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PhilA

1951 Pontiac Chieftain - Gearbox

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On 8/3/2019 at 6:04 AM, PhilA said:

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Further inspection showed the seam to be cracked a few more inches along the top. Cleaned it up and soldered it back up. I'm improving my technique.

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Pressure testing highlighted a small crack.

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Cleaned it up and added flux.

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Soldered up.

 

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High tech pressure testing rig showed no more leaks. Next test will be cooling the engine.

 

Phil

We'll be working on the rad next right after we finished installing the bumper and exhaust kits on the current truck project. I expect a lot of leak on the rad so I could use some of your tricks here.

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I had watched a few videos of people repairing radiators with solder and a flame. My take away from that was the way the heat is fanned to and from the area being worked- keeping the way the heat is in the metal is key to a good job.

However, my full take-away from this is:

1) A good acid flux. Buy the one with the most warnings on. The safer stuff works less well. Go to a proper plumber's shop

2) Lead solder. The non-lead stuff is really difficult to work with as a beginner. I used 60/40 electrician's, which isn't quite as strong but is easier to work with

3) Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean. Clean.

4) Clean a bit more.

5) Gas torch with a small but hot flame, the little chef ones for doing creme brulee work well.

6) Heat up the area a bit. The flux turning brown is an indication it is getting hot enough. Move flame away, touch solder to area. Move solder away, heat a little more, move flame away, touch solder. The on/off of flame to touching the solder is probably a half second a go. flame/solder/flame/solder. I worked this just by holding the gas torch at the limit of my wrist's motion, and twisting my wrist and letting it go back to its limit so the flame falls back to where you had it easily. If you heat too much the solder just buggers off all liquid-y and doesn't seal. You have to be working the solder just on the verge of solidifying- heat it up so it just melts but isn't to the shiny-silver runny stage- that's about a quarter second of gas flame away from "just melting". The technique takes practise but if I can do it anyone can lol.

 

--Phil

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Uh, thrust washer B16 is unavailable in standard thickness.

Waiting to hear back what it was originally, maybe .099". Oversize is available, .109" and .119"

Mine is worn to .087" and has gone through the copper to the steel by 0.002"

The face it contacts is quite badly worn so the oversize may take up the slack correctly. Book does not go into detail of oversize washers in this location.

Phil

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Aha, 0.090" were mine. There's a guy listing parts in Massachusetts, I'll give a call tomorrow morning and see if he's still doing business. He lists The standard plus the oversize.

The endfloat is a combination of all the thrust washers allowing the main shaft to move. If I put new 0.090" washers in, that'll tighten 0.019" up to 0.015" backwards and that'll be back in tolerance. It seems most of the thrust is to the front of the gearbox. "Measure the lash and pad it out at the slack end" is the way it's calculated. Adding a 0.109" would bring it locked up solid tight so that's no good. Hopefully this guy still has the standard ones.

Phil

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The main shaft end-float is a compound of all the thrust washers and machine faces between the main center bearing and the back of the gearbox, so 4 washers and a shim.

When the gearbox was still all in one piece I measured the lash and it is 0.019", which is just outside of the 0.004-0.018" specification.
The thrust washers are quite worn. One is all the way through the copper coating, and regardless needs replacement. They measure 0.087" and 0.088" respectively, new they are 0.090" so I just ordered 2 new standard thickness ones and a slightly thicker main shaft end-float washer to bring me back into spec.

--Phil

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Regarding your radiator repair.

I used to take our Stock Car radiators to a Radiator specialist for repair at £20 a time. The shale damages the veins.

One day I watched him do it. He used exactly your method, plenty of flux and careful with the heat.

I now do my own, just like you, and him.

At the track if no time to change the rad, we just stick a ball of Quik Steel into the water spurt. Looks a mess but works fine.

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I just stopped at AutoZone and they've changed up the transmission fluid they stock. Up until 2 weeks ago, they stocked Dexron-IIe. Now, they've rearranged everything and the oldest type oil they keep is Dexron-III compatible "universal" oil.

