I'm back and need new chambers.

[ThaddeusW]

Okay,

So I got the chambers off this weekend.

Yesterday I devoted about 4 hours to getting just the bad chamber off. At first I tried to be gentile and came to realize that everything is rusted up and frozen pretty good. The bad spring chamber I took off by applying air from a big compressor directly to the quick release valves for the spring brakes. I then removed the spring can from the service half thinking everything would be easy after that. I was wrong. The cotter pins on the clevis to the slack adjusters were frozen, even a punch wouldn't drive them out. I tried filing them down until the ends were flush with the pin and drive the pin out but again, the pin was frozen tight. I then said screw it, im going to replace everything. And cut the clevis with a angle grinder. Thankfully the bolts holding the slack adjusters were coated with anti-seize, they came right off with no problems and just a wrench.

Today I took the second chamber off and again I had to cut the clevis but I learned from yesterday and got the chamber off in under 30 minutes. Big difference in time. I will use this chamber to measure the stroke. I have come to learn long stroke means 3 inches of stroke and regular means 2.5 inches, only a 0.5" difference not that much longer. At work I can better rig up air lines to release the spring and apply the service brakes to take a good measurement.

I want to switch to auto slack adjusters, anyone have any input on that? I figure that while I am at the rear brakes I should be smart and replace as much as I can seeing how this truck had sat for 7-9 years. No sense in taking chances with the most important part of the truck, brakes. And anyone have any recommendations, Bendix, Gunite, etc?

[Joe Ditchkus]

I like the manual adjustment slacks. Not much work to keep adjusted in a hobby truck. We run auto slacks in our work trucks because they are mandated. Auto slacks are OK if they keep working. Just my opinion. Joe D.

[Joe Ditchkus]

I forgot to mention auto slacks are about 3 times the money. Joe D.

[Gmerrill0516]

looks like some good advice. The cans on my 815 are spring brakes but the yokes are welded to the side of the rod sticking out of the shaft. It looks real tight between the frame and the wheels and the centers don't quite line up. I intend to find or make up something a little less crude. Can anyone say what the issue is and offer a solution? Thanks and glad to see another guy back in the fold.

Greg

[ThaddeusW]

I forgot to mention auto slacks are about 3 times the money. Joe D.

Boy, you ain't kiddin. I took a look and see that manuals are about 20-25 bucks each while Gunites are around 80 each and Bendix around 90 each.

Think ill stick with the manuals for now. Makes sense as with the low miles I wont be adjusting them very often.

Thanks for the input.

[farmer52]

Boy, you ain't kiddin. I took a look and see that manuals are about 20-25 bucks each while Gunites are around 80 each and Bendix around 90 each.

Think ill stick with the manuals for now. Makes sense as with the low miles I wont be adjusting them very often.

Thanks for the input.

Ron (39 Baby Mack) will adjust them if you visit Gerhart's. He did my MH but I am still waiting for the invoice.

[thomastractorsvc]

looks like some good advice. The cans on my 815 are spring brakes but the yokes are welded to the side of the rod sticking out of the shaft. It looks real tight between the frame and the wheels and the centers don't quite line up. I intend to find or make up something a little less crude. Can anyone say what the issue is and offer a solution? Thanks and glad to see another guy back in the fold.

Greg

Can you get a picture I don't understand what you are getting at, unless you are saying someone tack welded the yolks to the threaded rod

[Mike]

Can you get a picture I don't understand what you are getting at, unless you are saying someone tack welded the yolks to the threaded rod

That is the way I felt also, I did not understand.

mike

[Gmerrill0516]

Can you get a picture I don't understand what you are getting at, unless you are saying someone tack welded the yolks to the threaded rod

Yah that's what I was attempting to write. The yoke is welded to the side of the rod rather than screwed onto the end of it. It's to accommodate the apparent offset between the can centerline and the adjuster centerline...looks funky and might make an inspector nervous.

Thanks

[thomastractorsvc]

has the wrong slack adjuster, yes not dot approved

[Gmerrill0516]

has the wrong slack adjuster, yes not dot approved

So is the cure to buy new brake cans with slack adjusters as a set? Does that fix it? I've never purchased this stuff before...(rookie)

Thanks

[39 Baby Mack]

Ron (39 Baby Mack) will adjust them if you visit Gerhart's. He did my MH but I am still waiting for the invoice.

Invoice to follow!

Ron

[thomastractorsvc]

They all sell individually.

Since I cant look at it, my thoughts are you may want to replace everything.

The brake chambers might be able to be reused if they are long enough that you can cut off the old welded on yolk and add new ones with the jam nut, but chances are they will be to short and for the cost of that stuff may not be worth the effort.

They should look something like this one

[Gmerrill0516]

Yes, that is what I need. When the time comes I'll bring a set up with me and I can lay it out and match up the correct offset adjuster to work with new cans. Mine work well but are rusty and for not too much money it will be right and beyond question.

Appreciate the information very much. Thanks

Greg

[Maddog13407]

I have seen a flat homemade adapter plate bolted to the brake chamber bracket with one bolt from the chamber and the other t the bracket then use the offset slack. seems to work. someone on here has a picture of it.

[Gmerrill0516]

This is what they look like. The cans are real tight in there mounting. The guy had told me they had to rotate the clamps that hold the can together to vet the ends with the bolts to clear the wheel and drum. Any way I'll pull a set and bring it with me to the parts place and hopefully a standard set up will replace this mess without any modifications.

Thanks

Greg

[BC Mack]

good photo....

that modification would have a dot guy busy filling in your ticket..!!!

looks like you need to consider an offset slack adjuster as there doesn't appear to be room for a longer s-cam.. picture was posted earlier IIRC.

not much room there..!!!

BC Mack

[gearhead204]

ive seen both offset slack adjuster arms and off set clevis and since slacks come in different lengths and that's obvious the slacks been changed. I'd be for finding a proper parts list for that setup. as for having to turn the clamps I remember are 87 value liners having smaller chambers 24 or 27 they also did some steeped chambers I don't know about the b models. I'd say do a little home work first to get it right. (too damn many lawyers in this world)

[Gmerrill0516]

Thanks for the help. I'll have some conversations with Watts Mack at some point when the budget is less constrained. Maybe they can tell me. I've got the factory paperwork on the way too although if it's like the 49 L model the numbers don't mean anything anymore. I can always talk to the local guys as there are a bunch of the 80 series trucks in New England and I can take some pictures and ask some questions of part numbers if they might know.

I guess it's good I asked...the more I read here the more I learn that the DOT and local constabulary frown upon inferior equipment with a large money grab!

Thanks guys

Greg