I'm looking to buy an old school bus to convert into a RV. Knowing nothing about air brakes I thought I might need to do a little research before I make a purchase. What area of the system should one be concerned ? I've found one '92 ford chassis 71 passenger Carpenter that had a 5.9 cummins, allison auto and air brakes. It took a long time for the pressure to build and would quickly bleed off when the engine was shut off. It appeared to be leaking from a small round cylinder mounted to the front of the pump. Pressure regulator? There's a hole on the back side of this part where it was escaping. Brakes felt OK when driving. It did seem to be a real pig re performance. Slow to get to 55 and not much more speed left. Odometer shows 135K, engine sounded good, no smoke, very clean oil. I thought it would have run better. Title shows it to weigh 16K empty, 28K gvw.
Found another candidate. 91 Int, DT466, 7 spd, hydraulic brakes. 98K miles. I'm liking this combination more than the 5.9, 3 spd auto.
the little cylinder was the governor, pretty cheap and easy to replace. But there could be a check valve or other problem that is causing the air leak out the governor exhaust. Do you plan to put a lot of miles on this beast? If so air brake maintenance will be much cheaper than hydro in the long run.
Before you buy anything you might want to check with your insurance company. I've been told that around here they will not provide coverage for a school bus converted into a motor home. I can't prove it but would hate to see you go through all the work and then find that out.
Last i read on the 7 spd trans. Junk. Lots of them blown up.
For everything you want to know about air brakes, go to the Bendix website and download the air brake handbook. Don't have the time right now to get the direct link for you.
I did my homework on this. Insurance is no problem if the title says "motor home". Checked with the local dmv and got the details on having it switched over from 'bus' to 'motor home'.
What's the problem with this box? 98K doesn't seem like many miles and I'm pretty easy on stuff. Hoping I can get a few more out of it. The Allison automatic scares me more than any manual. At least i'm in control.
Also- If you get it to motorhome you won't be required to have a CDL. A bus at 28K GVWR will require one. Also- I bet if you check the horsepower on the 5.9 its pretty low, but can likely be turned up. But I had a 5.9 with a 3Sp auto in a Dodge 3500 and she was turning pretty tight on the interstate which sucked fuel like I do lemonade on a July day. So beware the combo. Maybe great in town, but out on the open road??????
Air brakes are meant to work this way. The air pressure is what holds that break open without air pressure the brakes lock. That is so when you are driving a rolling house down the road and you have a brake system failure your truck is still going to stop eventually..
I sure like the DT 466 Engine a lot better.Company only had one truck with the 7 speed and they sold it with the same one in it . 300,000 on the speedo , But had always heard the 7 speeds were weak.