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Projects Mild custom '51 Pontiac Chieftain

Discussion in 'Traditional Customs' started by PhilA, Nov 4, 2019.

  1. Dave Lee
    Joined: Nov 5, 2019
    Posts: 7

    Dave Lee

    My pontiac wipers also have throttle fade like most of them , there was a kit for chevy 235's so you could move the vacuum to a different location eliminating most of the fade, just don't remember who built it
    Balcamp (napa auto parts) had one but discontinued it.
     
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  2. tubman
    Joined: May 16, 2007
    Posts: 5,325

    tubman
    ALLIANCE MEMBER

    This is a great thread. I never would have thought that I would spend almost an hour enthralled by someone redoing a '51 Pontiac, but I just did. One thing this did do is make me appreciate my '51 Ford a little more, as it was well cared for it's entire life and never had "Bubba" messing with it. I don't know if I would have had the perseverance to tackle all of the piddly little tasks this this entailed. Good Work!
     
  3. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    I did a little reading just now and the only thing I could see with reference to vacuum wipers (other than the electric kits) is a booster pump integral to the fuel pump. Mine has that pump but the wiper motor seems to leak worse than both the motor and pump can keep up with.

    Phil
     
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  4. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    I just dug through the pictures I took when I had the wiper motor apart and I'm sad to say I took many fewer than I thought I had.
    20181231_153222.jpg
    This is the only one I did not put from the series. The side plate comes off. There is a tongue spring that holds the mechanism tight against the metal. The cam is driven by the wiper motor arm itself. As it moves, it pulls the spring over-center and that snaps to the opposite side, pulling the yellowed plastic piece with it.
    The yellow plastic piece is a valve. It directs the airflow from one side to the other, volume of which is controlled by the regulator valve on top. It is the piece that makes the wipers wipe just a portion of the screen, and the regulator valve at the top opens up to one side and makes them return to their parked position when they are turned off.

    --Phil
     
  5. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    "Why this car is automatic
    It's systematic
    It's hydromatic
    Why it's greased lightnin'!"

    Well-known lyrics, I think we'll all agree. Greased Lightning my car was not (and truthfully, I doubt it'll ever be).
    Put into Dr it would engage forward motion. Applying a little light throttle and the car would move. Trouble is, the manual states that the car should be in top gear by about 15-18mph. It would be to 15 or so then if I snapped the throttle shut it would change gear, normally to third, occasionally 4th. Slowing down it would change back down to 1st at just above walking pace. It also made the Exxon Valdez look leak-proof.

    Note that this is my first foray into the world of the GM Hydra-Matic. I've owned cars with automatic gearboxes before but they all worked well and didn't need any work, just maintenance. So, I figured that the valve block was maybe a bit fouled up and that it'd just need a few new seals. So, seal set was procured and I made a start on tearing down the gearbox.
    A couple of things I learned from this I'll share with you now. A high mileage Hydra-Matic will still work, even if it's internally in very poor shape. If you feel the urge to pull one apart you will need at very least the new seal set as all the seals I had were no more good or tore when I took the thing apart.
    Plan for it to turn into a lengthy, protracted rebuild.
    Plan to take it completely apart to inspect.
    Expect the cost of it to be about 4x what you had initially hoped on it being.
    Remember to go to the store and get a box of Zip-Loc bags to put all the nuts and bolts in.
    You will need a very very clean surface to work on. I bought some baking trays from the dollar store.
    Decent set of circlip pliers- I bought a Snap-On set that are the same model as used in the pictures of the manual. They are sold as brake pliers.
    Get a copy of the proper service manual. The original GM manual is actually really very well written.

