A full 24 hours later than planned, I got some more gearbox work done this evening.
I stripped it a bit further and started with the valve block and found, in the process, the output speed sensor behind the block.
This view shows the Kostal connector that links the valve block to the ECU and the wire that goes to the output speed sensor.
I had a reason for removing the valve block. I pondered if it was possible to get at the oil filter from behind it to enable it to be removed with the 'box in situ
. Althouh you can see it, and even undo the 10mm renatining bolt, sadly it can't be wriggled out due to the length of the pickup tube
Shame really as it might otherwise have been possible to swap the filter without removing and splitting the gearbox. Oh well, it was worth a go...
I then disassembled one of the clutch-packs (a brake actually). Brakes are often bands in many autoboxes but the 4HP20 does not use brake bands at all.
Followed by the 1st sun gear shaft and hub
And then I was defeated by this nut...
That was as far as I could go. To get that nut off will need a special tool. It hides one clutch pack and it is not vital to go there yet (hopefully).
I then began the reassembly of the 'box as I also wanted to practice that and clear space in the workshop for the 'box still currently on the car.
I have lots of photos of the reassembly and I'll post them in a full reassembly guide on my website in due course.
This photo shows a very essential special tool in action to enable the diff to be replaced without damaging the oil seals. Because they work in reverse to a normal manual gearbox driveshaft seal, damage to them will be inevitable if this tool is not used. This tool is in the kit very kindly loaned to me by DickieG. Thanks Richard!
I discovered two very imprtant things in reassembly. Reassembly IS NOT
a straight reversal of my initial disassembly method and secondly, to just replace the filter and check the oil pump, all that is needed is to split the gearbox without any disassembly of the epicyclics and clutches being needed at all...
The reason the reassembly is not a straight reversal is that the first sun gear and hub (the one in the photo above) is retained on the main shaft via a "C" clip and if the shaft and front clutch assembly is inserted lastly, the "C" clip will not engage and the sun gear will be out of place and fret against the oil pump.
It was only during reassembly it dawned on me a lot of the disassembly I did was strictly unnecessary but interesting and useful none the less. It really shows the value of practicing the job before doing it for real.
Fially, I popped the torque convertor on and held it in place with another special tool from the set. This tool prevents the TC from dropping off during removal and replacement on the car.
With the TC in place I could see how deeply in the bellhousing it sat and allowed me to gauge if a removal of the 'box from the car without removing the engine was possible. Looking at it and looking at the flange on the car (after removing the inspection plate on the lower half of the bellhousing), I reckon it is, just, if the pressure regulator is removed and maybe the hydractive sphere block moved. To succeed, the 'box will need to clear the flange (flywheel - surprisingly thin) and then move forward about and inch and a half and then rotate downwards and forwards to enable the diff to clear the edge of the subframe. It'll be tight but worth a go. It only needs to move sideways about half an inch to clear the flange.
I've never seen such a tiny starter motor as is on the V6
I've seen bigger windscreen washer motors
It fits in a funny way too...
Hopefully more progress tomorrow...