Layshaft bearing failure (2014)

Still undecided on the bearing I will use. I'd like to use one of the ball bearings from Mick Hemmings but I haven't ruled out the roller.
I haven't heard of a failure with either one. Definitely won't cheap-out here.

Maybe I can finish dismantling the box tonight and see how bad the damage. Hopefully the inner race is still attached so I can remove the bearing
otherwise I'll have to locate a blind puller.

This is sobering reminder just how quickly things can go bad with these bearings. The transmission was working flawlessly giving no indication of a problem right up to the breakdown. I'm not surprised if riders have been hurt/killed with this type of failure.

My Norty's rear locked up at 40 mph. with cars honking up my derriere so yes it can be life threatening. Had to push it over another lane to shoulder with more honkings. Bike developed an intermittent tic-sound with kicklever moving on it's own. So any similar symptoms are your warning to baby bike to a stop or a pullover to park. I opted for roller fix , many miles on it now. :|

Hi

I recently decided to have the gearbox bearings checked as I didn't know the history of the bike. You know the feeling when you are out riding and a little voice in the back of your head is saying you really should get that bearing checked. As it was being stripped down we knew something was not right when the bearings came out relatively easily. We ended up with a couple of chipped gears and a crack in the shell in the usual place. I'm using a new gearbox shell from Andover Norton and replacing the damaged gears.

It looks like the bearing had previously blown and damaged the gears and cracked the case. The previous owner just replaced the one bearing and put it back together.

At least I'll now have peace of mind !

I dismantled the rest of the gearbox tonight and everything was looking good, all the gears came out looking great with no damage and snug bushes.
I spotted e a few bits of bearing cage in the bottom sump of the box. When I pulled out on the layshaft the inner bearing race pulled out of the bearing and all the balls and the chewed-up bearing cage fell into the sump. It looked pretty grim but I consider myself lucky. The only dilemma now is pulling out the outer race from the shell. I suspect I'll need some sort of blind bearing puller. I've been cleaning out the shell with lots of WD40 in a pump spray bottle letting it drain out the drain hole into a pan. Wiping everything down along the way. I'll follow this up with a magnet, vacuum, compressed air. I've ordered the Superblend bearing and gasket kit from Old Britts.
Should be fun.

Anyway, here's some pictures for your enjoyment:

Being a late model it might have stacked bushes in the sleeve gear, some have two bushes with a space in between and the outer bush can move inwards.

MSc

I have seen the bearing come out with a couple of seal picks or scribes pushed in when the case has been heated it drops out easy.
You won't be touching the sleeve gear will you!
Happy days

That's true. The unloaded bearing race might pop out easily with some heat on the case.
No, wasn't planning on touching the sleeve gear. I did notice when I spin it by hand it feels sluggish, some drag.
I've got the drive chain removed so I was thinking I was feeling the oil seal resistance, or some interaction with the clutch basket (still attached).
Maybe someone can suggest a theory on this.

I never had any luck getting the outer shell from mine with heat, even though I had the GB completely out and heated it in a gas grill. I ended up making a blind puller with heat too, but I seem to be the exception. I didn't have any problems with the crank mains. I used the Hemmings bearing and it's been fine.

Well my first attempt at removing the outer bearing race failed.
I heated the GB shell to around 225-250 and tried various home brew methods of pulling it out but it wouldn't budge.
I'm going to pick up a slide hammer blind bearing puller tomorrow at Harbor Freight and give that a try.

Try getting it really hot ,use heavy leather gloves and knock the box on a chunk of softwood. Drop an icecube into the bearing outer-race to shrink it too. Hot and cold.

That space is a little confined to work in but careful placement of a few MiG spot welds will shrink the race enough that they fall out.

I made a puller out of some real long #10 machine screws with hex heads, piece of thick al plate and some wood blocks. You have to grind down the hex part to get it in behind the race and also get them in there as they won't go in together. If I could find it I'd take a picture, it's around here somewhere. I'd be surprised if the store will have one that fits. I still had to heat it.

Hi MSh
Please hurry with your bearing puller.

Torontonian said:

Try getting it really hot ,use heavy leather gloves and knock the box on a chunk of softwood. Drop an icecube into the bearing outer-race to shrink it too. Hot and cold.

Click to expand...

Sounds like some weird sexual practice.

