If you're just joining us, last month, we embarked on an adventure that will hopefully turn a racy red Mach 1 Mustang into the corner carver that it should be. Equipped with a 351 Cleveland and three-speed automatic transmission, our subject '72 Mach has the foundation for speed, as well as the looks. Last month, we overhauled the front suspension using Mustangs Plus' Super Starter kit, and this month, we finish up the rear suspension upgrades.
Mustangs Plus offers the Super Starter kit for all '65-'73 Mustangs. While each kit contains basically the same parts, Mustangs Plus custom tailors the selection to each vehicle and owner's needs. The Super Starter combines three subsystems into one big package that includes a spring and hand-ling package, a suspension rebuild package, and a steering upgrade package.
The back half of Mustangs...
The back half of Mustangs Plus' Super Starter kit includes new leaf springs, shackles with bushings, U-bolts, and new Grab-A-Track shock absorbers.
It's a great and inexpensive way to revive your old tired Mustang and equip it with new components from top to bottom. The revised spring rates and mounting options should tighten up handling dynamics, and lower the car about an inch for a lower center of gravity and a more modern and aerodynamic look. Prices start at $799.95 for the Super Starter kit, and Mustangs Plus backs every component with a lifetime guarantee.
To suspend the rearend of our '72 Mach 1, Mustangs Plus' Bill Faull set us up with a 41/2-leaf, mid-eye spring. The 4 1/2 represents the leaf count, with our set utilizing four full leaves and a half leaf on top of the main leaf.
"We put the half leaf on top of the main leaf to add strength to the leaf springs without adding a lot of stiffness to the ride," says Mustangs Plus General Manager Bill Faull.
"These are designed for the street-oriented driver who jumps on the gas now and then. These springs have a strategically placed extra leaf to minimize wrap up and help prevent wheelhop under load. They will set the rear of your Mustang 1 inch below stock ride height."
We began the installation...
We began the installation by raising the car and setting it on a pair of jackstands. Then the wheels were taken off and the rear axle was supported by a floor jack.
Over time, your Mustang's ride height can change if the leaf springs on the car have started to sag. If they are in full droop, the Mustang may be sitting 3-6 inches lower than normal. Depending on the look you are after, Mustangs Plus can accommodate most all enthusiasts.
"The standard-eye spring would put the rear back to stock ride height, while the mid-eye spring would put the rear 1 inch below stock ride height," notes Faull. "The reverse-eye spring would put the rear 1 1/2 inches below stock ride height. Most people match the leaf eyelet to the front coil spring that they are using, if they are relocating the upper control arms, and if they want a rake or not."
For those who are into the more technical details, Mustangs Plus offered the following information regarding the spring's rates for the Mustang rear leaves:
| GT Leaf |
165 lb/in |
| 4 Leaf |
165 lb/in |
| 4 1/2 Leaf |
175 lb/in |
| 5 Leaf |
195 lb/in |
| 5 1/2 HD |
300 lb/in |
Add 500 lbs for load rating
Due to scheduling issues with our track venue being closed for the season, we had to postpone our follow up testing. We plan to have the full evaluation, along with some other modifications coming up in the June '11 issue. We're also looking at several performance mods to help unleash the hidden potential of this sleek Pony in the issues to come. In the meantime, dig into the captions and photos to see how easy it was to upgrade the rear suspension of this '72 Mach 1 Mustang.
We raised the jack to take...
We raised the jack to take the weight of the axle assembly off of the leaf springs.
Raising the rearend also allowed...
Raising the rearend also allowed easier removal of the replacement gas shocks that were on the car. Along with the rusty suspension parts, we'll be replacing the rusty exhaust soon too.
Access for the upper shock...
Access for the upper shock bolts is through a pair of holes located at the front of the trunk. It's much easier to remove the upper portion of the back seat and get at them through there, however.
The U-bolts are up for removal...
The U-bolts are up for removal next. Someone sloppily welded the old leaf springs to the plates, but the welds had long since broken and were not an issue.
Carefully remove the U-bolts,...
Carefully remove the U-bolts, being sure not to disturb the brake lines in the process.
We then tackled the rear shackles...
We then tackled the rear shackles before removing the front bolts.
Thankfully, our Mach has been...
Thankfully, our Mach has been very cooperative in its disassembly, needing little-to-no penetrating oil to remove the old parts. Perhaps our filly is getting excited at the prospect of being able to run at a competitive speed once again.
Since the Mustangs Plus kit...
Since the Mustangs Plus kit comes with new shackles and bushings, you'll need to remove the stiff, dry, and mostly likely rotted factory rubber bushings from the sleeves in the frame.
We're halfway there, and only...
We're halfway there, and only about half an hour into the job. Wouldn't it be nice if all mods were this easy?
The new bushings went right...
The new bushings went right in, and the bolts feature positive stops to prevent from overtightening the fastener. We ran the nuts down, but did the final tightening once the weight of the vehicle had compressed the suspension.
When installing the new springs,...
When installing the new springs, make sure the locator pin properly mates with the spring perch.
The new U-bolts are next,...
The new U-bolts are next, and include lock washers to secure the nuts. Draw them up evenly to ensure that the U-bolts are not canted.
The new Mustangs Plus Grab-A-Track...
The new Mustangs Plus Grab-A-Track springs are in. We went with a mid-eye, 4 1/2-leaf spring to drop the ride height 1 inch, and give the Mach 1 commendable handling prowess when thrown into a turn.
Whether you're hitting he...
Whether you're hitting he track, hitting the street, or both, Mustangs Plus' Grab-A-Trak suspension components are a great way to renew your Mustang's handling prowess.
The new rear shock absorbers...
The new rear shock absorbers come with mounting hardware as well as new bushings.
We found one of the upper...
We found one of the upper shock bolt access covers down in the hole, but unfortunately, the other was missing. Mustangs Plus offers replacements if yours have wandered off as well.
Unsprung weight moving around...
Unsprung weight moving around undampened is unsafe and can make the ride not very enjoyable, or worse. These Grab-A-Track shocks are a good replacement for worn OE units.
The Mach's ride height is...
The Mach's ride height is much improved, and will look great around the set of aftermarket wheels we have planned for the car. Check back with us for a proper track flogging, ride quality assessment, as well as the other future modifications we have planned.