Jeff Shaw Gearbox build

[MiniDave]

I decided to start a new thread on this because it's turning out to have some "challenges" 

I'm pretty much out of the Mini engine/gearbox rebuilding game, but I still don't mind doing one occasionally for a friend, that's how I wound up with this one - the owner intended to do it himself, but then his job changed and they moved him to Connecticut for a year, maybe more - the only hope he has of getting his car back on the road was if I took on the gearbox repairs.

He bought this car about a year ago and has never been able to drive it - it simply would not go into 1st or 2nd gear. Once I got it over to my shop I could see why, both first and second were pretty torn up, and to top it off once I got it taken apart I found the internal shift linkage bound up for the 1/2 engagement.

He ordered a bunch of parts in advance and once I got it apart I gave him a list of small bits plus the cross pin diff, even tho it's rocking a stock 998. In for a penny, right?

I also found a ton of sludge in the bottom of the case, along with lots of tiny bits of gear teeth. I've never seen this much sludge in the bottom of a Mini case before, the owner's dad said the car came from Louisiana making him wonder if it might have been a flood car - hence the complete repaint and new interior. Just speculation tho....

So I got it all apart and today I'm starting to re-assemble. First in was the internal shift linkage - the operating bits that sit on the central pin were rusted to the center support - at least the 1/2 one. I probably managed to knock 3/4 and reverse loose when I locked it into 2 gears to get the nuts off either end of the mainshaft - the ones torqued to 150 ftlbs. Everything got cleaned and polished and moves smoothly now.

Next - he sent a new 1/2 shift fork which is made somewhat differently than the old one, I put it in and don't see where there will be any interference - at least I hope not cause I will have to remove everything to get it back out! I laid the old mainshaft/gear assembly in and it all looks like it will clear.

Then I disassembled the main shaft, and ran into the first real challenge. Like a Sprite the gears are locked onto the mainshaft with some pins engaged into a special washer. They usually require 3-4 hands to get them out and back in place, but I've developed a few tricks to get it done by myself. However......the gear I'm trying to reinstall seems smaller inside than a Sprite - where I could insert the pins after the gear is in place on a Sprite, there just isn't enough room to do that on this gear.

Going to require some thought.....

 

[MiniDave]

Work continues, next step is to assemble the mainshaft - I have a new 2nd and first gears to install, 2nd and 3rd have those same pins the Sprite gearboxes use, however the Mini 2nd gear is smaller in diameter than the Sprite so it was impossible to locate them in the holes in the shaft. So, what to do?

I decided the only way was to slide the gear up, put the pins in, squeeze them in till the gear would slide down past them, leaving them in place. To do that I used some SS safety wire around them, as I tightened the wire it pushed the pins in, then after the gear slid down into place ALL I had to do was cut the wire and remove it - which proved to be yet another "challenge". I managed to get it cut and they popped out. Next I had to push them both in again so that the retaining plate would go down over them - that took about another hour of fiddling till I finally won that battle too. The problem arises because the pins both push against a fairly stiff spring in the center, if you manage to get one in, the other pops out.

Third gear was much easier as it only has one pin, it snapped right into place. With the hard part done it was just a matter of putting all the pieces back where they needed to go, then drop it down into the case. Next was the laygear - as you can see in the pic, the old shaft was just starting to gall and the small bearing had failed. Putting it in is a bit of  fiddle too as you have to maneuver the center oil pickup down into place as you roll the laygear into its location, making sure the thrust bearings don't move. a couple extra hands would have helped with all of these tasks!

Once that's all in place install the two main bearings, put the snap ring in the first motion shaft end, and the big nut and lock washer on the pinion bearing end (don't forget the pinion gear!)

[MiniDave]

The cover plate bolts go thru the case and into the oil pickup pipe flange, I'm not sure the lockplates are absolutely necessary but I always put them in and bend the tabs over.

On the pinion gear end there is a small plate that fits in slots on both the reverse gear shaft and the laygear shaft and is held in place by one of the bolts in the pinion gear bearing retaining plate. The trick here is that the bearing retainer plate has a shim, the shim has to go first, and the locking plate goes in over it, then the bearing retainer plate bolts in - I've seen many a shim bent because people did it wrong. Then more lock tabs need to be bent once the bolts are torqued.

Everything turns freely and smoothly, so ....result!

[MiniDave]

Next I decided to build up the cross pin diff, but first you have to disassemble the entire diff assembly, including pulling the large bearings off each short shaft that the pot joints attach to.

I was disappointed to see that the cross pin housing came with the cross shafts already assembled into it, which meant I had to take it all apart - that's no big, except if the shafts are tight in the bores as there's very little to get ahold of to get them out. The main cross shaft had been driven into place and there were burrs on the ends of the shaft which I had to dress, along with the edges of the bores that shaft went thru, that added quite a bit of time using 1000 grit paper to polish it all to fit.

Once done it all went together smoothly and turned freely......I got as far as installing the crown wheel tonight, and called it. This car has a 3:44 ratio, which I think is perfect for a 998 motored car. More as it happens.