Brake Update B63

[Mack B63SX]

Hey guys,

I was wondering if you could shed some light on Maxi brake conversion on a B63 with s-cam roto-chambers. There seems to be a need for an offset bracket of some sort. Correct me if I'm wrong but an offset slack adjuster may be in order to do this too. Any help on this brake modernize job will be greatly appreciated! Thank you.

[Rob]

Hey guys,

I was wondering if you could shed some light on Maxi brake conversion on a B63 with s-cam roto-chambers. There seems to be a need for an offset bracket of some sort. Correct me if I'm wrong but an offset slack adjuster may be in order to do this too. Any help on this brake modernize job will be greatly appreciated! Thank you.

Do you have cast steel backing plates, or stamped steel? Are the rears 38,000, or 40,000 or greater?

Rob

[Mack B63SX]

Hey Rob,

Thanks for the reply. My backing plates are cast steel. I believe the rears are 38,000 but not sure. How does one determine that on these old rears? I'm pretty new to this game in case you cant tell! Thanks for the help.

[Arcticmack]

Hey Rob,

Thanks for the reply. My backing plates are cast steel. I believe the rears are 38,000 but not sure. How does one determine that on these old rears? I'm pretty new to this game in case you cant tell! Thanks for the help.

This is where Im at too Mine are 38's Im gonna do a compleate retro job on the brakes found a doner for al the newer brakes( maxi's) all bolt on stuff so am going that route, gonna be nice having 4 maxi's to hold her on Hills we have here. simple to hook up too. only thing is I wonder if the front axle Budd Hubs from a b73 later model will fit my 58 b63 california spoke spindles, if so then Ill go that route as well. then can put on the super single budd Alcoa wheels on front.

Arctic.

[Rob]

Most of the 38,000# axles that I've been around have the stamped steel backing plates that are more of a dust guard that anything. The cast steel backing plates are on 40,000# and up setups. They support the original rotochambers and will not clear anything larger than a type 20 modern chamber. If you cut the mounting ears for the rotochambers off and add an extension to them, then mount offset slack adjusters you can get type 24/24 chambers mounted readily as they will now clear. If you want to go to 30/30 type chambers, (reccomended), then you need to get longer "S" cams and use an outer support for them. I've seen people use "R" model mounts, and/or fabricate their own to make it work. If I remember correctly, the "R" model type chamber mounting brackets mount to the center of the axle housing and will mount the chamber more internal to the center of the truck.

I've never actually performed this myself, (type 30/30 mountings) but have seen it several times on B model Macks and I'm going from memory.

Glenn will probably come along and clarify in a bit.

Rob

[Mack B63SX]

Thanks Guys, I'm thinking that the offset bracket and type 24/24 is the route I may take. I have a donor source for the cans, but I doubt the backing plates off of a Freightliner will bolt up to a mack rearend without hassle. Any further ideas would be a great help.

Arctic Mack I got lucky on my B63 all budd wheels! This helps quite a bit on the rears too. If I'm not mistaken the hubs should be interchangeble.

[Rob]

Thanks Guys, I'm thinking that the offset bracket and type 24/24 is the route I may take. I have a donor source for the cans, but I doubt the backing plates off of a Freightliner will bolt up to a mack rearend without hassle. Any further ideas would be a great help.

Arctic Mack I got lucky on my B63 all budd wheels! This helps quite a bit on the rears too. If I'm not mistaken the hubs should be interchangeble.

That is the easiest approach and the 24 series of chambers will stop all but the heaviest of loads adequately.

Rob

[Freightrain]

For whatever reason, my B had center type mounts on it? Maybe someone changed it years ago, but took my roto's off and 30/30's fit right with lots of room.

Talk about stop-on-a-dime brakes!

[Rob]

For whatever reason, my B had center type mounts on it? Maybe someone changed it years ago, but took my roto's off and 30/30's fit right with lots of room.

Talk about stop-on-a-dime brakes!

All of the single rear axle B models that I've seen had the center mount brake can just as yours, and my daughters trucks do. It was just the tandems that had rotochambers, (at least from what I've seen). I never quite knew the difference, or benefit to using rotochambers in the first place except for physical size as they are smaller. From the difference in cost of maintenance, I can't see why they were used Maybe it didn't used to be that way when they were commonplace?

Rob