Trango
Member
- 735
- 23
- 18
- Location
- Boulder, CO
Hi Group,
I have been extraordinarily busy over the past few months, and one of the projects has been to retrofit S cam drum brakes to my front, 5 ton axle. These are Meritor 16.5x7" air brakes, which I feel are going to be much much better than the stock juice brakes. I had a set of these brakes already installed on the rear axle on my 5 ton bobber, as this is what Memphis trucks retrofits onto 5 ton REAR axles as their S-cam conversion, and I had horsetraded for a pair those rear axles with those brakes installed (along with a brake-less front, 5 ton axle).
But, I still had to take one set and (very nontrivially) retrofit them to the front. I'm posting here just to put the info out. In a forum that hosts such standout posters and such great documenters such as gringeltaube, I regret that I only have a few pictures.
Here's some items that I needed to do:
- Extensive modification of the backing plate, including precisely re-clocking the mounting holes and removing material from the "back" edges of the plate. This is one place where a custom fabricated piece would excel.
- Clearancing and clocking of the slack adjuster tube to slide down the groove in the knuckle just behind the kingpin, also cognizant of being able to swivel above the level of the leaf spring
- Light grinding of the knuckle (not enough to significantly compromise either steering or weight carrying, in my estimation)
- New placement of the return spring between the shoes, out of the radius of the hub
After all is said and done, I would have likely have been better served by swapping the axle in toto for a commercial, bottom loading, s-cam braked unit. However, I know the military axles very well, and I had all of these parts already (and the price was right).
I know that I have definitely de-rated the Q-series brakes to an extent, through removal of some material on the backing plate. I am not terribly concerned, however, and I intend to give this thing some panic stops (with subsequent inspection) as part of testing. My truck weighs somewhere around 14,000 lb and has 14" wide front rubber - I would imagine that brakes meant to service a 60k pound truck are probably going to be ok.
Total time to modify all parts was around 50-60 hours. The challenge itself spurred me on, and there were a few "showstoppers" where I found a creative solution to get around what would have otherwise been a no-go.
Overall, I'm relieved that it "went".
Anyway, I'm prevented from working on wiring the last of my truck by a rainstorm here tonight, so I figured I'd post up about this project.
Best,
Bob
I have been extraordinarily busy over the past few months, and one of the projects has been to retrofit S cam drum brakes to my front, 5 ton axle. These are Meritor 16.5x7" air brakes, which I feel are going to be much much better than the stock juice brakes. I had a set of these brakes already installed on the rear axle on my 5 ton bobber, as this is what Memphis trucks retrofits onto 5 ton REAR axles as their S-cam conversion, and I had horsetraded for a pair those rear axles with those brakes installed (along with a brake-less front, 5 ton axle).
But, I still had to take one set and (very nontrivially) retrofit them to the front. I'm posting here just to put the info out. In a forum that hosts such standout posters and such great documenters such as gringeltaube, I regret that I only have a few pictures.
Here's some items that I needed to do:
- Extensive modification of the backing plate, including precisely re-clocking the mounting holes and removing material from the "back" edges of the plate. This is one place where a custom fabricated piece would excel.
- Clearancing and clocking of the slack adjuster tube to slide down the groove in the knuckle just behind the kingpin, also cognizant of being able to swivel above the level of the leaf spring
- Light grinding of the knuckle (not enough to significantly compromise either steering or weight carrying, in my estimation)
- New placement of the return spring between the shoes, out of the radius of the hub
After all is said and done, I would have likely have been better served by swapping the axle in toto for a commercial, bottom loading, s-cam braked unit. However, I know the military axles very well, and I had all of these parts already (and the price was right).
I know that I have definitely de-rated the Q-series brakes to an extent, through removal of some material on the backing plate. I am not terribly concerned, however, and I intend to give this thing some panic stops (with subsequent inspection) as part of testing. My truck weighs somewhere around 14,000 lb and has 14" wide front rubber - I would imagine that brakes meant to service a 60k pound truck are probably going to be ok.
Total time to modify all parts was around 50-60 hours. The challenge itself spurred me on, and there were a few "showstoppers" where I found a creative solution to get around what would have otherwise been a no-go.
Overall, I'm relieved that it "went".
Anyway, I'm prevented from working on wiring the last of my truck by a rainstorm here tonight, so I figured I'd post up about this project.
Best,
Bob
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