The Stovebolt Site Forums The Shop Area Driveline Disc brake conversion for 41-46 AK trucks

I’d love to add a disc brake conversion to my mostly stock ‘46, but I want to keep my factory 15” Artillery wheels. Is there any disc brake conversion that will work with the factory wheels ?

Also, does a disc brake conversion require a different master cylinder? If so, is there one that will allow using the original pedals and location?

I know that for the TF trucks, CPP says you can use the original wheels if you get spacers (3/8"?). I personally dislike wheel spacers, but a lot of people run them just fine.

I don't know if their AD kit works the same way, but I suspect it does. Can't hurt to call and ask.

As far as the master cylinder, yes you need a new one. It is fairly easy to get a manual cylinder that just bolts up in the stock location.

If you want a power booster as well, then you have to get creative. Look at Gord&Fran's installation. He moved the mount toward the back of the truck and extended the rod but kept everything else the same. That seems like a clean solution to me, even though it does involve some modification. From inside the truck, you would never know.

Dltalfa,

Here is a long ago thread that discussed your topic (found through using the Search the Site link in the left margin ) that may be helpful.

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/522844/46-disc-brake-conversion.html

If you do your own search, you will find several other threads that may also be of help.

Be sure to provide any info or sources you may come across as it may be helpful to fellow 'Bolters' looking to do the same kind of work.

Dan

On a further note, I did a bit of searching for existing disc brake kits being offered on-line for '41-46 1/2 tons.

Found at least 3 vendors offering them, but for the most part all either indicate they "will not" or "may not" fit stock wheels.

The original wheel design just doesn't have enough space in the design to fit over the non-standard disc brake set ups without using wheel spacers (most folks recommend to stay away from this idea for safety sake).

Your choice on what you decide to pursue.

Dan

Thanks Gdads51. That article doesn’t address my questions. I have combed through the searches but can’t find the answer I had asked. I’m asking if anyone knows of a disc brake kit that can be used with the original artillery wheels. Also wondering about what master cylinder to use. Was hoping someone knew of a kit that would work᠁.and more detailed info about a master cylinder that would fit in the original location and use the original pedals.

Or, do the proper work to get your 4 wheel drums working properly and they'll stop as quickly and safely as a modern car.

No, I have not called “every” supplier. I don’t even know who to call. That’s why I made this post, was asking “does anyone make such a kit”. I was attempting to utilize the knowledge and experience of the forum members to guide me where to look.

Thanks Otto. My current drum brakes are all new, front to back, including new master cylinder, all new brake lines, new wheel cylinders and new shoes and springs. But I was under the understanding that the disc brake kits took it to another level of stopping, more like modern brakes.

Many people have the mistaken belief that disc brakes "stop faster". This isn't true. In many cases stopping distance may increase.

The only advantage disc brakes have over drums are that they don't overheat under repeated, high speed braking that might occur during an autocross or riding them down a mountain.

They also have fewer parts and are easier to service and maintain.

Tractor trailers, dump trucks and the like all use drum brakes.

If you drive like a normal person, your drums will do a great job stopping your truck.

My '56 Cadillac has been my primary transportation for 20 years. There have been a few emergency stops in that time and 700 mile drive through the Appalachian mountains. Never once did the brakes even give me a hint of failure or cause me to worry that they might. They don't lock up or overheat.

I've been on this Stovebolt site since 1999, and I have yet to see any brake kits mentioned that work with stock wheels without some creative work. So I am going to say NO, there is no kit available for what you are asking.

My truck is a '37, it's had the same basic frame and drivetrain as your, and very close to the same weight. Mine was modified back in the late '60s. I added disk brakes so the wheel bolt patterns matched. The truck wasn't drivable when I purchased it out of the fence row back in '99. I run a 1970 250 engine and T-350 automatic transmission, so my weight bias is likely shifted some from a stock truck.

I can tell you the pedal effort is quite high with manual disk brakes. I am using an aftermarket brake lever with the correct manual brake ratio, Ford dual resivoir master cylinder, GM single piston ( '70 - '79 ) calipers and rotors, and GM '70 - '79 Camaro / Firebird rear drums. The braking system is a basically a Firebird with different master cylinder. Kit was from Master Power Brakes.

