2 Wheel, 4 Wheel or 6 Wheel Disk Brakes

on Your GMC Coach?

by Bill Harvey, GMC Western States

For years GMCers have been considering upgrading our coach braking systems with all-wheel disk brakes, but the price has been prohibitive. Now, thanks to the eagle eye of the GMC Western States Technical VP, Frank Condos, it is economically possible and practical. Frank noted that hot rodders and four wheelers have access to all wheel disk brakes through a small independent manufacturer located in Colorado.

The Streetrod Manufacturing Company, Inc. (TSM Inc.) has been producing bolt-on front and rear disk brake kits for Ford, Chevy, GM, Chrysler, Toyota, Jeep and even Jag cars and off road vehicles for the past several years. TSM is a small two man shop started by mechanical engineer, Cliff Jones, as the result of his experience building and racing streetrods and 4WD trucks. The fact that the shop is small but with a very well equipped machine shop says a lot about the quality. This is not a production line situation. This was further evidenced by Cliff’s willingness to consider equipping a GMC Motorhome with rear wheel disk brakes just to see if it could be done.

Since we couldn’t find the necessary wheel and hub to check sizes, I volunteered my coach as the test bed. I should note that I had had Ray Curtis install the "Anstett" brake system over a year and a half ago and was very pleased with the system. I felt that the coach "stopped like a car", but it was in the interest of GMCers to try the rear wheel disk brakes.

Everyone knows that disk brakes have many advantages over drum brakes primarily because they cool more quickly. This makes them better for heavy braking, high speed stops, multiple braking, trailer towing and mountain driving. The latter is a major factor here in the west. Disk brakes have the physical advantages of being self adjusting, self cleaning and have less rotating weight than drums. Pads are much easier to change than brake shoes. And disk brakes provide more consistent, even braking than drum brakes.

TSM can provide complete kits for one or both rear axles for $610 for the front rear (mid) axles and $590 for the rear axles, plus shipping of course. These kits include rotors, spacer plates, calipers with mechanical parking brake fittings, high performance pads, caliper brackets, necessary hydraulic hoses or lines and Grade 8 bolts and washers. The competent mechanic should be able to install each axle in a few hours, including the time it takes to bleed the brakes and readjust the parking brake.

Do you need disk brakes on both the mid and rear axles? It has been argued correctly that the mid axle brakes provide most of the braking for the rear end. However, to obtain the primary advantage of disk brakes, i.e., lack of fade for continuous braking, it appears better to have disks mounted on both the mid and rear axles. Otherwise the rear axle drum brakes may overheat and cause boiling of the brake fluid with resultant brake pedal softness. (For that matter, it might be better to disconnect the rear axle drum brakes and plug the line if you are going to mix the systems.)

In as much as rear axle disk brakes are not subject to the loading torque of the mid axle, it might be better to either use smaller pads or proportioning valves on the rear axle to reduce the tendency of these lighter loaded brakes to load up and skid.

This is a good place to provide the standard disclaimer: What you do to your coach is your business. Neither the writer, GMC Western States or TSM, Inc. assumes any responsibility for your installation of the brakes or their performance. I have attempted to present the pros and cons of disk brakes, but it is up to you to determine if you want to continue with your OEM brakes, upgrade with the "Anstett" system, add disks to the mid axle only or go all the way with all 6 wheels.

If you have or can get calipers and pads, TSM will subtract $280. If you don’t want parking brake calipers, you can save another $180 per axle. By the way, the difference in price between mid axle and rear axle kits ($20) is based upon the need for new metal lines to the calipers. I recommend that you call Cliff and discuss your specific needs with him. There are some things that can be done with the parking brake to clean up the system. You’ll find that he is willing to take time to discuss the installation and answer questions. (I suspect that Cliff and his assistant, Skip, may be in the market for GMCs one of these days.)

TSM can be reached at 303-688-6882 or fax 303-660-4660 or email: tsmmfg@aol.com. There is also a website, http:www.miraclemile.com,