Time Warp said:

That space is a little confined to work in but careful placement of a few MiG spot welds will shrink the race enough that they fall out.

Click to expand...

Yes effective but a tad agricultural.

DogT said:

I made a puller out of some real long #10 machine screws with hex heads, piece of thick al plate and some wood blocks. You have to grind down the hex part to get it in behind the race and also get them in there as they won't go in together. If I could find it I'd take a picture, it's around here somewhere. I'd be surprised if the store will have one that fits. I still had to heat it.

Click to expand...

Pure doc Brown from back to the future.

You gotta love this forum.

The outer race seats flush with the bearing pocket so getting any puller behind it is doubtful.
I've picked-up a blind bearing puller from Harbor Freight which uses a slide hammer and various diameter attachments.
I'm pretty sure this puller will allow me to pull from the inside bearing raceway. I'll heat the GB shell with the puller attached to the
outer race which should act like a heat sink for the steel race keeping it slightly cooler. That's my theory anyway.
I really want to avoid any prying on the GB shell that might damage it. It looks quite thin at the lay shaft bearing pocket.
I may need to cut a groove slightly deeper into the raceway with my Dremel.
I'll report my results later tonight. Wish me luck.

http://www.harborfreight.com/blind-hole ... 95987.html

mschmitz57 said:

I'll heat the GB shell with the puller attached to the
outer race which should act like a heat sink for the steel race keeping it slightly cooler. That's my theory anyway.

Click to expand...

Try some of this http://www.alliedelec.com/search/produc ... fgodWiQAKA just as you get ready to bump the slide hammer. With the aluminum case warm, the sudden chill to the race should assist in gaining some extra clearance.

Thanks a lot for starting this stupid thread! I'm now officially going to lose sleep, wondering when my 74's going to grenade on me!

Nathan

MSh

Toronto is on the mark got to get heat into it and it will fall out easy.

auldblue said:

Time Warp said:

That space is a little confined to work in but careful placement of a few MiG spot welds will shrink the race enough that they fall out.

Click to expand...

Yes effective but a tad agricultural.

Click to expand...

Far from it if you know what you are doing, the weld deposit shrinks and the outer race will fall out with no loss of metal (interference) to the bearing bore.

Success!
The Harbor Freight bearing puller worked like magic.
The puller has 4 different size expanding puller attachments that thread on to the slide hammer. It's really designed to pull from inside
the inner race but the tool fits into the raceway perfectly. I had to use the largest attachment (1.25") to fit properly inside the outer bearing raceway but it snugged-up nicely. I left the puller attachment in the outer race as I heated the GB shell which helped cool the race via thermal conduction. I used an infrared thermometer to monitor the shell temp. When the temp reached 175-185F I figured I'd give it a try.
I was gentle with it and after a few light taps with the slide weight I could see the race moving outwards with each tap.
It popped out after around 6-8 light taps. I'm a happy camper!

So like I said, the puller was pulling from the bearing raceway, not from behind the race. The race was flush with the shell.
I got this puller kit at HF for around $60 (with a 20% off coupon) but I see similar pullers on eBay for around $45.
I'm sure I'll use it again for wheel bearings instead of using a hammer and drift like some stone age mongrel.

I have to say I wish I'd checked this last winter when I have the bike on the lift.
If you suspect you might have an original Portugal bearing in your GB and you've never opened-up a transmission I suggest you do it.
It's very straightforward. Old Britt's has an excellent technical web page dedicated to dismantling / reassembling the AMC box (this is why you should buy your Norton parts from them ). I also have a INOA transmission service video that I bought ages ago which came in very handy.
The AMC box is dead simple. It's not hard work, actually pretty satisfying in a mechanical sense. I've never been inside any of my gear boxes before so this has been interesting. If your bearing is still intact it makes it so much easier to remove. I was very fortunate to have this fail in front of my house at 20mph. It gave me no warning before this happened.

Here are some pics for your enjoyment:

That puller may work if it will get behind the race. I got the head of my screws behind it so there must be a bit of distance there. I found it. It's a bit of rube goldberg of course and it was a real pain to get the screw heads lined up.



I had 2 GB that I had to use it on. I just couldn't' get the heat to work unless I was afraid of too much heat. I used a gas grill and the crank case shells fell right out but not the GB.

Way to go. That looks easier than what I did, but HF is about 80 miles from me and it wasn't much of an option.