    20190721_161354.jpg
    Because, well- that's nice clean hydraulic oil. You know the car shows where the host has just bought a used car on the cheap, pulls the dipstick and proclaims "The oil's clean, that's a good sign"? Well, this was not necessarily the good sign I had hoped for.
    20190721_161402.jpg
    On one of the other Hydra-Matic threads here on the HAMB, somebody knowledgeable made an apt remark- getting a Hydra-Matic off a seized engine is not an easy task. This is very true, as the flywheel is actually part of the fluid torus (note I didn't say torque converter, this one doesn't have a torque converter, and I'll cover that in a little bit).
    There are 30 bolts around the periphery of the housing. You have to rotate the engine and gearbox together to access all the bolts around the periphery.
    If you cannot get the drain plug out (mine was stuck fast) then expect a lot of fluid to come out between the flywheel and torus when you split it open.
    20190721_171351.jpg
    The i-8 engine comes from an era before the art of thin-wall casting had been perfected. This gearbox is the same and is a heavy old beast. Note the bolt in the top? That's the lifting point, usually just a threaded hole. I used my engine crane to lift the gearbox out- my guess is about 300-320 lbs.

    Next thing you will need is a sturdy workbench. The one running down the side of my garage is heavy-duty enough but it has a base that prevents the wheels of my engine crane going under it, and as such stopped my from lifting it up. I didn't fancy putting my back out for a lump of iron so built a little workbench from some old wooden shelves I had.
    20190722_220009.jpg
    Nice height to work at, easy to reach all around and not too small that the gearbox cannot be rolled over without too much fear of it falling off.

    20190723_160654.jpg
    The side pan has two levers- gear selection and throttle modulator arm. I had marked the position with Sharpie but noted afterward that I did not need to as they are both keyed for position with teeth.

    20190723_161603.jpg
    Side pan off. The lower bolts do not have star washers- they have copper sealing rings. Don't lose them, thye like to get stuck to the pan instead of coming away with the bolts. What we are looking at here is the valve block on the left, some pipework, the end of the governor and the reverse gear lock-out mechanism.
    There is a specific order to remove all these parts. the manual says "remove pipe"- that's what it means. All the pipes are just a push-fit.
    At this point I decided to remove the torus because it's heavy and bulky and made turning the gearbox upside-down to remove the lower pan almost impossible- note that in the manual the gearbox spends most of its' time upside-down.

    20190726_165330.jpg
    There's an 1 1/4" nut on the end of the driven shaft. It should be done up to 50lb/ft, mine was finger-tight but had been saved from undoing by the lock-washer. I bent the lock-washer carefully back and undid the nut. The driven torus then just pulls off the shaft. The silver bit in the center is the oil pressure relief valve. Make sure it moves freely.
    20190726_165355.jpg
    Circlip pliers time. The driving torus is secured in place by quite a large circlip. Remove that and it pulls off the splines.

    20190726_171018.jpg
    Ditto the drive housing. That left the 3 shafts poking out. Note the dribble of oil. It had been leaking for a while.

    20190726_171025.jpg
    One thing that did make me smile was the clutch-pack style sprung shock absorber in the back of the drive housing. Note that all three of those parts on the bench rotate independently. The big bowl part actually brings the turning force in from the engine, and directly to the first gear set. The output of the first gear set then goes forwards to the turn the inner torus, which turns the outer torus. that turning force is then sent to the second gear set and from there out (via the reverse gear set) to the rear axle.
    That design means that, in first gear, the torus is spinning more slowly than the engine- and at 375 RPM idle is turning about 220RPM which is not fast enough to drive the car forward or make it creep. My guess is the designers didn't want the automatic gearbox to be too alien to people who has never before experienced one. So, on the flat you can simply engage Dr at idle and the engine takes up a bit of load but the car does not move. Pressing the gas then brings the revs up sufficiently to propel the car forwards- the result is a very very smooth take-up and launch.

    More to follow.

    --Phil
     
    Last edited: Nov 10, 2019
  6. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    20190730_112751.jpg
    Before you go any further, make sure you have your copy of this. This is not a gearbox to dive into blind.

    20190730_181315.jpg
    First, I used some clamps and stuff to hold my dial gauge in place to measure the end-float on the driven shaft. It wasn't actually too bad, just over-spec at 15 thou'.

