Alignment specs after Shelby drop

[Dalton]

I finally did the drop in my car last weekend but now I need to get it aligned. I've seen several recommendations for the proper alignment specs but thought I would ask. One suggestion I saw was:

Toe 1/8" in
Camber -1/2 to -1
Caster +2 to +3

What should I go with?

Thanks!

[shelbydoug]

That's it presuming you have power steering?

-3/4 on the  camber but depends on the tire. You need to try it and see if there is too much side loading.

You need to watch the front of the fender lip from the caster. The setting will bring the tire further forward in the opening and could scrape there.

You MUST do a bump steer elimination kit. It's mandatory. If you don't, the car is going to change lanes without you moving the steering wheel.

[Dalton]

Yes, I have power steering.

Which bump steer kit do you recommend?

[shelbydoug]

There are a few. Go look at Cobra Automotive. You can call them for advice. Good for a newbie to this.

[Dalton]

Would this bump steer kit work?

https://baer.com/Baer-Tracker-Tie-Rods-3261002.html

[shelbydoug]

http://store.cobraautomotive.com/bumpsteer-kit-for-1967-69-spindles/

What it does is raise the mounting points of the tie rod ends on the spindle arms. I used a different kit from a different manufacturer that no longer makes them.

I trust Cobra Automotive.

[Dalton]

I definitely trust them too. I drool every time I flip through the catalog!

[texas swede]

About 40 years ago I did the drop on my 67 in accordance with the Boss 302 chassis manual.
First I replaced the power steering with a manual steering and I set the alignment to:
Toe-In 1/8"
Camber -1/2 degree
Caster + 2 degrees.
Still have that set up and have never regretted it.
Texas Swede

[shelbydoug]

You want to make sure that you have enough toe in. Toe in measurement is ALWAYS an approximation. A little too much is better then not enough. 1/4" is a little too much for tre wear basically.

A radial tire, because it has soft sidealls is tougher to get just right. With a radial tire use 3/16" total. 1/8" is ok for a bias ply tire.

This is what keeps the car tracking strait.

You should be able to take your hands off the wheel at 100 or so and the car goes straight.

A harder, shorter front spring modification like shown in the Boss 302 chassis manual helps. When you cut it to get the spring rate, you probably will need to shim them.

I just used the solid poly, Mr. Gasket 1" spring doughnuts and that's just about right.

You want to finish all of the front modifications before you align everything.

I went with a 1-1/8" front anti-sway bar, poly bushings on everything and a 1.5" upper a-arm drop with ball joint wedges.

You would think it rides like a truck but it's more like a Lincoln with a soft ride. 680in-lb front springs.

The only one that ever noticed anything was Jim Cowles. He noticed that the top of the hood didn't line up with the other cars while we were all parked together. He decided it was about the thickness of his fist lower? Silly boy.

[roddster]

  First I've heard of the need for a "bump steer elimination" kit.

[shelbydoug]

The cars stock bump steer ever so slightly. Lowered upper a-arms...forget about it.

If you're driving an original '65 GT350 and never noticed it, better check your pulse, you might be dead? (They're nasty...those ain't bumps in the road)

[mlplunkett]

I like the idea of lowering the car but not so much that it's obvious and it sounds like you achieved that. A lot of the cars in photos seem to ride high in the nose. Are you using shortened springs and then adding back some of that with the 1" spring donut? How much does the typical 1" Arning drop lower the ride height? Does switching everything to the poly bushings have any effect over the amount of road noise that comes through?

[shelbydoug]

I like the idea of lowering the car but not so much that it's obvious and it sounds like you achieved that. A lot of the cars in photos seem to ride high in the nose. Are you using shortened springs and then adding back some of that with the 1" spring donut? How much does the typical 1" Arning drop lower the ride height? Does switching everything to the poly bushings have any effect over the amount of road noise that comes through?

If you are asking me (not sure), I've done two drops. First I did the Shelby 1" drop. Then there was a guy in Utah offering a 1-1/2" drop with a complete kit.

Shelby did the 1" drop because it was the most that you could go without having to use wedge spacers on the lower ball joints to keep them from locking up. 1" IS NOT the optimum drop.

The guys name was Boyd and autocrossed a 68 GT350. He pointed out (righfully so) that
something in the 1-1/2 to 1-3/4 was. He originally offered the kit as 1-3/4, then backed out to 1-1/2 due to customer use issues.



I've got the 1-1/2" in the car. It uses supplied aluminum ball joint wedge shaped spacers, specially milled thick flat washers and a 1/8" steel pattern plate that you bolt in place using the original holes, then use to drill new holes, then leave it in place as reinforcing to the shock tower.


