Shelby 1" drop vs 1 3/4" negative wedge drop

65cpe69mach1 · Jul 21, 2004

What are the pros and cons of the negative wedge 1 3/4" drop compared to the standard 1" Shelby drop?
Other than the price of the negative wedge kit.
This would be on a 65 coupe.

slackr · Jul 21, 2004

DarkBuddha posted a write up here:
http://groups.msn.com/DBsMustang/suspensionmodificationsteps.msnw
BobV did a write up on his home page here: (look for tech pages)
http://www.gt350clone.com/
corner-carvers has a good write up here:
http://corner-carvers.com/wiki/index.php?Vintage Mustang Tech

I think BobV's site explains and issue with the roll center being adversely effected with the extra drop of the negative wedge kit, and the shelby drop ultimately not being enough for the BEST handling due to ball joint angle issues...
But check it out, there's some good info on all those sites.

Opentracker · Jul 21, 2004

Just did some work today for a '68 coup track car with the 1 3/4" drop. No need for a wedge kit on this arm, check out the angle of the ball joint area.

For a street car there is no need for the 1 3/4" drop in my opinion, the 1" drop is plenty and the ball joint won't bind. The stock upper arm is very strong too, no need for tubular arms on anything but a full on race car. We do the 1" drop with stock arms to all the cars. The track cars get modified stock arms like this one and more than a 1" drop.

John

DarkBuddha · Jul 22, 2004

Wow, I think everything that counts got covered in 3 posts. Impressive.

HistoricMustang · Jul 22, 2004

Very good, very good indeed. No major bucks being spent.

John, is there any re-enforcement added to the metal when the second hole is cut? Just wondering if there should be some stress concerns, especially on the race cars at speed.

HistoricMustang
www.historicmustang.com

Opentracker · Jul 22, 2004

John, is there any re-enforcement added to the metal when the second hole is cut? Just wondering if there should be some stress concerns, especially on the race cars at speed

I'm not sure what you mean by a second hole? I cut a wedge out of the side of the upper arm like this,

bend the arm and weld it up. The bottom of the arm gets boxed similar to the ones Cobra Automotive uses. No worries about them coming apart at speed or under braking.

John

usedtobe 67p51d · Jul 22, 2004

The only thing that I'm worry about is that I've scene a photo of few of the cut and weld arms fail. If I was using a cut and weld arm I would add a lot of extra metal!

HistoricMustang · Jul 22, 2004

Yes John, I now see what you are saying and this should be OK.

HistoricMustang
www.historicmustang.com

Opentracker · Jul 22, 2004

The only thing that I'm worry about is that I've scene a photo of few of the cut and weld arms fail. If I was using a cut and weld arm I would add a lot of extra metal!

This brace will tie the ball joint area in with the metal at the spring perch and shaft. It's still in mock up, so if it doesn't look safe I'll change things. The boxing Cobra Automotive and Maier racing does, doesn't include the ball joint area. This brace is my own design, the ball joint area should have some support in my opinion.

John

Stock arm....

Not stock arm....

usedtobe 67p51d · Jul 23, 2004

the extra metal would be three times stronger if it was welded to the flanges.

Mosse · Jul 23, 2004

I was thinking of doing the same to my upper arms, but didn´t feel comfortable welding a vertical seam to the arm, if you know what I mean. I had same kind of aluminum wedges made in machine shop, as they sell as a kit. Which was a bit cheaper...

Opentracker · Jul 23, 2004

This is a Cobra Automotive arm. Notice how they cut the arm to change the angle of the ball joint area and there is no extra support for the ball joint. Cobra sells only the best and this arm is not ever going to have problems. They run these arms on the fastest Mustangs in the country. I just can't A-Ford to buy a set for each of our track cars so I make my own stuff. My brace will run 1/2" off the deck of the arm, supported at the spring perch mounting point by thick wall tubing to allow access to the spring perch bolts and welded to the inside area where the perch sits. The Cobra arm is welded at the flanges only. I'm not sure how this can be three times stronger but I'm willing to learn. We inspect the cars often for cracks and worn parts. I'll be looking close at theses arms once they hit the track. Thanks for the input.

John

Opentracker · Jul 23, 2004

Did some more work on the arms today. The brace will have a bit of a arch to it like the Cobra Automotive brace.

The blue tape shows where the brace is inside the arm.

I made a bunch of paper templates to give to who wants one. I have not made the holes for the spring perches yet, it will get some.

It will get welded up soon and I'll show some photos of the finished piece. Looks plenty strong to me but I'm up for any critisism.

John

bnickel · Jul 23, 2004

hey john, awesome work as always. if you have enough of those templates i'll take a set. hopefully i will have a little extra money pretty soon so i can do some of this stuff too.

vrooom · Jul 23, 2004

can you scan it in or make a PDF?

That looks great. Now how can we get a template of the angle you made on the control arm? (the cut you made)

How much are you dropping these? 1 or 1 3/4 inch?

Thanks,

Josh

Billgear · Jul 24, 2004

John,

Your work is looking awesome!! I had a question and a pic that i could share. I was wondering why your not welding the new box section at the edge of the arm? Have you thought about a screw in balljoint, seem like it would be really easy to include the edge of the balljoint bung in the new boxed area for strength.. I have a pic of the side of the Cobra arm for reference..

here

Opentracker · Jul 24, 2004

hey john, awesome work as always. if you have enough of those templates i'll take a set. hopefully i will have a little extra money pretty soon so i can do some of this stuff too.

Total cost so far is $1.83 for the steel. Send me your address and I'll send out a template.
..........................................................................................................

vrooom,

I don't know how to do the PDF stuff. I would rather make it from a real template myself. I'll ship them out for free to anyone who wants one. Email me at myradpc@earthlink.net and give me a mail address. I don't have a template for the cut on the side. MrPantera did the mod to the arms on his '67. The side cut can be made by using his method, if you have trouble let me know. This car is getting the 1 3/4" drop.
..........................................................................................................

Bill,

Thanks,

I'm going to weld in the boxing plate full circle. All the way around the edge of the arm and all the way around the spring perch area. I wanted the arms to look stock, even a quick glance under this arm may not tell the whole story. I'm not trying to deceive anyone, just make it look stock. The screw in ball joints that fit the Mustang spindle have a spring in the bottom like the lower ball joints do in our cars. In my opinion it's not safe to use as a upper ball joint on a car that has the coil spring on the upper arm. Thanks for the pic of the side of the Cobra arm, I hadn't seen that angle of it before (nice spring perch). I'm sure you recognize the other Cobra arm and the table.

John

HistoricMustang · Jul 24, 2004

John great stuff and proof that you do not have to spend a ton of money to make these great machines perform.

My hat is off to you!

Henry

65cpe69mach1 · Jul 24, 2004

You guys are a wealth of info.

BTW, where do you find the 17/32 drill bit to drill the new holes in the shock tower for the Shelby drop?
I've tried Sears, Lowes and Home Depot. No luck.

Hack · Jul 24, 2004

65cpe69mach1 said:
You guys are a wealth of info.

BTW, where do you find the 17/32 drill bit to drill the new holes in the shock tower for the Shelby drop?
I've tried Sears, Lowes and Home Depot. No luck.

I got mine at a local hardware store. You have to find an "old school" hardware store that has everything and anything. If I were you, I'd ask around locally if you don't have any ideas off the top of your head. Or just look in the yellow pages and call around. That could save you some time driving all over town.

Shelby 1" drop vs 1 3/4" negative wedge drop

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