    20190803_112551.jpg
    I pulled the lower pan off. Note the excess blue sealant all over it- provided courtesy of the last person who'd been inside the gearbox. Remember the nice bright red, clean looking fluid? That belied the real state of the contents. That smelled badly burned, too.

    20190803_114044.jpg
    Carefully rinsed out with gasoline, the gritty texture is revealed. Black sooty friction material I can deal with, metal shavings less so. If you look carefully, in the middle you can see a round globule of metal. Yes, that's a melted globule, not just shavings. The inside of this gearbox has been white-hot. That's not a good thing.

    20190803_123023.jpg
    I cleaned it all thoroughly. That represented about a tablespoon and a half of metal shavings. I also took to the sealing faces with my DA (orbital) sander, with a 220 grit pad on. Where the bolts are tightened down (usually over-tightened) it bends the metal up and makes high spots. The result is that even with a new gasket there is potential for leaks. Sanding the high points off helps the new gasket seal.

    20190803_123029.jpg
    Why stop there? Cleaned the exterior surfaces.

    20190803_125445.jpg
    Painted. The original color of the gearbox appears to be battleship gray. I picked a very pale blue.

    20190803_125703.jpg
    The oil strainer lifts off, and the front pump pickup tube comes off after its two retaining bolts have their locking tabs bent up and are removed. Mine was covered in metal shavings and detritus.

    20190803_124756.jpg
    The side the oil strainer sits against.

    20190803_124802.jpg
    A mixture of alloy and steel shavings. If you see all this, prepare your wallet- it can be fixed but it gets expensive real quick. That doesn't just stand for this gearbox, it's anything mechanical.

    20190803_125231.jpg
    Carefully cleaned all that up and started following the manual's procedure for tear-down. Visible in the top there, nearest is the front band servo, then the larger one on its' side is the rear band servo. The pipe with the blue sealant(*) on is the rear pump pick-up pipe, the one running at a diagonal to the front servo is the rear pump pressure feed.
    *Please do not be tempted to do this. Ever.

    20190803_161828.jpg
    After slackening the adjustment bolts off, the servos just unbolt and can be set to the side. It is a remarkably modular design for its' age. The valve block lifts out, the rear pump and governor assembly all unbolt and pull out.

    20190803_161819.jpg
    Make sure you have lots of space to put everything. There are a LOT of bits.

    20190803_161836.jpg
    The drums are now visible, the oil pump (right) undoes and pulls out. the tailshaft/reverse gear set comes out after the bolts around the back of the rear drum are undone. Zip-Loc bags and a Sharpie for the bolts. Once the tailshaft has been taken off and the driveshaft/planet gears have been removed there's nothing to stop the drum falling apart. The manual recommends a special tool, a piece of metal bent into an L and a hole drilled through is not hard to make, it uses one of the bolts to hold the clutches in place.

    20190803_181306.jpg
    Yeah, even more parts than before.

    20190803_181215.jpg
    The drums are held in with a main-bearing-cap style clamp which has bent-over securing tabs. Empty case there still weighs a good 40 lbs or so. I cleaned everything down with gasoline. Do not use cotton shop towels or paper- those all shred and leave little bits of lint stuck to the sharp parts of the casting and will eventually get into the hydraulics. I recommend old teeshirt style cotton.

    20190804_113351.jpg
    As with a lot of this gearbox, the two drums are held onto the drive shaft with circlips. I pulled them apart and the central bearing/fluid delivery sleeve made a clicking noise pulling off. One of the rings was broken (pictured), the rest were melted into the steel of the fluid delivery sleeve.

    That did however represent all of the component parts removed from the case.

    More to follow.

    --Phil
     
    Last edited: Nov 10, 2019
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  7. goldmountain
    Joined: Jun 12, 2016
    Posts: 2,439

    goldmountain

    Keep this up and you will have everyone here wanting to overhaul a hydramatic.

