1948 3/4 ton GMC

[Michael_e]

I've got a friend with a 48 GMC 3/4 ton and has 8 lug wheels and he wants to put disk brakes on the front and a later model 8 lug rear axle out back. The rear axle is not a problem, but finding a kit to convert the front to disk brakes
is seeming to be impossible to find. Does anyone know of a supplier who makes such a product? Or are there any newer 8 lug type of spindles that will fit the original 48 GMC front axle?
Thanks
Mike

[mr48chev]

I think we tossed that around a couple of months ago when someone else asked pretty much the same question. I'm sure that there isn't a kit available but a couple of guys with decent mechanical skills and fabricating skills along with being able to visualize e abla bit might be able to do it pretty simply.

If the front drums come off the hubs you might be able to use a 73/80 or so Chevy/GMC 3/4 ton front rotor which slips on the 4x4 hub. You might have to make or have a spacer ring made that went between the hub and the rotor to keep it centered on the hub.
Then a guy would use the matching calipers that fit the front of the same truck.

You would have to fabricate or have someone fabricate the caliper brackets. You might talk one of the outfits that makes caliper brackets for the rear of 3/4 ton tuckst for conversions into making a set of brackets that have a pilot hole drilled to center the bracket on the spindle but aren't finished as they would be to go around a rear axle.

[whitedog76]

I have my templates right now at the machine shop.

I'll know in a couple days what the verdict is.

Here's what I'm working on.

http://s1074.photobucket.com/user/wh...98174699168064

[dwcsr]

Originally Posted by Michael_e

I've got a friend with a 48 GMC 3/4 ton and has 8 lug wheels and he wants to put disk brakes on the front and a later model 8 lug rear axle out back. The rear axle is not a problem, but finding a kit to convert the front to disk brakes
is seeming to be impossible to find. Does anyone know of a supplier who makes such a product? Or are there any newer 8 lug type of spindles that will fit the original 48 GMC front axle?
Thanks
Mike

All the info I've seen on this swap is sketchy at best. I haven't seen anyone as yet post a how to that actually finished the swap. Several over on Stovebolt.com started some good threads and then go off on a tangent for axle swaps and other ideas that sway from a conversion for the stock axle.

Depending on the year 47-52 and 53 up have a different spindles, later being better. I know there will be some machine work involved and the caliper bracket will have to be fabricated.

I'm doing a 47 1 ton in the next 2 weeks and have some parts lined up so as soon as I start it I'll post it. Its not going to be an off the shelf bolt on so expect a little machine work and welding.

I expect the swap will be $500 or so in parts by the time I get bearings, $250, seals, $12, rotors $40 each. Calipers $80 each unless you have a core, hoses $25, Brackets $??.00, possible spacers for the disc.

[mr48chev]

Originally Posted by whitedog76

I have my templates right now at the machine shop.

I'll know in a couple days what the verdict is.

Here's what I'm working on.

http://s1074.photobucket.com/user/wh...98174699168064

What calipers are you using, they look familiar as i probably did a few brake jobs on the same model as the donor rig but I can't think of what they came on.

[dwcsr]

Originally Posted by whitedog76

I have my templates right now at the machine shop.

I'll know in a couple days what the verdict is.

Here's what I'm working on.

http://s1074.photobucket.com/user/wh...98174699168064

what spindle diameter do you have?

[whitedog76]

The calipers are the rears from a 2003 and newer 2500/3500 van.

They're basically the same as what the Silverados and Tahoes use on the front, they just mount a little different.

I'll be using the same ones on my rear also. So I'll have 13" rotors and dual piston calipers on all 4 corners.



I have a 54, so it's the 52-59 spindle, which is 1.496" on the large end.

[dwcsr]

Originally Posted by whitedog76

The calipers are the rears from a 2003 and newer 2500/3500 van.

They're basically the same as what the Silverado and Tahoe's use on the front, they just mount a little different.

I'll be using the same ones on my rear also. So I'll have 13" rotors and dual piston calipers on all 4 corners.



I have a 54, so it's the 52-59 spindle, which is 1.496" on the large end.

I think I'm going to have to make a press on sleeve to make up the difference in the early spindle and the later bearing.

[whitedog76]

You could alway's just use the later style spindle.

Or you can have your spindle turned down to accept a tapered bearing.

Again, it's more machine work, but you could have it so the seal rides on the spindle vs. the bearing, and you could have bearings that are readily availible.

Take a look at the Timken catalog for bearing sizes.

http://catalog.timken.com/WebProject...bookcode=trb12

There's nothing wrong with the stock ball bearings either. They have plenty of load capacity. Ball bearings roll easier and run cooler than tapers do.

[dwcsr]

I have a line on some later model spindles and that certainly would be easier. Hopefully there in good condition.
Turning down the early ones I don't think would work he wants to use this truck as a 1 ton work truck from time to time so I need to err on the safe side.

If Texans didn't have the habit of hauling 4 tons in a 1/2 ton truck turning the spindles would be an option.

[whitedog76]

I looked at the Timken catalog after I sent the messege, I don't think it would do any good to turn down the early spindles anyhow. The outer bearing is an oddball size, there's nothing that would fit. It's still plausible to turn down the newe spindles for a tapered bearing conversion. At the most, you would only be taking it down to 1 3/8" which is leaving plenty of meat on the bone and not signifigantly affecting strength.

On the newer spindles, you will have to use the later kingpin also, the 48s are too short.

[dwcsr]

Thanks for the tip on the pins, It needs pins anyway so I'll get what fits later ones

[dwcsr]

Have the spindles for a 54 on the way and bearings that should fit without much machine work

Timken for 53 to 59 1 Ton and I believe 3/4 Ton
3339/3387 1.5 ID and 3.151 OD
1975/1922 .875 ID and 2.25 OD

Not sure of the assembled width but if I have to trim the hub or shim the hub it won't be much. The truck is going to the blaster this week so I won't have any work on this for 10 days or so.

[mechanixman]

Here is the build page for my 8 lug disc conversion. I've got everything but these darn brackets made. I've made a few prototypes, and each have a little quirck that won't make them work right.
http://67-72chevytrucks.com/vboard/s...d.php?t=586788
If you want a quick rundown, 2000-2014 2500 and 3500 chevy trucks and vans have rotors that fit without any modification. The only thing you need to do is drill out the stud holes on the hub to receive bigger studs. With that, your rotors are done.
Calipers come off the same vehicle, the problem with those (for me at least) is the calipers are awfully large, and would hit the rim. So I'm going to add 1/2" spacers in between the rotor and the wheel. Last piece of the puzzle are the brackets that hold the caliper to the spindle. And that's where I'm stuck right now.

[Apachemike]

Would these work? I'm a newbie so go easy on me

http://www.ebay.com/itm/350973126802...%3AMEBIDX%3AIT

[OrrieG]

Mechanixman, were you trying to use stock era correct steel wheels that would not fit?? Or was it an offset issue with aftermarket wheels??

[mechanixman]

Orrie,
I'm using the 16in ford wheels.
Close enough to stock without being split rims.
The place it is hitting is about where that red circle is.

[dwcsr]

This kit is correct for 3/4 and 1 ton. It doesn't use any half ton pieces. Works with 16" and 17" original wheels, has a 13" disc, uses 2500 HD parts

http://www.ebay.com/itm/1947-1955-Ch...e=STRK:MESE:IT

here are the install instructions
http://www.thehollisterroadcompany.c...converion.html