gearbox guru required please

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flibity

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hi peeps, im putting my gearbox back together and ive found my new bearings to be a wee bit loose. ive got some shim stock hanging around and was wondering if anyone else has had good results with it in this situation. cheers, john
 
Which bearings are we talking about? If the bore holes are loose enough for shim stock, the cases are toast!

Cheers Richard
 
just the larger bearing in the case, and its not much, havnt measured it yet but its probably less than a thou. just enough to let the bearing fall out when the box is cold.
 
Loctite® Bearing Retaining Compound should do the trick. Some have even used JB weld. I would not smear JB all around but maybe 6 point around the clock.
 
Check the little bit of alloy between the main shaft and layshaft bearing seats on the case for a crack. That is one typical area where they fail.

If there is a crack there consider welding the bearing seats and case and then remachine.
 
So many shells are cracked between the two drive side bores.
THere is a thread on the board that illustrates way of securing
bearings with a countersunk allen. Doubt that rewelding and
boring will help for very long. This is a design flaw with this
box. Perhaps if you secure the bearings when the box is
new it will keep the box intact. I rather doubt it.
 
Jim Comstock and me and everyone else that's tried Locktite on ANY bearing race in engine or tranny failed to hold - so you and the others posting could be the first.
There are literally 1000's of Cdo AMC gear box shells in piles of alloy scrap in shops around the world with wallowed out bores. Damhik. You are stuck with trying JBW and not get it in the race track or buying another. Cdo AMC shells have a notch cut on the drive side of bolt mount a thick spacer washer goes, that costs over $250 for this very special feature so expect to pay $400-500 for Cdo shell -or- like me pay only $250 for identical Atlas shell -that thank goodness- lacks the super expensive hassle prone notch feature, so Atlas shells slip right in and out of cradle like they were made for it forever more. I have yet to hear of any success repaired the bores or the crack in the AMC gb "tain't". I've 5 gb shells on hand, 3 of them are loosey goosey to try JBW or sell with the beer cans.
 
Quick check : new shell from Andover 400 bucks plus PP from the other side.
Its new though not used.
 
[urlhttp://www.accessnorton.com/gearbox-crack-t6787.html][/url]
My cure is a bit over the top, there are easier ways.
 
This is a tough one,you're already damned if you don't. My Mk 111 has a roller bearing replacement where the original was. The machinist I paid to do this conversion overbored the case and pressed in a sleeve that created an interference fit for this new bearing. It has not let loose for the 8000 or so miles I drove before switching to Crazy Combat life. Locktite is false insurance ,you need metal to metal and the bearing must be centralized as well ,so a new box is good advice. The important bearing seeing as it is apart is the roller layshaft. You are about to spend coin my friend.
 
As I mentioned previously, look back at older threads for
the one where the bearing is held by a recessed washer and
an allen. If you do this before the case is hammered you
may avoid this for some time.
I put in the roller on the layshaft drive side but would
just go for a ball if I did it again. Probably easier and
the ball will do fine anyway. The roller is overkill.
 
He- he heee. Ain't the internet fun. At least I'm here to laugh after my gearbox siezed up with cars screeching to a stop blowing horns up my tail back when. Roller.
 
For what it is worth, I had the misfortune of a failed Portuguese layshaft bearing on my race Commando. The failure caused the case to crack between the bearing bosses and through to the outside.

After welding and a quality remachine of the bearing bores I continued to abuse the gearbox on the track for a few seasons without incident.

Weigh out the costs of a replacement shell and compare it to the weld and remachine option. If this is a street application then it should have a relatively easy service duty.
 
Consider the expertise and finesse to line bore welded up cases and likely hood of it working out first time around. Who covers the repair then? If this is a fairly reproducable method then there's plenty of need for its economy and preserving shells. The steel sleeve was a neat idea I didn't know if enough meat to get away with. Enough that jigs and special tooling might be self supporting? I've 3 shells out right now, one with big bearing size hole though its thin hide and the other two needing a tightening up.
 
thanks for all the answers guys, . ive used it in other positions before with prefectly satisfactory results. but really all i wanted to know was if anyone has actually used the shim stock in this actual position before, and how effective was it. cheers
 
as much as i value comnoz expertise , i HAVE used loctite (green) to repair a cracked box , on condition that the bearing has only spun and not wobeled in the cases
make sure your case is CLEAN and put your bearing in the case , then put some drops on the groove made by the bearing and case so it can drain in (put some on the bearing as well )
this will not work if your housing is no longer round but oval

ps to clean i wash (srcub) with methanol and then put in a hot place (consevatery or behind rear window of car , in the sun ) with the bearingside (closed end ) up so any drip can fall out ; heat the case and look what comes out ,then do it again
i i have done it and do not know of that bearing coming loose again ,the bike is still running around
 
Methanol is an amazing cleaner of impregnated oils , so is M.E.K.,no smoking,outdoors best.Try not to breathe too.
 
Hi,
Mick Hemmings in UK is a Norton Gearbox wiz kid (he's quite old really).
He has made a Norton Gearbox Strip & Rebuild DVD for the Norton Owners Club.
Its available through the NOC website for shipping anywhere in the world.
Our branch in UK has one for branch members to borrow.
If the problem you have is not on the DVD I am sure mick would give advice to you to fix it.
I dont think he does e.mail but you can phone him or write to him.
His address is 72 Overstone Road, Northampton, NN1 3JS, UK
Tel: +44 1604 638505 Fax: +44 1604 631838.
Mick & his wife Angela are really nice helpful people & sell lots of commando spares worldwide.
Best of luck, Don
 
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