    Sent from my SM-T350 using The H.A.M.B. mobile app
     
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  8. stuart in mn
    Joined: Nov 22, 2007
    Posts: 1,826

    stuart in mn
    Member

    As a long time Pontiac fan, I'm enjoying this thread very much. :) Someday I'd like to have a straight 8 car, preferably a 1950 fastback.
     
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  9. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    20190804_161459.jpg
    This here is the "fluid delivery sleeve". It serves a few purposes.
    First and foremost, it is bolted into the main bearing style brace in the gearbox case. That is drilled with 2 oil passages from the valve block. Each one goes to a drum, to fill the center up, move the annular piston and apply the clutch.
    Second, it supports the rear drum on one edge.
    Third, it supports the driven shaft from the torus.

    As you can see, it was very badly scored where the bearing had failed and had allowed the drum to contact. This had melted the oil control rings in place, also.

    20190804_161505.jpg
    That there is the bearing that scored the end up so badly. You can see also where the section that should only have the rings touching was rubbing too.

    20190804_161552.jpg
    Luckily the shaft that runs through the center is made from incredibly hard steel and had survived intact. The planet gears were also all good on their bearings.

    20190806_200211.jpg
    The drums themselves are fairly straightforward in design; a sliding annular piston is held in place inside the drum. Interleaved steel plates, half of which are plain steel (the "steels"), half with a special coating on (the "frictions"). The steels are notched on their outside edge, which line up with pegs on the exterior of the drum and rotate with it. The frictions have teeth on their inner edge which mesh with the sun gear. The planets of that sun gear mesh with teeth on the drum outer.
    The planets are normally free to rotate, and the action of the sun gear having fewer teeth than the ring means as it rotates, there is a reduction ratio across it. If the clutches are engaged, the planets cannot rotate and the input then rotates at the same speed as the output (direct drive).

    20190806_173532.jpg
    The clutch packs had been slipping badly, most likely due to low oil pressure because the system was leaking past the rings. The seals for the piston were also brittle, meaning they will have been leaking badly also.

    This slipping caused a lot of heat, and that had burned all the friction material off and then everything inside became metal on metal, which is a recipe for disaster. You can see that the oil has carbonized onto that steel (above), and that there are areas of bluing of the steel so it's been at least 1000 degrees F.
    That excess heat began to soften and destroy the bearings.
    Because everything is nested, one bearing failing deep inside the gearbox affects the alignment of the rest of the shafts- that then puts it all out and things rapidly go downhill from there.

    Phil
     
    Last edited: Nov 11, 2019
  10. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    Earlier I had made mention that if you planned on taking a Hydra-Matic apart, to completely disassemble it and perform a complete inspection.

    20190811_110717.jpg
    Reason being, you get to find little gems like this. That's the front servo primary return spring. It and the servo boost rely on that spring providing tension, which, in a broken state it couldn't.

    20190811_132742.jpg
    Next up, I started with one of the very central core parts of the gearbox- the front oil pump. It is driven directly by the engine, and has integral pressure relief and external pressure regulation.
    The pressure relief was totally jammed with swarf, so that was freed up (little gray circle bottom center of the right hand part) and the pressure regulator was getting stuck in the bore also. The pump itself wasn't in bad shape so I prised the old seal out and removed the oil control rings.
    20190811_163738.jpg
    Circlip pliers ahoy. They got a good workout doing this gearbox.

    20190811_164431.jpg
    I used the old seal as a drift to knock the new one in place. All nice and centralized.
    Note that the screws were so tight I had to buy a bigger screwdriver to undo them, ideally I could have done with a rattle gun to free them off.
    I redid them back up to factory torque, 20lb/ft.

    20190811_200540.jpg
    Finally, one of the shuttle valves from the front servo- shows how much swarf had been pumped around the system and found its way into absolutely everything. Burned up friction material gets all up into the valves also and causes them to become sticky and makes the gearbox a lot more lumpy than it needs to be. Given that the design allows for 2 gears to be selected simultaneously (one of the things the later TH350 cannot physically do) and that'll happen if the 2-3 or 3-4 valves get sticky, it's a good idea to take it all apart and ensure the hydraulics are spotless.

