Gearbox Teardown with plenty of pictures

Perhaps you can begin the grinding process (should you choose to go that way) with the bush out of the gear, then put it in?

It's a frustrating fiddly process, DAMHIK. Best of luck.

Yes this is the only gearbox bushing that needs reaming to size. I replaced mine a few years back and stupidly tried to open up the diameter with abrasive wrapped around a shaft. I did get it to fit nicely in one place but with a taper at each end! It should be done properly with an adjustable reamer to 0.6885/0.6875". Since then I bought a new gear which comes with the bush sized and was badly needed anyway. Best of luck....

I was thinking of putting gears in an oven, thuse relatievely easy to modulate temperature. I don't think 3-500 degrees is going to have any affect on hardening. I think it's not until you get hot enough to turn the metal a colors, such as red that you are in trouble. Am I right?

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I don't think you will run into trouble in the oven, but for the record, the annealing process starts with ANY color change. It doesn't have to be cherry red. When tempering blades (knives, chisels, etc) I don't let them go past "straw" as blue or purple is too soft. If these colors don't make much sense, look at the headers on your bike!

I would keep it below 400 degrees F.

Russ

No reason to go above 250-300 degrees F. 250 didn't quite work for me, but 275 did.

We used to run some parts through a temper oven for 2.5 hours anywhere from 300-450 degrees and hardness would go down 5-10 rockwell.

As the gearbox just needs a short time I don't think the parts would be affected. The parts conduct so fast a few min is prob all it needs to get up to temp and expand

Keith1069 said:

Yes this is the only gearbox bushing that needs reaming to size. I replaced mine a few years back and stupidly tried to open up the diameter with abrasive wrapped around a shaft. I did get it to fit nicely in one place but with a taper at each end! It should be done properly with an adjustable reamer to 0.6885/0.6875". Since then I bought a new gear which comes with the bush sized and was badly needed anyway. Best of luck....

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So reaming it is.

I dropped the gear off to get reamed. I'll have it back Wednesday but won't get a chance to assemble this for a bit. I also left the kickstart shaft and it's blind bushing. I tried heating it up and icing the bushing to no avail. Hopefully it comes out easily.

In the meantime I tried to get as much done as I could.




Getting the first bearing in.

Huge question, I hope someone has the answer:

Which way does this bearing go in? It's the infamous layshaft bearing and this is obviously the roller bearing replacement.


And the sleeve gear bearing. This was easier.


And the last question is does this look like the right position?

Dave....I've been enjoying watching your progress with your gearbox. Soon I'll be replacing the layshaft bearing in mine, but the teardown won't be as extensive as yours, as I'll be keeping the gearbox on the bike. Did you ever find out where you got the gearbox overhaul kit from? Norvil has a couple of kits, was it one of theirs?

on the roller layshaft brg.fit the outer in the case and the inner race flange faces 4th gear and goes on the shaft with 4th and 3rd gears. 4th gear has a smooth side, it faces 3rd gear. you will fit the layshaft assm. after 4th sleeve gear.
it does appear as you gave the the quadrant timed correct

bill said:

on the roller layshaft brg.fit the outer in the case and the inner race flange faces 4th gear and goes on the shaft with 4th and 3rd gears. 4th gear has a smooth side, it faces 3rd gear. you will fit the layshaft assm. after 4th sleeve gear.
it does appear as you gave the the quadrant timed correct

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Thank you!

singring said:

Dave....I've been enjoying watching your progress with your gearbox. Soon I'll be replacing the layshaft bearing in mine, but the teardown won't be as extensive as yours, as I'll be keeping the gearbox on the bike. Did you ever find out where you got the gearbox overhaul kit from? Norvil has a couple of kits, was it one of theirs?

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It might actually be easier to pull the box out, depending if you are yanking bearings. Don't be intimated, it's not that big a deal. There aren't that many parts and it's just a matter of putting them back in the right order. :mrgreen:

Apparently a Fair Spares kit perhaps from Waldrige. Hope that helps.

