Saturday, June 11, 2016

Steve Austin: Continued

After a short layoff to watch my oldest niece graduate high school, I'm back and ready to get serious with this gearbox.

Let me know you the completed assembly, then get down to the gritty details...

First up: rebuild the 3/4 synchro assembly.  So I figured I ought to look at the new synchro rings I got in the kit.  The new one is different from the old one... I'm thinking the one from the gearbox is the original part from 1965.

The synchro rings are definitely worn, though.  Here's a shot of the old ring and the new ring.  See the slope on the old ring?  That's just about worn out.


I found a blurb on Mini Mania regarding the synchro rings they sell and how to determine the wear on them... it says that when you fit the ring on the baulk cone (on the gear), there should be a roughly 0.063" gap between the ring and the gear.  Roughly.  The new rings measured out between 0.060" and 0.062", so I think the baulk cones are fine.  The syncho rings are worn out if the gap is less than 0.030".  The old rings measured at about 0.040", so there was life left, but not much.  Not bad for 87,000 miles.

Now, on to rebuilding the 3/4 synchro assembly... and yeah, it sucked.  There are three springs and detent ball bearings that go poing! very easily.  I almost lost two in the garage.  I've read posts that recommend you do all this in a big clear bag, but I couldn't make that work.  What did work for me was to hold the balls in place on the springs and push them in one at a time with a screwdriver while applying downward pressure to the gear.  It's hard because the balls have to fit all the way into the gear before the gear can fit inside the selector.  But with perseverance and a little luck, it turned out okay.

You can see how the assembly works in these photos.  In the first photo, the selector is in the '4' position (would be engaged to 4th gear).  In the second, it's in the '3' position (engaging 3rd gear).


The instructions say to load the assembly onto the third motion shaft, but it's not convenient to do so until later, so I put it (and its new synchro rings) back in its bag.

Next up is 1st gear with its 2nd gear synchro assembly.  It has the following number:

Just think about the person that 50+ years ago etched that into the gear.  I wonder what they'd say now, if they are even still around.

The assembly (with the 2nd gear synchro ring) fits on the back (long end) of the third motion shaft.  Here it is in the '1' and '2' positions.


I got new bearings in the kit from VB, and funny, the third motion shaft bearing is a Moss part!  The bearing isn't the same as the original, and comes with shims to make it fit properly.  In the end, I decided to use the original bearing because it wasn't worn and I wasn't happy with the amount of play in the new bearing.  I'm going to see if I can return it.  But I took pictures anyhow for the curious.  Moss does a nice job with instructions here.


The next job is to install the bearing in the plate that holds the shaft in the gearbox.  For this, I used Big Hammer and Large Socket.  Always install things by applying force to the part that is in contact with the mating surface.  In this case, it is the outer bearing race, so a big socket to apply even pressure is required.  I gently tapped the bearing in until the circlip was flush against the plate.  Be very careful that the bearing is fully installed and level with the plate.  I tested by spinning the assembly to verify it didn't wobble.  I didn't have to hit the socket very hard to drift the bearing in, so if it doesn't go, there's a problem.

Next is to install the bearing/plate assembly to the third motion shaft. For this, I needed a long pipe so I could apply pressure to the inner bearing race (which is touching the shaft).  I found that the handle of my 3 ton Sears jack was a perfect fit.

Then, install the spacer shaft, speedo drive gear, shim, locktab and nut, and voila!  The third motion shaft is fully assembled.  I put the 3/4 synchro assembly in place for the picture.


On to the first motion shaft... same drill with Big Hammer and Jack the Handle.


It's time to assemble stuff into the case.  This is where I found that the Haynes instructions didn't work.  The instructions say to install the reverse gear, then the laygear (sort of), then the first motion shaft, then the third motion shaft.  No.

The problem is threefold:
  1. The reverse gear gets in the way of 1st gear when you try to install the third motion shaft, if the reverse gear is installed with its shaft.
  2. The laygear (being held in place with a long socket extension) also gets in the way of 1st gear.
  3. The 3/4 synchro assembly can't get past the laygear if it's held in place with the socket extension.
After a bit of trial and error, I worked out a better way.
  1. I installed the laygear, but left it in place without anything holding it in aside from some assembly lube on the thrust washers.  (By the way, I ended up using my original front thrust washer and the .128" rear thrust washer to get a clearance of 0.003", which is to spec.  So I'll be returning two washers, saving me $20.)
  2. I installed reverse gear, but not on its shaft (just left it sort of in its place in the case).  You have to do this now because you can't fit reverse gear past 1st gear otherwise.  I found this out by not installing reverse gear and having to take the third motion shaft back out.
  3. I installed the first motion shaft by drifting the bearing into the case (again, Big Hammer and Large Socket) and actually, all the way through the case.  You can't install it from the bellhousing side because 4th gear doesn't fit through the opening.  But once I drifted the bearing through, I tapped it back a bit, installed the circlip, and tapped it home.  (That circlip was a real pain.  I modified a ring spreader so I could install it.)  It fit pretty easily, so again, if it's not going in, there's a problem.
  4. I put the 3/4 synchro assembly in place on the first motion shaft.  It doesn't really have anything to hold on to, but the synchro ring works just well enough to hold it in place.  I did this because you can't get the 3/4 synchro assembly past the laygear when it's installed on the third motion shaft.  DON'T FORGET TO INSTALL THE 4TH GEAR SYNCHRO RING AND THIRD MOTION SHAFT ROLLER BEARING.  I almost did that.  That would have been bad.
  5. I installed the third motion shaft, fitting the shaft into the 3/4 synchro assembly, until the bearing plate just contacted the case.  The plate has to be put in position just right so the remote control housing will fit... more on this later.
  6. I installed the reverse gear onto its shaft, lining the shaft up with the hole for the locator pin, and installed the pin.
  7. I installed the laygear shaft, which took a little fiddling but the long socket extension helped line everything up.  The laygear shaft has a specific rotation position relative to the case, shown in the photo below.
  8. I then lined up the rear bearing plate and tapped it in place by the procedure below.
Here's some pictures.  The pictures don't exactly match the instructions above, because I took them the first time I tried this.  But the instructions above do work.



Installing the bearing plate is a bit tricky.  The Haynes instructions just say "install it".  When I took it apart, I marked the position of the locating pin.  Theoretically, it should go back in that spot and fit properly.  In this case, theory and practice don't line up.  The only way to know it's exactly right is to install the remote control housing.  So I worked out this procedure:
  1. Line the pin up with the mark and tap the plate "mostly" into position, about halfway. If you didn't mark it, take a guess based on the remote control housing.
  2. Fit the remote control housing and gently tap on it to rotate the plate, until the bolt holes line up with the case.
  3. Remove the remote control housing and tap the plate the rest of the way into place, making sure it's completely seated.
  4. Fit the remote control housing again to verify.
With this method, you don't even need the mark.  But it helps.  You can barely see the difference between the mark and where the pin ended up.  It's slight but critical.  The result is perfection.


The result...

Next time on our regularly scheduled program... installing the selector forks, selectors, and buttoning everything up.

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