Stuck on layshaft roller bearing

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Combat_Kid

Combat_Kid

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Hey all,

I’m currently rebuilding a ‘72 gearbox and have gotten stuck. I ordered the AN rebuild kit which includes the roller bearing for the lay shaft. However, I’ve run into a problem. The inner raceway of the roller bearing won’t fit onto my layshaft. I’ve cleaned it with emery cloth but it’s still not even close to fitting. Has anyone else run into this? What’s the best way to approach this? I’m tempted to get into the raceway with my dremel but wanted to run it by you guys before going there.
 
Bearing races are very hard steel and not easily ground. In any case, a bearing is a precision piece that you wouldn't want to hand alter.

First, check with your source to make certain that you have the correct bearing.

That bearing is an interference fit so it should not just slip onto the shaft. It's designed to not turn on the shaft.

If it's right, freeze the shaft in your freezer over night. Heat the inner race with a heat gun or oven (at 400* F). Once the race is hot, get the shaft from the freezer. Drop the bearing race onto the shaft and tap it home with a soft mallet or block of wood. It should fit with a little persuasion.

If your case is intact, you may have to do this with the outer bearing piece as well. Heat the case and freeze the bearing.
 
Thanks
BrianG said:
Bearing races are very hard steel and not easily ground. In any case, a bearing is a precision piece that you wouldn't want to hand alter.

First, check with your source to make certain that you have the correct bearing.

That bearing is an interference fit so it should not just slip onto the shaft. It's designed to not turn on the shaft.

If it's right, freeze the shaft in your freezer over night. Heat the inner race with a heat gun or oven (at 400* F). Once the race is hot, get the shaft from the freezer. Drop the bearing race onto the shaft and tap it home with a soft mallet or block of wood. It should fit with a little persuasion.

If your case is intact, you may have to do this with the outer bearing piece as well. Heat the case and freeze the bearing.
Click to expand...

Thanks, Brian. I would assume the bearing is correct as it came in the full rebuild kit from Andover. I have the Mick Hemmings DVD and while he is using a ball bearing, I figured I would have the same ease of fit. His layshaft just slips right into the inner race. I’ll try the heating method next
 
Brian has it nailed. Heat and cold. Heavy leather gloves. Tap onto shaft , evenly around to prevent crooked.
 
Is there a reason you cannot measure them both (shaft and race) to see what's happening?
Is it possible that the new race is not correct in the first place?
 
Mr. Rick said:
Is there a reason you cannot measure them both (shaft and race) to see what's happening?
Is it possible that the new race is not correct in the first place?
Click to expand...
Caliper is currently in a different state. Trying to get it shipped to me. I can tell you that the roller bearing has the following on the inner race:
NJ203-E-XL-TVP2-C3

Does this jive with bearings others have used?
 
I'm a heat gun fan. So agree with heating the race. I also agree with not using a dremel on the bearing. However! I might polish the end of the shaft and relieve the edge at the end of the shaft with a fine file so that it isn't a sharp angle. A small burr can be a big pain in the ass! See the disclaimer below before proceeding but I would make the end of that shaft shine.

Russ
 
rvich said:
I'm a heat gun fan. So agree with heating the race. I also agree with not using a dremel on the bearing. However! I might polish the end of the shaft and relieve the edge at the end of the shaft with a fine file so that it isn't a sharp angle. A small burr can be a big pain in the ass! See the disclaimer below before proceeding but I would make the end of that shaft shine.

Russ
Click to expand...
Thanks for that. Planning on going for the heat gun technique when I can get back to it.
 
FWIW, Harbor Freight sells a digital caliper for under 20 bucks that works well enough for most garage applications.
 
I recently took apart two gearboxes from 1972 the same day. The first layshaft came out of the ball bearing with a little pulling. The second one pulled the ball bearing out of the case and it was VERY difficult to get the ball bearing off the shaft. Both gearboxes had sat for about 40 years.

To me, the ball bearing must be tight in the case and the layshaft must snuggly slip into it. Not sure how to put a layshaft in with the ball bearing installed - never done it.

Of course, this headache goes away with a roller bearing once it is properly installed.
 
marshg246 said:
Not sure how to put a layshaft in with the ball bearing installed - never done it.
Click to expand...

On gearbox reassembly, the ball bearing (Hemmings ball, preferably) can be fitted to the layshaft first.
With the case heated and sleeve gear in position Edit: but not pressed fully home, the bearing and layshaft are fitted as one, after which, there's usually no reason to remove the layshaft.
 
Last edited:
And prior to trying this, how far should the inner race go on to the layshaft? Should it contact the layshaft fourth gear?
 
If the bearing slips easily into the case, look closely at the thin web between the two bearings. It is often cracked, allowing an easy fit into the case. This minor consideration is not terminal for a street ridden Norton, but I wouldn't use it for a racer. If the fit is not really tight because of this small crack in the web, use a bearing cement like Locktite to secure the outer race and things should be fine.

For measuring bearing fit, I recommend a micrometer rather than a caliper. They are more accurate. You will likely find that the bearing bore spec is the same as the shaft size. This is called a size-on-size fit and it will secure the bearing properly. Also, the heat/cold trick will work great on this type of fit.
 
When you go to do the hot/cold procedure be ready! The hot things cool off quickly and the cold part warm up quicker. So have all your tools and parts at the ready and perhaps make a few practice runs so you have an idea about how this is going to go. You don't want to be off searching for the correct size drift or your bigger hammer at the most inopportune time.(speaking from experience)

If you are going to use the oven to heat up your parts make sure they are perfectly clean or they will stink up the house and make the wife mad.(speaking from experience)
Nowadays if my wife comes into the kitchen and sees me sitting next to the stove wearing an oven mitt and reading the Norton repair manual she just shakes her head and leaves the room. (transmission in the halve shell with a side of roller bearings)
Wrench On
Dave
 
Success! The heating method worked great. It did blue the inner race but it works fine. Now to get that proper shimming done...
 
Getting the inner race to a blue colour probably is excessive and will soften the steel and likely shorten the service life of the bearing. I would not use this inner race!
 
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