1968 gearbox needs help

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Onder said:
Fear is a strong motivator.
Click to expand...

Odd.
Less than an inch above that crack is a much bigger hole in the shell, no one seems to worry about.
I have seen a fix where the bearing recess was opened up and the bearing was replaced with a blind bronze bushing.
That was on gearboxes used in Wasp sidecars. They really got a beating..
I said it before and I'll say it again:
If you want your gearbox to last, get rid of that heavy clutch..
 
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illf8ed said:
Check this ad on eBay
Item number 362870787852

Now going back the other way as this case could indeed be original. Will see what others say.
Click to expand...

Have a look at the font used at the engine. Why would g/b stamping be significantly different? We had a similar discussion recently re. frame number stamping of a P11 frame. The conclusion was that it was bogus / not genuine. In this eBay ad, the g/b shell looks to be new or at least younger than the crankcase, and the top lug looks as if it has been ground. Stamping isn't quite where I'd expect it to be.

However, there are many reasons why mechanical parts need to be replaced. Personally, I couldn't bother less, unless a time capsule of a bike was what I was aiming for. This would require the genuine frame to be present as well.

-Knut
 
How loose does the bearing get if the housing is cracked? Does it worsen as time goes on or does it just stay the same?
Does the bearing eventually spin in the gear case? Does the bearing loose alignment?
One of the problems with a bush is the machine work needed to set it up, ie, align bore it and with the bush on the kicker
side. Not everyone has a tool room at their disposal or even a lathe. Replacing balls and rollers and needles is with it the
average riders skill set.
Like me.
 
If you look at it from another view the reason the shell cracks is because of the catastrophic failure of the layshaft bearing
Not because the shell just cracked for no reason
And welding it could warp the case out of shape making matters worse
Fast Eddie said:
You’re obviously braver than me Ludwig. If I did that, here’s how it would end ...

View attachment 15491
Click to expand...
I seized a geabox only once and I'd never want to repeat the experience and that was on a Yamaha yr5
I'd just passed my test so it was the first bike bigger than a 250 that I'd owned and I thought it was the fastest thing on the planet!!!
A local mate of a mate had a jock Kerr big bore honda k4
He wanted to race me, so I thought I'd better try the yam out on my local test track IE dual carriageway!!
Redlining through the box until I was doing just over an indicated 90mph the back wheel locked solid
I dumped the clutch and was stamping on the gear lever whilst all the cars I'd been overtaking were now overtaking me but on my inside!!!
Finally at about 40mph the gearbox broke free and the wheel started turning I was now frantically trying to find a gap in the traffic so I could coast to the side of the road
Adventualy I managed to get across and stopped on the side of the road just sitting on the bike to reflect about what had just happened for a few minutes
Sorry to the original poster I seem to have gone off track!!!
 
illf8ed said:
Dave and Ron,

Since replying I’ve found a few examples of the “1” exactly as stamped on this ‘68 case. Machivmotors on eBay for example has ‘68 crankcase and gearbox case. My other two Commandos also are ground at the top where the number is stamped. My ‘69 has the same stamped “1” you said was not used.
Check this ad on eBay
Item number 362870787852

Now going back the other way as this case could indeed be original. Will see what others say.
Click to expand...
ebay trans noted below

1968 gearbox needs help
 
baz said:
If you look at it from another view the reason the shell cracks is because of the catastrophic failure of the layshaft bearing
Not because the shell just cracked for no reason
And welding it could warp the case out of shape making matters worse

