The Stovebolt Page
Installing Patrick's Rear-end
by Fred Stevens
I've just finished putting together a "how to" for installing Patrick's 3.55:1 ring and pinion set in 1947-1954 pickups. (There is at least one other vendor I know of who sells similar parts but I have no idea how good / bad their instructions are. My main goal was to help some one that had Patrick's instructions in their hands and then would run into something they didn't understand.) So, I thought that I'd put some of the things I ran into down on paper while they were fresh in my mind. I hope this helps some one else. This is a good project to do with a helper! ~~ Fred
Click on the existing images for larger view ~~ Editor
Time for a New Rear-end?
Got all your parts?
OK, you've got the new ring and pinion AND the optional installation kit, right? You'll need to replace all the bearings and oil seals that you run across. Also, you have Patrick's five page instructions. Here goes.
First, let me strongly recommend removing the floor pan above your transmission. PITA, I know, but you'll be thankful after it's out. The whole job will go much easier if you do this first. There are 11 clutch head sheet metal screws holding it to the floorboards. Have fun, I did. A little Kroil on each screwhead and a couple of downward taps with a hammer first will help removal. You may have to use a hammer and center punch to spin out a couple of stubborn ones. You also have to unhook the gas pedal and remove the starter pedal and bellows so you can flop the floor mat back. Drain the transmission now, you'll want to replace the gear lube anyway.
You'll need a bottle jack to help hold the torque tube up while you unbolt the ball seal and transmission mount. You'll also need a hammer and 1/4" punch to unfold the safety tangs from the U-joint bolts. Those require a 3/8" box wrench. Loosen the dust cap at the back end of the ball seal and slide it back as far as possible. Then slide the ball seal back so you can work on the U-joint. When that is unbolted, you can slide the U-joint back, lift the torque tube as high as possible, and remove the U-joint, ball seal and dust cover forward. There was JUST enough room to weasel these parts past the transmission tailshaft in my truck.
Now to the back end
Drain the carrier housingdown, remove the back cover, wheels and brake drums. Patrick's instructions are easy here. Just follow them to remove the spiders, spacer block and axles. Now you can unbolt the lock nuts that hold the third member to the carrier housing. Invite a friend over. He's gonna "steer" the front of the torque tube while you slip the third member off the studs. You have to go FORWARD with the unit far enough so the ring gear clears the housing. This will be the first of many times that you're glad you removed the transmission cover.
Drag the unit out from under. I set the third member up on a couple of good sawhorses to work on. If you've got a huge workbench and really big vise, use that. Do like Patrick sez, mark the two bearing caps and relevant saddles they bolt to. You DON'T want to learn about 1950's factory tolerances here. Patrick's instructions are clear and simple for carrier bearing and ring gear removal. Nothing too tough here. Don't forget to have some brass vise jaw protectors handy.
Likewise, removing the pinion gear and driveshaft from the torque tube is straightforward. Have a piece of brass round stock or maybe a small chunk of oak handy. A few taps on the splined end soon had the pinion gear and shaft out. Now you can grind the head off the 5/16" rivet that holds the pinion gear to the drive shaft and wedge the splined pinion out of the shaft. Mine came out pretty easy.
Here's a good place to stop and clean EVERYTHING. I just took a whole day, listened to some good bluegrass, and cleaned up everything that was apart, plus the transmission. You'll appreciate this later when reassembling.
Pinion gear assembly
Pay close attention to the order of the parts on the pinion shaft. The bearings are a no-brainer, (watch for the preload notch on the big bearing) but I was unclear on the purpose of the oil control washer and the bearing retainer ring flopping around on the pinion shaft. I almost put the bearing retainer on backwards even after reading Patrick's instructions closely. Just remember that the beveled shoulder on the retainer ring is where the three retaining lock ring bolts push on and preload the big double row front pinion bearing.
About here, I should comment on the two bushings that are pressed into the front of the torque tube. They support the driveshaft and U-joint assembly. The back one has an oil seal in it to keep oil from the transmission from getting into the torque tube. Patrick says to use a six foot piece of 1 1/4" pipe with a coupling screwed onto the end. This pipe is gonna be your best friend for a while. You need to know that the torque tube bushing in the back, toward the differential, is 1.750" in diameter, and it is pressed up against a shoulder. The coupling that I bought at Home Depot had an outside dimension of about 1.780". I had to disk sand it down to about 1.710 to get past the shoulder in the torque tube. The bushings aren't that tight a fit, so if you're whaling away with a 14 lb. sledgehammer and the pipe is ringing like a church bell, you're probably pounding on the shoulder, not the bushing. You are warned. By the way, this pipe also worked very well for knocking out the axle bearings and seals.
