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Discussion Starter #1
Has any body installed a roadster shop spec chassis on a 67 mustang fastback yet - This was just released at SEMA this year and I am looking for a ref on the product before I jump into this. I want to put it under a painted fastback and install with a coyote motor.

Also what does this do to the value of the car It is a S code GTA but missing original block so not wanting to go back all original
 

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Also what does this do to the value of the car It is a S code GTA but missing original block so not wanting to go back all original
Cant speak on that chassis, but just curious on why you’re concerned on value if there’s no desire to go back to factory original?

Modifying your car from factory original means that you can’t compare your car’s value to that of a similar factory original. You have a totally different car at that point (given the modifications you intend to make).

Value can go up or down, however... if you started with a plain jane 6 with no options in the most common colour, then installing a coyote motor and super chassis, then I think it’s reasonable to assume that the value would be more than original. Do the same modifications to a Shelby, and the opposite would most likely be true.

Make the car your own, and not worry about what the car is worth. Chances are that you won’t get back what you’ put into it. And that’s ok.
 

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From what I have seen on the Roadster Shop website, there is a ton of fab work to install that chassis.
The Schwartz performance chassis seems like a much easier install.
 

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This is new to me! Thanks for letting us know about it. It's so new that I bet that green 68 is the only car with it installed. It looks like an innovative approach. It's a middle ground between an ultimate full chassis welded into the uni-body and the more common shock-tower-delete suspension with frame connectors added.

Since it slips over the existing frame rails, it adds strength and stiffness, but all that redundancy adds significant weight. You end up with a vestigial set of rear frame rails. I don't think I like that extra 500 lbs gained. Of course, you'd have to start with solid frame rails or the whole approach is pointless. So if you must replace your rails, this bolt-on approach is less attractive than a full, integrated chassis. The starting price is attractive, then you add all the required fiddly bits and it gets a bit pricey. I suppose it's also "reversible" by the loosest definition.

I'd want to see video of that green 68 on the track, autocross, and strip before I considered using it. But given that it's the Roadster Shop, I'd be very shocked if it didn't behave very well. RS makes da' good stuff. Expensive good stuff.
 

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Nice, but very expensive it seems to me.
Wonder why the drawing of it attached to a car shows the original rear frame rails still on the car? Seems like removing those would be one of the benefits to this.
Russ
 

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I emailed and asked about weight, but never got a solid answer.

I am sure their front suspension geometry is superior to anything stock from 50+ years ago. Combine that with R&P steering and a 4 link rear suspension with a panhard rod, and I bet the green car drives awesome. The LS3 disguised as a Windsor doesn't hurt :p

Andrew
 

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I am sure their front suspension geometry is superior to anything stock from 50+ years ago.
Oh lordie, here we go. This is one of those "trigger" topics. I would say the consensus here at VMF is a strong "No". The bottom line is that while these modern shock-tower-delete suspensions aren't "superior", they also aren't any worse than the original Arning design.

You must carefully define "superior" when comparing the original Arning design suspension to the aftermarket shock-tower-delete designs. What are your goals? I always advise against the shock-tower-delete kits unless you're fitting a big 427 side-oiler or Coyote in an early Mustang. If you want 10" to 12" wide front wheels, then you might also consider an aftermarket suspension using C5/C6 spindles.

I am one of the lone voices trying to draw a distinction between the crappy 1980s "Mustang II" kits and the modern shock-tower-delete designs now available. The fact is that the original Arning design and the aftermarket "MII" suspensions both use SLA "short-long-arm" double wishbone geometry. Therefore, they have similar handling characteristics overall. The Pinto/MII suspension was crap due to reasons other than basic SLA geometry. Nothing good came from Detroit in 1974.

Klaus Arning had objectives and worked under corporate profit goals differing from the goals of modern hot-rodders and racers. Tire and road conditions in the 1960s were totally different. So of course the original Arning design has cheaper parts, larger travel, softer ride, and transmits less road vibration than aftermarket "performance" suspensions. But a guy named Shelby demonstrated that the Arning suspension can be transformed into a kidney-rattling track beast with minimal surgery and a few tweaks.

