Cracked gearbox shell fix idea

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I contacted Quaife today, but they sell ALL Norton parts to Mick Hemmings! Will call Mick to see what he thinks.

Interestingly, I went to see Tony Smith today (the quite famous ex-Commando racer) to get his qualified opinion on the condition of my gearbox internals, and a few other Norton topics (how cool is that, to have such knowledge to call on? Lovely guy too). And when I mentioned the cracked case he said "Yes... I've heard of that... Never had a cracked case myself though"

This is a guy who raced them 10/10ths in the day... and he never suffered a cracked case! What the hell are we doing wrong then?
 
Fast Eddie said:
I contacted Quaife today, but they sell ALL Norton parts to Mick Hemmings! Will call Mick to see what he thinks.

Interestingly, I went to see Tony Smith today (the quite famous ex-Commando racer) to get his qualified opinion on the condition of my gearbox internals, and a few other Norton topics (how cool is that, to have such knowledge to call on? Lovely guy too). And when I mentioned the cracked case he said "Yes... I've heard of that... Never had a cracked case myself though"

This is a guy who raced them 10/10ths in the day... and he never suffered a cracked case! What the hell are we doing wrong then?
Click to expand...
Those cracks (in the taint area) are caused by the design. 12K miles on my cracked case ( plus some portion of 12K miles before that) I'll let ya know if it's a problem.
 
Fast Eddie said:
This is a guy who raced them 10/10ths in the day... and he never suffered a cracked case! What the hell are we doing wrong then?
Click to expand...

My 850 has a crack,the 750 doesn't.
I would put it down to the poor machining generally on British bikes of the period,it could be as simple as not being able to hold tolerance on the interference fit of the cases bearing bores.
The amount of case material between the two bearings (0.060" - + ) defies any form of logic so even a 'thou could be the difference between cracking and not.
 
My 850 had a fine crack in this area too. The new bearings have been inserted with loctite. No problems since. But there haven't been any problems before.
 
Fast Eddie said:
Interestingly, I went to see Tony Smith today <snip>
And when I mentioned the cracked case he said "Yes... I've heard of that... Never had a cracked case myself though"

This is a guy who raced them 10/10ths in the day... and he never suffered a cracked case! What the hell are we doing wrong then?
Click to expand...

Comparing regular road use with someone who runs maybe 1000 miles each season, who swaps g/b shells every season, who runs superblend bearings and possibly a belt drive, is like comparing apples and peaches. You may do the same and you will probably see your g/b shell last .... or maybe not, depending on the torque output of your motor. In their racing days, the Commando suffered transmission breakdowns quite often. Replacing the standard g/b was a necessity on the high-performance bikes.
 
mdt-son said:
Fast Eddie said:
Interestingly, I went to see Tony Smith today <snip>
And when I mentioned the cracked case he said "Yes... I've heard of that... Never had a cracked case myself though"

This is a guy who raced them 10/10ths in the day... and he never suffered a cracked case! What the hell are we doing wrong then?
Click to expand...

Comparing regular road use with someone who runs maybe 1000 miles each season, who swaps g/b shells every season, who runs superblend bearings and possibly a belt drive, is like comparing apples and peaches. You may do the same and you will probably see your g/b shell last .... or maybe not, depending on the torque output of your motor. In their racing days, the Commando suffered transmission breakdowns quite often. Replacing the standard g/b was a necessity on the high-performance bikes.
Click to expand...

Tony raced in the '70s, no belt drives and I doubt a new gearbox shell every season, but 1000 miles as season certainly tops.....and regular checks of teh internals....but he would have had a high primary ratio on some bikes, though running as production he maybe should have had an alternator fitted on some of the bikes which may have limited that approach.

I suggest we reverse the question though, ask yourself what Tony was doing right? I actually never thought of him as a ten tenths rider, why? because he won races by being fast and smooth. I suspect he gave the gearbox an easier time than most...certainly his style and experience meant he was rarely in the wrong gear....a style unlike the very fast Bob Smith who won several races most weekends in the season, and went home to rebuild a gearbox after most of them.....

I built a box in late '75, raced it till the end of '79 and never took the end cover off, the trick there was it was a 4 speed and the ball bearing in place of the bush in the end of a kickstart shaft......which gives better layshaft location...like a Manx box

Replacing the standard gearbox as you note was actually the downfall, as most people used 5 speeds and they weren't (and with a high horsepower motor still aren't) up to it......enter TTi....with bigger shafts and double sleeve gear bearings...and much thicker shells...oh, and wider spacing on the lay and mainshaft...

Mick Hemmings makes a nice gearbox, but I wouldn't personally recommend you use it hard with 750cc and above full house race motors!
 
SteveA said:
mdt-son said:
Fast Eddie said:
Interestingly, I went to see Tony Smith today <snip>
And when I mentioned the cracked case he said "Yes... I've heard of that... Never had a cracked case myself though"

This is a guy who raced them 10/10ths in the day... and he never suffered a cracked case! What the hell are we doing wrong then?
Click to expand...

Comparing regular road use with someone who runs maybe 1000 miles each season, who swaps g/b shells every season, who runs superblend bearings and possibly a belt drive, is like comparing apples and peaches. You may do the same and you will probably see your g/b shell last .... or maybe not, depending on the torque output of your motor. In their racing days, the Commando suffered transmission breakdowns quite often. Replacing the standard g/b was a necessity on the high-performance bikes.
Click to expand...

Tony raced in the '70s, no belt drives and I doubt a new gearbox shell every season, but 1000 miles as season certainly tops.....and regular checks of teh internals....but he would have had a high primary ratio on some bikes, though running as production he maybe should have had an alternator fitted on some of the bikes which may have limited that approach.

