me too, and wood has several advantages, including cheapness, ease of work, and quite importantly, it wont ever damage a metal part, like shims.
It will not rust with age
Erica knows what she is doing and has excellent guidance for this job too
(maybe she has selected an alloy rod ?)
@Erica_Moss maybe you can go into rebuilding Moss gearboxes as a sideline?, finding someone you could trust to rebuild one must be getting harder and harder
I’ll probably use wood. I did scope out both rod and tube at our biggest local metal supplier and the sales person thought they’d all be pretty true to 1". I asked the machine shop that surfaced my flywheel how much to turn an aluminum one down to .98 and he said 60 bucks, on top of the 10 to buy it, and all the fuel, and time. So I think wood is my friend here. If I had a bin full of old jag spindles I’d just cut one down.
I do have a full spare JS Moss box and will end up with two of everything after mine is finished so I might build that one box, depending how mine turns out. It’s only a business opportunity for people with Bill’s skills and tools. The few remaining parts are all used at this point and require refurbishment to make usable again. I can’t really do that. I’m not sure what people with XKs and 3.8s are going to do when they’re no longer very serviceable.
I think we have pretty much reached reached that point: had I kept my car, I most definitely would not have bothered to fix the Miss, but to replace it with some flavor of five speed.
I spoke to a guy in Victoria, Australia probably about 30 years ago
I cant recall his name but he called himself something like “Old gearbox rebuilding” and he specialised a bit in Moss gearboxes, and he had made 1st gears, synchros and other parts.
He would not sell any parts, you had to send your GB to him for rebuild
At that time, some classic racing of these vehicles was still being done out here
I sensed he was an older man than me, quite reserved, so it improbable he would still be doing it
If anyone would have heard of him, it would be @angelw ?
I agree with Paul that 5 speeds will go in
I have a few Moss boxes ranging from MKVII to MIX.
I dont intend to throw them away unless I have to
I will offer them for sale whole, and if unwanted, I may take them apart and sell the pieces individually, which can be worth much more.
That is one way old Moss GB can be kept going, having some used parts available
I have thrown away many old gearboxes, including Jaguar boxes, only to later find out certain parts are absolutely unobtainable, the only possible source is good used parts
When I was hurriedly cleaning up my shop to move out of it in 2001, I threw away about 11 tons of various stuff.
I shan’t bore you with a listing of all that was in that tonnage, but in and amongst it, were at least four Moss gearboxes.
Oh well.
Had a busy day redoing half of my progress. I had to remove the layshaft to replace the dummy shaft with a .98" oak dowel as Bill suggested. Good call I think as I found a couple needles dislodged despite being as careful as I had been. The length of the shaft is 8". This is the orientation of the part stack. The flat side of the small inner rings sit against the landings in the center of the gear. These plus the next outward rings retain the needles.
The left bronze one is of course the configurable spacer available in several thicknesses. It, plus the needles are the only parts available new here. Allowable gap is .002-.004. Mine is .002.
Next it’s time to start assembling the synchro sleeves. I’m starting with the 3rd/4th as I’m still trying to workout what to do about the somewhat worn 1st gear stop. These are the parts. 1 shim on each spring gave me 58 pounds of separation force.
It is critical to follow the manual closely on this assembly. The inner synchro sleeve has two center hubs, a tall hub, and a short hub. The tall one must face forward towards 4th gear. The outer operating sleeve has two chamfered edges, large and small. The large chamfer also faces forward towards 4th gear.
The shallow shaved teeth on the operating sleeve line up with the through holes for the plungers. The manual is confusing because it talks about the two shallow teeth matching with the opposing plunger holes, but it fails to mention that one of those teeth is on top/front, and the second is on the bottom/rear of the part. They look like this.
Assembling these is intimidating but pretty simple with a little care. Definitely use a bag because the balls are going to want to sproingggg. I did the whole operation in a plastic bag, with a large hose clamp to compress the balls. NOTE here: tall center hub and large chamfered edge. This is the front of the assembly
Even with the clamp it’s not going to just pop together, but it’s stable and you can stick the whole thing, including bag in a bench vice with a large socket in the center, and it will push the clamp off and snap it all together easily.
