Author Topic: Vintage Shelby Mustang Suspension Mods  (Read 3548 times)

Jim Herrud

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Vintage Shelby Mustang Suspension Mods
« on: February 25, 2018, 02:00:46 AM »
This topic is inspired by comments from shelbydoug and zray in the thread on “Recommendations on Street/Track Tires”.
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"........Also, regardless of what the factory did with the Boss 302's, a rear anti-sway bars on these cars is a no-no. ......."
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I have yet to see a rear sway bar (on a 65/66) that actually helped anything.
My input seemed to be a bit off topic there, so I thought I’d start a new and more generic one. Since many Shelby owners are unmotivated to modify their cars in this manner, I thought it more appropriate to put this in the Replica/Tribute section.

I autocrossed my 65 Fastback in the 80’s/90's and it initially had stock-suspension with the classic vintage Mustang understeer. It was, by far, the oldest and slowest Mustang in the class.

One of the club guys suggested I contact a “vintage” Mustang racer that he knew in California by the name of Frank Stagnaro and gave me his phone number. I didn’t know him from Adam. One evening, I called him out of the blue. He was very gracious and over next 2 hours, he gave me tons of info – much of which I had insufficient background to appreciate. Note that Stagnaro’s car was (and still is) technically light-years ahead of mine.

Based on his suggestions, I made a number of suspension changes: Shelby/Arning drop, stiffer/lower front & 4.5 leaf rear springs, bigger front bar, 5/8” rear-bar, Panhard rod, Koni shocks and of course, better tires. I know I should have made changes one at a time, but then again, in autocross, you don’t have a consistent track to quantify the changes.

The car performance improved considerably and the balance went from understeer to oversteer. The changes didn’t shoot me to class champion, but I was thankfully now less slow and almost mid-pack. (Driver skill is likely a constraint here ;)) It’s difficult to conclude that the rear anti-roll bar is responsible for the oversteer, but I’ve heard from several sources that it definitely contributes (as the gentlemen above have inferred). The biggest benefit (for me) is that driving an oversteering car is a hell of a lot more entertaining than an understeering one, if not necessarily faster.

I’m currently completing more upgrades to the car, aiming for better balance. Adjusting/disconnecting the rear bar will be one of the tuning variables. There’s tons of info available now on suspension physics and setup, but it is geared mostly for modern cars. I’d be interested to see what others have done to their vintage Shelby Mustang suspension and what experience they’ve had.

Thx,
Jim
Shelby Buff. I'm a driver - Not a docent.
I used to be a “Vintage Car” guy. Now I’m just a “Vintage” car guy.
"There's never enough horsepower - Just not enough traction." - C.S.
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8T03S1425

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #1 on: February 25, 2018, 11:16:03 AM »
I’ve done the 1” drop on the upper control arms on my Shelbys pre-71 Mustangs. I also use tires one size up from stock, and upgraded the shocks to Konis. I made these changes partly because I read they improve handling, partly because I think they improve the looks of the stance, and partly because I think they’re fairly easy to do and not unduly difficult to undo.
I have owned 8T03S-01425 since 06/76.
I owned 6S2295 in 1973 & ‘74.

2112

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #2 on: February 25, 2018, 11:33:26 AM »
How can a Panhard bar, with fixed connection at each end, and not providing the same geometry to each side of the car, not induce it's own steering issues if a sway bar connected by end links, (the same way on both sides) does?


shelbydoug

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #3 on: February 25, 2018, 11:49:22 AM »
The 1" drop is then and still is a compromise. The number that you want is actually 1-1/2".

The issue then was that with more then 1" you would overload the ball joint and jamb it.

The issue is that when you go to the 1-1/2", you need a wedge spacer for the ball joint. Today, that isn't a problem.


If you are affraid of the 1-1/2" drop because it isn't "a 'stock' modification", then guess what? Neither is the 1". That makes it a "modified" car too?  ;)


The pro-rear anti-sway bar people are going to point to the 69-70 Boss 302's. The anti (like me) will point you to the factory raced R models, T/A cars.

ALL RACERS need to determine the criteria to attempt to satisfy, then find a solution.


To me, we are dealing with ancient technology on an ancient platform. IF current technology can make it better, then good for you, but there is a lot of evidence that they were maxed out for all time way back then.

Why argue now with what was successful back then?


IF you notice what I have done is just copied what was successful then.

Now frankly for me, this is all academic. ALL OF IT. I'm not going racing. I can't afford to throw $100,000, a year into a fantasy of Walter Mitty-ism.

I find comfort in the past. It helps me enjoy this present.


I'm just very satisfied with having the most bad-ass Sopwith camel on the block. But that I am admittedly into gross overkill. I already had everyone at the blue stripes and scoops.

I'm not running 620hp at 8,200 rpm like Curt is but then again I don't need a bunch of $35,000 engines a year but then again you won't find those race cars on the street either.
68 GT350 Lives Matter!

shelbydoug

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #4 on: February 25, 2018, 11:55:53 AM »
How can a Panhard bar, with fixed connection at each end, and not providing the same geometry to each side of the car, not induce it's own steering issues if a sway bar connected by end links, (the same way on both sides) does?

A Panard bar is really only needed with tires that are sticky enough to cause the rear springs to be overloaded, twist them and allow the axle not to stay parallel (OK...perpendicular) to the body.

IF you ever saw the Trans-Am racing of the day, you could rename it as "death wish" racing. It seemed like EVERY SINGLE team driver from any camp was attempting to prove he had a death wish and it WAS possible to break the car without crashing it?

You just had to see it to believe it.

The Panard bar (although I have one) is only a racing type necessity?


