Need Help Assembling Gearbox

jaydee75 · Jul 24, 2012

Somehow I got all my gears in one box and now I don't know which gear goes where. All the instructions I found just refer to them as 1st gear lay, 3rd gear mainshaft, etc.
Can someone give me a chart showing how many teeth are on each gear so I can sort them out?
Thanks,
JD75

L.A.B. · Jul 24, 2012

http://www.oldbritts.com/gearbox_info.html
http://www.oldbritts.com/gearbox_a.html

jaydee75 · Jul 24, 2012

Perfect! Thanks so much. Now back to work.
JD75

drones76 · Jul 24, 2012

jaydee75 said:
Perfect! Thanks so much. Now back to work.
JD75

Digital cameras are a wonderful thing. I use my camera phone to document as I disassemble so I have a reference. Of course, for the gearbox, the Old Britts site is great.

DogT · Jul 24, 2012

Here you go, it's easy.

Good luck.

Dave
69S

AntrimMan · Jul 25, 2012

is it possible that the OB written description has the words main and lay inverted? Check the tooth count.
All the best.

L.A.B. · Jul 25, 2012

AntrimMan said:
is it possible that the OB written description has the words main and lay inverted? Check the tooth count.

Yes it does, well spotted.

Also, the factory manual lists layshaft 4th as: "14t" when it is 18t.

http://britmoto.com/manuals/Manuals/750_man.pdf

Correction

Late Commando 2nd gear pair are 18/23 not 19/24

jaydee75 · Jul 25, 2012

I'm sorry guys, but this is really confusing. Not only does Old Britts page have the main and lays backwards, I also have different tooth counts on several of my gears.
Here is a picture of what I have laid out. Do I have them in proper order and labelled right?
Thanks,
JD75

AntrimMan · Jul 25, 2012

yes, the tooth count is correct for main and for lay.
I imagine the main sleeve (4th main)is still in the bearing inside the case.
All the best

drones76 · Jul 25, 2012

I remember going through the same issues when I did mine, including the number of teeth. It took two nights until it made sense. Swooshdave has a good thread and lots of pics of his gearbox rebuild.

This pic is when i disassembled mine. I wired them in the correct order and orientation as they would go back on the shafts. See if this helps.

I do remember going through the OB site and making sure that the gears meshed and released as they said they should when going through the gear progression.

It was one of the most satisfying things I worked on when it all came together.

AntrimMan · Jul 25, 2012

I can show photos of the assembled shafts mated together later tonight (in about 2 hours) if someone else doesn't in the meantime.
The photo's are back at the ranch, per se.
All the best.

L.A.B. · Jul 25, 2012

Yes, some book/manual info appears to be wrong!

Late model 850 2nd gear is 18/23 not 19/24.

kevbo82 · Jul 25, 2012

I'm also doing my gearbox right now, and have zero experience with it. When i took it apart i laid all the pieces out in exact order like an exploded view, and i will only move/clean one piece at a time and put it back in place before moving another lol. I see old school mechanics take hundreds of bolts and throw them in a pile, i need to bag and tag every little bit and make sure. time is money they say, i say taking my time saves me money!

Hobot · Jul 25, 2012

IIRC only two of the cogs of 1st or 2nd confused me on which side to face inward on shafts. Other cogs go in one obvious way. Drawn diagrams are just at edge of resolution to make sense which way the trick cogs face, the first time around.

dougmatson · Jul 25, 2012

I just did mine last week so here are some pic's of mine
Lay shaft

main shaft minus sleeve gear still in case

case with both shafts

inner case with shims for layshaft

all three units of tranny

AntrimMan · Jul 25, 2012

Doug has some good shots above and as I mentioned previously here are some with the shafts complete and mated together...

before you assemble and button it up I suggest you give a real good look over the gear tooth contact areas to evaluate the wear.
Also be confident the bushings are in good shape too.
All the best.

ellaeaton · Jul 27, 2012

Yes, Fred had the number of teeth on those gears switched in his article. It's been that way since 2004, so nice catch - it's been fixed.

jaydee75 · Jul 28, 2012

Doug, those are great pictures. Where did you get that hex nut on the clutch operating rod cam holder? I like that.
JD75

lbridges · Jul 28, 2012

jaydee75 said:
Doug, those are great pictures. Where did you get that hex nut on the clutch operating rod cam holder? I like that.

Pretty sure reading somewhere that Doug is running a hydraulic clutch. The pic on CNW's website explains some of the look, but not the hex shape.

dougmatson · Jul 28, 2012

Hydraulic clutch slave from CNW, works great too.

Need Help Assembling Gearbox

jaydee75

L.A.B.

Moderator

jaydee75

drones76

DogT

AntrimMan

L.A.B.

Moderator

jaydee75

AntrimMan

drones76

AntrimMan

L.A.B.

Moderator

kevbo82

Hobot

dougmatson

AntrimMan

ellaeaton

jaydee75

lbridges

dougmatson

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