'Fast-forward' to January this year (2022), when I finally had some clear time at home to get working again, and got the Carawagon's overdrive built back up.
I'd managed to get all the new parts needed for the overdrive ordered before heading down south, so these were on hand to get cracking:
Not everything for Fairey overdrives is listed on the regular Land-Rover parts websites, but most parts can be found elsewhere without too much effort. These units are fully metric and use mostly generic bearing sizes, etc. - all still manufactured today. I may well post a list of the suppliers I used in the relevant section on this forum.
I've invested in a small blast cabinet recently - the overdrive top cover served as something of a test piece. It's a very satisfying process:
The main casing received similar treatment, with gentler glass beads rather than aluminium oxide. Not absolutely spotless, but pretty close:
The coupling sleeve was the first component to go back together, with a new bearing:
As everything had been sat out on the bench for nine months, I made sure to thoroughly clean and degrease all parts for reuse, to clear any accumulated dust etc.:
New bearing and circlip fitted to the input gear:
The original synchromesh hub was retained, with just the detents replaced. This can be a troublesome process, so the job was done inside a small box, to limit the possibility of steel balls being launched across the garage. On this occasion, it all went together first time, with no issues:
New output gear shaft bearing and seal fitted to the front of the casing:
Replacement mainshaft bearings in place. There's a thrust bearing pack below the lower radial bearing:
Output gear shaft positioned over the mainshaft. The end of the mainshaft is supported by a steel cylinder of slightly smaller diameter, allowing both components to sit in their service positions. My choice of garage ale should be familiar to those who 'inspected' the local pub during the 2018 Christmas Do in Herefordshire:
Laygear with its bearings and shims roughly in place. The layshaft itself cannot be inserted until the output gear shaft is in position, so a socket extender bar is here used to keep everything roughly located:
With the synchromesh hub held roughly in position inside (until it engages with the mainshaft splines), the casing can be brought into position over the output gear shaft (with the first synchromesh cone in place) and mainshaft. The two metal supports keep all components in their approximate service positions; they are not properly connected at this point:
The laygear can now be brought into mesh with the rear output gear, and the layshaft tapped in. This has to be done with care so as to avoid damage to the layshaft thrust bearings or shims - it can take a few attempts to get everything lined up:
Radial and thrust bearings being built up behind the synchromesh hub - these sit inside the input gear. The second synchromesh cone should also be fitted at this point:
Input gear and bearing in place. As stated in the disassembly post, the bearing isn't a press fit, so should slide in fairly easily. For reasons unknown, however, I always find it rather reluctant to line up. Got there in the end, though:
The original mainshaft shims were a bit battered, so I measured their combined thickness at intact points and found equivalent replacements - easy enough, with them being metric. The required thickness here was 0.35 mm, though this does vary between units:
Once the shims are in place on the mainshaft, the final thrust bearing pack can be positioned, leaving just the two circlips to fit to the mainshaft (there is a second, thicker circlip under the spacer visible here). All the internals are finally held together once this is done:
The rear cover is now back in place (with a new o-ring). All that remains to fit before replacing the top cover is the selector mechanism: fork, shaft, detents and dust cover:
One complete main Fairey overdrive unit. Isn't it pretty?:
The only extra thing I'll do to this is fit a more substantial breather - I find the standard 'hole with split-pin' affair allows the unit to spit oil once warmed up on a decent run. I've stored a small tub of the correct 'Rocol' anti-scuff paste with the overdrive, to be applied to the mainshaft splines before fitting. It's crucial to use the right stuff there, as the splines and coupling sleeve teeth wear incredibly quickly otherwise.
That brings this thread essentially up to date with Carawagon progress. I'm aiming to have plenty more to write about over the coming weeks and months, though - it's about time.
Phil