Mopar suspension upgrade for improved handling
TVS Offers True Performance
Kevin Harper - November 10, 2011 10:00 AM
1 Hotchkis started out by testing the Challenger in stock trim. The 440-powered car was quick in the straights, but slow to respond in the corners, suffering from body roll and impaired braking. Chassis flex and roll affects how the weight of the car is divided on the tire contact patch, which in turn affects the brake response.
2 Hotchkis offers a complete package (TVS) or allows components to be purchased singularly. We chose to use everything Hotchkis has available for the E-body. Our install included geometry- corrected tubular upper A-arms, adjustable tie rods, adjustable strut rods, sport leaf springs, subframe connectors, and front and rear sway bars. This Challenger already had upgraded 1.03-inch torsion bars, but we did add the Hotchkis spec’d Bilstein shocks on all four corners.
3 Originally a drum brake car, our test Challenger had been fitted with later model Dodge disc brakes in the front.
4 With the car safely on the hoist, the first step is to back out the torsion bar adjustment bolt to allow for movement in the lower control arm. Tie the caliper up so the brake lines aren’t damaged, then remove the tie rod end and separate the ball joint from the spindle.
5 If your car still has splash shields, remove them. Loosen the upper control arm mounting bolts and pull the stock upper control arm out of the frame mounts.
6 The stock Challenger A-arm suffers from changing caster as it moves on the road. The Hotchkis tubular A-arm changes the mounting point through the use of a custom bracket, and this minimizes bumpsteer. This laser-cut bolt-in relocation bracket puts the arm further out, eliminating caster gain and allowing for increased adjustability during alignment.
7 We had to slightly notch the stock mounting tab to allow the proper fitment of the Hotchkis bracket. It was a simple thing to make the space with a hand file.
8 While tightening the arm, check the Heim joints for smooth movement. Bolt on the new ball joint and brake assembly. The Hotchkis kit can be used with any shocks, but we chose the recommended custom-valved Bilsteins for our project.
9 Strut rods don’t get much attention, but they can be the cause of lower control arm movement during cornering or heavy braking. The Hotchkis TVS includes adjustable strut rods with Heim joint mounts instead of the stock rubber bushings and threaded end. Hotchkis adjustable strut rods positively position the lower arm to improve responsiveness. They use a high-articulation 5/8-inch aircraft-style rod end for smooth range of motion.
10 Hotchkis tie-rod assemblies help prevent unwanted movement. Like the strut rods, the design uses Heim joints instead of the conventional ball joint ends. The tie rods are also adjustable to maintain proper geometry. These Hotchkis adjustable steering tie rods work in conjunction with the new A-arm to eliminate bumpsteer. If you aren’t familiar with the term, bumpsteer is the change in toe-in and toe-out as the car moves up and down throughout the suspension travel. A stock E-body has over one inch of bumpsteer. With the Hotchkis components installed that is reduced to 1/16-inch, about the same as a modern Challenger SRT8.
11 One of the biggest improvements that any muscle car fan can make to their car is the addition of a sway bar. Not all Challengers and ’Cudas came equipped from the factory with even a stock front bar. For those cars, Hotchkis offers weld-on tabs for the stock lower control arms.
12 An aspect of the Hotchkis system that appealed to us was that none of the components require radical changes to the frame of the car. “We know Mopar owners like to keep the ‘soul’ of their cars,” John Hotchkis told us when we started this project. “We wanted to show people that they can make a car handle with rear leaf springs.”
13 To start the rear suspension installation, unbolt shocks and remove the U-bolts holding the stock leaf spring hangers. If your springs have never been changed, these U-bolts may be difficult to remove. We recommend air tools. Depending on your hoist, you may need to support the rear axle before removing the leaf springs.
14 Like the front A-arms, Hotchkis uses a revamped bracket to change the mounting point of the rear leaf springs. Notice that the Hotchkis springs feature a lightweight three-leaf design as opposed to the stock four- or five-leaf set-up.
15 Once the new springs are in place and loosely bolted up, install the new shocks. Don’t tighten the shackle and spring-eye bolts until the car is off the jackstands to prevent pre-loading the bushings.
16 There are two parts of the Hotchkis install which require a “permanent” alteration to the car. The subframe connectors are welded in the front and the rear sway bar mounting brackets must be welded in the rear. Both of these welds are small and could be removed to return the car to stock if desired.
17 Once the brackets are in place, install the rear sway bar with the supplied U-bolts and brackets, but don’t tighten them yet.
19 The Hotchkis Sport sway bar is adjustable, allowing the driver to dial-in understeer and oversteer into the car’s handling setup. We started with the middle hole.
20 The only part of the install which can’t easily be done in a driveway is the installation of the subframe connectors. If you don’t weld, Hotchkis recommends asking your local muffler shop to take care of this step.
21 Skid pad g force numbers improved from .78 to .85, the slalom speed went from 59 mph to 64 mph and the road course lap time dropped from 1:19.772 to 1:17.480. Those are real world results.
For Your Information
Hotchkis Sport Suspension
With the increased popularity of combining car shows with autocrosses, drag racing or track days, we’re seeing more muscle cars being built to look as good on the track as they do in the show field.
When the trend of building corner-carving muscle cars first started, most of the options for suspension upgrades involved heavy modification to the stock frame, which left those of us with commitment issues reluctant to break out the torch, especially for cars like a 1970 Dodge Challenger.
The lack of available aftermarket suspension for Mopar muscle cars meant that a driver hoping to put his or her car on the track would have to choose between cutting up a valuable collector car or continuing to dread mountain roads and curving freeway on-ramps.
Not anymore. There are now options for bolt-on suspension upgrades which allow stock-appearing classics to take curves like modern sports cars.
We first took notice of the Hotchkis Mopar offerings when we saw the company’s R&D Challenger (nicknamed “E-Max”) wowing the crowds in a company-sponsored autocross. The owner of the blue ’70 you see here was impressed too, but she was loathe to give up her car’s stock “sleeper” looks by going all out with big wheels, tires and brake upgrades.
“Many people think it’s all or nothing with these cars,” says Hotchkis founder John Hotchkis. “They aren’t necessarily all-out racers. They just want to feel confident driving their classic car on a twisty road. The Hotchkis parts are designed to offer dramatic improvement by themselves, as well as providing an excellent platform for later upgrades, which makes them a perfect choice for everyone from drag racers to street cruisers.”
We headed over to Hotchkis Sport Suspension to see if their Mopar TVS could really transform a stock big-block pony car from dull daily driver to racetrack ready, without compromising that daily driver reliability.