The Stovebolt Site Forums The Shop Area Driveline 48 GMC brake conversion

A while back a few of you may remember my post about buying a 55 cameo. Well, turns out, lack of parts and info has taken me down a different path. I have since purchased a 48 GMC 3/4 ton truck that I am absolutely in love with! It has a Straight 6; the original motor and tranny. It is a deluxe cab, with 5 windows and everything is still in tact (i.e. dash, gauges, seat). It is believed that the mileage is acutal at 56,000. Before I go any further, no I don't want to sell it! I'd like to do a disc brake conversion seeing how the brakes don't work at all right now. I would appreciate any suggestions and helpful hints as to what brand to buy or better yet what not to buy. I also plan on changing out the engine and transmission to something a little more modern (possibly a Nailhead?). Any and all information will be greatly appreciated! Thanks!

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Hey,

I am getting ready to put a "nailhead" in my '48...if you need help let me know.

Bill

The common disk conversion kits are all designed for a 1/2-ton truck. The spindles are different on the 3/4-ton and the 1/2-ton kit isn't going to work the way it comes out of the box.

Unless you are commited to keeping the truck a 3/4-ton you might consider swapping a 1/2-ton axle in the front so you can benefit from the available conversion kits instead of designing your own conversion.

I'm curious why you would choose a nailhead for this swap. Starting in '55 GMC installed Oldsmobile and Pontiac V-8 in pickups. I've always thought a fun swap would be a 455 Pontiac with the GMC pickup valve covers and GMC labels.

Hey Rox, You have the GMC clone to my truck. I have been driving my truck stock (56 - 235) for over a year now, approximately 40 miles per day. I have almost no complaint about the brakes that came on the truck. We dont have much traffic here, but I have driven in Amarillo without any troubles. I plan to upgrade to a dual chamber master cylinder and replace the ancient lines at some point, but if you drive defensively, there's no reason you need discs until you get it completely rodded out. At that time, I would replace the straight axle with a more modern front end. Just my thoughts. Enjoy your truck.
Ralph

I'm putting a nailhead in it b/c I want something fast...and also b/c a good friend of mine had one that way back in the day and said it kicked butt. Thanks for reminding me about the disc brake conversion being different from 1/2 ton to 3/4 ton...I've read it 100 times but still basically forgot. I'm thinking about replacing the whole front end now with something from chassis engineering or fatman's now...what are the thoughts on that idea? Also Bill's 50- what tranny are you putting behind your nailhead? I'd really like to have a LaSalle 3 speed top loader but I doubt I'll be able to find one. Thanks you all for all of your help, please feel free to give your .02 anytime.