The truck stops just fine, I have an adjustable regulator on the rear brake line to limit pressure to the drums, without the regulator the rear brakes locked up very easy. It drives well, doesn't dart around on hard stops, and has zero brake fade. But the pedal effort is high, it takes a strong leg to quickly stop. A power booster would cure that, but I have lived with it for 23 years now and see no reason to change. I drove drum brake cars for years, even drag raced with them, and like mentioned above, the only difference you will tell is fading of the drum brakes with repeated heavy use and little cool down time. As drums heat up they expand, the system can't keep up with the expansion, so the brakes feel weak. Disk don't expand the same as drums.

I will say this, with the old style adjustable tie-rod ends and draglink ends, the truck would dart to one side as it took up slack in all the joints. They were in really good shape, all rebuilt with new balls and sockets. They are suppose to have some slack to take the road vibrations out of the steering wheel. When I switched to the modern type of joints the darting around went away. You also need a very good steering box with no play, mine is a 1941 I rebuild with mostly NOS parts, so it was basically new when I installed it. I drove for years with a NOS '37 steering box, they are gear on gear type boxes. The '41 gear box uses roller balls for less effort and has a slower gear ratio for even less effort at slow speeds.

I have never driven an old truck with drum brakes so I can't say one is better then the other, but as it is now, the wheels will lock up pretty easy, so I have plenty of brake horse power, far more than needed. In your case with stock skinny tires and wheels, lock up will be more of a problem. I have 205/75R15 front, 235/75R15 rear modern soft radial tires with plenty of meat on the ground, and a 50/50 weight split front to rear, that's around 1700 lbs on each axle. I have had the truck on a four wheels scale system. I have a front sway bar, all new springs, and modern gas shocks, and the most important thing, 3 point seat belts.

If you want it look stock, keep it that way. Make sure the parts you have are in great shape, with the best brake shoe material you can find. There are a few venders who sell the better linings, I've seen them mentioned on numerous site I watch, and everyone raves about how good it works over the one size fits all material being sold over the counter. Better linings and good drums should be all you need for a good brake system.

Hope this helps,
Joe

Bill Hanlon could be the guru on this.

No disk brake guru here.

My experience is installing a kit from Buffalo Enterprises (he's no longer making them) on my '57 GMC 102 about 25 years ago and getting a 3/4 ton spindle turned down to allow use of a CCP 1/2 ton disk brake setup on my '52 GMC 152. The PO had a hot rod shop in Conroe Texas install a 1/2 ton disk brake kit on the 3/4 ton truck by turning down the spindles to 1/2 ton size. I drove it 30K miles and had a bearing failure on one side (my fault, I wasn't keeping up with bearing lube) that damaged the spindle and spacer. I found another spindle and had a local machine shop turn it down to emulate the 1/2 ton spindle with the spacer that CCP supplied.

As for master cylinder retrofit, seems typ is to use the C3 Corvette manual disk brake master cylinder (ca:1980) 1” bore, you can find a version with outlets on both sides which might make line routing easier than mine. I found it relatively easy to fab a bracket from a heavy duty L bracket found at my local builder supply. Welded a gusset in one side drilled it for master and mounted it to the existing master cyl bracket and tranny.

As for brake choice, each for his own situation:
my truck was a mismatch from the PO of bendix on rear huck on front which drove my decisions, front cyls were pitted and orig master shot, pedal was very heavy. Putting the dual master and new everything inside the hucks, put a prop valve on the rears as they locked up quick in hard stop test, pedal still very very heavy. Seemed like the matchup/ balance of huck/ bendix was just not right.
Just finished switch out to ‘54 front bendix brakes with all new cyls springs hardware drums studs etc, pedal is significantly lighter, very solid pedal with right amount travel, . It was not a cheap conversion even though bendix parts are a lot less expensive and very available. Got ‘54 backing plates and hubs from fellow ‘bolter, +$260. at machine shop + all new parts, not exactly cheap to complete but nothing is, I’m good with it.
Each his own.

Chuck

Joe, would you happen to remember the names of the vendors who sell the better linings?

I came across this thread by doing a search on the same topic. I wanted to do a disc conversion on my truck while keeping my stock artillery wheels. I keep reading it won't work, and have been told the calipers will hit the rivets on the inside of the rim. Mine are 17" wheels, though, and wondering if the conversion just doesn't work on the smaller diameter artillery wheels?

But at this point, I'm becoming more used to the idea of just keeping drums all around, and possibly upgrading them if I can.

Thanks.
Ron