Pontiac renovations, part 26.

Work continued on the gearbox with the arrival of a box of parts.


A brand new oil delivery tube (for the clutches), a pair of clutch lids for the drums, new clutch friction material and steel packs, a set of new bearings and some other odds and ends.

Front servo

I started with the front servo, which was due new oil rings and a new main spring (the original fractured).

Front servo piston assembly

The front servo has a couple of independent pistons inside, separated by a couple of springs. It is all held in place by simple geometry and during assembly everything liked to get out of line. After a few failed attempts where springs launched themselves or the piston fell out past the rings I magnet to get it all reassembled.

Front servo rebuilt

I fitted new bearings (more on that later…) and started rebuilding the reverse gear mechanism.

Reverse piston return spring

The reverse piston is pushed back from being activated by a wavy spring steel washer. The original had broken in half. This appears to have been the reason the gearbox was taken apart originally. The broken part appears to have come free and become mangled up in the rear epicyclic gear set.

Brake light switch

I took a bit of a break from mechanical parts of the gearbox to work on the wiring. I fitted the replacement new brake light switch, as the old one had failed.

Headlight loom

I bought some new wire and rebuilt the headlight loom.

Turn and park light wiring

I redid the turn and park light wiring, as there were a bunch of Scotch-Lok connectors and excess wiring in the harness. I added a good ground and connected it all up.

Light wiring block

The wiring was then terminated at the rebuilt terminal block.

Bulb wiring terminal

I ordered some rivets, which are soldered to the end of a wire to form a terminal in bulb holders.

Rebuilt bulb holder

With the bulb holders rebuilt, I started to run new wiring under the dash.

Wiring spaghetti

This began to turn into a complex task, despite the wiring in the car not being too many circuits. The brake lights and front indicators all wire through the turn signal switch.

Turn signal flasher and switch connector

The original connector was loose to the switch and the wiring was a little crispy. I took the connector apart and started to de-solder the wiring.


This demonstrated just how flammable the old wiring is- it caught fire very easily and did not put itself out.

Flasher circuit harness

The harness was loomed up neatly, with wires for the brake lights, front indicator bulbs, wiring to the brake light switch and wires for the dashboard telltale lights.

Dash harness

I built the loom up for the dashboard and connectorized it for easy connect/disconnect.

Dashboard lights and gauges

I connected the dash up to test. All the lights work, the dash dimmer operates, the ammeter registers current and even the fuel gauge registers not-empty.

Clutch pack debris

With wiring completed, I turned my attention back to the gearbox. I pulled the clutch packs apart and discovered a lot of metal debris inside, a lot of melted alloy.

Annular piston

I fitted new bearings to the clutch pack after cleaning it all up. The new parts fitted together nicely.

Clutch pack reassembly

The clutches are made up of a number of rings, friction material rings with centered teeth that grab the sun gear and steel plates that locate on pins to lock the gearset solid and stop the thing being in reduction.

Clutch pack rings

With all the clutch rings in place, the piston assembly then sits in the top and is held is place with a large snap ring.

Front and rear drums

The drums then locate onto the fluid delivery sleeve, which in the book calls for a special tool to compress the oil rings down for easy assembly.

Improvised tool

I improvised and wrapped wire around the rings to hold them compressed.

Front drum on

The front drum went on easily because access is good.

Both drums on

The rear drum… not so much. However, both fired on successfully after a long fight.


I then started to refit it all into the case. I then started to run into trouble with it all not fitting. I decided I needed to order some more parts to adjust lash.

Dirty chrome

While I was waiting for parts I went back to working on the wires. Part of that included wiring for the heater fan. The fascia panel was particularly dirty so that was cleaned up.

Dirty panel

The switch for the fan was rewired at the same time, the switch itself being in good condition.

Clean panel with switch

I rebuilt the dome light because the switch did not work. It had corroded and the contacts had become poor and had caused the plastic to become distorted.

Dome light switch

A little work with a craft knife and sandpaper saw the plastic in the correct shape again with the slider being spring loaded against the terminals.

