The Stovebolt Site Forums The Shop Area Engine Shop Best quick front disk conversion

I need to tow a small boat with my 1948 1/2 ton. I'm sure the truck will handle the load except for the brakes. I've seen many posts and advertisements for front disc conversions. Question: Which is the easiest to install and get working quickly? All current brake components on the truck are new. It looks like the truck has non-stock 15-inch wheels with stock brakes. I know that I might need spacers for the front wheels.

I would say that the kits for the original axle are about the same. The kits they sell for the six lug, in my opinion are worth the money. They generally give you a 12 inch rotor. The kits for the 5 lug disc brakes, generally give you an 11 inch rotor. They are roughly the same amount of work to install.

You may have clearence issues with the 15 inch rims and 12 inch brakes. You will have compatibility issues with the 5 lug brakes, and your 6 lug wheels.

Your stock spindles have to be in pretty good shape for both conversions. The 6 lug conversion uses your stock hub. You will need to seperate it from the drum to reuse. Now would be a good time to convert to roller bearings. The 5 lug kit has the hub integral to the rotor and comes with roller bearings.

If your king pins are worn or sloppy, now would be a good time to change those as well. make sure your entire steering geometry is in good repair as disc brakes will put more strain up front.

Last thing to remember... You can't just slap disc brakes on without changing the master cylinder. You should deside if you want power brakes or manual... both master cylinders are available for the advance design trucks. The new brakes will have to be "replumbed". New lines will have to be cut, bent, and flared to fit. Don't forget about residual pressure valves.

Good Luck!

While I agree with bigbadswingdaddy, personally I wouldn't worry too much about changing the brakes over to disks. Since you already have new components in your stock system and you aren't towing anything too large, I'd say that the stock system will be ok for what you're doing. The real trick is to make certain that the adjustments are correct, fluid level is ok, and no air in the lines. You'll be suprized at how effective the stock system is when it's properly setup/maintained.

Because of the expense of disc brakes, many people simply update the master cylinder. As longbox said, the stock brakes should work for your application. You could also try a power brake booster and 2 circuit master cylinder for increased braking potential and safety. Later on if you decide to add disc brakes, it won't be as big of a job. You may even be happy with just a booster.

That will probably stop you from walking around in circles all the time because the over developed muscles in your right foot!

Another option to think about is converting your huck brakes to bendix brakes. The difference is huge and you may find that enough to make you feel confident stopping even with the boat behind it.

SwingDaddy did a good job summarizing the disk conversions. Everything I thought of was covered in his description. I did my own several years ago.

The issues

I will be towing about 3000 lbs. but not very far and slow. I have a couple hills on the way to the boat ramp. I could try it with these brakes but I'm a little worried about stopping out in the intersection as opposed to beind the white line. My old truck was an 85 GMC 3/4 ton with front disks and it handled this boat like it wasn't even there. What about the kevlar shoes. Do they make much difference?

On the disc conversion kits that come with a power booster. Can you really get the power boost unit, new dual master cylinder, and bracket underneath the truck without a bunch of fabrication? It looks like CPP only offers the 6-lug kit starting with 1949. I didn't know there was a difference in front brakes from 1948 to 1949.

Are you sure you have a '48? Vent windows on the doors started with the '51 model year.

The gas tank is underneath, and it had lever-action shocks. Looks like a 1948 with swapped doors. Sure wish I could find a serial number though.

Jim Carter offers 6 lug disc brakes for your truck. You could also get them from Buffalo.

When I put the dual master with booster on my 59, I had to relocate a pulley for the ebrake back a few inches on the frame. Everything else was straight forward, The new master will be way under the seat. Typically you check fluid in it by using your finger. You can use a squeeze bottle to fill it up.

If you convert Huck style to Bendix on the front do you have to change your master cylinder. They are different for each application. Probably only in the bore size.
Is it better to have a larger diameter bore or a smaller one and does anyone know the bore of each type?

I have seen master cylinder rebuild kits listed from 1941-1959. A smaller bore will generate more pressure, and use more pedal travel. A larger bore will generate less pressure, and use less pedal travel.

In English... you won't be getting as much of a workout if you select a smaller bore. 1 inch will stop a truck faster than 1 1/4, with less foot pressure.

I don't know the bore type of the Huck or Bendix brakes. I thought it was 1 inch. Most of the hipo manual brakes use a 1 inch bore.

If you want to save some money converting to disc brakes, here's how:

The disc brake conversion consists of a few basic components:

1. Rotors (70-77 camaro) ($20 ea @ FLAPS)
2. Calipers- standard GM metric calipers, ie 70-77 camaro) ($15 ea @ FLAPS)
3. Brackets- can be bought separately for $100 +/-, or fabbed at a metalworking shop.
4. Caliper bolts ($30 +/-)
5. Studs & tire nuts- standard ($30 +/-)
6. Flexible brake line - standard ($30 +/-)

Searching around you may be able to find a template for the brackets and then someone can cut them from flat stock for you at a metal working shop, or you can do it yourself. Some vendors sell just the brackets, I think Speedway motors sell just the bracket.

When you do the rotors, you should upgrade the bearings to more modern roller bearings. These bearings are a standard bearing you can get at any parts house if you know the part number. Maybe someone who has done the conversion or has pictures of the bearings before they put them on will post it. If no one helps out, you can figure out the correct roller bearings by measuring the OD of your spindles and the ID of the rotors and then spending some time at bearing house.

You should also upgrade to a dual master cylinder. There are of course kits to buy, or you can buy just the bracket and find the master cylinder, combination vavle and residual valves separately.

Also, you should check your king pins and replace them if they are too worn.

CPP sells a kit that includes, rotors, bearings, calipers, brackets, master cylinder, and proportioning valve for $375, which is probably less than $100 more than what you'd spend tracking all that stuff down yourself.

On another thread someone mentioned that the inner wheel bearing is the Timkin A-13. The outer bearing was listed at Timken A-2.

I've found that the stock Huck brakes on my truck stop really well the first time, but you will get some pretty serious fade after stopping 2 or 3 times from 60 mph. I can lock up all 4 wheels on my truck if I want. If you can anticipate the fade, and don't let yourself get into trouble, then you can tow a boat with stock brakes. If you want to be able to drive it like a modern truck, then convert to disc. They dissipate heat much better and don't suffer from fade.