Thread: Gearbox rebuild

The gearbox scares me... possibly because it's the only thing I've never pulled apart. Please keep the photos coming.

As for syncro, I'm surprised there are real metal bits there, I thought it worked by magic

Great post Bob

some magic words for installing your casing bearing shells and the like.

loctite 609, 620, 567 (for plugs and through bolts), AND..

prelube the center shaft support bearing with (and infact all the bearings and the reverse gear, the selector forks then dump the remainder into the box) the semi liquid grease for the defender swivel hubs (or any other semi liquid moly/mineral oil based grease)

while the box is apart...

the cover at the top at the back that you can access through the center seat, in the section under it drill about a 5mm hole through to the main body of the case, when it comes time to fill/top up the oil, remove the fill plug, pour the oil in to the small section and let it fill up till the oil comes out the fill plug.

its the rusty plate on the top of this box thats held down by 2 screws.

alternatively, do what that blokes done and put a series IIA selector rod top plate on with the removable breather plate. (well ok he hasnt hes put SIII guts into a late IIA)

I am thinking that Land Rover gearboxes are pretty simple things, I got the assembled mainshaft fitted to the casing then learnt the subtle art of the fitting the layshaft which seems to need an enormous amount of dexterity to drop snugly into its bearing. As I sat contemplating my success I realised I had omitted the bearing retaining compound on both the mainshaft bearing and its retainer. Reading the manual is one thing, doing what it says is another!

Anyway, after some disassembly and reassembly with retaining compound added, I was ready to fit the bell housing. Pity I fitted the other end layshaft bearing before I realised the bearing retainer had to go on first. Oh well, when you have burnt major hours, what's another? I believe the manual also detailed this process and if I had reviewed it during assembly I might have omitted this mistake! Fortunately I own a bearing puller so this stuff up was fixed without effort or resorting to a hammer.

I have also learnt that my lovely partner who can turn out meticulous craftwork is completely cack handed when it comes to helping with mechanics. Like, here dearest, hold this gearbox while I tighten up this weird nut with the bit of pipe I have carefully ground to fit then welded a socket into so I can give it the 100 foot pounds of torque the manual calls for. Doesn't work. No matter how I instructed, she couldn't understand the principal of stopping something rotating. I had to go to plan B, which involved bits of wood plus climbing onto the bench and sitting on said assembly. Sadly plan B didn't work either but before total frustration set in I had a eureka moment and decided that the best way to accomplish this task would be to fit the gearbox to the vehicle first. Does the manual tell you that? If so I missed it.

The gearbox was the easy bit. It was the engine mounts that finally convinced me that this vehicle was designed by an Englishman with unmarried parents. At this stage I was also pondering the sensibility of burning scores of hours repairing an outdated old relic just so I can trundle down the highway playing mobile roadblock whilst enduring a cacophony mechanical noise. The problem here was I got 4 lovely new gearbox/engine mounts and while the gearbox end was a piece of cake, it was the engine end that required contortion, struggle, grit in eyes and swearing to complete. Not to mention hours either. Glad I did it though, the perished slanting old bits of rubber that the vehicle left the factory with were way past their use by date.

It was then time to attack that weird nut again. Sadly my torque wrench only goes up to 80 foot pounds. So I gave it 80 then added a bit which had the effect of lining up the locking tab perfectly. 100 foot pounds is seriously friggin tight for something that I unscrewed by hand! Still, I guess the said Pommy engineer with parents out of wedlock new more about mechanical retainers than me. 100 foot pounds (or thereabouts) it got.

And so it goes, or will hopefully go when I burn another heap of hours getting everything else back together. My dearest is attending a craft fair all weekend. Hopefully she will make a few bucks. Home alone, I am working on Landy, I guess it keeps me off the streets. Fingers crossed, a test drive will happen Monday!

Well, no test drive has happened yet. Reassembly is a lot slower than disassembly. I also decided that I was rushing things just so I could go for a drive. Considering it has been nearly a decade since I last drove this car, I am now thinking another week or so doesn't really matter at all and there is no great hurry. I also figure while it is up on blocks I really should do everything that needs doing.

All that aside, progress has been really good. The gearbox is in, both drive shafts are back on and the hand brake is all working just fine. The gearbox and transfer case are full of oil and leak free so far! The only problem I have had has been when I replaced the clutch master cylinder, the brake line twisted, but today I got some brake pipe, so hopefully my flares will seal and I can bleed the clutch tomorrow.

For those that are reluctant to tackle gearboxes, probably the easiest thing so far has been the actual rebuild. Single handed removal and refit is a lot bigger of a job! With the gearbox on the bench, the manual and a bit of time, this gearbox has been very easy to pull apart and get back together. That said, some whitworth sockets and some quality circlip pliers are required, a decent bench and a bearing puller help a lot and of course an engine crane to get the gearbox out, onto the bench and back in again is pretty much essential.

I miss this stuff....

this is the heady days of being a mechanic...

well done, I hope it all goes as well for you as it sounds it is.

Well done mate post some pictures of the finished master piece!

Well, it got a test drive today, no seat box yet (just in case) but all four gears and reverse function well and it no longer jumps out of second. Funny, after nearly 10 years of not driving it, the first thing I did was try to hold it in second going down my driveway. Old habits die hard it seems and holding it in second is no longer necessary

The hardest part of this whole repair was not the gearbox itself, this can be placed on the bench and contemplated at leisure, it was the removal and refit. The most notable for awkwardness was the (new) engine mounts and refitting the drive shafts. The drive shafts came out easy but on a creeper underneath, refitting them was time consuming, contortion inducing and awkward. The manual says there is a locating peg but mine has offset bolts so they need to be rotated, there is only one position where the bolts will go in.

Anyway, I will get the seat box back in soon and post some pictures on my other thread.