The Stovebolt Site Forums The Parking Lot Big Bolts 1959 GMC 9600 dump truck - Resurrection

Hello everyone,

I have a Canadian GMC 9600 with a dump box that I plan to wake up for use as a dump truck around our farm. From what I gather from the styling, I think it is a 1959 model.

The serial number on the door frame is:
Model: 9653
Serial: 99653612514D
Engine: G20626

The engine is a bit of a mystery to me. I think it may be a 261, but I cannot find a block number next to the distributor that would tell me for sure - It is painted green and the valve cover seems to match pictures of other 261s that I have looked up. It also has a Rochester B Carb that I have already cleaned up and put a carb kit into.

I have some wiring inside the cab to redo (Mice have chewed it up, and the headlights did pull enough current for the plastic connectors to melt) but I also have some other pretty big issues to deal with as well

- First off, the brake pedals goes straight to the floor, and the master cylinder looks deteriorated enough to make me doubt it will hold brake fluid in.
We do have a hydro-boost master cylinder that we pulled off of a 2009 Dodge 2500 me and my dad were thinking we could put in and delete the old vacuum boost system, but that also means we need to install a power steering pump onto the engine. Does anyone have any information on adding an extra pulley sheave onto the front of a in-line 6? There is tons of stuff for V8s, which is somewhat annoying for me.

- I think I need a water pump, but the aforenoted tons of V8 parts make me think I am not looking in the right places for parts. Where would I go for a rebuilt water pump, or at least a rebuild kit?

- The vacuum valve top cover for the two-speed axle is broken. (See image below.) What are my options for repairing this?

Thanks for any help, I'm sure I'll have a few other question as I go though.

Welcome to the site. Looks like you've got a lot of the details set out here! That should help with your questions. Big Bolts is the place to start.

Hope you don't mind that I fixed your image links. Some folks may not be able to open an image that's a download. Now they can see them right off.

The afternoon crew should be coming on soon.

Hi Puffie40, welcome to the site. I can't help with the 6 cylinder questions, my big bolt is a stock 283 V8. The 2 speed shift valve is pretty simple, it looks like the crack is not in the vacuum portion, you should be able to reinforce the housing with some light metal. The HrydoVac system worked well for thousands of trucks, I rebuilt all of the wheel cylinders, master cylinder, and HrydoVac, brakes work like a charm.

Welcome!

Maybe if you gently disassemble the vacuum switch then you can use JB Weld or the like, to glue it back together. Another option is the plumber's putty epoxy stick that you just cut off as much as you need, then knead it together to activate. About 4 minutes of working time, but it hardens up into a nice, strong, workable plastic that can be made into any shape. Will fix bicycle frame or coffee machine, sometimes in the same day!

Welcome Puffie40!

Lots of resources and info available in Stovebolt, and yes even some to help with your Canadian GMC.

Here is a link that will help decode your truck serial number. See the right side lower section for Canadian info.

Lots of other GMC Truck related info throughout that site. Here is the Home Page to get you started.

On your engine question, there has been several other recent conversations in the Engine Shop related to identifying Canadian GMC engines.

From this reply post on Canadian 235 and 261 engines this info should give you a clue on where to look for the casting numbers and dates codes on your engine.

Take and post some pictures of your engine casting numbers and the "stamped" serial number machined pad directly behind the distributor. We can help better identify what you have with that info.

Looking forward to seeing more questions and pictures so we can try to help you out.

Puffie40,

Me being the curious type and enjoying searching for possibly elusive parts, a little web searching located this GM# 3812762 2 Speed vacuum shift control that looks exactly like your broken control piece.

A further check of GM parts wiki, a search engine for GM part numbers shows this control fits 1955 2nd series and later Chevy 2 speed rear axles. Should be the same as your 2 speed, but I couldn't find an actual GMC parts book to confirm. Perhaps one of our resident GMC guru's can chime in to confirm or not?

Unfortunately that eBay seller indicates down in the ad description that they ship only in the USA. A fellow Bolter may be willing to help you out in acquiring and re-shipping to you in BC, or maybe you could get lucky and find a fellow BC Bolter that has a USA address for shipping already established???