 

That made me think. Possibly the wrong oil had been put in, because the seals are rock hard and split like so much cheap plastic, and the only bearings that are bad are the phosphor bronze ones in the hubs. 

 

That would explain why it wore to such extremes.

 

Phil

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Cleaned out the governor. The B weight would get a little sticky in the bottom of the bore; a thorough cleaning has resolved that and now sees both weights falling freely under their own weight when the governor shaft is rotated.
That'll certainly have been a not-changing-gear issue.

Phil

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I assume there are similar issues to with EP80 gearbox oils where GL5 notionally replaces GL4 in most people's minds...when it really doesn't...GL5 is fundamentally incompatible with gearboxes containing yellow metals, and will wreck them in short order.

This is a common issue which has come up among Lada owners, especially given the commonality of GL4/5 "universal" oils, which plainly aren't when the two standards are quite different things and are actually mutually exclusive pretty much if you delve deep enough into the data sheets.  A GL4/5 oil is never going to be fully GL4 compatible...

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Agreed, and this may have been part of the issue here. No telling. The front band being incorrectly adjusted, stuck valves, leaking seals.. you name it, it had it.

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With the governor clean but yet to receive new rings, I turned my attention to the valve block. Apologies for no pictures of it apart as I was trying to keep clean but it's all reassembled now. Imagine valves that were stuck, passageways full of black sludge and a general look of malaise.

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Now, it looks new. All the valves slide freely as per spec.

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Added bonus, the thrust washers for the drum arrived. You can see the old ones and just how bad the worn one was.

More cleaning tomorrow. I didn't want to but I'll need to pull the reverse mechanism apart in order to clean it out because every single piece has to be spotless before it goes back together.

Phil

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Root cause of the failure of the gearbox. A nice cascade failure; this spring failed, tension on the front band was lost, the band slipped causing the clutch to slip, heating the clutch, which heated the bearings causing them to fail.

 

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Had to add to my toolbox today. Big screwdriver. Why? Slotted head screws to hold the front oil pump together. WTG GM.

 

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Even so I had to saw out one and drill out another. Still, got it apart, cleaned all the crap out of it and de-burred the pressure relief valve so it now moves smoothly.

 

Phil

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Trying to move forward, got a lot to go yet.

 

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Another hallmark day though. First new parts going back onto the gearbox. Two oil control rings first, for the inside and outside of the fluid coupling housing.

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Used the old seal to knock the new one in.

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Looking better, that's the part there that was leaking like a sieve before.

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Next up, rear servo. Not liking the look of that spring.

 

Phil

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That's my worry. The manual is remarkably vague about taking it apart, too.

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Big new screwdriver allowed me to undo the large plug on the side of the front servo.

Inside is this shuttle valve; it acts as a plug to the servo bore until the 4-3 downshift is activated, when it moves along and dumps the pressure from the servo, causing the downshift.

It wouldn't have worked, the thing was stuck firm. It took five minutes of persuading it against the bench for it to begin to move. It now slides freely in the bore and even the spring clip locates correctly in the hole in the other side of the piston.

All back together, awaiting spring.

Rear servo and reverse mechanism to go.

 

Phil

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Careful use of muscle and clamps saw this undone without sending any part of it into orbit. That spring is as strong as it looks. 

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It also has plenty of friends inside helping to push everything apart. 

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That and enough in the way of metal shavings inside to make a 1:32 scale model of the gearbox.

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Thoroughly cleaned, the 4 moving parts (all spring loaded) aligned and piston rings located without breaking any. Torqued up and ready to go. 

This one I liked doing. It's the only part so far that's not cost me any money.

Phil

 

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Final list compiled. $560 in parts (some new old stock, some preloved but good). Thank my dear old Mama for gearbox spares.

Got some new bearings to go in, that's going to be fun, both taking the old ones out and putting the new ones in.

Hopefully should be able to get that ordered tomorrow. 

 

Phil

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