Got the parts back from the shop. For anyone local it's Schnell Automotive on Lombard. My rule of thumb for finding a good shop is if it's been around forever and if full of history. They've been around for almost 60 years! Bad shops don't tend to stick around as long. This one always has hot rods and race cars. Also a good sign.

I had them hone a Bultaco barrel a while ago and I know they aren't afraid of the old stuff. Reaming is perfect. And the got the old bushing out too. I check the new bushing for the kickstart shaft and it looks like it won't need reamed. I might get a chance to put it in Sunday nite, if I'm lucky. The just the layshaft bearing and then it's all ready to assemble.

Well, except the shifting stuff on the outside of the inner cover is missing. So that will have to wait...

Dave, I have some extra used stuff here, If you need anything just let me know and for the price of shipping it's yours, Chuck.

Hortons Norton said:

Dave, I have some extra used stuff here, If you need anything just let me know and for the price of shipping it's yours, Chuck.

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I actually drove past Long Beach a few minutes ago. In fact I'll be back by tomorrow. Down here on work. Lovely weather ya'll having. :shock:

LOL LOL HA HA, Yea this wet stuff is kinda strange around here. Chuck. :mrgreen:

Like I said, more work on Sunday nite.


I believe this is the third and forth on the layshaft.


So, here's what not to do. I slipped this spacer on the sleeve gear thinking is would distance it from the bearing. I don't know why I did this and I even thought it wasn't right but I still did it. Kind of like some women I've picked up at bars... but I digress.

So I assemble the gearbox and for some reason I can get it to shift into fourth. Well, it kinda does but the camplate is not quite all the way to the detent. I take it apart, recheck the camplate location. I do this several times before finally taking this "spacer" out. Then it works perfectly. Sigh. If you don't know this is the spacer which allows the seal to work.


And this is where it's suppose to go...


Layshaft bearing and sleeve gear installed.


Third gear lay and layshaft installed.


Third gear main and selector fork. Old Britts mentions that it helps to shift to third to get the selector fork into the camplate. They are right. :mrgreen:


First gear lay. Second gear lay with selector is behind it.

<Picture missing>
All in there. Shifted just fine through the gears. From my hazy past I recall that Triumph boxes like to be in neutral for assembly. I left this one in neutral too. What gear should it be in to finish the assembly?


New kickstart shaft bearing in place. Fits perfectly over the layshaft.

I'm missing the nuts for the inner cover so layshaft end play will have to wait.

So that's it for the gearbox for now. Back to the cradle and drill another hole if I want one of the adjusters to face forward. I haven't decide if I should drill the extra hole, someone mentioned with a belt drive you'll set it once and most likely never touch it again. And that it's not impossible to adjust, just takes a few more swear words. Of which I have plenty...

swooshdave said:

From my hazy past I recall that Triumph boxes like to be in neutral for assembly. I left this one in neutral too. What gear should it be in to finish the assembly?

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You can leave it in neutral, it doesn't matter, unlike Triumph boxes which need their quadrants timed to the camplate before the inner cover is pushed fully home (don't forget to fit the knuckle roller to the quadrant before you fit the cover!).

with the roller bearing on the lay shaft you will want to check tho end play at the kick start shaft or you could have trouble with it jumping out of first gear. I like to keep it between .010 - .025

bill said:

with the roller bearing on the lay shaft you will want to check tho end play at the kick start shaft or you could have trouble with it jumping out of first gear. I like to keep it between .010 - .025

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Good point since it will be excessive - I just completed mine and it was about .030 .035 of end play. I was able to use one of my old iso shims as Old Britts suggested to space it out correctly. I had to open the center up a bit with a drum sander to slip over the kick start shaft but it worked great.

BTW - thanks for documenting the process it has been very helpful!

Any shimming will need to wait until I can get the inner cover nuts. Actual amount of shimming will probably vary by box as there have to be a bit of variation.

I'm going to shoot for .005, let's see what the first measurement is.