that those pants are covering.

With that, I will stand by my opinion that while awfully pretty, that suspension wouldn't be a good track choice and that it is indeed a swingarm setup. It's a poor one because the axle mount is rigid. (truck arms are swingarms too but I differentiate only because of the torsion factor)

Gotta be careful about making claims on this board......


Wally

[F1 Speed]

Wally,
Your 100% correct about being careful in how you state things on this board. Especially in this suspension section where there seems to be a lot of opinions and because of that things seem to be taken out of context as to what was really trying to be stated. To clarify further I was only trying to convey My own personal experiences with this set-up as to anything else that I personaly have delt with in the past. With that said I to stand by my opinion about this set-up. For my project I think it will be perfect for what I intend on using my car for.

[69boo307]

What exactly is a 'swingarm' setup, and what part of the setup pictured causes it to be one?
My HTH truckarm setup looks very similar. The arms mount to a crossmember, they attach the axle in the same way as these, and there is a horizontally mounted panhard rod with spherical ends that keeps the rear end centered under the car. One end attaches to the driver side of the axle, the other end to a frame mount on the passenger side. The only difference I see here is the coilovers, I have coil springs on adjustable spring jacks and the shocks mount outside them in the stock location.

what's different about this one?

[yody]

i believe(more of a guess here) that those arms "swing" up and down, since they are ridgidly mounted to the crossmember there is no "twist" to them. I believe most truckarms use a bushing in the front which allows the arm to flex some or "twist" kinda like a leafspring with a rubber bushing in the front. I would think that setup would cause major bind, also I think an I beam is much stronger than what is pictured there(??)

[Mean 69]

Yody, close, but there is really more to it, and it is all about the I beam itself. I would imagine the forward pivots use some form of spherical bearing, which is fine, it will act largely like the rubber type bushing, though it will indeed cause a little more bind in pure roll.

The real issue is the ladder-tube type bars. They are a LOT more torsionally rigid than an I beam. In order for this setup to work at all, there must be some way for the arms themsleves to deform in roll. The reason is that the forward intersection point for the arms is not at the same point. If you extended the two foward points to become one central pivot point, and used one bearing (thus creating a rigid triangle between the two truck arms, and the rigid rear axle, it would basically be one solid structure), bind would not be an issue. But, because the two forward pivot point are NOT at the same place, they MUST be able to move freely from each other, geometry demands it. Because they are largely constrained by the bushing/bearing, etc, something ELSE has to give in order for the thing not to break. For the traditional truck arm, the torsional flexibility of the I beam (really strong in pure bending, but relatively "soft" in torsional bending) is that "ELSE." The approach here may be an improvement in the pure bending (i.e. along the vehicle centerline, largely vertical forces), but creates a far more rigid torsional structure: bind.

M

[Travis B]

I have been waiting for someone to answer that question......Why they need to flex and bend.....
I have asked several people that same question, I even asked the guy I spoke with at metal works but he was not a liberty to talk about it!
Thank you Mean69

[69boo307]

ah, interesting. My setup has big rubber bushings where the truckarm attaches to the crossmember, and I have the I-beam style arms.

[Travis B]

ah, interesting. My setup has big rubber bushings where the truckarm attaches to the crossmember, and I have the I-beam style arms.

Are you happy with your set-up?
Who did your work or where did you get your stuff!

[TLWiltman]

If this helps...

The standard truck arm is not only an I-beam (strong in bending, weak in torsion as mentioned), but is actually two channel sections stitch-welded together. (weaker yet in torsion?)

... ][ ...

It's crude, but an illustration nonetheless. Also, there is a company by the name of Speedthane that makes bushings with different compounds. There are, IIRC, 4 different compounds, each of a different hardness. In addition, there is the monoball (seldom used by the NASCAR guys, shocks the tires too much apparently). By what I can figure out, the bushings are used in various combinations to control roll steer and how hard the tires get "hit" under power.

So it seems to me...

1-the bushings are designed to deform during changes in power application (braking/acceleration), as well as during roll, in a fairly predictable and controlled manner. All due to geometry already mentioned.

2-the arms are designed to flex torsionally in roll. Again, in a fairly predictable and controlled manner.

So I'm a little skeptical...

1-while there is bind in the system it is, as we would call it in my line of work, a "planned event"-"mitigated accordingly". While the truck arm is a simple system in terms of packaging and installation, it seems that the planned use of bind makes the system somewhat more complicated when the design is changed/modified.

2-that said, I would be pretty skeptical of anything that changes the design much from how it's currently used. NASCAR uses the design in a very specific way. The HTH stuff doesn't deviate much from that (merely for fit within an established chassis). The MetalWorks design is a pretty radical departure from standard, and that departure is made in a functional part of the design... Testing is in order here.

