Cracked crankcase.

comnoz · Aug 30, 2013

john robert bould said:
So, I assume the case flex's around the bearing bore at high RPM?

It is only metal and it is shaking. Everything is flexing. How much and how long can it take it is the only question. Jim

john robert bould · Aug 30, 2013

Jim, Have you ever had an out-rigger bearing, Laverda's have one in the primery case?

comnoz said:
john robert bould said:

So, I assume the case flex's around the bearing bore at high RPM?

Click to expand...

It is only metal and it is shaking. Everything is flexing. How much and how long can it take it is the only question. Jim

comnoz · Aug 30, 2013

Here is the first of many outriggers. Note the added metal around the main. It still broke. Jim

Matchless · Aug 30, 2013

Firstly, the gearing I am currently running is 36/72 primary & 20/42 final which gives 4.2 to 1. This seems ideal for my use. Previously I ran a 21 tooth gearbox sprocket giving 4 to 1 but found that whilst it was good for high speed cruising, it wasn't lively enough off the mark & out of corners. I would really like a TTI five or six speed box but they are rather expensive.
Secondly, I think Mr Schmidt has been reading my mind. It is looking like a very expensive rebuild. I was at one time drooling over the 1007 Jim was testing what with all that torque, but maybe this would push even Maney crankcases a bit too hard.

john robert bould · Aug 30, 2013

Jim, Yes thinking about out-riggers, the crank held firm at on one end would cause high stress .

comnoz said:
Here is the first of many outriggers. Note the added metal around the main. It still broke. Jim

comnoz · Aug 30, 2013

john robert bould said:
Jim, Yes thinking about out-riggers, the crank held firm at on one end would cause high stress .

comnoz said:

Here is the first of many outriggers. Note the added metal around the main. It still broke. Jim

Click to expand...

I wouldn't try to hold the end of the crank solidly. I only used outriggers to help keep the trans intact. It certainly helped with that. Jim

1up3down · Aug 30, 2013

I get onto the motorway & cruise at 5000 to 5500rpm, approx. 90 mph on current gearing, for between 50 & 80 miles. This gets me to some fantastic & fairly traffic free roads. The bike then gets thrashed up & down the gearbox but hardly ever revved beyond 6500.

yeah ok, so ban me for forum blasphemy but I gotta say it

you beat your bike, you beat an old long stroke pushrod vertical twin by holding it at yes high rpms too long

and then when you were done with that you decided to "thrash" it up and down the gearbox AT high rpms

yeah, you got what you deserved, you beat your bike and now you deal with what you decided to wrought

go get a 20 year old Japanese four and beat the crap out of it for fun then, but not your Norton

ok I am ready, fire retardant suit on, start calling me names but I sticking to what I said

Dances with Shrapnel · Aug 30, 2013

Matchless said:
I was at one time drooling over the 1007 Jim was testing what with all that torque, but maybe this would push even Maney crankcases a bit too hard.

They race 1,007cc Nortons across the pond and from what I hear they are durable so you should not worry. Heavy crank with light weight rods and pistons would be the kindest to the engine and running gear and would yield a relatively low vibration (nice) ride. Going with a lighter crank will certainly give you the "wow" factor with useable torque out of the turns. Take a look at Steve Maney's 1,007cc engine package and then price out what you think want going with an 828cc rebuild and you will be surprised that there's not that big a difference.

john robert bould · Aug 31, 2013

Think about reducing the upper rev limit a bit,at the end of the day ,these are not jap 12000 rpm super bikes.they are 50's sloggers, long stroke 360 twins with aged parts.
OK they will do the business for short " bursts] but long sustained Hammer will take it's toll, as you have found out. I am speaking from experiance!!!..my mates combat back in 1973 one day deceided to spill her guts on the A34, racing a works...........VAN!!! he was passing it with grand style...full bore, then BANG :!: a rod made a new window...Norton replaced the engine, it was the norm back then. So go easy on the motor...or hard on the wallet!

Matchless said:
Firstly, the gearing I am currently running is 36/72 primary & 20/42 final which gives 4.2 to 1. This seems ideal for my use. Previously I ran a 21 tooth gearbox sprocket giving 4 to 1 but found that whilst it was good for high speed cruising, it wasn't lively enough off the mark & out of corners. I would really like a TTI five or six speed box but they are rather expensive.
Secondly, I think Mr Schmidt has been reading my mind. It is looking like a very expensive rebuild. I was at one time drooling over the 1007 Jim was testing what with all that torque, but maybe this would push even Maney crankcases a bit too hard.

john robert bould · Aug 31, 2013

Think about reducing the upper rev limit a bit,at the end of the day ,these are not jap 12000 rpm super bikes.they are 50's sloggers, long stroke 360 twins with aged parts.
OK they will do the business for short " bursts] but long sustained Hammer will take it's toll, as you have found out. I am speaking from experiance!!!..my mates combat back in 1973 one day deceided to spill her guts on the A34, racing a works...........VAN!!! he was passing it with grand style...full bore, then BANG :!: a rod made a new window...Norton replaced the engine, it was the norm back then. So go easy on the motor...or hard on the wallet!