Now you have to remove the big nut that holds this assembly together. What I did, was put a 5/16" hardened allen bolt thru the hole where the 5/16" rivet was, clamp the splined area of the shaft in my vise with the head of the allen bolt just resting on the top of a vise jaw so that when I wrenched on the nut, the bolt head would "bind" and prevent the splined shaft from turning. Used a helluva big crescent wrench and a 2 foot pipe. The four parts you are salvaging from the old pinion assembly are:
1. The snap ring
2. The bearing retainer
3. The oil control washer
4. The nut
Reassemble the new pinion gear and its bearings and parts in the appropriate order and rivet it back together with the driveshaft. Now the fun starts. My truck had two shims under the pinion bearing, a .012" and a .018" for a total of .030". Patrick sez most trucks have a .016" or .018" shim in them from the factory, and to start by adding one of his .010" shims for a total of about .028". I called him and told him what I had. He said that's unusual, and I should aim for a TOTAL shim stack of about .028" which is .002" less than what I had. I tried this, and no way - I had a pretty high tooth contact which means I needed to add shims. I took a guess, and went back to my two factory shims PLUS one of his .010" shims for a total of .040" and the tooth contact was perfect. The short story is that I think that what ever you have for shims, you should probably start off by simply adding a .010" shim to them.
Patrick says to assemble the pinion gear, shaft and shim into your third member in a vertical position. That's a good idea, but it's kind of like loading a muzzle loading cannon thatísí pointed straight up. You WILL need a friend helping with this. I bored a 2" hole in a piece of 3/4" plywood with a hole saw and sat it on a couple of cement blocks that were on end. That helps support the torque tube assembly and leaves space underneath for the driveshaft to drop through.
Checking ring gear runout, and backlash are fairly routine. Follow Patrick's instructions. Kind of fun, really. I used a water soluble "blueing" that is for spotting pieces together and it worked well and showed up on the black gears. I've heard of some people using a little oil mixed with white oil-based house paint. Never tried that, Dykem hi-spot blueing is only about $2.00 at the auto store.
Patrick speaks about making a final tightening of the large carrier bearing preload nuts (the ones you borrowed the two pin spanners for) Ė his instructions read "Now go (2) notches past snug". Well, I'm here to tell you that I could only go (1) notch on each past snug, I don't think Godzilla could get (2) notches, at least not with spanner wrenches like I had. Do check backlash again and don't forget to torque down the bearing caps to about 115-135 ft. lbs.
Your last problem here is reinstalling the torque tube front bushing. Patrick gives you a one-piece bronze bushing about 5.75 long to replace the two bushings that you knocked out with the 6 foot pipe. You have to be careful here, as the bronze is easily deformed and then you'll have a right bugger getting the U-joint sleeve to slip freely in over the driveshaft splines. What I did was put the bronze bushing in the freezer for a couple of hours and then, just before installing it, I warmed the end of the torque tube up with a propane torch. I had a friend hold the OLD torque tube bushing in front of the NEW bushing, and commenced to tap it in with a short piece of 1 1/4" pipe. You want to drive the new bushing in flush with the end of the torque tube. I still managed to raise a burr on the face of the new bushing and the U-joint sleeve wouldn't start. Fortunately, I had a small, flat diamond file that fit nicely between the inside of the bushing and the splined driveshaft end and a five minute touch up had everything fitting nicely.
Third member back in
Time to put the third member back in the carrier housing. There is a procedure in the Chevrolet service manual for correctly shimming the ball seal to the back of the transmission. Briefly put, you want to put all four gaskets in first. Then, with the rear dust cover (the big knurled ring with the rubber seal in it) OFF the ball seal, and with the cork gasket NOT installed in the ball seal clamping plate, bolt the clamping plate to the back flange of the transmission and tighten it down. You should just be able to wiggle the ball seal around. Mine was just right with all four gaskets in. Do a search here on stovebolts.com under "ball seal" or "U-joint repair" for more info.
Now you can slide the third member back under the truck and have your friend guide the front of the torque tube above the crossmember and as high as he can lift it. This will give you room to slide the ring gear and assembly into its opening and onto the studs. Bolt it down. Assemble the axle drive gears, the axles and retainers and spiders. The spiders are a bit puzzling at first. Just remember they have to be exactly 180 degrees from one another so you can slip the pin through and the spacer block in. It just takes a combination of ring gear turning and axle turning. You'll see it after a try or two. Cover and gasket on and gear lube in. Time to move to the front.
Once again, on my truck there was JUST enough room to slip the ball seal and U-joint in with the torque tube jacked up as high as it could go. Don't forget any of the gaskets or seals here. Once you bolt up the U-joint, it's a little late to be putting the cork seal or dust cover on, eh? Transmission takes 1 1/'2 pints of gear lube. Replace your transmission floor cover, reassemble your gas pedal and starter pedal and fire it up.
If anyone catches any errors in this, email me and I'll make the appropriate changes.
1951 Chevy 1/2-Ton, "Lurch"
Bolter # 8402
St. Charles, Michigan
v. May 2006
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