65 GMC 3/4 Ton F-Series Frame Swap

[LoganPoertner]

I am new here and not sure if this is the correct place, but I am hoping for some help. I am frame swapping my 65 GMC with a 99 GMC frame. This way I can have a little stronger frame, disc brakes, and a nicer riding suspension. What are some things I might have issues with in the process. I plan on using the brake booster and master cylinder from the 99 with a stand alone abs module from speedway motors along with all the brake lines. I am using the gas tank, sending unit, and fuel lines as well. I will also be using a few other things but I am currently concerned on the struggles I may have swapping the frames. Any help in much appreciated. Thanks.

[FetchMeAPepsi]

Welcome to the forum, young padawan (you might be ancient, but I just saw Star Wars so go with it)
I can't help with the swap. More of a traditionalist myself, but I'm interested in seeing where it goes.
Got any pictures?

Did you measure the frames to see how far off they'd be?

[LoganPoertner]

I have not yet measured the frames. I do know the wheel base is 16 inches longer on the 99 frame since it is an extended cab but I am building my own flatbed so I'm not too concerned with that. It will also be a little better if I decide to tow with the longer wheelbase. Currently the 65 GMC is sitting in a tree line and has been for 40-50 years and it has not dried out enough to get it out yet. I do have all the trees cleared out to be able to get it. I know there not the best photos but its what I got.

[FetchMeAPepsi]

Dude you're having to put some sweat equity into rescuing this old fella! That's going to be a sweet truck.
You have no engine, a trashed interior, and an abandoned donor vehicle. Even though I'm a purist, this gets my approval (which is worth nothing, but whatever). It's going to be a fun project!
Do you know someone with a tractor that might be able to yank it out of there for you? Winter's coming and all that.

You're about 4 hours from me, i'll hop in the tractor and be there by January! (kidding, I don't own a tractor yet).

[LoganPoertner]

So the vehicle was my uncles and he is giving me some parts that he has. He originally was gonna put it back together shortly after he put it in the trees but never got to it. He has a motor and transmission for it among other parts. I would rather use the stock frame but I want better suspension and brakes. Surprisingly the frame is in great shape and the body isn’t too bad either. All of it is surface rust as far as I can tell. The plan is we are gonna try to winch it out onto the trailer or I will pull it out with my duramax. All the tires still have air in them since they are tubed tires so it shouldn’t be too bad. The problem is it keeps raining and isn’t currently dry enough to get out to them since I got to go through a bean field. Thanks for the offer

[James]

Personally I would leave the frame alone. Install power brakes. Attached is some pictures of my work on the brakes. The front spindles and rotor comes from an 82 GMC 2500. The brake calipers from an 82 GMC 1500. Then the master/power booster and proportioning valve is an aftermarket kit. The rear brake is the large Cadillac caliper with parking brake. The rear rotors and the caliper brackets was part of a kit (for a Dana 60 axle). Then plumb together. When connecting the power brake booster to the pedal, you will need to drill a new hole 1" above the old hole to obtain the proper ratio.

As for the ride, the front spring will be smooth enough. However the rear springs will need the overload springs removed and a few leaves removed from the mainsprings until you get the desired ride comfort. This will require shorter axle/spring U bolts.

[LoganPoertner]

Did the front brakes from the 82 bolt right up to the 65 axles or was there modification involved? Why did you use a 1500 caliper on the front not a 2500 like the rotors? Why did you use Cadillac calipers on the back not from the 82? Do you happen to remember what Cadillac the brakes were from?

[James]

My truck is a 1964, your truck I believed is the same. The only thing I had to modify on the front spindles was the ball joints taper is different. I use the proper reamer on them them to match the ball joints (do a trial fit to determine if it is require to be modified). One other thing I had to do to the spindles was to shorten the turn stops, wouldn't turn enough and now it match the specs in the manual. One other note, when converting to disc brake you will need at least 16" rims for clearance, and it does not matter if you install a 5, 6, or 8 lugs disc.

I don't remember why I used the 1500 front calipers instead of the 2500. It fit perfectly. It might have been because I had a old one laying around and it fit, so I did installed new calipers.

The rear disc brake uses the 76 - 78 Eldorado rear calipers with parking brakes. This was part of a kit from: https://www.tsmmfg.net/general-motor...rake-kits.html or https://www.rusticdiscbrakes.com/pro...-8-lug-dana-60 for a Dana 60 full floating axle.

I want to keep the 8 lugs wheel, which is why I didn't convert my truck to a 5 or 6 lugs hubs. I also got the rims from the 82 GMC and the hubcaps (see attachment).

[LoganPoertner]

Thanks, I will look into it and figure out what I will do. I still have to get it out of the tree line so I have a while.

[blang]

Good luck, sounds like a massive project you have on your hands. Interested in hearing how it goes!