Dome light switch operational

I then had to rebuild the driver’s door switch as it has seen some water ingress and was also corroded.

Door plunger switch

Now the dome light and trunk light both operate (though the trunk light mercury switch is unreliable).

Antenna installed

I fitted the electric antenna I had bought and tested operation, successful. No radio yet installed but it’s ready to go.

Bent steel

I had wanted to purchase an alternator that is fitted into a case that looks like the original dynamo generator, for two reasons. Firstly, the look of it and second, it utilizes the original mounting points. However, those are very expensive so instead I decided to build a bracket that mounts to the original points but correctly holds the alternator in line. Previously the alternator was mounted upside-down, with the main mounting point providing no reaction torque and the adjustment bolt hole holding it all up. As a result the alternator was sitting at an angle and the belt was slipping.

Alternator bracket

The new bracket holds the alternator in line with the pulleys and allows now for correct adjustment.

The alternator warning light won’t go out and I get just over 13 volts from it, so further investigation is required.

Timing marks

While I was working in the area, I cleaned up and painted the timing marks. There was a blob of white paint that covered all 3 marks (at 3 degree intervals). I found the timing was set very far off, close to 45 degrees. I re-indexed the spark plug wires and discovered the engine was very happy to idle smoothly when the timing was correct.

Clamped vacuum advance

I saw with my timing light that the ignition wasn’t moving with manifold vacuum. Discovered someone had clamped the vacuum advance arm with the condenser bracket. I freed that up and found the screw holding the condenser was far too long, had fouled the mechanism underneath and the plate was bent. I corrected that so now it advances but it does move a little far. There is a bendable tab that limits how much advance is applied, which will need modification to prevent light throttle from being lumpy without impacting idle.

Headlight beauty ring clip

Between times I had a thought and decided to make a new clip for the driver’s side headlight beauty ring. I had some baling wire, which is nicely flexible but has all the strength of putty. So, I bent the wire to shape then heat-treated it with my propane torch.

Heat treatment

The wire is heated to incandescent orange then quenched rapidly in cold water. This hardens the metal. A couple of repeats, then heating the metal up to a dull cherry red and letting it cool slowly brings back capability to be springy.

Headlight trim

The headlight trim is now securely held in place, which is an improvement over the previous implementation courtesy of the previous owner of gooey sealant. Which, incidentally didn’t work.

Gearbox reassembly

A bit of a saga occurred with the gearbox. I couldn’t get the main shaft endfloat correct. Everything was too tight and would bind up solid. I figured perhaps a bearing hadn’t seated well so gently tapped the mainshaft against the rear drum. This translated the force to the oil pump, which was the root cause of the problem. The bearing hadn’t seated correctly when I put it in and was sitting proud. As a result the retaining flange on the oil pump shattered (I think it had been weakened in the past). I ordered a new oil pump and the correct thickness shim which allowed me to reassemble the gearbox.

Rear servo measurement

The brake bands need to be carefully preadjusted for correct operation. The manual shows the use of a special tool- with care vernier calipers can be used. The setting is to dial the band in against the spring until the distance from the back of the servo to the actuator pin is 5 7/16″.

Rear band adjustment

With tension set, the locknut is tightened down and the rear band is done.

Front servo adjustment tool

The front servo needs to be pushed in 300 thou’ and the band set snug at that position. The servo case has a plug in the end which is tapped blind so it seals. The brass insert is a hydraulic fitting that I tapped a thread through to allow a bolt to be screwed down and push against the piston.

Domed end

I filed and rounded end onto the bolt and polished it so it could turn and push against the alloy piston without damaging it.

Front servo preload

A little bit of mathematics showed with the thread pitch of the bolt 5¾ turns were required for 0.3″ of travel. I set the front band against this and reinstalled the servo plug.

Painted gearbox

I reassembled and painted the gearbox.

Engine and transmission

I then cleaned up the flywheel and bolted the gearbox to the engine. I gave the engine an oil change and filled the gearbox with ATF. I started the engine up and engaged Drive and was greeted by the gearbox changing through all gears as the revs were brought up.

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