Now test the release force using a bathroom scale. Use a thin block in the center so it can separate when you push, but just far enough to test it, without the whole thing coming apart again. I got 60 pounds pushing very slowly, but only 56 pushing fast. But it’s also totally dry. With some lubrication I think it will be perfect.
Now insert two balls and plungers in the inner sleeve and install on the main shaft. The shallow tooth on the front of the sleeve, pictured above, must line up with this forward horizontal divot on the main shaft.
Test quickly to ensure that with the synchro sleeve slid rearward against 3rd gear, that the gear can no longer spin. This means the synchro is able to positively engage against the cone. In operation the outer gear would continue traveling rearward, partially separating from the inner sleeve, and would smoothly engage with the small keystone shaped teeth on the gear. The larger helical teeth of course engage with the layshaft cluster.
Before assembling the springs and balls on the sleeves, it’s a good idea to simply slip the two sleeves together and slide them both onto the shaft. Push against 3rd gear, and try sliding the outer sleeve rearward to engage with the teeth in all possible orientations and ensure that the two parts slip together smoothly no matter their relative position.
They might have a bad burr or chip that causes the parts to be less than smooth when coming together. You may need to hunt for new parts or experiment with a tiny fie. Both 3rd gear and its mating sleeve here are replacements, as is 2nd gear.
A very well-written description: methinks you should do a version of The Moss Moss Book!"
Thank you for the plastic bag idea. That can be used elsewhere also. I can’t say how many times a small bit went somewhere hard to find. Next time a small bit jumps when a plastic bag is in play, I’ll say your name in thanks.
I did exactly the same, no problem with a wood dummy shaft, it doesn’t even have to be exact diameter, mine was slightly loose & worked perfectly.
Very imortant to get that 60lb throw over pressure right. Mine were only 40 lb with poor synchro. After adjusting with spacers (washers) below the springs the synchro action is now very good, especially 2nd gear which is always the weaker one due to the heavier gear.
Yes I’m figuring I might have to double up a few shims on the 2nd when I do it. I purchased a nice used one and noticed upon dissemby that it had double shims in several of the holes from the factory. I wish the manual offered some advice on dry versus lubricated because that might very well change the value. I hesitated to introduce that though out of fear of picking up contamination.
Hi Erica, I would just clean out the holes & springs thoroughly & assemble with lube. It’ll give a false throw over value if it’s dry.
I’ve been hung up trying to work out a plan to replace the stop rivet on the 1st gear inner sleeve. I have a few of these and the best of them with the nicest 2nd gear synchro hub is also missing its stop rivet. The others are also worn. I think the reason these tend to fail is because the rivet is slightly domed so as the outer sleeve bumps it, it is able to start working its way deeper into the thin edge until it eventually passes right over it and then the box is hobbled. I have no idea how they managed to install these rivets. There is a mere 1/4" gap for a tool to fit behind the rivet. I’m guessing they carved up a rivet squeeze tool so it had the thinnest possible anvil. Given the cost of these tools I’m not keen on buying one let alone grinding it up. The rivet fits in this 3/16 hole, has a head less than 1/16" tall, and has a .22 head diameter.
I’m considering two options, tapping the hole to #12-28, and filing the head diameter of this screw down to .22, then cutting the length down, installing with red Loctite, and finally milling the head down to the correct height. The downside is it could back out. It doesn’t even have to back out all the way. If it even came out a little bit, the outer gear would hit it and it would prevent it from going into first. Also, I’m dubious that it will be very easy to tap threads into this very hard steel.
Alternatively, start with a plain 3/16 steel rivet, mark the exact spot on the shank where it comes out of the back of the part, and chuck it up and cut a slot for a snap clip. Also turn the head down to .22 diameter. Then cut it to length right behind the clip. The downside is that it will be more than a bit tricky to machine the groove so that the head is perfectly flush with the part, and it must be or again it will cause a collision with the outer gear. Even if the clip placement is perfect, repeated bashing from shifting might loosen it a bit, and this would again cause a gear collision.
