Why is Max Effort sitting...
Why is Max Effort sitting so low in the rear? Actually, it'll likely be lower than that. Read on to see what's causing our tires to tuck.
Rendering by Filip Trojanek
Project Max Effort's rearend assembly is all wrapped up, thanks to the solid-axle experts at Speedway Engineering and Currie Enterprises, so now it's time to get it underneath our Cougar with our first foray into the real meat of the build: the chassis and suspension.
The basis for our rear suspension is Griggs Racing's GR350 package, but the caveat is that ours is a bit different, since we're working on a unique platform. Although it is essentially a Mustang under the sheetmetal, there are a few small but important differences on a Cougar-mostly due to the wheelbase increase from 108 inches to 111 inches. That 3-inch stretch required some tweaks and adjustments to maintain the correct geometry. Griggs was able accommodate some of the alterations, but for the rest we put our trust in the engineering prowess of CorteX Racing's Filip Trojanek, and the vast experience of head fabricator for Project Max Effort, Ryan Kertz of Kertz Fabrication. From track cars and traditional hot rods, to vintage F1 and even architectural work, Kertz is a master fabricator with an eye for perfection.
Lucky for us, Kertz also spent several years at Griggs Racing as lead fabricator, so he's intimately familiar with their products and how they're designed to function. That's important, but it's what Kertz knows about making modern and vintage street cars and full race cars function at their peak on the track that makes the difference between good handling and perfect handling. Kertz and Trojanek often work together to test and take new ideas from CAD to reality. Whether he built 'em from scratch or just corrected others' errors, from his shop located just below Turn 11, Kertz has turned out many of the fastest cars lapping Infineon Raceway on any given day, including a few current record holders. He knows what works in practice, and he's a key player in making Max Effort a maximum performer. We're lucky to have him on board.
Here's the bare-bones GR350...
Here's the bare-bones GR350 torque arm kit we picked up from Griggs Racing. This stuff is exceptionally well made and Bruce Griggs is a racer who's done his homework to provide a serious suspension package for Mustangs.
In case you haven't guessed, this isn't a bolt-on project by a long shot. Sometimes making a suspension function ideally takes some slicing, though we just barely warmed up the plasma cutters and grinders this time. Kertz didn't really get to flex his formidable fabrication abilities on this stage of the build, but stay tuned because as the suspension and chassis prep continues you'll get a taste of what he's capable of, and why he's one of the best-kept secrets in performance street car and race car fabrication.
Early one rainy Saturday morning,...
Early one rainy Saturday morning, our build crew (left to right: Ryan Kertz, Filip Trojanek, and Joey Chatterton) stood under Max Effort and discussed where to begin-and drew straws to determine who had the misfortune of having to remove the stock fuel tank and it's incredibly aromatic old gas.
With the fuel tank, rearend,...
With the fuel tank, rearend, and leaf springs removed, we had a clean slate to start-metaphorically speaking anyway. There was plenty of grime, but thankfully no serious rust.
After creating clean welding...
After creating clean welding surfaces on the front and rear subframe assemblies, the GR350 tubular subframe connectors are slid into place. To position them, a plumb bob is used to align the bolthole at the rear of the connector with the forward mounting point for the leaf springs.
They say the first cut is...
They say the first cut is the hardest; not so much for us. We were ready and willing to slice a section of the truck floor to make room.
Here's a better look at the...
Here's a better look at the mounting point for our torque arm on the front side of our Currie Enterprises 9-Plus race case. Now you can see why we needed to opt for the anvil-like nodular-iron case rather than the lightweight aluminum; it needs to handle some serious loads.
To get our torque arm where...
To get our torque arm where it needs to be to correctly control antisquat on our '67 Cougar, our Griggs torque arm is 1 1/2 inches longer than a standard '67 Mustang.
An unexpected surprise; the...
An unexpected surprise; the Mustang mount for the torque arm wasn't wide enough for the Cougar's subframe 'rails. Chatterton resolved the issue by fabbing a replacement with a tab to mount the urethane bushings that dampen the arm.
The length of the torque arm...
The length of the torque arm matters, because it directly affects the antisquat of a vehicle. A shorter torque arm increases the antisquat which provides more bite during acceleration, but for a road race suspension it's possible to have too much antisquat which can lead to rear brake hop under threshold braking. It's a fine balance, but in general a torque arm suspension allows a significant amount of antisquat to be designed into the suspension while still maintaining good roll steer characteristics.
Our Watt's link mount has...
Our Watt's link mount has plenty of positions available for our bellcrank, should it become necessary to lift or lower it to tune the rear suspension. For now, we started with a typical location based on Kertz's experience.
This structure provides the...
This structure provides the frame mounting points for the links that will connect our Watt's bellcrank to the Cougar chassis and provide lateral location.
With it tacked into place...
With it tacked into place and the links bolted on, it's easy to see how everything works to keep the axle from shifting under lateral loads. Also note the coilover mounting bracket above; that's the reason we had to cut a section out of the trunk floor.
Before moving further, Kertz...
Before moving further, Kertz uses a plumb bob to double-check that the housing is centered in the wheelwells. We've got tons of adjustment, so moving it is not an issue.
While they're already longer...
While they're already longer than can be packaged in this location on a Mustang and provide better geometry, these lower control arms are just placeholders to position the rearend for now. We'll show you our real plans in a future issue.
The leaf springs are longer...
The leaf springs are longer in Cougars versus Mustangs, so the Griggs lower control arms also aren't long enough. After doing some quick math, Kertz used a piece of chromoly steel to fab two new ones of correct length.
With everything tacked in...
With everything tacked in place, we slid in our Koni double-adjustable circle track coilover shocks equipped with 10-inch long, 275-lb/in Eibach springs. Conveniently, Summit Racing Equipment keeps this badass combo in stock and ships quickly. Notice we mounted them upside down; it helps decrease unsprung mass.
Remember those tabs Juan Alaniz...
Remember those tabs Juan Alaniz welded on our housing at Speedway Engineering? This beautiful custom strut rod whittled by Kertz is the piece that connects them and provides extra rigidity for the axle tube.
Here's the final assembly...
Here's the final assembly with everything positioned and securely tacked into place. We may have some adjusting to do down the line, so we'll save the final welding. Got a Cougar and like what you see? Now that they know how to do it, this new rear suspension package can be ordered through CorteX Racing.