    Phil
     
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  11. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    I guess this juncture, with valves and pumps and all kinds of automatic transmission wizardry in the fray, a bit of an explanation of how this thing actually works is in order. Perhaps it'll help de-mystify the way it works (and why it does what it does).

    First up, the gearbox has a pair of hydraulic oil pumps. The front one you see above, it's a variable pitch pump capable of very high flow at low speeds and is driven directly by the input from the engine. The rear pump is connected to the tailshaft and is driven by the rear wheels. It is a single-acting gear pump and can provide high flow at high speeds.
    The rear pump is capable of providing enough oil pressure at about 15MPH to cause the gearbox to work and allow for the car to be bump-started if necessary. It also provides lubrication pressure for when the car is being towed with its' wheels on the ground.
    They both feed into a common pressure reservoir, which is regulated by a spring operated regulator valve in the side of the front oil pump.

    I'm going to assume the understanding of band-and-clutch operated epicyclic reduction gears (if you don't know how they work, go read this first: https://en.wikipedia.org/wiki/Epicyclic_gearing ).

    In N (neutral), both drum bands are released and as such they just spin with the engine and do not provide any output to the rear axle.
    In Dr, stationary oil pressure is applied to both bands, allowing both of the planetary sets to rotate and provide maximum gear reduction (one feeds into the other so doubling up on the reduction provided).
    In Lo (Low Range), the same occurs but the valve block is prevented from changing up higher than 2nd gear.
    In R (reverse), 1st gear ratio is locked in (no upshift allowed) and the reverse cone is engaged, locking the reverse epicyclic and reversing the output direction of rotation and at the same time adding a third degree of gear reduction.
    With the engine off, no oil pressure, 3rd gear is engaged by means of a spring. Selecting R engages a pawl on a ring gear locking the reverse drum at the same time. The mechanical advantage of 3rd versus Reverse effectively locks the gearbox solid and is used to park the car (hence the lack of a P position on these gearboxes).

    The gearbox changes gears based upon two factors.
    Primarily, it changes gears with road speed. The tailshaft output connects via a gear to drive the rear oil pump. It also drives a spinning governor. The governor is a simple device. It has a spinning weight that centripetal force attempts to pull up out of its bore, and oil pressure from the pump attempting to keep it pushed down, like a spring would. The faster the car goes, the faster the governor spins, the greater the force on the rotating mass and the further it opens against the oil pressure, allowing fluid to pass more the faster the car goes.
    This modulated oil pressure is fed to one side of 3 valves in the valve block. Each valve performs a function and puts the gearbox in a ratio set (1, 2, 3 or 4). Each gear speed valve has a progressively firmer spring than the last, so as the pressure rises, the first spring is overcome and the valve shuttles open, changing gear to second. Then faster, higher pressure, third, and then fourth.

    Under light throttle this process is complete by about 20MPH and top speed is engaged. This is ideal for gentle driving but if you are accelerating hard it's really a bad thing to have happen, as the full range of engine torque and power is unavailable in top gear at 20MPH.
    So, there is a valve attached to the gas pedal, the compensator, which is the second factor in determining when a gear change occurs.
    This compensator valve applies pressure to the valve set on the same side as the springs, assisting them.
    So, press quite hard on the gas pedal and the governor modulator pressure attempts to push the valves over to change up gears but is resisted more. The governor pressure has to rise to overcome it and the only way it can do this is for the road speed to increase. So, the gearbox changes gear at higher road speed the harder the gas pedal is pushed. The second function of the compensator pressure is to be applied to the drum band servos, to provide additional clamping force as the gears engage- the default is a gentle application to prevent a thump of gears at light throttle but positive engagement without slipping when under heavy load.

