The Stovebolt Site Forums The Shop Area Driveline 46 1/2 ton front disc conversion

I have read lots of threads and many of the product reviews but still cant find a definitive answer. Has anyone converted their 46 1/2 ton to a disc brake setup and been able to use stock 6 lug rims? It seems that most of the kits have fitment issues, and there seems to be very limited product specifically for the 41-46 truck. Do the 47-55.1 kits work on the 46? I am doing a budget build and want to be as original as possible, with a few creature comforts, and safety upgrades. A power disc kit would be nice but if manual disc is all that's available then its still better than drums for a daily driver, especially in NJ/PA traffic. A manufacturer and or a part number would be greatly appreciated. Thanks for the help and info.

Are you using 15 or 16 inch wheels?

If 16 inch I can help.

15 in rims. Already have a good set and would like to not incur the cost of new ones.

I put discs on my '38 but had to do some grinding to make them fit with 16's

I have a six lug 1/2 ton 1946 GMC and I put CPP disk brakes on it. I currently have Wheelsmith 15 inch artillery wheels and there are no clearance issues when using the narrow wheel spacers that come with the kit. I could make the stock 16 inch wheels fit if I grind about 1/8 inch of metal off a very small area where the wheel center rivets to the rim, again, not a lot of material but just the little tips of metal that appears as excess. I think it wouldn't effect the structural integrity of the rim because that 1/8 inch is just the very tip of the webbing and not anywhere where the outer ring and inner part of the wheel connect. I temporarily added 1/16 inch washers between the wheel spacers and the rims and the 16 inch wheels didn't rub the CPP disk brake calipers. Because I plan on using a 16 inch for a spare, I'll grind off that metal tomorrow and send a link to a picture of what I am talking about.

Bogart. Very much appreciate the pics

I installed the 47-55 kit from Performance On Line on my '46. With the factory 16" wheels and the supplied 1/4" spacer, I still had a bit of interference between the rim and the caliper. I ground about .040" off the caliper which gives around .020" clearance.

Steve

BigEdPA, I decided to gain the clearance by grinding the caliper instead of the wheel. In the photo album you'll also see I pointed out the amount of material that could be removed from the wheel but I think grinding material off of the caliper is faster than modifying the wheels. I used a hand held grinder and a flapper disk to grind away the material. Album showing amount of materiel to remove for 6 lug wheels to clear CPP disk caliper.

I bought the 1947-1955 kit from CPP and am really happy with it. CPP six lug disk brake kit. The kit works fine for the 1946. The only difference is that one of the bolts isn't the same size. After discussing the project with my machinist I installed the kit with no modification of the spindle (see the note from the manufacturer), I used a narrower bolt. I installed a dual reservoir master cylinder with no brake booster, i.e. manual disks and stock rear drums. I made a simple master cylinder bracket that mounts the master cylinder in the stock position. I also used a adjustable proportioning valve. but I'm not sure that's necessary. I also installed a 2 PSI residual valve that is recommended for the front disks when the master cylinder is lower than the wheel cylinders (possible if parked on a steep hill). Again, not sure if it is necessary but I thought it was cheap insurance and it works! I am super happy with the pedal feel and wouldn't even consider doing a power brake version of the conversion. My wife drives the truck often and it is just fine.

Good luck on your project! Let em know if you'd like more info.

David

Bogart, how do 15" artilleries have no fitment issues, but 16" need to have the calipers shaved? Do the wheelsmith's have shorter backspacing and or a larger negative offset that moves them away from the calipers?

Has anyone tried using 15" stock rims and altering the offset by using longer lug bolts and a spacer? I don't have a visual reference to know how badly the calipers interfere with stock 15" rims. 15" rims may just not work at all but I am still trying. Changing the offset would, essentially, decrease the backspacing by moving the wheel outward and farther from the suspension and caliper mounting brackets and calipers themselves. I think the backspacing on 15" early 50's rim is 4"? As my truck is disassembled, I can not take measurements on fender clearances with stock suspension to know how much of a spacer would be allowable.

Thanks for thinking this through with me

I think the Wheelsmith or WheelVintiques (I can't recall which ones I bought) wheels have narrower outer rings and therefore the inner area is similar in size to the stock 16 inch wheels. I believe they are basically the same offset although I haven't measured them to check.

Bogart, Do you have a photo or information on the dual master cylinder bracket you fabricated for a 46? Thanks!

I've made an album with some photos of my homemade bracket. If you need clarification, ask away and I'll try to clarify. This is a long bed truck so I may have more room between the transmission crossmember and the master cylinder. If you don't have the room, I would suggest a remote fill compact m/c like this remote tandem master cylinder.
Here's the pictures. The setup works perfectly and I wouldn't change a thing.

Bogart - thank you for posting all the pictures. This will be a big help.