The only other possibility is a 3/16" pop rivet, but I’m not super hopeful about its lifespan, given that it is softer, and hollow, and domed. It seems like it would even wear worse than the original part did.
Any opinions from the machining crowd?
None that I think you’re interested in.
Hello Erica,
The most viable method from your choices is the Threaded component. However, tapping the hole will be tough, as the parts are Case Hardened. I’ve not tested it, but the bore for the pin will probably be hard. It’s unlikely that area will have been masked to prevent case hardening (I do this when having Reverse Idler Gear Shafts for the all synchro gearbox, in the area of the lock, woodruff key), so to either drill, or tap it will be difficult. If you need to drill the hole to a tapping size, I suggest buying a solid carbide drill bit of the correct size. Even with a soft bore, the case at the start and finish of the hole will make it hard on the tap. Solid Carbide Taps are also available, but if you use HSS, buy a few and don’t let the tap get blunt; you may use a couple just to get through the case on the outside. Alternate between Taper, Intermediate and Bottoming Taps to get through the case at the Start and again at the Exit when you reach it.
I have a rugged, scissor device I’ve made with a slipper that fits inside the grooved area and then actuated by a press, but it’s of no use to you in Australia.
Regards,
Bill
You might want to ask a machine shop what they would advise. I would be concerned that I would break a tap and then have a very difficult time extracting it
Dennis
Thanks Bill, I do suspect the hole bore is hardened. It was certainly machined before hardening and it is a very precise 3/16 hole, with no deformation from all the rivet banging. I also can’t imagine why they would have cared about masking it. From the tapping chart I looked at, 12-28 should tap right into a 3/16" hole, but as Dennis says, I’m a bit stuffed if it breaks in there.
Can I ask why you prefer that over the rivet/clip idea? I was actually starting to lean that way in the last couple hours. I’d have hire a machinist to make them, as I don’t own a lathe. The shop that did my flywheel seemed very competent. I was thinking that due to the curvature of the sleeve, if they manage to cut the groove fairly precisely, it should place a flat clip under some spring tension and keep the rivet head pinned against the sleeve. A few drops of epoxy to ensure it never moves.
I had a feeling you probably had a proper tool made for this! I wonder how much round trip post would be 
Erica. You may be able to get an answer on the xk forum. I seem to remember that Rob Reilly has written a bit about moss rebuilds and I think the installation of stop rivets was discussed. Memory is a bit fuzzy but worth an inquiry.
Hello Erica,
I’d be worried about the clip letting go and going through the gears.
If you were to use a threaded pin, I would use a larger diameter so that the case hardening in the bore can be drilled out. Tapping will cope with the case hardening at the start and end of the bore, but not for the whole length of the bore.
With a bit of careful measurement, you can deform the end inside the groove by applying pressure to the outside end and is the way I used to do it.
Make a pin that is the right length to make contact with a pointed mandrel placed in the groove, before the pin is fully home. A ball bearing instead of the point works well.
In the making of the pin, form a shallow cup in the end face of the pin.
Permanent assembly relies on the cupped end being upset by the point, or ball bearing of the short mandrel by the time the pin is driven home.
Make the pin an Interference Fit in the bore. Freeze the pin in Acetone cooled with Dry Ice, or use Liquid Nitrogen and warm the 1st gear sleeve until its uncomfortable to handle with bare hands.
Be prepared and work quickly.
Regards,
Bill
Just to be sure we aren’t separated by a common language, are you speaking about the fillister head machine screw I showed above or are you speaking of a drive pin that has course threading on it?
So you’re suggesting after cutting to proper length, mount it so the end is up and drill into the end to create a hollow cone which would then be spread out by a ball propped up under it while inserting? I may be able to accomplish this feat. This it some delicate machining.
Last night I was contemplating just leaving the screw a bit long and adding a thin nyloc nut inside. With enough torque and red Loctite it would never loosen, but it’s a lot of extra weight. I’d probably have to drill on the opposing side to balance it.