    Additionally the governor has a second weight that is much more massive and engages by about 5MPH- this opens up a piston that physically prevents Reverse being selected once the car is moving forwards at a speed that would damage the gearbox.
    There is also a 4-3 kickdown, part of the compensator valve set that is engaged by pressing the throttle down more than about 3/4- below 65MPH it applies main line oil pressure to the spring side of the 4-3 shuttle valve, forcing the gearbox to remain in 3rd gear until either maximum pseed for 3rd has been reached and the governor pressure is greater than compensator+ spring and the gear changes up to top (or if the pedal is released and the kickdown valve is closed).

    So, all in all it's really quite a complicated, advanced design with a lot of features found in modern gearboxes. However, it can get a bit thumpy-bumpy on gear changes because the transition from 2nd to 3rd gear involves totally undoing the combination for 2nd and completely engaging the combination for 3rd, which results in either a momentary disengagement of drive (most common) or an engagement of 2nd and 3rd gears simultaneously which causes the engine to bog and the road speed to drop as the gears fight against each other, with the clutches or band slipping.

    Adjusted well it's actually not bad. The 1-2 and 3-4 gear transitions are very smooth- as good as any modern gearbox- but the driving experience is quite strange because there is no torque converter in the hydraulic coupling. The fluid coupling, above about 1000 RPM locks almost solid and driving the car feels much like a standard stick shift- press down on the gas and there's no flare of engine RPM, the car just picks up and goes with engine RPM rising with road speed.

    Now I understand it better, I can forgive its foibles and really think the way it works suits the car. Also, given how badly damaged it was and that it was still able to propel the car forwards is testament to how well built it is.

    --Phil
     
    Last edited: Nov 11, 2019
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  12. 392
    Joined: Feb 27, 2007
    Posts: 1,175

    392
    Member

    Nice ride and having fun. Good stuff.
     
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  13. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    20190811_165028.jpg
    Next up on the operating table- rear band servo. Note the large spring on the left hand side- that is there to hold the 3rd gear band on when the engine is off and the gearbox has no oil pressure. This is to work with reverse, as said previously to engage 2 gears at once and lock the gearbox up to park.
    In normal operation the servo is held off with oil pressure, the spring working as an assist.

    20190812_174153.jpg
    Thankfully the designers had a bit of foresight. They made the bolts long enough to take a good portion of the tension off the spring before running out of threads.

    20190812_174652.jpg
    Several pistons inside, springs and valves. There's a rapid release valve in the base of the secondary piston- a little spring steel flap with a hole in (fast flow one way,needs slow flow the other) to be clean underneath. It forms part of the system to gently apply the band under light throttle.

    20190812_181155.jpg
    Even more metal shavings. All flushed through. This servo is fairly simple. The metal shavings has gotten in even under the piston ring.

    20190812_210522.jpg
    After a bit of a fight holding the spring down with a woodworking C clamp, it's all reassembled with no more particles inside.

    Phil
     
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  14. Johnboy34
    Joined: Jul 12, 2011
    Posts: 1,335

    Johnboy34
    Member
    from Seattle,Wa

    Does the servo have seal rings? (rubber or metsl) Have already got parts for your trans? Thanks for showing it all.

    Sent from my SM-G900V using The H.A.M.B. mobile app
     
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  15. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    20190813_160940.jpg
    You can see the plate that the tailshaft is sitting on there- there's a set of bolts that hold it to the rear drum. Undo those and the rear retainer bolts and the entire assembly lifts out. First, undo the speedometer drive and set it aside. The main shaft has a circlip holding it in (surprise, surprise!) then it pulls out.

    20190813_163235.jpg
    And the rear main bearing. Or rather, what was left of it. There's the source of some of the molten metal globules in the oil pan, then.

    20190813_204446.jpg
    This is the cone of the reverse gear piston. The face there has a helix cut into it but, with the heat and steel chunks that got between the faces, the alloy melted slightly.
    IMG_3390.jpg
    For comparison, a good cone. I ran a pointed tool through the helix, removing the swarf and rough edges. It qualified for "good enough to go back in". It's not used often (only when reverse is engaged) and only slips if reverse is engaged when the car is still moving forward. Granted, the manual states you don't have to be at a complete halt to engage reverse but really it helps to prevent wear if you do.

