Low mileage, semi-basket build thread

[Rohan]

Re: New Norton owner, 74 850, Help!

You really don't want to be pulling off that inner race from the crankshaft any more than you have to.

Its not actually recommended that the inner race ever be fitted more than once ?
Even if it could be done without damaging it...

Someone somewhere has mentioned that they have a honed out (pair of) superblend inner, that they use for fitting and measuring the required shimming.
Slips on, do the measuring, slips off.
Once the measurements are established, the required shims and new superblend are fitted.

 

[concours]

Re: New Norton owner, 74 850, Help!

You really don't want to be pulling off that inner race from the crankshaft any more than you have to.

Its not actually recommended that the inner race ever be fitted more than once ?
Even if it could be done without damaging it...

Someone somewhere has mentioned that they have a honed out (pair of) superblend inner, that they use for fitting and measuring the required shimming.
Slips on, do the measuring, slips off.
Once the measurements are established, the required shims and new superblend are fitted.

Called "slave" bearings, it works ok if they are from the same maker/vintage and have proven repeatable.

 

[Time Warp]

Re: New Norton owner, 74 850, Help!

You really don't want to be pulling off that inner race from the crankshaft any more than you have to.

Its not actually recommended that the inner race ever be fitted more than once ?
Even if it could be done without damaging it...

Someone somewhere has mentioned that they have a honed out (pair of) superblend inner, that they use for fitting and measuring the required shimming.
Slips on, do the measuring, slips off.
Once the measurements are established, the required shims and new superblend are fitted.

Called "slave" bearings, it works ok if they are from the same maker/vintage and have proven repeatable.

Exactly,otherwise you would check the end float with the pre existing bearing and add the needed shimming to the new one when that is fitted. ?
Does the end float need to be within 2/10's of a thou.?

 

[Rohan]

Re: New Norton owner, 74 850, Help!

Does the end float need to be within 2/10's of a thou.?

The factory reportedly just assembled them, without shims ?
Apparently they felt the parts were similar enough that it couldn't get wildly out of hand.
This gave anything up to 20 thou - have we seen mentioned here before. (?)

With all the bits assembled there, can the crank go too far sideays anyway. ??
It can't drag the alt rotor and sprocket through the sidewall, or the oil pump skew gear either...
A big endfloat would have the roller bearing rollers heading off the inner race though...

 

[Rohan]

Re: New Norton owner, 74 850, Help!

Does the end float need to be within 2/10's of a thou.?

P.S. Where did this number come from ??
Thats even more accurate than the cammy motors need - and they need to be shimmed correctly, or the endfloat will destroy the bevel gear pairs.

 

[fatmatt]

Re: New Norton owner, 74 850, Help!

Checked out the parts bins, tore down the motor and photographed everything today. Got 2 rude shocks. The PO claimed the bike was on non-op. Not so much, back fees to 2009. Thanks, asshole. Also he neglected to mention that the reason he "just lost interest" in the project was because he broke a chunk off the crankcase when dis-assembling. Thanks again. Pics coming in a bit.

 

[fatmatt]

Re: New Norton owner, 74 850, Help!

What do y'all think? Can a machine shop fix this? Anyone know how easy it is to find a replacement? The only one on Ebay right now is $3800 for both halves in N.O.S. condition but I haven't looked elsewhere yet. JB Weld?

 

[JimC]

Re: New Norton owner, 74 850, Help!

https://sphotos-b-sea.xx.fbcdn.net/hphotos-frc3/1239675_4907520580569_1011134633_n.jpg

 

[fatmatt]

Re: New Norton owner, 74 850, Help!

https://sphotos-b-sea.xx.fbcdn.net/hphotos-frc3/1239675_4907520580569_1011134633_n.jpg

Oops, Thanks Jim.

 

[fatmatt]

Re: New Norton owner, 74 850, Help!

Two friends of mine saw the photo on facebook and offered to weld it. I assume there's more to it than that.

 

[Rohan]

Re: New Norton owner, 74 850, Help!

I assume there's more to it than that.

If they are good and capable welders of aluminium, possibly not.

Welding crankcases and alumium bits on bikes etc has been around for near a century or so.
Providing they degrease thoroughly, and preheat the cases, all should be good.

Aircraft welders do this sort of stuff every day.
Don't let someone practice on your cases if they have to re-learn how to successfully weld aluminium though.

 

[fatmatt]

Re: New Norton owner, 74 850, Help!

I assume there's more to it than that.

If they are good and capable welders of aluminium, possibly not.

Welding crankcases and alumium bits on bikes etc has been around for near a century or so.
Providing they degrease thoroughly, and preheat the cases, all should be good.

Aircraft welders do this sort of stuff every day.
Don't let someone practice on your cases if they have to re-learn how to successfully weld aluminium though.

The camshaft was already out of the motor when I got it. Will that radius need to be re-bored after welding? i.e. does the crankshaft just run through that area or does it ride on a bearing there?

 

[Rohan]

Re: New Norton owner, 74 850, Help!