I seized a geabox only once and I'd never want to repeat the experience and that was on a Yamaha yr5
I'd just passed my test so it was the first bike bigger than a 250 that I'd owned and I thought it was the fastest thing on the planet!!!
A local mate of a mate had a jock Kerr big bore honda k4
He wanted to race me, so I thought I'd better try the yam out on my local test track IE dual carriageway!!
Redlining through the box until I was doing just over an indicated 90mph the back wheel locked solid
I dumped the clutch and was stamping on the gear lever whilst all the cars I'd been overtaking were now overtaking me but on my inside!!!
Finally at about 40mph the gearbox broke free and the wheel started turning I was now frantically trying to find a gap in the traffic so I could coast to the side of the road
Adventualy I managed to get across and stopped on the side of the road just sitting on the bike to reflect about what had just happened for a few minutes
Sorry to the original poster I seem to have gone off track!!!
Click to expand...
When you welded, was there any special jig used? My concern is warpage. I had a crankcase crack welded then the two halves didn’t fit any longer.
 
illf8ed said:
When you welded, was there any special jig used? My concern is warpage. I had a crankcase crack welded then the two halves didn’t fit any longer.
Click to expand...

Numbers? Yes there are several styles of numeral punches. Why might have norton production moved to require a second set of punches with differenct gearbox from engine numbers. Atlas gearboxes are numbered @ different case location. Unless the production of atlas AND commando at the same time caused this work location seperation? By 127xxx the different style went away. now all the same...1 and "3" with a flat top...not curved

I had some cases welded but they were screaming hot from preheat at weld time. So it all shrinks down together as it cools. Al the welder has retired:(
I now have in my garage a Tenny industrial oven good to around 500 f for preheat and a miller syncrowave 300.
I have several gearboxes that need some welding including one with a bearing blow out just like Daves.
I think a machined brass plug in the bearing hole would help.
 
dynodave said:
Numbers? Yes there are several styles of numeral punches. Why might have norton production moved to require a second set of punches with differenct gearbox from engine numbers. Atlas gearboxes are numbered @ different case location. Unless the production of atlas AND commando at the same time caused this work location seperation? By 127xxx the different style went away. now all the same...1 and "3" with a flat top...not curved

I had some cases welded but they were screaming hot from preheat at weld time. So it all shrinks down together as it cools. Al the welder has retired:(
I now have in my garage a Tenny industrial oven good to around 500 f for preheat and a miller syncrowave 300.
I have several gearboxes that need some welding including one with a bearing blow out just like Daves.
I think a machined brass plug in the bearing hole would help.
Click to expand...
Don’t know, but could be Norton had more than one set of number punches and they weren’t the same. Pure conjecture unless we resurrect some line worker or foreman. Comparing the numbers on my ‘69 to this ‘68, the characters are the same and stamped in the same place.
 
illf8ed said:
When you welded, was there any special jig used? My concern is warpage. I had a crankcase crack welded then the two halves didn’t fit any longer.
Click to expand...
No no jigs were used the only thing that was special was welding it up looking over my shoulder for the foreman who happened to hate me !!
 
mdt-son said:
Have a look at the font used at the engine. Why would g/b stamping be significantly different? We had a similar discussion recently re. frame number stamping of a P11 frame. The conclusion was that it was bogus / not genuine. In this eBay ad, the g/b shell looks to be new or at least younger than the crankcase, and the top lug looks as if it has been ground. Stamping isn't quite where I'd expect it to be.


However, there are many reasons why mechanical parts need to be replaced. Personally, I couldn't bother less, unless a time capsule of a bike was what I was aiming for. This would require the genuine frame to be present as well.

-Knut
Click to expand...

If a machine instead of a human were stamping numbers at this time I might agree regarding uniformity and position. Might be interesting to find the assembler could be identified by his set of punches.
 
illf8ed said:
If a machine instead of a human were stamping numbers at this time I might agree regarding uniformity and position. Might be interesting to find the assembler could be identified by his set of punches.
Click to expand...
I'd suspect an apprentice may have had the job of stamping these numbers
Either way the neatness is influenced by many factors
Could be Monday morning
Maybe a hangover
Could be a Friday
Could have had a row with the misses that morning (the numbers would be stamped deeper)
There used to be an old saying about the fabled BSA RRT2 gear box
If the letters were stamped all over the place it was usually found to be genuine
If the letters were stamped evenly and straight it was likely to be a fake !!
 
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