I think that is what's being said. Then again, maybe I'm screwy:hammer:

[BRIAN]

F1 in your opinion it flat out is the best thing you have ever seen. You shared the pics and your opinions. There are always those that will disagree in some way. The technical stuff is very interesting reading. I think what a lot of guys fail to remember that these are STREET cars not full on race cars. In a street performance application how does this system stack up? Also where are all the suspension set ups from the guys who know exactly what is wrong with the above? I would think a particular set up works for a particular type of racing correct? I am not looking for argument and actually love the info. I just wish guys would stop judging everything as it was going on a full on race car for their specific application. I guess Metalworks is going to have to put that thing through the paces and then I will judge the results.

[sinned]

F1 in your opinion it flat out is the best thing you have ever seen. You shared the pics and your opinions. There are always those that will disagree in some way. The technical stuff is very interesting reading. I think what a lot of guys fail to remember that these are STREET cars not full on race cars. In a street performance application how does this system stack up? Also where are all the suspension set ups from the guys who know exactly what is wrong with the above? I would think a particular set up works for a particular type of racing correct? I am not looking for argument and actually love the info. I just wish guys would stop judging everything as it was going on a full on race car for their specific application. I guess Metalworks is going to have to put that thing through the paces and then I will judge the results.

No one has stated that is not the best from a full out racing point of view. I believe the point was that it will behave worse then the original design it mimics which is not the best design either. Your logic that some designs perform well only in a certain type of racing application is flawed in that it only applies to ladder bar type designs for drag cars. A 3-link, Satchell link, properly designed 4-link, truck-am, and even the C4L can all be designed to work well in many applications and some will excel at all aspects of automotive performance.



I believe the comment most are referring to
No, but it flat out smokes any leaf spring, 4 link or 4 bar that I have ever seen is what is creating the need for the technical correctness as even my half ass built C4L is a better system than that. We have had this discussion before...this is NOT the topic of this forum for "look at this blingness". If the design, install, built pieces look good too that is great but if the system is compromised in order to look better than that is not cool and is going to called out in THIS topic every time. In general discussion it would be met with lots of "ohh, aww, neat-ooo" comments.

[TLWiltman]

I think what a lot of guys fail to remember that these are STREET cars not full on race cars. In a street performance application how does this system stack up? Also where are all the suspension set ups from the guys who know exactly what is wrong with the above? I would think a particular set up works for a particular type of racing correct? I am not looking for argument and actually love the info. I just wish guys would stop judging everything as it was going on a full on race car for their specific application. I guess Metalworks is going to have to put that thing through the paces and then I will judge the results.

I respect what you're saying here but I still feel the need to address it point by point.

-I don't fail to remember that these are street cars. I'm merely building something more along the lines of a race car, slightly detuned so I could drive it to an event if I chose, rather than the other way around. I may be putting my opinion out for public consumption, but my opinions can only be based on my application.

-How would it hold up on the street? Fact is... I don't know. We've been merely discussing some possible shortcomings and the need for testing. IMO the stability of a rear suspension should be known before the street is even seen. A rear suspension in unpredictable bind is very dangerous. Snap oversteer is no joke. :injured: If you're lucky.

-Where's my suspension? I bought it from someone with much better fab skills than myself.

-Well, it depends on the kind of racing we're talking about. Road racers turn corners. Street drivers turn corners. So... road racing suspension designs can be made compatible with the street with small changes. Other forms of racing... meh...not so much. Doesn't quite work out so nice.

-Me neither. I prefer to call it "banter". I love the info. too.

- I don't (see 1st point). I judge it as if it were going on MY car. As if it were MY arse in the seat, and MY money on the line. "Caveat Emptor" "YMMV" "Due Diligence" "Let the buyer beware". IMO the reason NASCAR is always brought up when truck arms are discussed is, in part, because they are the only people who use it in a racing context and, in part, because NASCAR serves as a proof-of-concept. "does it work?" "yep" "Cool, let's use it". The Metalworks design has no real proof-of-concept AT THIS TIME. It stands to reason that they'll have to do a lot of work to prove that it works... SAFELY! (Safety is the #1 priority, all else follows. A dead man can't win)

-A-MEN!!:worship:

:cheers:

[BRIAN]

Guys like I said I love the info so do not take it the wrong way. Sometimes it just looks like everybody jumps to tear a system apart. Hey competition is what makes more products and better products available. I like everyone else I want that suspension shootout to happen to see what does what. The difficulty is finding a suspension that fits within the stock floor, handles well, doesnt bind (threw that in for you guys), can be used for straightline high hp use, and is ride height adjustable. Oh well?????????

[wally8]

Brian,

I look at "tearing a system apart" as constructive criticism. I could have used a more professional word than "suck" but this is my hobby, I don't have to be professional.

Constructive criticism is a tough pill to swallow for most but we can't have everyone throwing around baseless claims or this forum would start to "suck".


Wally

[TLWiltman]

Hey Brian,

I agree wholeheartedly with you about competition. As a matter of fact, I wish there was more competition in terms of 2nd gen F-body stuff (hint,hint,nudge,nudge). That said, I tend to believe that "constructive critcism" is a very strong 2nd when it comes to pushing product development.

As far as the rear suspension you're looking for... Wait around, I think there are people working on that.