I suggest we reverse the question though, ask yourself what Tony was doing right? I actually never thought of him as a ten tenths rider, why? because he won races by being fast and smooth. I suspect he gave the gearbox an easier time than most...certainly his style and experience meant he was rarely in the wrong gear....a style unlike the very fast Bob Smith who won several races most weekends in the season, and went home to rebuild a gearbox after most of them.....

I built a box in late '75, raced it till the end of '79 and never took the end cover off, the trick there was it was a 4 speed and the ball bearing in place of the bush in the end of a kickstart shaft......which gives better layshaft location...like a Manx box

Replacing the standard gearbox as you note was actually the downfall, as most people used 5 speeds and they weren't (and with a high horsepower motor still aren't) up to it......enter TTi....with bigger shafts and double sleeve gear bearings...and much thicker shells...oh, and wider spacing on the lay and mainshaft...

Mick Hemmings makes a nice gearbox, but I wouldn't personally recommend you use it hard with 750cc and above full house race motors!
Click to expand...

I gladly accept the correction Steve, I think Tony was a smooth rider, still is!

I too have generally been blessed with reliable gearboxes compared to my 'opponents' which I partly put down to being mindful of the cost and work involved in fixing a broken box, and this 'teaching' me to be more sympathetic!
Think I'll be sticking with the 4 speed box. I took my disassembled box to Tony for his wise opinion on its condition, and will be using it, albeit installed in a strengthened shell.
 
Would that be the Quaife that is on their site at £255? I recall you mentioned these are sold thru a dealer, not direct from Quaife. A bit strange that they do not sell direct but advertise the items on their own site with a price.

Glen
 
worntorn said:
Would that be the Quaife that is on their site at £255? I recall you mentioned these are sold thru a dealer, not direct from Quaife. A bit strange that they do not sell direct but advertise the items on their own site with a price.

Glen
Click to expand...

Yes that's the one I intend to us Glen, and yes, strange as it seems, Quaife were very clear that they sell all of their Norton parts to, and only to, Mick Hemmings (whether or not it is different outside of UK, I don't know).

I haven't had chance to call Mick yet though to check on availability etc.
 
I have just finished fitting a five speed Quaife gear cluster to my project engine. The quality is superb, I expect your strengthened case will be very good as well.

Glen
 
swooshdave said:
Anyone have a pic on how they strengthened it?
Click to expand...

This is a Commando gearbox with Quaife 5-speed cluster and Quaife shell that I used to use in my Commando PR. I think I sold this one to Kenny Cummings a few years ago. I did have to do a bit of grinding on the case to fit it into the Commando cradle, but it wasn't a big deal.

Cracked gearbox shell fix idea


The later 5 and 6-speeds where Quaife made the complete gearbox were a little different. This is a picture of a 6-speed Quaife I got from them back in the '80s.

Cracked gearbox shell fix idea


For those who notice such things, It had a Manx style mainshaft, not Commando. I originally bought it to use in a Manx, but ended up selling the Manx project, and eventually also sold the 6-speed.

Ken
 
Funny old game innit...

Despite Quaife clearly showing a strengthened gearbox shell on their web site, they don't sell it!

Instead they directed me to Mick Hemmings...

So I called and spoke to Angie, who politely informed me that they've not been available for years!

But, she explained that the AN shell is much beefed up and is the one to use.

So there you go.
 
I've a Quafe ribbed shell I had Ken repair lower bolt mount that was cracked. Its slightly trimmed to fit in cradle but was able to snag an TTI so my Quafe is available for less than I got it $250. The bearing bores definitely show the races got spun in it so planned to JBW fill as comnoz does em.
 
I wonder if loctite 621 might not be better than JB weld. After reading of Jim's use age of JB weld for this purpose, I used some of that around the new layshaft bearing in my Commando box. The bearing had obviously spun, but not too bad, it was still a push fit without heat differential.
I have since used Loctite 620 which comes with the warning not to use it on anything you plan to take apart soon as the bearing will be extremely difficult to remove. The instructions say it can fill a fifty thou gap and still provide a very strong bond!
I used it for installation of a new roller bearing in new Vincent cases, this was a bit of a mistake. The viscosity of it is such that it must be applied to the bearing surface before installation, not sucked in by capillary action afterward as can be done with thinner bearing retainer compounds.
After cooling the inner race no longer fit into the outer race , so I had to make a bearing lap mandrel and guides, then lap the outer race in line with all of the other bearings.
Some builders purposely use tight CN or even C2 clearance bearings then lap for alignment and true round in this way. It is a pile of extra work vs just plunking in C3 bearings, andprobably unecessary for all but race engines.
Back to the Loctite product, I would be inclined to try it for fitting of a slightly loose trans bearing.

Glen
 
Past threads have beat the dead horse to a mushy pulp on use of any loctite produce to hold engine or gear box bearings successfully on later inspection - so the reason the genetically gifted Nortoneer comnoz speaks of JBW here not loctite. Its fines in other less thermal leve and bore distorting applications. Best solution I saw was using the cleavage area to put in a plug and pin to trap races and beef up the area to boot. Next best is notching the race and bore a bit then melt in low temp metal mix that melts above heat developed in hard hearted racer fashion. I'd guess 300'F ish would be plenty and easy to melt right out so loose bore races drop right out again. I use this to put sharp bends in 1/4" tube. I'll use it to cap ends of header pipe filled with packed fine sand to bend too.
 
There are a multitude of different bearing retainer products by Loctite, from low strength and low fill capacity on up. The item I mentioned is an epoxy based type and may not be all that different from JB weld except it is a much heavier consistency.

Glen
 
Well Glen maybe its a new product you mention so please try it and let us know after a while.
 
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