5 ton air barkes

[OpieNoTool]

So i got this wrecker and im probaly have to redo the entyer brake system and frankley i dont trust the single line hydraulic system for a 35,000lb truck towing somthing of equal weight or less. Id like to convert it over to s-cam air brakes, ive seen a few trucks equiped with them aftermarket obviously like the cheap dump truck for sale in the classifieds. does anyone know what civilian backing plates, shoes, and drums i need. I have the pedal valve and all the air hoses. If anyone has information on parts or articals or have done this befor i would apreciate the help.
josh

 

[westfolk]

I was thinking that Boyce, maybe someone else, sold all the parts you needed to change over to straight air.

 

[G744]

The 900-series trucks already have straight air brakes on them. You can do the conversion with all military parts, much better IMO. They are Bendix wedge brakes, as going to s-cam pots would make the whole thing a lot more crowded when the axles flex. They will go almost 90 degrees different vertical. unlike any other suspension found on heavy American trucks.

The easiest conversion would be to swap out the complete axle assemblies, but you can replace the backing plates and go on from there. The rivets on the rears are really tough to get out without porking up the flange, so be warned. A bunch of air lines and valving will need to be added as well, not for the uninitated wrench at home.

Another way to go is pull the MC and put in an air treadle and use it to hit two separate air/hydraulic cylinders plumbed in an "X" pattern. That way you have a bit of redundancy without having to mod the axles.

The wet brakes on these old trucks are a lot smoother than any straight air brake, and are not short of power. Also, if you loose the air, you don't loose your a$$ as well--just the boost. New hydraulic brake parts and hoses are available from several surplus dealers....just to keep you out of auto parts stores. (cheaper, too).


dg

 

[Recovry4x4]

Hey Dennis, is there any reason that mod wouldn't work on a deuce? If you use an air treadle valve, would you just plumb a reservoir into the port that got fluid pressure from the master cylinder? What bleeding challenges would would that bring? IIRC, Tom Bauer once talked aout that very thing. Patiently waiting!

 

[OpieNoTool]

ive looked into the 800 series axels and my buddy dave p has the entire set but hes putting them on his tractor (i think), but he got his down in kentucky and theres not alot if any of those trucks up here to get the parts off of. Im a truck driver and am used to driving trucks with air brakes and to be honest i trust them way more than the wet sytem. we used to have an old oshkosh at work that had wedge brakes and they were awsome for stopping even better than the s-cam but when u had to adjust them it sucked. the reason behind my maddnes is i can get parts quite cheap through my dads company and my brother is a diesel mecahnic so we have the source and the brains to do it but not sure of what parts to use

 

[RF202]

I have run a number of trucks with air brakes, over the years, and tore several air lines off as well. The air brakes will, as we all know, automatically lock up when the air pressure drops below about 60 PSI. However, with a good compressor, they will usually keep working in spite of the leak from a damaged line. I am in favor of the air brake system over the hydraulic. In todays traffic, the congestion and speed of same is no place for the older single circuit system ---- too many lawyers out there looking for an easy check.

John