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Gearbox Reassembly

My previous post on this subject outlined what I discovered when opening up the old gearbox. In short, the 1st gear bush was inserted the wrong way around, causing overheating and failure of the bush, and the subsequent horrible gear whine when driving in anything other than first gear! With Covid-19 easing up, I was able to order new bushes, bearings and seals, and could proceed with the tricky task of reassembling the 'box.


Gearbox Parts Arrived

When I disassembled the 'box, I laid all 492 parts out neatly and logically on a dedicated workbench, figuring I'd thus remember how to put it all back together again..... Er, maybe my brain's not the youthful, effective, just plain sterling version it used to be, because it all looked pretty foreign when trying to figure out how to paste it all back together! Thankfully I had the workshop manual and parts catalogue, else I'd still be playing with the giant jigsaw puzzle to this day.


The main gearbox went together fairly successfully. Not having a lathe, I had to "lap" the bushes using water paper to get the right fit and end-float. Despite the old bearings feeling silky smooth, I did replace all bearings with new, as well as all seals (obviously). I tried replacing the notoriously bad selector shaft seals (square, plastic, archaic items) with o-rings, figuring they would provide a snugger fit, and thus keep the gear oil safely ensconced where it should be (which, on a Series Landy, is typically on your driveway or workshop floor!).


New 2nd/3rd Gear Bush Lapped and Ready
Main Shaft and Layshaft Assembled
Selector Shafts & New O-Ring Seals
Main 'Box Finished

The transfer box posed a more complex and taxing exercise... Despite getting the perfect end-float on the high-speed gear, and the perfectly on-spec pre-load on the tapered roller bearings of the output shaft whilst on the bench, when the shaft was inserted into the box (via an extremely complex gymnastics routine, requiring Olympic-level contortion and flexibility, nerves of steel and the patience of Job!), everything went out the window! A total of five such Olympic routines was required before the shaft was perfect (in the end, it was merely a non-cooperative circlip that was the culprit).


Output Shaft of Transfer 'Box

To finish the job off, each and every nut, bolt, plate and clip was zinc plated before being returned to its rightful home. Even though the insides of the transmission brake (a uniquely Land Rover arrangement, whereby the handbrake locks the drive shaft and not the wheels) were destined to be covered in gear oil (from the uniquely Land Rover arrangement of insisting the rear output shaft MUST leak no matter what you do, and in this case, directly into the transmission brake housing...) and covered with a brake drum, I still wanted all the internal parts to be plated, and look like new. The end result was quite pleasing.


Transmission Brake Backplate
Transmission Brake Insides

The final product looked really fine, and even better than a new one would, I imagine. Knowing the insides were all perfect and within spec was also reassuring. Not being able to wait for the engine to be ready before fitting to the vehicle, I went ahead and lowered the gearbox into her final resting place (hopefully that is not a metaphor!). Can't wait to try her out on the road!



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