Chevelle Suspension
Q I've got several muscle cars, some are keepers, others are waiting for good homes. With my ever-expanding collection, and ever-contracting budget, I need to pick my battles wisely. For disc brake conversions on a GM four-wheel drum setup, can the drum brake spindle be used? What aftermarket spindle (no drop) would I need? Would a 1-inch taller spindle and tubular upper control arm be wise to improve handling?
Trevor Law
Trochu Alberta Canada
A We gave the guys at Classic Performance Products (CPP) a call about this question. They specialize in updating these classic cars with disc brakes and better suspension. They had a couple recommendations. The factory 11-inch disc brake (part No. 6472SWBK-S, $449) would hit the upper caliper bracket mounting boss on a drum spindle. CPP makes a 10.8-inch rotor (part No. 6467WBK-S, $449) that works with a drum spindle, and mounts the wheel in the factory drum brake location. Factory 11-inch discs move each wheel out 7/16 inch, for a 7/8-inch overall wider track width. CPP also offers 13-inch disc brake conversions (part No. 6472WBK-P13, $699), but they must be used on a disc-type spindle. Many people have converted their drum brake spindle to a disc-type spindle by cutting the upper bracket mounting boss down about inch and re-threading the boss for a 5/8-inch 18 bolt.
Aftermarket control arms can help your car handle better. The limits of the stock control arm's adjustment won't allow the suspension alignment for maximum performance. Factory parts are made to give some performance, but mostly to keep tire life long. Hot rodders like us buy tires for performance, not life expectancy, so the more aggressive alignment with more tire wear is OK. Aside from a better alignment, the upgraded materials help too. Rubber bushings wear out over time and deflect quite a bit, changing the control arm's location under load. The polyurethane material is more rigid and lasts longer than the rubber. Worn out ball joints can give a sloppy feel and make noise, so new arms with new ball joints will give your front end new life. A set of upper and lower control arms from CPP will run you $733 (part No. 6472ULK), a very good price for the benefits.
We recommend using stock length spindles. Spindles that are taller than stock cause a change in the camber curve. The small gains you make in front corning traction will be lost in front braking traction (the most common place to pass on a road course is under braking while entering a corner). Unless you have an independent rear suspension, you can't get the same level of corning traction improvements at the rear of the car.
Source:
Classic Performance Products
800-522-5004
www.classicperform.com
Solving Sag
Q I have a '68 Camaro RS/SS 396. When the car is sitting, the vehicle slants to the driver side front. I have Moog coil springs, poly bushings, and the vehicle still sags. I recently bought 1-inch drop Global West springs. I have not installed them yet. Will this resolve the sag issue, or should I look at something else?
Phil Gonzales
Via the Internet
A There are a couple reasons your car might not sit evenly, and you should check some things out before you start throwing parts at it, although the Global West springs are a good upgrade. The first thing to check off the list is the frame itself. If the car has been in a huge wreck, it might've gotten twisted, but if the panels still line up fairly well, the chances of this being the cause are slim. Another thing to look at is the body mounts. Factory rubber mounts can become brittle and break apart over time, and if they work their way out you can lose about inch of body height. A flat tire is hard to miss, but something else to check.
If the springs aren't the same rate, it can let one side sag more than the other. Also, if the springs have been cut or trimmed to make the car sit lower, and weren't done evenly, you will get the same result.
The most likely reason your car has a lean is the placement of the springs. The lower control arms have a pocket that the spring sits in. It's not an even stamping, it has a ridge or a stop for where the end of the spring sits. It acts as a locator so that the spring lives in the same position on the driver and passenger side. If one spring is sitting in the pocket incorrectly, it can change the ride height and your suspension's alignment settings.
If all of the above checks out OK, make sure you aren't just parking on uneven pavement. As for the springs you bought, they probably have a more aggressive spring rate than the Moog springs, so throw them in. You might as well, since you'll need to check the spring's positioning anyway.
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