FWIW, that part number was replaced in November 1990 with GM# 2428149 and is also listed under the original part builder as Bendix# 2501124. Perhaps you may be able to locate one through a Canadian parts source???

Anyhow, hope some of this info may be of help to you. Good luck in your search!

Puffie40,

After you have posted 5 times on Stovebolt you will be able to PM members.

If you decide you want a better used housing PM me, I should be able to help.

Mike B

Thanks for the replies, I've had a busy week at work so I am mainly working weekends on it. Tonight I relocated the external gas tank bracket to the passenger side of the truck - this will shorten the fuel line as well as make the tank filler pipe easier to access with a jerry can. I plan to fit a fuel filter and electric lift pump to help out the mechanical fuel pump.


from the first link, I was able to decode the serial number as a 1959 2.5 ton truck. I just about had to stand on my head inside the engine bay, but I made out 3769925 on the starter side of the engine block. I did find this one website that confirms that block number is listed for the 261 engines: http://devestechnet.com/Home/TheVenerable261


I would be very interested. I did take the switch apart and it is just the top housing that is damaged. I sucked on the inlet pipe and confirmed the valve itself still functions properly.

I will get the mounting plate cleaned up and see what my options are.

It has been a while back but I had a custom pully made for my 54 3100 because I have a/c. He was a guy up in years I believe a GM retiree. I will see if I can find the bill of lading.This what I have found so far.. But classic industries have a big listing for this item. I have yet to look through my files. I don't believe it I found it. It is called Buffalo Enterprises, 360-652-7684. That was back in 2007. It was listed as a 2 groove damper, $200.00 plus $12.00 shipping.25625 Dahl Rd.Arlington Wa. 98223. I googled and it still shows.

I spent the winter fixing the dashboard wiring and managed to put in a new waterpump. I even found a new 160 degree Gates bypass thermostat in our miscellaneous parts shed that will fit in the housing!

The brake light wiring was in pretty tough shape. a couple of the wires were completely melted and then patched together with marettes, speaker wire, and hockey tape. I cut that all out and am going to rewire it.

I finally decided against fitting power steering or power brakes for now; I'll just repair the existing brake system. I did bring in a replacement 1950s master cyilinder and am relieved it will be a bolt-in replacement. There is a little bit of brake fluid left in the system and doesn't appear to be very bad looking, so I'm now rather optimistic that the brakes wont be terribly difficult to repair.

I do have a question though- the service manual does mention vacuum reservoirs being available on the larger trucks. What would it look like, and where would it be located? I was thinking of adding one just to make sure I had lots of vacuum available for braking.

I Noticed the grease cup on the distributor is interfering with the vacuum advance mechanism. Is this normal?

A vacuum reservoir will be a steel tank, typically mounted under the cab or step. I recently added a tank to my truck, it did not originally have one with only having the HydroVac brake booster. I installed a 2-speed rear differential and thought for good measure a reservoir would add some vacuum capacity for shifting and braking. I used an empty 30 lb. refrigerant cylinder as the reservoir and mounted it on the passenger side under the step. The factory provided a tee in the vacuum line and a hole in the frame rail at the tee.

I believe you can reposition the distributor to move the grease cup away from the vacuum advance. You may have to move the gear mating to the crankshaft by a tooth, making sure that you get the oil pump engaged as well. Your spark plug wires may have to be moved by one position on the cap.

On the vacuum reservoir, a good idea is to put a check valve between the vacuum source and the tank and the rear axle (or whatever is using the vacuum). That keeps the vacuum reservoir fully charged and available even if the engine isn't running.

If the truck came stock with HydroVac brakes, which it sounds as it did, there will be a check valve in the system mounted on the engine bay firewall. Follow the 1/2" vacuum line from the engine up to the firewall, the first thing should be the check valve.

I can confirm there is a hydrovac unit on this guy on the opposite side of the frame rail to the master cyilinder, and there is what I am presuming is the check valve mounted on the firewall:

I took the check valve apart and cleaned it, seems like better vacuum since I did that, it may have sticking partly closed and not allowing full vacuum to the HydroVac. Your pic shows the check valve.

