My 64 GMC 1500

[James]

A 1964 GMC 1500 Fleetside was will to my wife from her father. It has a 305E V6 with a 4 speed SM420 transmission. When I went to pick it up it had no brakes, a dead battery, and old gas in the tank. Body is in bad shape, no major rust just several dents.

I started to examine the truck for needed repairs.

I inspected the brakes system (it has 8 lugs drums on all four corner). I checked the Internet for replacement parts. I soon determined that it should be upgraded for safety. For over a year the hand brake was the only brake I had. I searched the Internet for an 8 lug disc brake conversion kit (trying to maintain the original look). The only thing I found was the rear axle conversion kit. I piece together part from an 81 GMC 1500 and 2500 front brake system. I fabricated my own brake lines. Installed a dual cylinder master cylinder with a stainless 7" dual cylinder booster and a proportioning valve. Modified the brake pedal and bled the brakes system. I also found the forward hand brake cable was coming apart and replaced it with a new cable. When I went to connect the vacuum hose to the intake manifold I discover it was installed backward. So I removed, cleaned, painted and reinstalled the intake manifold.

While I was cleaning the rear axle housing, I had drained it. Only a quarter of a cup of oil came out. I removed the cover and found the gears was ate up. I removed the rear axle and removed the 4.10:1 gear set and installed a 3.54:1 gear set with all new bearing. This axle is a full floater. When I removed the hubs and the bearings was filled with grease (instead of rear axle oil), the seal had ate a groove in the spindle. I installed new bearings and seals in the hubs. I repaired the spindle with Devcon titanium putty (has the best chemical and temperature resistance spec).

On the engine (while waiting on brake parts to come in) I replaced all hoses and flushed the coolant system, added new coolant, new points, condenser, and cleaned the plugs. I removed the valve cover and removed both rocker assemblies and cleaned out the sludge from the shafts. Reassembled and adjusted the valve lash (Hot). I then cleaned, painted and reinstalled the valve cover. Now that I got it running the water pump started to leak, I installed a new pump. While I was doing that I removed the fan shroud that was on it. It was butchered up when the air conditioner was installed (will repair it later).

I replaced the engine oil several times during the course of the work and the transmission once (with synchromesh oil). I had also had the seat recovered.

Now I have it in a running condition and now have 70 miles on it, from running around the neighborhood. Today I am removing the driveshaft to clean and paint it. While it out, on the two piece drive shaft, the support bearing is getting replace and I and looking into seeing what gear is in the transmission speedometer drive so I can correct the speedometer reading (may have to use an external device). I did place two picture galley on this site:
Brakes
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General Pictures
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[Funky61]

Very nice work James! Should stop nicely now and that gearing change is a nice move.

In the old photo what is that cone shape object attached to the cowl?

[James]

That is a work light that can be removed from the base to light up different area under the hood. Right now I have not repaired it but plan to do so and place it back on, might be in a different location when I put it back on.

[TJ's GMC]

Subbed and nice truck.

[jrmunn]

James,

I admire the amount of work that you have put into your 64 GMC 1500. I have a nearly identical 1964 truck that I have had for nearly 40 years (from my father) and am still using. You have had all the problems to fix at once, while I have been working on them over the years. Changing the braking system is a good call. I kept the drum brakes but did install a dual master cylinder after a nearly catastrophic loss of hydraulic brakes when one of the front brake hoses cracked open. It is a good thing that the emergency brake on these trucks really does work - but I too had to replace the front cable. My other major projects were new bed wood (the original lasted nearly 30 years and took another 10 or so with plywood over the bed before I got around to replacing it) and I recently installed a Holley 500 two-barrel carburetor that has given a noticeable increase in power at the expense of gas mileage. I installed a fan clutch thinking it might help mileage and engine noise, but haven't noticed a difference. And I put on newer wheels for tubeless radial tires that greatly improved handling and ride. Other work has been more routine - oil changes, grease, hoses, belts, points, plugs, ignition wires, wiper blades, clutch repair, changing water pumps and fuel pumps, etc. Next, I want to switch from the 4.01 to 3.54 rear end gears (as you have already done) with limited slip to help with fewer rpm at highway speed, better use of second (not counting compound low) gear on hills, and better traction in fields. I also have a Pertronix ignition and coil replacement that I hope to get around to installing, plus some gauges, switches, lights, and a new radio. And I have a 351E to rebuild and put in if the 305E ever gives out. With all this, it is a good truck for work, recreation and reminiscing, but I like the ride and convenience of newer cars for every day driving.

JRMunn

[cbeeker]

Old tread but curious if you added brake booster, or just duel master cylinder. I have 64 GMC 3/4 ton and want to upgrade. Not sure if booster way to go.

Charlie

[James]

Old tread but curious if you added brake booster, or just duel master cylinder. I have 64 GMC 3/4 ton and want to upgrade. Not sure if booster way to go.