    20190816_165528.jpg
    The piston is spring loaded and sits hard up against a circlip. The spring load needs to be taken off before you can take it apart. I made whatever Special Tool number the manual called for from six bolts and some nuts and wood.

    20190816_171053.jpg
    The manual states that you may need to free the piston up with some compressed air. So, I made a little tool to convert the Schrader valve fitting to a runner seal that goes over the hole the fluid would go to move the piston.

    20190816_174122.jpg
    It took a fair bit to get it to shift because the seal was so perished and leaked badly.
    Sure enough, the innards were full of swarf. Flushed all that out and removed all the old seals, which just fell apart.

    20190816_205912.jpg
    Next up, put a decent edge on a cold chisel because...

    20190817_123323.jpg
    ...out come the old bearings, carefully to not damage the metal they sit in. Most are a C shaped piece, rather than a solid ring. Finding the join makes it easier to break the bearing out.

    20190817_141217.jpg
    Fitted brand new seals, the center one fits in easily but the one on the piston itself gets caught up attempting to push it in because it gets stuck against the lip the circlip nests against.

    20190817_144111.jpg I ended up cutting up some sections of this plastic sheet (actually it was part of an old Cone Of Shame from when my dog was spayed) which held the lip of the seal in past the step of the bore allowing it to push in without damaging the seal any. The original dealer tool was a ring that was the same diameter of the lip. Oh well, they didn't have one when I asked.

    20190817_145803.jpg
    The funky wooden clamp pushed it all down together again, new seals that don't leak at all!


    Next!

    Phil
     
    Last edited: Nov 11, 2019
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  16. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    The servos have metal sealing rings. The swarf had gotten in behind them, but they were in good condition.
    20190821_195837.jpg
    Look carefully top right, the piston sitting on it's end, that's got a chrome ring sitting in there.

    The annular pistons for the clutches have rubber seals.

    20190821_181042.jpg
    I made a shopping list at Fatsco (www.fatsco.net), who come highly recommended for anything Hydra-Matic, old and new.

    Phil
     
    Last edited: Nov 11, 2019
  17. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    Finally, we reach the reason the gearbox was taken apart previously.

    20190822_161928.jpg
    This circular wavy washer spring. You see half of the old one in position- it would appear that previously this spring fractured and got caught in the ring gear, locking it solid. That's gotta have been interesting when that let go...

    Phil
     
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  18. Johnboy34
    Joined: Jul 12, 2011
    Posts: 1,335

    Johnboy34
    Member
    from Seattle,Wa

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  19. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    I have read in as few places that people say generally it's good for about 300 horsepower and about 450lb/ft all day long. Who knows what it'd do asked to go down a quarter mile a couple times?

    So yeah, it's not half bad!
    Phil
     
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  20. goldmountain
    Joined: Jun 12, 2016
    Posts: 2,439

    goldmountain

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  21. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    Sure is, I'm used to using it. Metal chips, then! Tomato, tomato!

    After all, you need to define things, I guess. This is coming from the country that has about fifteen names for different types of rain...

    Phil
     
  22. bchctybob
    Joined: Sep 18, 2011
    Posts: 2,639

    bchctybob
    ALLIANCE MEMBER

    Phil, I can’t thank you enough for walking us through this adventure. I’m about to attempt to reanimate my old Hydro that’s been resting for 15 years or so. For some reason reading your thread is making me feel more optimistic in spite of the carnage you found in yours. By all means tell us more.


    Sent from my iPhone using The H.A.M.B. mobile app
     
  23. stuart in mn
    Joined: Nov 22, 2007
    Posts: 1,826

    stuart in mn
    Member

    Swarf is a common word in the machining world.
     
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  24. tubman
    Joined: May 16, 2007
    Posts: 5,325

    tubman
    ALLIANCE MEMBER

    Boy, am I glad my car has a manual transmission.:D
     
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  25. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    Mine shows signs of having been ridden hard and put away wet for many years; if yours has had a little more sympathy over fewer miles I'd expect just a bit of moderate wear. However, if you pull the pan and give everything a push and a pull, there should be minimal axial slack. If your drums wobble, it needs checking...