MAYBE the Avon tires will have enough grip to put you into that category but my opinion is, if you actually are using the car to it's limits on the streets, you PROBABLY are a danger to public safety?
« Last Edit: February 25, 2018, 12:11:41 PM by shelbydoug »
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2112

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #5 on: February 25, 2018, 12:05:24 PM »
But a Panhard bar doesn't keep the axle parallel to the body/chassis.

A Watts Link does.

shelbydoug

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #6 on: February 25, 2018, 12:14:56 PM »
But a Panhard bar doesn't keep the axle parallel to the body/chassis.

A Watts Link does.

OYE! A Watts linkage is an "improved" Panard rod (of sorts).

The improvement is really only significant to a pencil neck. The combination of the Panard rod and the additional spring ARE ENOUGH to keep the fenders from eating the sidewalls of the tires.

Academically you are correct, but this isn't "digital technology". It's completely analog at an empirical cause and effect...practical effect.

There is always a +/-. Keeping the tires in line within a +/- 1/4" is/was all that is necessary.

IF it was that important you would have seen the IRS homologated at the time. It simply wasn't necessary and didn't make the car faster or even easier to handle, just more complicated when something went wrong...and unnecessarily more expensive to race.  ;)
« Last Edit: February 25, 2018, 12:39:36 PM by shelbydoug »
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2112

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« Last Edit: February 25, 2018, 02:29:04 PM by 2112 »

2112

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #8 on: February 25, 2018, 04:44:46 PM »
How are you mounting your Panhard bars?

Here is a bolt-in Watts Link;

http://www.fays2.net/fays2_watts_link_9_.html

SFM5S000

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #9 on: February 25, 2018, 05:28:22 PM »

One of the club guys suggested I contact a “vintage” Mustang racer that he knew in California by the name of Frank Stagnaro and gave me his phone number. I didn’t know him from Adam. One evening, I called him out of the blue. He was very gracious and over next 2 hours, he gave me tons of info – much of which I had insufficient background to appreciate. Note that Stagnaro’s car was (and still is) technically light-years ahead of mine.


Jim,

Frank Stagnaro utilized and tested just about every component from Maier Racing in Hayward Ca. (Bill Maier). He is the one (I believe) who also influenced and guided Mike Maier (Bill's son) so heavily who is one of the country's champion autocross drivers. Frank knows what it takes to make a vintage mustang handle (in an autocross environment).

Cheers,
~Earl J
« Last Edit: February 25, 2018, 06:59:11 PM by SFM5S000 »

s2ms

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #10 on: February 25, 2018, 07:03:35 PM »
The PO who raced 6S1757 in BP during the 70's modified the suspension with Ford 11/16" rear bar and Panhard bar, and Koni's, per the Boss 302 Chassis modification guide. The suspension was otherwise stock 66 GT350. All I can say is that setup worked quite well for him, he was well know as a very good and successful driver, no accidents in all the racing he did. All those parts are still on the car today for no better reason than they are part of it's race history. I have open tracked the car several times and found it to be pretty well balanced although was certainly not pushing it too hard. I am curious about the effect disconnecting the rear bar and/or Panhard bar would have on the handling, might have to try that as a future project.

Dave
Dave - 6S1757

Jim Herrud

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #11 on: February 25, 2018, 07:28:20 PM »
How are you mounting your Panhard bars?l

I have an 80's-vintage Maier Racing Panhard Rod kit. Maier's current kit is larger and appears to have more adjustability.  My left-side mount is welded to the frame & sheetmetal behind the axle. The right mount is welded to the back of the axle tube. The 4 photos show the mounts. The rod itself is not currently installed. The left side mount is painted grey - the right-side is black:






The Watts linkage allows axle movement up and down while constraining it to a straight vertical line, whereas the Panhard Rod forces the axle to travel in a slight arc as it travels up and down.  To see if I can eliminate the Panhard Rod, I am experimenting with another product from Global West called the “Del-A-Lum” bushing shackle kit. It is supposed to locate the leaf springs more precisely and reduce the axle side-to-side movement. GW recommends that no Panhard Rod be used along with their kit because the side-to-side arc-motion forced by the Panhard Rod can cause the bushing shackle kit to bind.


Hi Earl, I blame Frank S. for infecting me with the Shelby bug. I only talked to the guy once and that was a quarter-century ago, but he's still OK in my book.

Thx,
Jim
Shelby Buff. I'm a driver - Not a docent.
I used to be a “Vintage Car” guy. Now I’m just a “Vintage” car guy.
"There's never enough horsepower - Just not enough traction." - C.S.
Straight Roads are for Fast Cars. Turns are for Fast Drivers.

2112

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #12 on: February 25, 2018, 08:03:33 PM »
I would be interested to hear your results with the Del-alum bushings.

My hunch is the leaves will still twist a little but maybe not as much as I imagine. I also wonder what the NVH will be like?

Please update us.

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #13 on: February 25, 2018, 09:35:47 PM »
Here is a picture from Sweden and 6S923. Claude Dubois, the European Shelby importer
and race car driver put a Panhard Rod on the car and it's still there as you can see.
I tried to persuade Roland to remove it before restoring the car but he, just like Dave
said it's a part of the car's history.
Texas Swede

Bob Gaines

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Re: Vintage Shelby Mustang Suspension Mods
« Reply #14 on: February 26, 2018, 12:12:35 AM »
Here is a picture from Sweden and 6S923. Claude Dubois, the European Shelby importer
and race car driver put a Panhard Rod on the car and it's still there as you can see.
I tried to persuade Roland to remove it before restoring the car but he, just like Dave
said it's a part of the car's history.
Texas Swede
That is a unusual Panard bar compared to others I have seen.
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby