Hydraulic Brakes

[Speed]

:bmod1:

Hi all;

After driving my '45 EH home,I have some questions about my brakes.

Where can I find master cylinder and wheel cylinder kits for it? The parts stores don't even acknowledge Mack trucks,let alone stock parts for 'em.

What's the procedure for adjusting the brakes? I know on each backing plate there's an adjuster cam-bolt toward the top for each shoe,and if I remember right,there's an eccentric bolt with a jam nut for each shoe at the bottom. My problem is that I have one front (Left-front)and one rear (Right-rear)brake that dragged all the way home. Before I left I jacked up the front wheel and turned the adjuster back and forth until I had the least amount of drag,then I adjusted the bottom eccentric bolts too,but all that did was tighten the shoes again,so I reset them to the least drag and locked 'em down. Before I started I could barely turn the front wheel,and at the end,if I put everything I had into it,I could get it to spin about half a revolution.

Moving to the rear,I jacked it up,couldn't even move the wheels.(YES,it was in Neutral) I adjusted the upper cam-bolts as best I could and got ity freed up to about what the front wheel started at. I tried to break the eccentric jam nuts loose but even with a 3 foot cheater bar on the wrench and me jumping up-n-down on it,no joy.

I finally gave up and settled for checking the drum/backing plate occasionally for extreme heat build up on the way home. Didn't seem to get very hot. As things warm up,the brakes seem to free up a little,to a point where if I knock it out of gear at about 15 mph,it actually coasts a little ways,finally rolls to a stop,and I can barely feel the brake "set" as the truck stops.

So,how do I get the brakes backed off enough to remove the drums? And whats the correct procedure for adjusting those piggies?

Thanks!

Speed

:bmod2:

[Packer]

I'm still a ways from getting it done but I'll have both diff's out of my '48 sometime. Might be able to work some thing out.

Getting my two speed rear and front axle sand blasted this week and after compleat inspection and rebuild, I'll slide them under and have some parts left over.

Start gathering your plunder and we'll get a trade in the works!

Packer

[Speed]

:bmod1:

Hi all;

After driving my '45 EH home,I have some questions about my brakes.

Where can I find master cylinder and wheel cylinder kits for it? The parts stores don't even acknowledge Mack trucks,let alone stock parts for 'em.

What's the procedure for adjusting the brakes? I know on each backing plate there's an adjuster cam-bolt toward the top for each shoe,and if I remember right,there's an eccentric bolt with a jam nut for each shoe at the bottom. My problem is that I have one front (Left-front)and one rear (Right-rear)brake that dragged all the way home. Before I left I jacked up the front wheel and turned the adjuster back and forth until I had the least amount of drag,then I adjusted the bottom eccentric bolts too,but all that did was tighten the shoes again,so I reset them to the least drag and locked 'em down. Before I started I could barely turn the front wheel,and at the end,if I put everything I had into it,I could get it to spin about half a revolution.

Moving to the rear,I jacked it up,couldn't even move the wheels.(YES,it was in Neutral) I adjusted the upper cam-bolts as best I could and got ity freed up to about what the front wheel started at. I tried to break the eccentric jam nuts loose but even with a 3 foot cheater bar on the wrench and me jumping up-n-down on it,no joy.

I finally gave up and settled for checking the drum/backing plate occasionally for extreme heat build up on the way home. Didn't seem to get very hot. As things warm up,the brakes seem to free up a little,to a point where if I knock it out of gear at about 15 mph,it actually coasts a little ways,finally rolls to a stop,and I can barely feel the brake "set" as the truck stops.

So,how do I get the brakes backed off enough to remove the drums? And whats the correct procedure for adjusting those piggies?

Thanks!

Speed

:bmod2:

Thanks Packer;

don't know what good I'll be for trades-most everything I've replaced was shot beyond my ability to raise from the dead.

Let me know what you need and I'll see what I can scare up in my area.

Any idea when you'll be rolling through Elko? I found a parts store that could come up with numbers for the hydraulic kits,so I ordered a master cylinder kit,should be here first of the week. as soon as I can get the brakes adjusted loose enough to remove the drums I'll rebuild the wheel cylinders and install the HydraVac I pulled from my GMC parts truck,and get the shoes relined if they need it. I'm going to look for a gear driven air compressor,it looks like the current ones might fit my engine too. (They might not have the same gear pattern,??) Aside from that and plumbing air lines and tanks,all that needs doing is a good cooling system flush. Oh-I need to get some bumper markers welded too. I built some for the Mack after punching a hole in my neighbor's redwood fence parking the truck a few days ago with the front bumper. (I didn't think the bumper stuck out that far...) Still pondering how to fit some lights on the tops.

Also got the air horns installed,mounted an air tank on the right running board bracket,between the board and the frame,and an inflator valve right next to the battery box cover. (They sound great! )

Just scored some decent carpet today,so the Mack's getting carpets made tomorrow.

That's about what I've done on the Mack lately.

Speed

[CML Service]

Hi Speed,

I've never worked on Mack hydraulic brakes but I've worked on others of that vintage. Often the rust will build up between the shoe and lining causing brake drag. The adjusters are generally in two groups, Major and Minor. Major adjusment is for initial set up then minor is for maintenance. One that I have worked on is the Wagner Hi-Tork. That type has five adjusters per wheel and you set the shoe clearance to the drum with a feeler gauge through the backing plate. I have many of the old Motor manuals that cover these early brakes if you need info.

As for master and wheel cylinders. My persomal preference is to send them out to be bored and sleeved with brass. I've done a couple trucks that way and it works well. You never have to worry about corrosion in the cyls again. I have the name and number of the shop I used if you need it. The ones I did were 46 and 47 IH KB5. I did these two trucks for a customer who uses them for his catering business. These trucks run nearly every day and with all the equipment weigh in about 15,000. The first one I did actually made it into Wheels Of Time in a feature article.

Send me a email if you need any more info.

Chuck