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Anybody got a source for BIG GMC brake parts? I have a feeling I'm going to be needing some front wheel cylinders very soon. 54 GMC 630 with hydraulic brakes, two wheel cylinders per side. Thanks in advance!
Jerry

Jerry,

Are the wheel cylinders for your 54 similar to those on an M211?

http://www.alfaheaven.com/MilitarySection/6x6%20Trucks/M135.html#M135Brakes

May be another source option?

Paul

probably not but since I don't have the drums off yet I can't be sure. This one has the Lockheed-type brake with two single-acting wheel cylinders and a bridge pipe between them behind the backing plate. It looks like the M211 has Bendix brakes from the illustration.
Jerry

I have some fire trucks that I am cutting to make truck tractors out of them and converting them to air. Find out what you have. One of the fire trucks actually had working brakes on it when I drove it on the flatbed.
https://picasaweb.google.com/108197...Gv1sRgCNS1tJOwg6umTw#5594559258454934978

That pic looks very similar to what I'm working on, maybe just a little newer. I should have things apart in the next day or two.

http://www.hunt101.com/data/500/503_GMC_002.JPG

Thanks!
Jerry

Does that '55-'59 have a 370 Olds in it?

I have 2 of them with a 370 Olds and 2 with a 324. The one pictured has a 324.

Ken,

On the one you have that the brakes work on, could you look and see if it has 2 wheels cylinders per wheel, or one.

Thanks,

Ed

I am going to be on a rather early flight tomorrow morning and will return Sunday. I will look when I get back.

OK- - - -progress! Slow but steady. I got the RF (pass side) brake apart this evening, and found just about what I expected. Both wheel cylinders are stuck tight, with the pistons corroded to the casting. The rest of the brake system looks OK, plenty of lining left, good springs, a smooth drum surface, and good wheel bearings. The cylinders got a bath in KROIL and a little massage with a Propane torch, and they'll soak overnight and all day tomorrow while I do an inspection in Chattanooga. I'll dismantle the driver's side tomorrow evening.

Good news- - - -it appears that one wheel cylinder casting number will work on top and bottom, and most likely it will fit the other side as well.

Wagner-Lockheed casting # FE-3073 fits top and bottom of the passenger's side, and the bleeder screw will work in both threaded holes. That's a really good indicator it will also interchange to the other side of the front axle! If I can't get the pistons free, or the cylinders are too pitted to rebuild, we only have to search for one wheel cylinder for all four positions! The brakes are a very big version of the same style setup used on 1940's and 50's Chrysler product cars, and some Ford truck applications. It has one single-piston wheel cylinder for each brake shoe, and a steel pipe behind the backing plate to connect the two to a single flex line. There's a bleeder screw on both wheel cylinders.
Jerry

OK, more progress- - - -my local NAPA store can order their version of the wheel cylinders, NAPA part #37315- - - -at approximately $100.00 each, plus a small shipping charge! I'm going to make a concerted effort to salvage what I've got before I ask Ed to spend that kind of pocket change!

I'll try to get a link to a picture posted soon so our resident big rig expert can have a reference to go by. Thanks to everybody for offering help, advice, and suggestions!
Jerry

Good news- - - - -at least the first two wheel cylinders are rebuildable! Nasty, gunked up, and in need of a little honing, but nothing drastic like a sleeve job seems to be necessary. Now all I need to do is find some 1 3/8" wheel cylinder cups!

No, the driver's side isn't apart yet- - - - -my Superman pajamas are in the laundry! Maybe tomorrow after the dentist gets done whittling on my teeth! Yes, I have to be there for that procedure- - - -can't mail 'em in!
Jerry

Sounds like you'd better wear those pj's to the dentist too!

Woo-Hoo! Got the wheel cylinder cups on the way, here tomorrow- - - -a 10-pack is $20.00! That's enough for a couple of rebuilds- - - -another 60 years' worth of life for the old beast!
Jerry

OK, got the driver's side apart- - - -a little worse than the right side, but maybe I can make things work without breaking Ed's piggy bank! The wheel cylinders are getting an overnight soak in KROIL and I'll open them up in the morning.

One thing I can say for sure- - - -those front brakes haven't worked since Bill and Monica were playing hide the sausage!

