High-Performance Steering and Suspension Upgrades
A few tricks from our Tech Insider on steering and suspension setups for street and track.
Words: Larry Shepard
Typically over the past few years in this column, I’ve discussed engines and engine-related technologies, such as new blocks and heads, or cams and manifolds. Readers like to science-out their engines. Next in popularity is the basic drive-train, such as torque converters or rear axles. The one subject area that tends to get left-out most frequently is items relating to the car’s steering and suspension systems. This time around, I’ll focus on street or dual-purpose vehicles and related upgrades to the steering and suspension parts rather than the race car hardware. While there may be some overlap, the street parts tend to have flexibility for application, where the race parts work best in racing.
Even in our limited discussion over the past few years of steering and suspension, the steering end of the deal has been left almost totally out, so I’ll start there. Ten years ago, any steering discussion would have been very short, but it can be much more complete today. With any given muscle car project, you might want to convert your car from power steering to manual steering. This swap requires more than just the new steering box. In the old days, you had to change the steering column also. Today you can use the special adapter (P4510637). The manual steering box is lighter and tended to come standard with a 24-to-1 or 26-to-1 ratio (same gear but different ratio because of body style’s specific geometry). If you have a manual box, you can upgrade the ratio to 20-to-1 by using the new worm-and-ball assembly (P4007612) that can be installed into your existing box. Some of the mid-1960s A-Body cars had a 16-to-1 manual box as an option. This was a popular conversion in the 1970s until the parts were no longer available and then they became very hard to find. A brand new, 16-to-1 steering aluminum box is now available from Flaming River (www.flamingriver.com) or Mancini Racing (www.manciniracing.com). I would not recommend this ratio for the big block cars—383s, 440s or HEMI®s. It seemed to work best for drivers in road racing or rallying but was not popular with drag race or circle track racers—too quick and too much effort. The 20-to-1 ratio is the better compromise.
Another overlooked topic is brakes. With all the custom approaches used on street or dual-purpose vehicles, perhaps the most popular brake part has been the adjustable brake proportioning valve (P5249088). This valve is inserted into the rear brake line on rear-wheel-drive muscle cars so you can adjust the brake balance front-to-rear to compensate for big/wide rear tires, big engines, more or less weight etc. There is also a brake pushrod (pedal to master cylinder) P5249316AB or an adjustable version—P4510640. Almost all ’60s and ’70s era muscle cars used disc brakes on the front and drum brakes on the rear. There are a few cars that also have drum brakes on the front. In any of these conditions, if you want to swap them for disc brakes or 4-wheel disc brakes, there are complete systems available from SSBC (Stainless Steel Brake Co.) and Mancini Racing including parts for the 8 3/4" axle. Brakes are related to wheels and the typical 14" x 5.5", 15" x 5.5" or 15” x 6.0"/7.0" Rallye wheel or 500 wheels are available new from several suppliers in the aftermarket. The longer wheel studs for use with racing-style aluminum wheels are available (P4120625 for drum and P4120610 for discs) and the production chrome lug nuts (02823848 right, 02823849 left) add a nice touch to most steel wheels.
The overall suspension topic is divided into two general areas—front and rear. I’ll start with the front since it has to hold up the engine and is the least discussed of the two. The key to the front suspension on RWD muscle cars built in the ’60s, and ’70s was the torsion bar. While the B- and E-Body cars share the same torsion bars, the A-Body bars are shorter. A resto torsion bar (at .870" outside diameter) would be for HP small blocks or 340/360s. The 383/440 A-body bar is the .890" bar (P5249150). The upgrade, HD/HP bar for the big blocks would be the .920" bar (P5249151). On the B- and E-Body cars, the resto bar for the 440 and HEMI big block cars has a .920", so the upgrade bar is the .960" (P5249158). The torsion bars are held in with a special clip and use a seal—both in kit P5249609 or clip only P4876097.
All the front suspension large parts after the steering parts and the torsion bars, are still serviced. The upper and lower ball joints and the pitman arms and idler arms are available from Mancini Racing. The production control arms are stamped steel designs. There are tubular-steel (fabricated) control arms available from Magnum Force (www.magnumforce.com); these are Mopar®-approved parts and Mancini Racing. The lower control arm, which has the torsion bar mounted at the inner pivot, has a strut that goes from the outer end rearward to the frame. There are bushings on each end and they should be replaced with HD bushing—P4529183 (A-Body), P4529184 (B- and E-Body). Remember that street cars should have a front sway bar. Most drag racers remove the front sway bar for weight reasons.
The main part of the rear suspension is the rear leaf springs. They should be replaced in sets. There is a left spring and a right spring. This built-in bias is more important on larger displacements and higher torque engines. The HD B-Body rear springs, as used on the big blocks (440s and 426 HEMIs) is P4452982/983 (’66-’72). The big block springs (440 and HEMI) on the E-Body is P4452984/985. The upgrade rear springs for a HP A-Body 440 or HEMI (including a crate motor swap) could be P4510268/269, but I prefer P4120863/864 (either manual or automatic). A handy spring clamp P4120470 can be used for fine tuning—add to the front segment of the spring unless the spring’s rear clamp has been lost. The leaf spring has an eye at the rear—7/8" on the A-Body (bushings P4452986) and 1" on the B- and E-Body (P4452987). The rear spring eye connects to the frame with a rear shackle—straight B-Body (P5249716) or straight A-Body (P5249715). The Super Stock (racing) rear suspension typically offsets the springs inboard for increased rear tire clearance and this causes the shackles to also be offset. A similar situation exists on the front with the front spring hanger—a U-shaped bracket that bolts to the frame and holds the front spring eye. For best tuning you would like to have an adjustable front spring eye location, which requires a special spring hanger with two hole locations (available from Mancini Racing). The problem is that the Super Stock (racing) hardware, which is commonly available from Mopar Performance, is designed for use with SS springs, which are shorter by 2" in the B- and E-Body cars. Therefore these SS hangers are longer, plus the A- E-Body SS package has offset in the hangers for the springs being moved inboard. If you want to use bigger rear tires than the production muscle cars did, then you may also want to offset the rear springs inboard. All this offset hardware is available from Mopar Performance. The key to moving the springs is new rear-axle spring seats (P4120074).
The rear shocks attach to the frame above the axle and extend down to a special plate that is below the spring. The spring plates are made in a mirror image—right (P4876518) and left (P4876579). The stud that mounts the shock to the plate and nut that holds it on are available from Mancini Racing. The rear shocks want to be longer than stock—A-Body manual transmission (P4529516), automatic P4529514 or B- and E-Body automatic (P4876515). Don’t forget the adjustable pinion snubber like the 8-3/4" unit P3690181. Additionally check the rear u-joint angle and adjust as required using the 1-2-3-degree pinion shims in kit (P4529536), also sold individually.
The hows and whys of all this hardware are discussed in the Chassis Book P5007160. Also it will tell you how to align your front end to solve a problem or increase your performance on the street or at the track.
