The evolution of springiness

I could not give you any useful information on car suspension springs or shocks. Zero. I had a feeling though that the suspension in the Mustang would need to be replaced.

If I don’t know anything about springs, how do I know I need to replace them you may ask?

The obvious place to start is at the front of the car. The little Ford 302 weighs well under 500 pounds. I think the 3 speed trans is around 75 pounds. Let’s say a conservative number would be a little over 600 lbs for the drive train. The engine that’s replacing the 302, by itself, is 680 lbs. Add in the weight of a Tremec 6-speed and I can safely guess that the stock springs are going to have a hard time supporting this added weight.

When I ordered the Boss 429 shock towers from Kevin’s Kustoms, I also ordered a set of front springs. The Cammer is very close to the same weight as the Boss 429, I think the Boss engine comes in a little heavier.

Had my plans stayed as simple as I started with, the Boss 9 springs would have worked well but the plans evolved.

Let’s look at the back of the car.

Most old Mustangs have that rear squat. The butt is usually sagging under its own weight. My Mustang wasn’t like that, it sat ass high. When I first saw the car I thought the springs had been replaced. I didn’t see any shackle extensions sticking down. It wasn’t until I crawled under the car that I discovered why the car had a good stance: Gabriel Load Carrier Shocks. These are gas shocks with light coil springs built on them. They kind of look like coil overs but they’re only designed to augment the existing rear springs, not replace them.

Finding the Gabriels justified my wanting to start fresh and upgrade the old leaf springs as well.

What inspired me to get the Mustang was a picture of a Boss 302. I didn’t really know anything about the car other than I liked its paint scheme.

After bringing the Mustang home. I went in search of and bought a complete set of Ford service manuals. During the search I also found a couple of books that were offered to Boss 302 owners. One of the publications is called “Boss 302 Chassis Modifications”.

In these pages I found out that Ford was serious about helping the club racer or any weekend warrior, for that matter, who wanted to try their hand at road racing type events, modify their cars for competition. The Boss had the potential to be a serious MoFo.

The more I read, the more I wanted to create a Boss 302, not just in appearance but in performance as well. With one exception being the 427 SOHC replacing the Cleveland headed 302. A Boss 427? Maybe a Boss SOHC.

I found out that one feature both Boss models had, which was supposed to help control suspension squat on hard acceleration, was the addition of staggered rear shock absorbers.

My car has a conventional set up, both shocks are in front of the rear axles. The staggered set up has the right shock in front of the axle housing and the left is behind

I naively thought that all I needed to convert my car to staggered rear shocks were two right side, lower spring plates/shock mounts.

I found some guy on ebay selling several sets of the plates I needed and ordered two right side plates.

I received a message from the seller soon afterwards.

He wanted to make sure I knew what I had bought. I assured him I did. He then figured out what I was trying to do and asked me if I knew that the conversion also required an upper mount which was entirely different from the stock set up. I said, Whuut?

I needed one of these.

This is the kit I bought. It is from a company called Sanco Specialties out of Texas. The company was shut down following the disappearance of the owner, Forrest Sanco. He and his girlfriend took a trip to the Bahama’s in a private plane and were never seen again.

Last time I checked, National Parts Depot has filled the void and is selling a similar kit. It’s a weld in piece and requires a little bit of fabrication work.

At the time I bought this kit, I was less than brand new to Mig or Tig welding. In days of yore, my high school shop teacher tried to teach me stick and gas welding. A futile effort on his part.

I had plans to start the rebuild at the front of the car and work my way back and it was my hope that by the time I got to the upper shock mount, I would have what some novice might call welding skills.

Now that I’ve talked myself into getting new springs and modifying the rear shock mounts, all I needed to do now is to pick out the springs I need.

I’d have as much luck figuring out and selecting the proper spring rates on my own as I would throwing a dart at a chart on the wall.

Once again I take a dive into the internet and I come up with an online catalog for Eaton springs. Leafing through these virtual pages I find that Eaton has a couple of offerings for the Boss 302. Are these really rated for the Boss? Hell if I know. I compare part numbers to see if the supposed Boss springs share the same number with other offerings for the 1969/70 Mustang and find no other listing. I find comfort in that.

I placed an order for the parts knowing that the car would have to go on a diet to allow the springs to work properly.

The springs arrived two weeks later. Being limited by lack of skill and work schedule, I have no idea when I’ll be ready to install the springs. The floor is almost finished and the car should be close to being taken off of the jack stands. You would think that somewhere in between these two events is when the springs would be put into service.

Yeah, that’s what one would think, wouldn’t they?

Almost 21 Century Suspension