Bogart, I looked at he CPP Kit you referenced above. This kit does not contain a hub set. Not being 100% familiar with the 46 drum brakes, did you press the hub out of the drum to use for your truck? I looked at my drums and it appeared they are riveted in , so I am not sure if pressing the hubs out is even possible. CPP does make a kit with hubs, without saying more expensive, but at least there is an option.

When you look CPP hubs kit..........it comes with taper roller bearing. It recommended you should replace the stock ball bearing with roller bearing... so when you price the roller conversion costs the hubs kit starts to look better.

Ed,
As I recall, my drums were attached to my drums by swedged metal. I. E. metal that is smashed into place around the lug bolts to hold them in place. You can see the squiggly line around the lug bolts in these pictures.
Those are the swedged. swedged lug boltd

I'd never heard of a swedge before but to remove the drum from the hub a swedge cutter is used to cut out the metal around the lug bolt to a depth of about 1/8 inch deep. If you try to drive the lug bolts out without using the swedge cutter you'll ruin the hubs. Some machine shops have the swedge cutter. They are difficult to find on line but they are just like a hole saw. Come to think of it, I think I cut the lugs off since they'd be replaced and I drilled out the center before driving them out. Make sure you don't touch the hub holes because the new bolts have to fit in the hub very tightly. If in doubt, take it to a machine shop. If yours are just riveted then I think you can drill them out and the disks will stay in position once assembled without the rivets since they are smashed between the wheel and hub by the lug bolts /nuts.

With the hubs removed from the drums you can order the tapered bearings if you wish and have the old bearing races replaced with the tapered races and you are good to go. The CCP kit comes with new lug bolts that you can install in the old hub by sticking them through the hub, and using a stack of washers under the lug bolts, tighten the nuts to pull the lug bolts through the hub. It's a super tight fit so alternate from one lug to the others in a cross pattern until they are pulled into place.

One last thing. They recommend that once you have the hubs and disks mated, take them to be turned on a brake lathe to true them up. Mine were slightly out as measured with a dial indicator but I can't tell that they aren't perfect.

It sounds like a lot but it's all worth it and really not that difficult if I could do it.

I haven't done this to my '46 yet, but I did a disc conversion on a '67 Dodge pickup recently that had swedged lugs on the stock drums. I carefully ground off the heads of the lugs on the inside of the brake drum and pushed the studs out from behind because I didn't have a swedge cutter. The swedge is only on the threaded side of the stud, the inside is just a flat head.

Never heard of swedging either. Is swedging a word? Anyway, learned something new today. Thanks, this is why the Bolt is an amazing place to come to. And Showkey, I might have to agree with you on the bearings vs hub kit cost effectiveness.

From yourdictionary.com, third-person singular simple present swedges, present participle swedging, simple past and past participle swedged) To shape metal using a hammer or other force.

We learn about trucks and Grammer here!

In the case of the wheel studs, a more descriptive term would be knurled. Very common way for wheel studs to be fastened in place. The head in back is what secures them as well as the press fit of the knurled section inside the hole. They usually can be driven out from the front with a BFH. Typically doesn't hurt the hubs to drive them out. There's enough give in the knurling to let them come out without hurting the holes.

[on edit] Never heard of swedged wheel studs before, even though I restored a Model A Ford way back when. I recalled they had knurled studs as I described above. Just found this site that is a pretty good description. Swedged wheel Studs. I guess I learned something new today also.

I'm familiar with swedging back in my plumbing days as a kid when we used a swedge tool (basically a chunk of cylindrical steel with a tapered section) that we used to expand the end of a piece of brass sink drain tubing so it fit over another piece and we could solder the two together (cylindrical lap joint). Inserted the swedge, tapped it in a bit with a hammer, then tapped around the tubing to loosen it up and pulled the swedge out. Steel pipe welding reducers are also called swedges.

(EDIT) I just saw the edit to the former post. That is a good link to explain way better than I could about swedged lug bolts!

I respectfully disagree that we are talking about the same thing. Yes, many lug bolts are knurled. The ones that are swedged or swaged (using a swage tool) normally require a swedge (swage) cutter such as the one of here Swedge cutter if you want to save the lug bolts and not harm the hubs. If one could simply drive out lugs that are swedged, there would be no need for a swedge cutter. I think the confusion comes from most of our trucks not having swedged lug bolts. My guess is that most have knurled lug bolts pressed in as you describe. My 46 GMC 1/2 ton had swedged lug bolts and that complicated things (again making me think, why does everything have to be so difficult!) My recommendation is that if your lug bolts are swaged, do not press them out if you intend to refuse your hubs.

Your pics with the squiggly part around the lug sure looked like knurled lugs, but I can't disagree with you. I wasn't there to see them in person. As I said, I hadn't seen swedged lug studsbefore, even though I owned a Model A that apparently had them. I don't recall having to replace lug studs on it, but in my defense, it was nearly 60 years ago.