I'm not sure why the '65 owners don't notice the bumpsteer issue with the car other then they are already cross circuited brains because of the loud side pipes and whacky Detroit-locker? Certainly the numb-nuts phenomenon is not necessarily just limited to Shelby owners but it does seem at times to be prevalent?

Initially I was using the Boss 302 chassis modification booklet in 72 or 73 when I was doing this and also went to the "off highway front spring". That required the spring to be cut 1 full coil off of the spring to get the desired rate of 680 lbs.

The issue that became apparent, was that it lowered the car to full Trans Am race height which for various reasons was not a good idea on the street.



Initially I found that the 1" rubber "Mr.Gasket" spring spacer installed on top of the spring put it right about where I wanted it. That is essentially at the top of the tire/wheel well opening with a 235-60-15 tire on 10 spokes, as opposed to a fender over the top of the top of the tire with a "slammed" look.  Later that spacer was changed to a full poly by Just Suspensions along with replacing all rubber with poly bushings. I would recommend those changes.


The bump steer is another issue all together. With bias ply tires (Goodyear E70-15) besides riding like it had concrete tires would catch a seam in the road and the car literally would change lanes by maybe a half lane?

I later extrapolated that number to be at 70 mph and a full lane at about 100 mph.


When I went to BFG radials you could tune the suspension with tire air pressure but not enough to eliminate the bumpsteer.

At first I didn't know what it was. Shelby guys would come up to me asking about the lowering of the a-arms and asking how bad the bump steer was? Numb nuts that I was at the time, I investigated and found that many of the current racers were using "bump steer elimination 'kits' ".


Being cautioned by Curt Voght, he said the kit still needs to be adjusted according to "my own car" and the arc needed to be measured through the travelling path. Well, long story short, I was good right out of the box. So I left it alone using Boyd's kit, which is still on the car.


Now considering that this is just a "street car"...ahhhem... and I don't race against him and Scotty, I'm good.

As the folks at "Cobra Automotive" will tell you, every little thing that you do to the suspension, makes the car a little better.

At this point, that's proprietary information but suffice to say, the car isn't stock and let's leave it at that.


Now, Walter Mitty that I apparently am, with the addition of the T/A dual Holleys, I'm driving a T/A car in disguise on the street. I don't know if it is exactly 500hp, since I don't have the dyno in the garage...yet, but "it'll do". 


I tried to post a picture that would answer your question about the ride height but it won't upload. Send me a PM with you email and I'll email it to you.

[oldcanuck]

If you decide to do the 1" lower springs, who's springs are best as several suppliers advertise them ?

Since I'm sure we have members that have done it both ways..... how does the end result differ ?

Also what does this do to the alignment specs ?

Thank You,

BG

[shelbydoug]

j

If you decide to do the 1" lower springs, who's springs are best as several suppliers advertise them ?

Since I'm sure we have members that have done it both ways..... how does the end result differ ?

Also what does this do to the alignment specs ?

Thank You,

BG

I did the drop using Ford springs from the Boss 302 chassis parts list in the '70s. I would recommend that you talk to Curt or Scotty at Cobra Automotive for their recommended substitute.

Some are concerned that this is a race only modification. After running it on the street for 40 years I can tell you that it is not. It is a very streetable modification.

Those modifications in the Boss 302 Chassis modification booklet are from Kar Kraft, not Shelby and are more modern changes then what was used on the '65 GT350.

For the race cars, it was only a starting point.


The alignment specs don't change. 3/16" toe in, -1/2 to -3/4 camber, 2 to 2-1/2 caster with power steering on the street. As much as you can get without the tire hitting the fender.
You will set the camber to where the tread rides flat. Mine is at about -5/8 degrees.

The other modifications take care of the body roll and averages the most tread on the pavement at all combinations of turning. That's what it's all about.

Stock, the tires roll over on the outside of the tread. That's why the cars are done by 70 mph. Ford didn't build race cars for the street. "Shelby's" were just a trim package to them. "Performance" on the street was racing stripes.


Most race cars are going to go more on negative camber but too much slows down the car down the straights.

A dedicated autocross car would likely use much more.

Also depending on the driver, over 2-1/2 positive caster with manual steering makes it difficult to turn the car. Effort goes way up, but the positive caster keeps the car going straight under power.

I find that on my 68, 2 degrees of + caster will make the tire hit the lower portion of the fender at the lower end in the front of the opening. I also don't need more then that.

The Panteras by comparrison with the GT4 configuration, 10" wide front wheels need twice that much, 4 degrees to stop the jiggling through the steering down the straights.

Race only Mustangs with wider front wheels may need more caster? That I don't know?


I can tell you that these specs I've given you will work on any street driven car. A race car, that's just the start and you likely will need to adjust them depending on the track, surface conditions and tread compounds so that's not a casual setting. Every team and driver will likely vary.


You also need to do work on the rear for serious handling, It isn't just the front. That's another subject.