Now leap ahead 50 years to modern conditions: sticky 35-series tires on 19"x10" wheels and 15" brakes which almost never see a dirt road. For most of 1965 rural and suburban America, modern ride heights were unthinkable due to road conditions. Nowadays, who cares about having large wheel travel in a car driven only on smooth asphault? Who cares about a little road noise and extra "road feel" with a 500+ hp semi-muffled torque-beast stroker under the hood? Who cares about a cost difference of a few thousand dollars overall? We're only talking about one car here, not millions rolling off an assembly line. Hot-rodders want top-shelf quality and tuneability, not penny pinching.

The one major difference in geometry are the aftermaker designs using C5/C6 Corvette spindles. The Roadster Shop and Detroit Speed & Engineering Alumiframe suspensions are both different from the rest and OEM. How significant is the difference? I dunno, but I like it. Besides being lighter and stonger, these spindle have better scrub radius and steering axis inclination than the 1960s design. The upper/lower wishbone arms may be a tiny bit longer than other designs. The Corvette spindle is also taller which can give an improved camber gain curve. Overall, it's a very clever spindle design. The upside is that you can fit giant engines, tires, and brakes in a 66 convertible. The downside to the taller spindle is that you must use a 18" or larger wheel. Many Mustang folks strongly dislike that look, especially on a 66 convertible.

Will the average hot-rodder notice handling improvements over a similarly tuned Arning design? Doubtful. It all comes down to your personal goals.
 

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Well said hsvtoolfool! There are just so many ideals and compensations to them. 50/50 weight bias....but 911's seem to do ok without it. SLA superior to spindles but BMW's aren't too shabby. Reducing inertia to rotation.....944 turbos weren't exactly slouches on the road course. The work arounds and the end goals and purposes are just important. Audi's have horrific weight distribution on whole but can be a reasonable track car. Ladder frames are horrific, but Corvettes made them work for some time as did Shelby for that matter. Huge turbo lag is disgusting but who would doubt the success of the 917.

I do believe that the Arning design if reduced of manufacturing and mass production limitations is a great design. I do also believe if you work too much outside its original parameters like 18x10 with 200 wear tires or better using modern brake leverage there ARE better mouse traps available today. I love my S&T suspensions on several cars, but if we are to compete with the GM front clips running 315/355 combos I witnesses last weekend at Midwest Muscle Car Shoot Out, it may require more than Ford gave us to start. Disappointingly the fasted 1st gen Mustang had an LS engine between the shock towers.

I've been intrigued by RS for years and have had several discussions with them as I love the engineering aesthetics and the tall spindles. I've added C6 spindles to other chassis with a remarkable difference felt. The Schwartz chassis has proven itself by results, but just seems awfully 2 dimensional (I guess the factory unibody adds the 3rd) and I haven't gotten great response from them in direct contact in regards to this. Yes, it certainly looks simpler to install in a semi to fully finished car.
 

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Well said hsvtoolfool! There are just so many ideals and compensations to them. 50/50 weight bias....but 911's seem to do ok without it. SLA superior to spindles but BMW's aren't too shabby. Reducing inertia to rotation.....
Hit my trigger :)

50/50 is NOT the ideal weight distribution. It's just been pedaled as such for decades by manufacturers because that's the best they can do with a front engine car. The 911 is the opposite with too much rear weight and somewhat quirky handling characteristics. The ideal will be around 55% rear weight, depending on the car, and how much power it has to put down. Due to front tire scrub and cornering drag, a cornering car needs some excess rear traction (weight) to apply the HP required to overcome this drag.

As far as Moment of Inertia, the Corvette has the worst possible driveline layout, like a dumbbell: heavy engine out front, heavy transmission out back. The Boxster/Cayman has pretty much the ideal drivetrain location and rear weight bias. Corvette seems to agree, since the next generation is finally a mid-engine design!

P.S. It's interesting to note, a less-than-ideal design tuned to perfection will usually beat the "ideal" design poorly implemented. The Boxster is a great example, it has a "crappy" strut-based suspension with poor camber gain, yet it's the performance standard all in it's class are compared to.
 

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Discussion Starter #16
RS Frame is installed with coyote motor This frame is super nice looking forward to the first drive
 

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Discussion Starter #18
I would be willing to assist anyone with questions I can save you lots of time on what is needed to make this work I have lots of info if needed to make this chassis fit
 

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Congrats! I have too many questions. Who did the work? You? Roadster Shop? Do you have build photos? What was your bottom-line cost? I can't wait to hear your first impression on ride quality and handling.
 
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