Gearbox Assessment - What Did I Discover?

AntrimMan - good observation on bolt slot clearance. MIne was so self augured out I'd missed that aspect to know. Will do it on the new kick shaft next time around.

Heat will soften JBW as well as expand the case, but JBW still remains gooey so bearing may need help by extra hard slamming down or a way to grab it.
I'm tending to the low melt alloys that would just flow away like wax but stay solid as can be until melt point reached.

Pegging the bearing may not center it and may crush the roller clearance some.
Its the last resort for me if the below don't recover an expensive gear box shell.

A partial list of melt temps and alloys
http://csalloys.com/Specifications.htm

Here is the latest. I took some dimensions of the bearing and the bearing bores using a telescopic gauge.

Here is the main shaft bearing.



Here is the main shaft bearing bore. Looks like a just a snug fit.




Here is the lay shaft bearing.



And the lay shaft bearing bore. Is this still in JB Weld range of fixing?




I took an average of three measurements and the result is the difference shown in the photos above. All the bores look nice and clean with no hairline fractures. I think I should be good to go unless somebody with more knowledge throws in a penalty flag for thinking this way.

What is a good dimension difference between bearing and bore for a nice snug fit?

You are doing a good job there. I used the Permatex 64000 bearing retainer, but after reading comnoz, I would most likely do the JB weld thing. My layshaft was tight, but my LS main bearing was apparently spinning in the GB, but not to a large degree because I only saw slight marks and it came out with the shaft when I pulled it out. So I only used the bearing/shaft retainer on the mainshaft bearing and on the mainshaft bushings, but I also only used 2 original size bushings. I should have used 3 like some have suggested and grooved them. My outer mainshaft bushing was eaten up by the circlip about 1/8", and looked pretty rough. I think the pics are in my 'Phoenix' thread.

Dave
69S

I'd say you need JBW in the layshaft bore as Al case bore will only expand more than the steel bearing from road heat. May be tricky to get right amount of JBW in there and not moosh into the bearing. JBW does not chemically bond so will need some texturing of surfaces to get it to bind well as the case expands. It can take over 24 hr for it to set up enough to trust. May have to wait for it to set up a bit not to just drool into a puddle. It does creep for hours unless restrained some how by physical barrier or magnetic flux. Or have the thing machined for set screws.
Or just run it as is and see if your fate turns out better than piles and piles of ruined shells.

I think if it was mine I would use a very light layer of JB weld in the bore before you push the bearing in. Will not likely give any trouble. Jim

Gosh you real mechanics make it sound so simple. People like me though run into such issues that even when bore's too big, it still takes good heat and frooze bearing to get it started in bore. Hot heat will make the JBW both flow more yet set up faster. One man's sense of thin is another's over dose spill over excess back it out clean it up to try it again - thinness : (

I think acetone might dissolve JBW, but will verify by look up or testing before hand. I'll careful apply thin grease on rollers, knowing what I know about my fumbles with JBW and need to actually do this bodge. Oil alone may prevent drips adhering but not so sure it'd keep a drip hardening as steel filled object in race.

JBW has a standard time set 500'F mix and a ~300'F Kwik set mix.
http://jbweld.net/products/index.php
Original is a lot stronger but may scare the un-experienced in the over frying pan hot temps to release it. I don't mess around with a mere torch on shell and cases no more [unless just a mere rust fused and bent fastener] no sir Its so worth it to get a pancake head tank top LPG space heater and get the whole darn thing swelling before the steel in a bearing can get hot and drop right out with the JBW goo too. While hot a super magnet may pull left overs out the nicks.

Hobot — now I'm concerned. While I can accept that JB Weld could be better than Loctite Bearing Retainer for holding bearings in place in worn bores, it does worry me that one would have to get the casing that hot to remove them.