There's no need to remove the distributor to re-clock the housing. Just loosen the pinch clamp below the housing and turn the distributor one wire position, and re-route the wires. You will need to reset the ignition timing, however.
Jerry

I opted to pull the distributor because I couldn't get a good enough grip on the slotted pinch bolt screw. I turned a spacer up so I could replace it with a 1/4" hex head bolt. While I was in there, I replaced the well-worn ignition points and condenser.

I was putting the distributor back in, and wiggling the motor back and forth to get the distributor to engage with the oil pump, when I made the realization that the motor is turning over a little TOO well for an engine with the transmission in gear! I'll focus on getting the motor running to confirm it, but I'm thinking a new clutch is on the horizon.

Looking on RockAuto I found a couple of clutch kits with the part number MU54731B and MU90911. Will either of these fit my 261? It has a five-speed transmission.

This weekend I soldered the frame back onto the radiator, and it appears to hold water just fine. I finished wiring up the ignition and headlights, poured some two-stroke gas down the carb and after determining I had the timing a classic 180 degrees off, got it to run!

It does look like I will need to change the manifold gasket as there are some leaks on the back end. I'll take a wrench to the manifold to see if the bolts are loose.

It seems the clutch does have some grip, from cranking the motor the flywheel needs to "wind up" a partial turn before the driveshaft starts to turn. I've never actually seen this before - the clutches on our farm tractors are more like a light switch so I'm not sure if this is a feature for the two-speed axle or something else.

Since I got the motor part on the run, I pulled one of the front hubs to look at the brakes. One of the brake shoes is rather thin but I think I can reuse it. The wheel cyilinder is pretty crusty with powdery corrosion behind the dust boots.

Any idea what the part number of the wheel cyilinder is? I saw on another thread someone mentioned the part number NAPA 15315 but I'm not sure if that was in response to my question there. I presume the wheel cyilinder size is based on the piston bore size?

Got the front drums and brakes done. Me and my dad turned the drums and also machined the hubs to take a 85mm OD, 63mm ID, and 12mm thick double-lip rubber seal to replace the old felt seals before repacking the bearings with fresh grease. I also threw on a couple cans of black rust paint on everything so it preserves the metal until next time I need to open it up.

Took the rear passenger side brake apart, and we have axle seal problems. The drum is absolutely soaked in gear oil.

Can the oil be cooked out of the brake pads, or will I need to re-line them?

When I rebuilt all of the brake system on mine, it had basically new shoes on all four corners prior to my ownership. The rear left had oil on the shoes, I used engine degreaser, then lacquer thinner, then cooked them in the outdoor bbq grill at a low heat until it stopped smoking. Cleaned them up again just to get the ash off, I have not had any trouble since putting it back together.

Thanks for the BBQ suggestion! I cleaned as much of the oily brake dust off as I could with the varsol parts washer, and I'll go find a old BBQ to bake them in.

It does appear there is some pitting on the rear bearing where the seal rides. I'll check to see if a speedi-sleeve exists for this diameter as finding a replacement bearing for the rather odd-looking spindle shoulder might be a headache.

I got replacement rear wheel cylinders in today from RockAuto. There was brake fluid inside the rubber cups of the passenger side rear, so I think I found why the brake lines were empty. I need to wait on seals and repair sleeves which are coming in from Ebay, so their delivery time is dependent on the good ol' USPS. I'm probably going to have to spend the next couple of weekends preparing the parts for reassembly anyway, so no worries there

Since I asked about wheel cylinder part numbers earlier, I'll confirm what I used here for anyone else in the future with a 9600 who might read this thread:
The numbers were found on this thread

Front Left (Driver side): Raybestos WC19091
Front Right (Passenger side): Raybestos WC19090
Front Rubber brake hose: Raybestos BH36548 (Two are needed)

Rear wheel duo servo cylinders: Raybestos WC18197 and WC18196 (One of each is needed for each wheel)
Rear rubber brake hose: BH25664 (If your brakelines jump from the frame and tee off with steel lines like mine, you only need one)

The rear hub seals are SKF part number 36340 (4 7/8" OD x 3 5/8" ID x 3/4" T). I am using a SKF 99363 repair sleeve to cover the pitting on the bearing hub.