Here's one of the passenger side cylinders:

http://www.hunt101.com/data/500/GMC_front_wheel_cylinder_0011.JPG

http://www.hunt101.com/data/500/GMC_front_wheel_cylinder_0021.JPG

http://www.hunt101.com/data/500/GMC_front_wheel_cylinder_0031.JPG

Jerry

OK- - - -it looks like all four wheel cylinders are rebuildable. The pistons needed quite a lot of cleanup- - - -badly corroded and gunked-up with congealed brake fluid, but they responded to some polishing on the lathe. Next comes honing the housings and reassembling with new rubber cups. The dust caps are the only things that aren't salvageable, so at some time in the future it would be a good idea to locate some correct rebuilding kits and swipe the dust boots out of them. This rehab is not intended to be a full rebuild- - - -just a way to make the truck safe to operate on the way to Denver!
Jerry

The driver's side wheel cylinders were in much rougher shape- - - -badly pitted, with major corrosion and damage to the pistons from the brake shoes getting wedged against the drums and causing drag and overheating. I had to do a LOT of honing of the cylinders to eliminate most of the rust pits, which made the pistons a really sloppy fit. A couple of hours at the lathe, and we've now got a pair of new, custom-fitted wheel cylinder pistons, about .005" oversize, with the right amount of slip fit. The rubber cups will take up the oversize without a problem- - - -loose pistons aren't an option! If Ed decides to do a major rehab once the truck gets to Denver, he can send the wheel cylinders back to me for a full rehab, including a stainless steel sleeve in each one. That's a lifetime fix, not a half-donkey patch job like I'm doing now!

http://www.hunt101.com/data/500/New_piston_001.JPG

http://www.hunt101.com/data/500/New_piston_004.JPG

Jerry

Nice work Jerry

Looks good Jerry.
You had to hand grind a special tool to cut that counter bore and still leave a boss in the center to drill and tap.
We'll talk about machine shops, when we meet up in KC.

Don

I've been custom-grinding tool bits since I was in UT engineering school in 1963- - - -fun stuff! The center boss that mounts the shoe contact piece is actually just a drilled hole. I had to tap the hole in the original piston and use a piece of all-thread and a big socket to pull the pistons out- - - -they were stuck TIGHT! KROIL, heat, and then a mechanical pull!

Progress report- - - -the front brakes are reassembled, bled, and adjusted- - - -no leaks! As soon as I get the front wheels installed in the morning and adjust the rear brakes, it's time for a shakedown cruise! It looks like the road trip is going to happen on schedule.
Jerry

Great Jerry
I should have all my ducks in a row by Sunday.
Then head to KC on Friday.
PM with my cell number will follow tomorrow.

Don

OK- - - -test drive update! I just returned from a 30-mile loop, all state highways and back-country roads, no interstate travel. The truck likes 50-55 MPH in 5th. gear, with one short run a little over 60 with no apparent strain. 40-45 in 4th. feels good, and granny low gear isn't necessary for starting from a stop sign. The coolant temp runs 160 degrees with no strain. It got up to 175 on a long uphill pull in 5th gear, and immediately dropped back to 155 coasting down the other side. Oil pressure is rock-steady at 43 PSI. The steering is pretty good, and there's only a slight wheel balance shimmy at highway speed.

There' still a minor brake issue- - - -the rear brakes don't want to respond to adjustment, and it takes one full pedal stroke plus another half-stroke to get a firm pedal. Then they're a little slow to release. The parking brake works very well. It's a HUGE disc brake on the back of the transmission with two sets of pads, and I fabricated some linkage from the handle in the cab to the brake assembly shortly after Ed left the truck with me. I'll drive defensively and anticipate my stops whenever possible. I'd strongly recommend a full brake job as soon as possible once the rig makes it to Denver.

It's a HEAVY rig- - - -front axle weight is 5260 lbs., the rear axle carries 5940 lbs. Total weight with me onboard and a full gas tank: 11,200 lbs.

Now, if the weather would just cool down about 20 degrees! Wishful thinking, huh?
Jerry

Looks like the weather will cool down for your trip.
Call me if you have any issues.

Don

5th gear is .85, rear axle ratio is 6.5, 50 mph is about 2500 rpm.

Jerry, all sounds good, I will get after the brakes right away.

It looks a bit cooler here, too.

Your method of camping on the road sounds familiar, I usually stop at small airports, where they have nice lawns for sleeping, have to watch out for sprinklers coming on, though.

OK, this refugee from a Mad Max movie is in Missouri! I just checked into the Super 8 in Kennet. Too hot and sticky to camp out tonight! The truck's running pretty good, but I might try tinkering with the point gap and timing a little before I hit the road in the morning. It likes 55-60 MPH, but down around 40-45 it backfires a little at times. Sounds like late timing.
Jerry

Could also be an exhaust leak, especially if on deceleration. Great progress, looks like about 200 miles by my large map.

It's got the deceleration pop, (more like a BANG!) and the exhaust flange gasket is pretty much gone, but the pop back through the carb was late timing. It's running a lot better now with a few degrees more advanced dialed in, and the exhaust note has changed from a roar to a purr. Gas mileage still sucks, though! LOL!
Jerry

Jerry,

I plan to look for some 4.11 gears for it.

Ed

4.11's will make 5th. gear pretty much redundant. I'd suggest a 4.56 or 4.88 if it's available for a good compromise between load pulling and top gear cruise RPM in 5th. A 4.11 with the OD and tire height you've got would put 5th. gear cruising speed somewhere in the 80 MPH range. That would be white-knuckle speed for me!
Jerry