Matchless said:
Firstly, the gearing I am currently running is 36/72 primary & 20/42 final which gives 4.2 to 1. This seems ideal for my use. Previously I ran a 21 tooth gearbox sprocket giving 4 to 1 but found that whilst it was good for high speed cruising, it wasn't lively enough off the mark & out of corners. I would really like a TTI five or six speed box but they are rather expensive.
Secondly, I think Mr Schmidt has been reading my mind. It is looking like a very expensive rebuild. I was at one time drooling over the 1007 Jim was testing what with all that torque, but maybe this would push even Maney crankcases a bit too hard.

RoadScholar · Aug 31, 2013

One approach to added reliability, JS lightened pistons/rods, Falicon one piece crank, with a 65% balance factor.

The cases were shot peened and then vibratorily tumbled with ceramic media.

I don't thrash this engine, but I do expect it to be tolerant of an occasional burst to 7000 RPM.

Cha-cha with your mistress, waltz with your grandmother...

jseng1 · Aug 31, 2013

RoadScholar said:
One approach to added reliability, JS lightened pistons/rods, Falicon one piece crank, with a 65% balance factor.

The cases were shot peened and then vibratorily tumbled with ceramic media.

I don't thrash this engine, but I do expect it to be tolerant of an occasional burst to 7000 RPM.

Cha-cha with your mistress, waltz with your grandmother...

How much was the crank?

Delivery time?

Is there a radius on the PTO shaft?

weight?

RoadScholar · Aug 31, 2013

How much was the crank?

Delivery time?

Is there a radius on the PTO shaft?

weight?

PM me

Matchless · Aug 31, 2013

Yes, how much indeed. I'm starting to feel a very large bill coming on. Can't find a price on the MAP website.
I think I will need to sell a bike to pay for all this fancy kit. Anybody want to buy a '59 Venom clubman? Alternatively I'll swop it for ...
A pair or Maney cases
JS rods & pistons
Falicon or Mamey crank
Comstock head re work
TTI 6 speed 'box
Racers seem to hold their motors between 5000 & 7000 plus for a seasons racing using this type of tackle so it should be more than good enough for me. Ultimately though, It must still retain that magical feel. What I call SMOOTH vibration. Nothing else feels as special as a good Commando!

bwolfie · Aug 31, 2013

found these
http://www.ebay.com/itm/NORTON-COMMANDO ... 13&vxp=mtr

Matchless · Sep 1, 2013

Thanks for posting the MK3 cases, but I think I would be better off with a set that are not machined for a primary chaincase. As I'm using a belt drive, I can machine the pr. case to suit as Jim C suggested.

lynxnsu · Sep 1, 2013

comnoz said:
Here is the first of many outriggers. Note the added metal around the main. It still broke. Jim

could it be that welding those cases actualy weakened them ?
we used to shrink (crimp) a large steel ring around the boss on the drive side and never had one break (until , yes the crank broke...) however this was before Maney cases were available , or we could afford them

comnoz · Sep 1, 2013

lynxnsu said:
comnoz said:

Here is the first of many outriggers. Note the added metal around the main. It still broke. Jim

Click to expand...

could it be that welding those cases actualy weakened them ?
we used to shrink (crimp) a large steel ring around the boss on the drive side and never had one break (until , yes the crank broke...) however this was before Maney cases were available , or we could afford them

There is no question that the heat from welding weakened the cases. It is basically impossible to weld aluminum without affecting the strength.

I think the shrunk on ring is not a bad idea but I have not tried it.
I haven't seen it my self but I was told they will still eventually crack starting at the bolt holes even with the ring in place. Jim

Hobot · Sep 1, 2013

So what is the cheap way to get going again and still enjoy routine close to the ton all day long day after day yet not ruining like heart less racers over 6000 rpm much as they can? There is the decision to make of sticking with real Norton or jumping fences too. But in the end we just die off so what the best logic to apply while ya still can. I hold with use the snot out of what ya got and let someone
else worry with the results & remains after you make your memories to go to sleep with a shit eating grin and lingering adrenalin tremble twitching.

concours · Sep 2, 2013

hobot said:
So what is the cheap way to get going again and still enjoy routine close to the ton all day long day after day yet not ruining like heart less racers over 6000 rpm much as they can? There is the decision to make of sticking with real Norton or jumping fences too. But in the end we just die off so what the best logic to apply while ya still can. I hold with use the snot out of what ya got and let someone
else worry with the results & remains after you make your memories to go to sleep with a shit eating grin and lingering adrenalin tremble twitching.

+1 on ridin em.

22T front sprocket let's me rock with modern traffic as needed to slab cover miles and get to the good stuff. Also, the long stroke tractor engine as previously mentioned is best left NOT wrapped up tight continually. Let the torque do the work. Save the revs for Honda's and racing bikes.

Cracked crankcase.

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