I have the brake cyilinders, shoes and pads all sorted out now. I had to take the rear drums to a machine shop to get them turned because they were too big for our lathe.

Both sets of rear shoes had oil on them. In what felt like the most rednecked thing I've done on this project, i brought home a old propane grill from the dump, fixed it up so it would catch fire, and baked the brake shoes in it. It seemed to work like a charm.

All four wheel cyilinders appear to have been leaking - I found brake fluid behind the rubber caps on jist about all of them. I'm hanging onto everything I'm replacing until I'm certain it can't be rebuilt.

I threw about six cans of spray paint on the tire rims and the brake parts.

While I'm putting in the rest of the brake lines, I took the external parts off the rear differential. I popped the back cover off and cleaned the disgusting metallic sludge out of the bottom of the diff housing (it didn't seem to have anything terribly concerning in it).

My next objectives are to clean up the vacuum shifter, and I had to scrape a quarter-inch of grime to get at the bolts holding the pinion housing on, so I need a new seal up front.

Hang onto the wheel cylinders as they can be sleeved with stainless steel or brass and made better than new. White Post Restoration provides this service with a lifetime warranty...

Mike B

I took the pinion and vacuum shifter apart this weekend. Getting the pinion nut off was a challenge- i had to heat the nut with the torch almot cherry red before it decided to start turning, and a bearing puller was needed to get the yoke and double cone bearings off.

As I expected, the pinion seal was worn out and the seal lip was non-existent. A deep groove has been worn into the driveshaft yoke, but I am going to move the seal forward into where the felt collar would have sat instead of finding a repair sleeve.

It turns out that the pinion seal (Old P/N CR 3653618) is a fairly universal seal size that GM used into the 1980s, so I was able to cross reference it to CR25970 / National 411330N

Fun fact about the pinion nut: it it 1 1/8 -18 thread, which is finer that 12 threads per inch specified by the UNF standard. Turns out it is another standard referred to as extra-fine (UNEF) threads, and special taps and dies are available if, say, you wanted to chase the threads.

The vacuum shifter had some oil inside, likely from the axle, but that washed out with some varsol. There was another oil seal inside here with the old P/N CR 374534. I cross referenced that seal to SKF 9960. There are some felt packing just below the oil seal that I am unsure of how to approach. I will probably just clean it as best I can and reinsert into the housing.

While I'm waiting on seals for the rear axle, I decided to pull the steering gearbox both to clear the way to run the new brake line, and also reseal it since it is a ball of grease.

I also plumbed in a temporary fuel tank to the carburetor and got the motor fired up. This allowed me to raise the dump box to get a good look at the hoist mechanism. The front of the cyilinder is greasy, but I'm not sure if that is from the fill cap or the packing.

One thing that has me a little concerned is I found (another) one of the frame crossmembers is broken. I knew the furthest back crossmember was buckled from someone yanking hard on it with a chain, but discovering this one makes me think I should probably take the dump box off and do some proper frame repairs.

Thoughts on how I should repair it?

That crossmember looks like it has a doubler on the bottom that's riveted on (rivet where the crack is.) I would line up the crack and weld it, then weld a fishplate on, possibly a couple of pieces of angle iron over the top and welded longitudinally.

For the pinion seal on the steering gearbox, I measured 1.375" on the shaft and 1.750" on the housing. This cross references to SKF Seal number 13509.

You are correct, it has doublers on both sides. I like that reinforcing plan - I'll get the box pulled off, and hopefully by then I'll have the truck able to move so I have an easier job getting the welding leads to it.

Well, I still need to get the hydrovac hung up, but I got the fuel system hooked up and actually drove it around the farm for the first time!

I think I lucked out on the motor, as it idles smoothly, has no major leaks, and does not seem to blow any blue smoke that would be indicative of oil burning. I did have to pull the manifold to replace the gaskets and had to replace the exhaust manifold because of a huge crack. I managed to find a replacement locally. I also had to change out the oil lines going to the oil filter.

We got our first big dump of snow this week, so I'm going to ramp down the work until springtime. I have some frame crossmember repairs to do, and I also plan to take the transmission off so it can be re-sealed. It is a huge ball of grease!