Charlie

Because I converted it to 4 wheel disc brake I added a 7" dual brake booster and modified the brake pedal to make it work correctly. Here is a picture of the brake master cylinder/booster:
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[jrmunn]

Cheeker,

I did not add a brake booster. The truck came with a vacuum boost that my father removed because it was too sensitive (but probably necessary to the first owner who carried a camper and found the 305E underpowered for the weight). I would be cautious about adding a booster if you don't need it for a load. My rear tires lock up on a moderate stop, even with the larger radial tires, and this could be dangerous with added brake power and sensitivity. On the other hand, I can still push hard on the brake pedal.

jrmunn

[James]

Cheeker,

I did not add a brake booster. The truck came with a vacuum boost that my father removed because it was too sensitive (but probably necessary to the first owner who carried a camper and found the 305E underpowered for the weight). I would be cautious about adding a booster if you don't need it for a load. My rear tires lock up on a moderate stop, even with the larger radial tires, and this could be dangerous with added brake power and sensitivity. On the other hand, I can still push hard on the brake pedal.

jrmunn

I wonder if the vacuum boost/brake booster on your truck was added for the original owner. A common mistake when added is to use the same hole in the pedal. This would make the brake pedal sensitive. The proper way is to drill a hole 1" below (to reduce the pedal ratio) the manual brake hole to reduce the sensitive. With my vacuum boost/brake booster it is not sensitive and I normally have an empty bed.

On another note. If you have 4 wheel drum brakes then that would also make it sensitive. I have 4 wheel disc brake.

Just my thought.

[cbeeker]

Cheeker,

I did not add a brake booster. The truck came with a vacuum boost that my father removed because it was too sensitive (but probably necessary to the first owner who carried a camper and found the 305E underpowered for the weight). I would be cautious about adding a booster if you don't need it for a load. My rear tires lock up on a moderate stop, even with the larger radial tires, and this could be dangerous with added brake power and sensitivity. On the other hand, I can still push hard on the brake pedal.

jrmunn

I carry the Pullman Camper with stuff inside, but certainly not a load. Thanks for your communication as I hoped just adding new dual master cylinder and reworking brakes would be adequate, without a booster.

[jrmunn]

cbeeker,

This is mostly in reply to issues James brought up. He makes a good point about reducing booster sensitivity. I don't really know how my booster was connected or who put it in (factory, dealer, or previous owner) because it was out before I started working on the pickup. But I haven't found any extra holes or bolts for connecting one. I have 4-wheel drum brakes, and the most weight I carry is a load of oak wood. When loaded, the rear brakes don't lock unless I push really hard, and I try to leave lots of space to stop. Use of dual cylinders and disc brakes in trucks came along at about the same time, so I would expect them to work better together, and the add-on systems I have seen use some sort of proportioning valve to regulate front and rear fluid flow, but I don't know how these work. In fact, I sort of gave up on learning new auto systems when points were replaced with computers and my timing light was replaced by more expensive equipment. I guess one reason I keep the old truck is that I can still work on it. My 2008 Dodge is much nicer to drive and the diesel engine pulls a lot more. But someone else fixes it.

jrmunn

[cbeeker]

Thanks for the communication. Agree driving my 2004 Tundra for daily use is the way to go. 64 GMC with Pullman Camper is just for fun use. But want it safe beyond single master cylinder. Ordering new shoes and wheel cylinders, and dual master to install before my next outing.

Charlie

[jrmunn]

cbeeker,

Good luck with dual cylinder. Installing cylinder was easy. I got one for first year GMC used it - and it fit. Problem for me was bending a line to fit under engine to get to fitting for line to back brakes. Then used plugs for front line. I don't remember why I went under engine except to get to other side where fitting was.

jrmunn

[James]

My brake lines run under the engine, was how the original line ran. I used a welding rod and bent it to make a pattern. I bend it around everything and make adjustment here and there then transfer it to the brake line.

[cbeeker]

Cheeker,

I did not add a brake booster. The truck came with a vacuum boost that my father removed because it was too sensitive (but probably necessary to the first owner who carried a camper and found the 305E underpowered for the weight). I would be cautious about adding a booster if you don't need it for a load. My rear tires lock up on a moderate stop, even with the larger radial tires, and this could be dangerous with added brake power and sensitivity. On the other hand, I can still push hard on the brake pedal.

jrmunn

So, my plan is buy a dual master cylinder, and as you suggest- no booster. Seems the 67 Chevy C20 is first dual made. Any idea if this will match holes for my 64 GMC 3/4 ton?
Charlie

[cbeeker]

cbeeker,

Good luck with dual cylinder. Installing cylinder was easy. I got one for first year GMC used it - and it fit. Problem for me was bending a line to fit under engine to get to fitting for line to back brakes. Then used plugs for front line. I don't remember why I went under engine except to get to other side where fitting was.

jrmunn

Assume you refer to first year 67 GMC 3/4 ton???

Charlie

[Prowbar]

James,

Is that an aftermarket airco system, and are you going to repair it?

[James]

James,

Is that an aftermarket airco system, and are you going to repair it?

Yes I am planning on getting it working again. Attached is the data plate of the John E. Mitchell Co. evaporator unit. When I got the truck there was no freon in it. Currently the York compressor been removed and planning on updating the compressor to something newer. Been working on other projects and I don't know when I will be able to get back to it (not high on my priority list).