PhilAndrews

'51 Chieftain - Transmission overhaul

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Posted (edited)

I used to drive my Hillman by ear- clutchless changes. I was taught mechanical sympathy by my father, so I hear you.

 

I just know that the car is gonna be driven by other people and not everybody has such a good grasp of the concept.

 

 

I've just booked myself a week off work, hopefully get everything buttoned up and get the car rolling again.

 

--Phil

Edited by PhilAndrews (see edit history)

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The tach/rpm subject reminded me of my motorcycles. My cruiser is 5 speed and I was used to "listening" to that engine. I then picked up a mid 80's Yamaha 4 speed. I had difficulty reading the Yamaha's engine, always thinking there should be another gear to shift. I had to use the tach to get used to it. I've since chopped it into a bare bones bobber without it's tach. I now know it's sound. The tach was helpful for me and would be for other drivers of Phil's car. If it was me, I'd have no tach because nobody is driving my car! LOL

 

Good luck with the Hydra, that stuff sounds fun but WAY over my head!

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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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Posted (edited)

The valve block isn't so good.

The governor plugs do move a little in their range but bind up badly before coming out.

The shifter valves are so-so, 1-2 is ok despite having been full of black gunk but 2-3 and 3-4 are sticky.

I need to inspect with an eyeglass and bright light the bores and valves.

 

Phil

Edited by PhilAndrews (see edit history)

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Posted (edited)

Thorough cleaning has seen the valve block totally back within spec.

 

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This I am happy about because I was concerned I would need to try find a new one.

Plus, the thrust washers arrived in the mail today, that was quick.

 

 

Phil

Edited by PhilAndrews (see edit history)
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Looking at it, I didn't trace the passages but the big weight A on the governor.. I'm guessing that engages the reverse lock out at low speed, and the smaller B brings the pressure up to change the gears?

 

Phil

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20190811_132742.thumb.jpg.9aa46056d94ef8896409b3d7c3d94c03.jpg

This took three hours to get apart because someone decided slotted head screws were good to hold it together. Not so.

 

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Root cause failure: front band servo spring fractured.

 

Phil

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Freed up the overpressure relief valve in the pump and reassembled it with two screws for now.

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Installed two new rings on the pump nose, where the fluid torus case sits.

 

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Then, using the old seal as a mandrel and as block of wood I knocked the new seal in place. Special tool not available so that worked nicely.

 

I like this because this is where it was leaking very badly from before. The old seal was totally unserviceable.

 

Phil

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Posted (edited)

I had not been able to remove the large plug on the front servo. With my new screwdriver, that changed.

 

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This is a good representation of the muck and metal chips I've cleaned from the hydraulics. The 4-3 valve was stuck solid, took a good 5 minutes of thumping the case against the bench, wiggling the valve and swearing to get it out.

It now slides smoothly in the bore.

 

One down, rear servo and reverse mechanism to go.

 

I think I may epoxy a strong magnet to the underside of the lower pan to magnetize through the pan and attempt to collect up any remaining metal chips, too.

 

 

Phil

Edited by PhilAndrews (see edit history)
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Transmission place says Dexron-III for the oil. They've been having people use it with no ill effects.

 

--Phil

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Rear servo time!

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Careful use of clamps and muscle and a bit of rude language saw it all in pieces.

I think there are more springs than any other part inside.

 

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It also contained enough metal chips and swarf that, if collected, could have made a 1:32 scale model of the gearbox.

 

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All pistons realigned, rings seated, springs compressed and bolts torqued down.

 

I like this piece. None of it was broken. It was just dirty.

 

Phil

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20190816_165528.thumb.jpg.a053bb7a0628f6c09cf9e567bef685eb.jpg

I built special tool J-4670 out of bolts and plywood. General Motors engineers look away now.

 

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With the spring clip removed, application of some compressed air saw the piston removed. So far the reverse gear assembly is the only part that's not been full of swarf.

 

Rebuild parts ordered. Hopefully should be in mid-way through next week.

 

Phil

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20190817_123323.thumb.jpg.a15667e202c518c7a50bef164a91233e.jpg

Old bearings removed.