    Phil
     
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  26. loudbang
    Joined: Jul 23, 2013
    Posts: 31,466

    loudbang
    Member

    Really enjoying you detailed posts. Keep them coming.
     
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  27. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    I figure that they may be helpful if not interesting- by now all the secrets of this box of cogs should really have been given up, but they are regarded by many as black magic that should be only prodded at with a stick from a safe distance. It's really not much different from rebuilding an engine. If you've the aptitude and skills to do that, this is similar in construction and principles of operations and rebuild.

    I figured I'd document it and let others know what I found- the manual does have troubleshooting but what they could not account for when the book was written was the change in hydraulic fluids available over the years and metal fatigue. However, I would say this gearbox probably had a design life of 10 years, maybe less, and somewhere between 80-100 thousand miles before it was considered junk. If the maintenance schedule was adhered to however, there was a much better chance of it lasting that long. I consider it a good thing that this one lasted as long as it did. For such a mass-produced, consumer item it is really made very well, with a lot of thought and not too many compromises in the design.

    --Phil
     
  28. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    20190828_101158.jpg
    Herein began the rebuild. There are a couple of bearings that are unavailable, but in this case a pair of more modern ones side by side fit perfectly. Just take care to line up the oil channels when fitting them.

    20190828_102149.jpg
    Similar fittings- one thing I will stress early on with pictures of bearings- you may find buying some dry ice and sitting the new bearings in it for a while a help, to shrink the bearings down. One absolute MUST is to ensure none of the bearings sit proud, as this WILL screw up the endfloat measurement, which is critical.
    20190828_105919.jpg
    Ugh, more melted metal. The guts of this drum were obliterated. The springs had also been very hot and as such had annealed and lost a lot of their spring. I ordered replacements. Cleaned all of that out thoroughly.

    20190828_112512.jpg
    Brand new friction material. Note that the rings need to be soaked in hydraulic oil before being fitted- these pictures were for the magic of television (and mostly so I could take pictures without getting oil all over my camera), they all got stripped down and oiled.

    20190828_112745.jpg
    Interleaved steel and friction plates. Next up, before putting the top on, take the center and get all the friction plates aligned. For this you need to channel your inner safe-cracker because it feels like turning a safe dial back and forth to locate it through each set of plates.
    Note also that the 8-cyl version of the gearbox has a few modifications compared to the 6-cyl, one of which is more friction rings in the clutches. The other is a change to the pressure regulator valve set.

    20190828_121733.jpg
    Two drums with new clutches and new bearings. Quite satisfying. Also the friction material is compatible with DEXRON-III oil (forget not that DEXRON is a friction modifier, the original oil had some different characteristics).

    20190828_132533.jpg
    Don't forget the circlip! It's buried way down in the center of the drum.

    20190828_142038.jpg
    The oil rings on the fluid delivery sleeve have little clasping fingers. Take care not to break them, they're brittle.

    20190828_144611.jpg
    The manual states there's a special tool to squeeze the rings so they'll slide inside the drums. Twisted wire is a right fiddle and causes a lot of cursing but it does work.

    20190828_162532.jpg
    Another circlip and the Special Tool that holds the drum together. Nearing readiness to reassemble into the case...

    Phil
     
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  29. Johnboy34
    Joined: Jul 12, 2011
    Posts: 1,335

    Johnboy34
    Member
    from Seattle,Wa

    I've done a couple C4 fords, a couple T350 chevies so I'm really enjoying your endever into this one. Those drums look heavy!

    Sent from my SM-G900V using The H.A.M.B. mobile app
     
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  30. PhilA
    Joined: Sep 6, 2018
    Posts: 877

    PhilA
    Member

    That's a way to describe them, yes! Mounted together they weigh in at about 40 lbs.

    Phil
     
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