Marquis Front Air Brake Chambers

[Pat Long]

After driving rigs for over 40 years I believe my Marquis could do a little better with stopping performance from my brake chambers.  My front and tag chambers are size 24, and my spring driver axle chambers are size 30.  I have been thinking about using the front chambers to a size 30 for a little better stopping power.  I don't drive 2 feet in front of the hood ornament, I drive at least 1 mile ahead, or as far as I can see ahead so as not to drive blindly upon trouble.   Just wondering if anybody has done this and the outcome in performance and ease of use.   Thanks in advance for all comments.

[Dave Atherton]

Pat, the way air brake setup on vehicles the front axle is set up for doing 40 % braking
and stopping power and the rear brakes do 60 % braking and stopping power. Making
change putting 30/30 brake chamber on front axle would affect stopping control on your motorhome.
Putting equal braking on the front axle will pose  a control problem. Would suggest review
Air system setup with D.O.T Reg's for bus operation or call MFG like Bendix, Midland, Mentor
Wabco for how brake operation would affect your motorhome. Dave Atherton Retired Cat mechanic

[Gerald Farris]

Pat,
When Beaver first installed the Meritor ADB brake system like your coach has on the 98 Marquis, they used T-20 chambers on the front axle and the braking performance was so poor that they recalled those early production coaches and changed them to T-24s.

I replaced the front air chambers on my 2000 Marquis with T-30 chambers and I was pleased with the results. I had a 40 ft. coach, so no tag axle and I was only getting about 30 to 35,000 miles on rear brakes, 90,000+ on fronts and poor braking. However after changing to T-30 chambers on all axles, the stopping improved and the brake pad life went to the 45 to 50,000 mile range on both axles. I drove it for 100,000 miles after the change with no adverse driving characteristics that I ever noticed.

There have been several other owners of similar coaches who have made the same modification that I know of, and all were pleased with the result. However, since this is not an approved modification, you have to decide its feasibility for your application at your own risk.

Gerald 

[Jim Murray]

Gerald is 1000 % CORRECT , GO WITH THE 30' s ,  Like a lot of us have already done.

[Steve Huber Co-Admin]

If you have the misfortune to be involved in a bad accident and they find your brake system has a non-factory approved modification, you may find yourself is a difficult situation.
Steve