 

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Everything cleaned up, new seals put in.

 

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Awaiting new bearings and a broken spring washer that I missed.

 

Phil

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I revisited the governor last night. Initially I had assembled it and it was ok but after being left it decided to bind up if I tapped it down to the bottom of the bore with my finger.

 

I had gone to it again and it was a lot better with the governor on the bench but once it was torqued down onto the plate it was binding slightly in a few points around its rotation and that was bugging me.

The rest of the system (valve block more so but will be trouble is it is dirty) is more tolerant of imperfections such as scoring of bores or dirt in the hydraulics. The servos are driven by regulated high pressure oil; the valves that operate them are also driven by high pressure oil. The governor weights are pushed inward by high pressure oil but are drawn outward to open up by the forces imparted upon the weights by the action of them spinning.

Therefore, that loading is intolerant of any external influence- dirty bore, sticking weight) and the effect is knock-on and quite large to the rest of the system- the governor oil pressure being a vital part of the way the gearbox determines what gear to be in.

So, I redid the lapping of the valve with it torqued down into the housing and now it doesn't stick. Hopefully that will resolve a lot of the issues this gearbox had- it would certainly explain why it would hold in first gear for a long time and then change when the throttle pedal was snapped shut- the resultant drop in oil pressure upon closing the throttle on the compensator system likely caused the governor to un-stick and move outward, causing the gears to dump and shift over to 3rd. I know the valve block was all jammed up on the 2-3 valve so nothing was wanting to move smoothly.

 

UPS has my box of parts from Fatsco right now, hoping that'll be in tomorrow, maybe Thursday. It'll be nice to get a move on reassembly- clean down and reinstall will hopefully be all in one go.

 

--Phil

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Correct me if I'm wrong, but the ignition switch for this car is that as fitted to late 40's thru mid 50's Chevy trucks?

 

I'm finding a lot of Chevy truck part numbers for other things too. 

 

Phil

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20190825_164429.thumb.jpg.014b918d11068e0ed5131aca31b3227a.jpg

New wire run and loomed up.

 

Headlights are hooked into the dimmer switch, that's tested good for tonight. Need a few more colors of wire for the individual wiring circuits. Progress.

 

Phil

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20190826_121304.thumb.jpg.34d1681694918a3b676b636b056858fa.jpg

Yesterday was busy with wiring. Started with the tail light circuit and associated parts. Rebuilt the lamp holders for the ash tray and glove box by de-soldering the eyelets that form the positive terminal and fitting new wire.20190826_122504.thumb.jpg.e7069ec754ae85d7e27e1efc1b683922.jpg

No frayed insulation now. The ash tray light is strange- pull the tray out a fraction and the light comes on and illuminates the floor. Pull the tray all the way out and the light illuminates nothing at all, blocked by the tray.

Rebuilt the glovebox light holder also, and serviced the switch.

 

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The rest of the day was spent pulling wire for the loom. I have the parking light and headlight circuits connected and operational by the switch. Today hopefully I'll trace out the turn signal switch wires and get that connected up.

 

I'm waiting on some brass eyelets to arrive so I can rebuild all the dash illumination bulb holders.

 

Phil

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Posted (edited)

That it certainly is, but well worth doing. Most of the wires where they entered a plug or light socket had crumbled away to reveal conductors, so well overdue replacement.

 

I've somewhat over-wired the car- I hate small-gauge wire over a long run for high-draw things like headlights. The lights were specced 16ga for the low beams and 14 for the high. Both now have 10ga to the terminal blocks and 12ga to each light. They are noticeably brighter now. The dimmer switch could do with replacement; that is about the only piece I cannot take apart to fix. Eveything else (terminals, wires, switch, fusebox) has been stripped and cleaned. Every little helps. I now only have about 1/5th of a volt drop from the battery to the headlight connector. I call that good enough!

 

All the bearings I needed have arrived in so I'll be making a start on that to clear the bench tomorrow, I think.

 

Phil

Edited by PhilAndrews (see edit history)

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