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Post 37
April 2016

Gearbox Complete

land rover series 3 gearbox components

And final assembly commence. Here are the major components about to be reunited. I’ve included this picture in case anyone wants to see the arrangement at the end of the mainshaft.

land rover series 3 gearbox components

Everything bolted back together. A bit cumbersome wrestling with the heavy lumps, but nothing complicated.

land rover series 3 gearbox components

And Fin.

Gearbox Wrap Up

I’m way behind with the blogging so I have plenty of miles on the gearbox now to give a good report of the end result.

Speedometer drive leak.

The oil seal at the back of the speedometer drive did nothing. The land on the output flange (that the seal runs against) was worn. The flange can easily be removed by just taking off the cover plate for the transmission brake. A speedy sleeve over the flange and problem fixed.

First Drive Gearbox Report

First drive was aborted because the vehicle became jammed in reverse. Bit of a panic but not a major. There’s an issue with the replacement gear levers. The base of the older gear levers has a steel ball shape at the end with an O ring to prevent rattling. The new version (what you get when you buy a replacement) has a smaller end with a large rubber ring. The problem is that the squishy rubber can compress enough for the gear lever to squeeze out of the reverse gear gate when reverse gear is engaged, so the lever ends up outside of the gate mechanism - thus giving the impression you are jammed in reverse, because reverse is still selected while the lever swings around in nothing. The easy fix was to put the old lever back in, which can’t slip through the same gap. So I’ll have to source a better old lever at some stage (mine has been welded back together a couple of times).

First Drive Second Attempt

Taking of up the driveway, 1st and second are very stiff to engage. I replaced the 1st and 2nd gear synchro unit with a new britpart piece. The stiffness went away after a couple hundred km’s and first and second now slot in nicely.

The box was a bit noisy to start with, though I was testing a rebuilt motor and clutch at the same time so it was a bit hard to identify every unusual sound. Anyway, over time everything has settled down into the normal land rover cacophony.

Gearbox Over Time

Going from third to second requires some care to avoid a crunch. This became apparent as I started to drive the vehicle harder, so maybe it’s just me. Less speed and the gear slots in nicely. I don’t know if this is normal or not, but next time I would consider a genuine 1st/2nd synchro.

Third gear pops out on overrun. This is a problem I will have to fix. Under the right combination of circumstances third will pop out while descending hills. For normal road driving this hardly ever occurs. But when driving gravel backroads I use third all the time, on/off the throttle downhill, and this is exactly what causes the gear to pop out. First thing I checked was the easy fix - the nut at the back of the mainshaft. I had to use my crappy homemade special socket tool, and it was very difficult to put 120ft/lbs through without it slipping off. Anyway bruised knuckles and elbows later, I did tighten the nut a bit more (next time I rebuild a box I will buy the correct tool), but this wasn’t the problem. I suspect the springs in the 3rd/4th synchro are the issue. I replaced the synchro unit with a britpart replacement. I still have the old part so I’ll change over the springs or purchase new genuine springs. In any case the box has to come out, so I’ll live with the problem until I have an excuse to pull the box. The internet says the little springs can be changed in situ, so maybe I’ll give that a try.

Parts Wrap

I used Britpart replacement gears pretty much throughout. As per above, in hindsight I would go genuine for the synchro units, or just retain the old pieces unless they are the cause of a problem. Ideally, genuine for everything that runs on the mainshaft and layshaft. But at the time I didn’t know if the gearbox and engine rebuilds were going to be a success, so couldn’t justify a massive investment.

For bearings and oil seals I used good brand aftermarket parts anyway, as the price difference is marginal. Timken for bearings and Corteco for seals. These are good quality parts so I can’t see the point of paying a fortune for something in Land Rover packaging. I wouldn’t touch britpart or bearmach bearings.

Gear Lever

Don’t buy one. All of the replacement levers have the larger rubber bung on the end. Land Rover changed the design but kept the same part number. Try and find a good second hand one with the steel ball design instead. I don’t know when the change occurred.