The cam runs in 2 bronze bushes, one either end of the cam.
The whole length/middle of the cam just runs out in the breeze.

Its a little difficult to see fully whats going on from that angle, but it looks like the weld would be well clear of the cam bearings.
It would all have to be done well enough so that its oil-tight, however.
A good welder could advise.
You have nothing to lose by trying - apart from the original VIN number on the engine.
Which is well worth trying to keep.

Those new cases were silly prices, good used should be way less than that ?

 

[fatmatt]

Re: New Norton owner, 74 850, Help!

The cam runs in 2 bronze bushes, one either end of the cam.
The whole length/middle of the cam just runs out in the breeze.

Its a little difficult to see fully whats going on from that angle, but it looks like the weld would be well clear of the cam bearings.
It would all have to be done well enough so that its oil-tight, however.
A good welder could advise.
You have nothing to lose by trying - apart from the original VIN number on the engine.
Which is well worth trying to keep.

Those new cases were silly prices, good used should be way less than that ?

Yeah, another thread here has me considering Maney cases and JS light weight pistons and Carrillo rods. I'm stopping by my friends shop tomorrow to let him assess the possibility of repair. He's a talented mechanic that I trust. I'm pretty sure he can handle it. If he can, I'll go w/ a stock rebuild, if not I may start throwing some money at it.

 

[Time Warp]

Re: New Norton owner, 74 850, Help!

Does the end float need to be within 2/10's of a thou.?

The factory reportedly just assembled them, without shims ?
Apparently they felt the parts were similar enough that it couldn't get wildly out of hand.
This gave anything up to 20 thou - have we seen mentioned here before. (?)

With all the bits assembled there, can the crank go too far sideays anyway. ??
It can't drag the alt rotor and sprocket through the sidewall, or the oil pump skew gear either...
A big endfloat would have the roller bearing rollers heading off the inner race though...

Does the end float need to be within 2/10's of a thou.?

P.S. Where did this number come from ??
Thats even more accurate than the cammy motors need - and they need to be shimmed correctly, or the endfloat will destroy the bevel gear pairs.

It was a piss take and a toolmaker spec.
The query is why bother with ground old super blends for checking purposes,the fabled barrel shaped roller element which of course never made any sense as it would have next to no load bearing capacity given the outer has to be flat to assemble it. :lol:
You get your to be case split Norton engine to a state where a dial gauge can be used to check existing end float.
Lets say it is around 0.015" and you want 0.010",logic says a 0.005" shim would get it in the ballpark as the case is still assembled including part line sealant,perhaps some 0.002" or less
Why bother with an old ground bearing to check even if it is a duplicate of that being used on reassembly ?

Here is something to ponder.
End float set at 0.010" cold,how much is the end float with the oil and cases at maximum operating temperature.
I would hazard a guess it would increase to around 0.013" / 0.014" as a minimum.
That in turn might suggest a operating clearance of 0.010" (0.007" cold) might be a good thing.

Of course when I got to that stage the other week on my 71 750,the end float was measurable with a rule,had some radial clearance and still had the original MRJ bearings both sides and stock journals.

 

[Rohan]

Re: New Norton owner, 74 850, Help!

Why bother with an old ground bearing to check even if it is a duplicate of that being used on reassembly ?
.

Probably because a lot of folks start with a basket case motor. ?
I did, and learned the old bearing trick along the way - after.
Can be applied to earlier and other motors, without superblends.
When you want to check that the odd collection of stray parts will satisfactorily go together.

As was mentioned/discussed here earlier, the factory reportedly assembled them (superblends to cranks) with no shims and no checking, so it can't be real critical ?
Not like the cammy (ohc) Norton motors, where it is critical.

We are singing from the same songsheet about "superblend" bearings ?
- obviously they have to be parallel rollers, give or take a few thou on the very edges.

 

[X-file]

Re: New Norton owner, 74 850, Help!

All bearings aren't created equal,as far as centrality of the inner race relative to the outer race.They're close,but the difference between one and the next can often amount to 0.003" change in end-float.You can measure the difference before you fit them;I use a dial gauge,but there could be other ways.

Minimum end-float is good,but you still need some when the engine is cold.There's likely to be about 0.005" more when the engine is hot.
It always pays to see how central the conrods are in their cylinders,before you decide where to put shims.As much as anything,this is all about keeping the conrods as central as possible.

 

[edgefinder]

Re: New Norton owner, 74 850, Help!

All bearings aren't created equal,as far as centrality of the inner race relative to the outer race.They're close,but the difference between one and the next can often amount to 0.003" change in end-float.You can measure the difference before you fit them;I use a dial gauge,but there could be other ways.

Minimum end-float is good,but you still need some when the engine is cold.There's likely to be about 0.005" more when the engine is hot.
It always pays to see how central the conrods are in their cylinders,before you decide where to put shims.As much as anything,this is all about keeping the conrods as central as possible.

My Ducati F1 750 has angular contact main bearings. It wants .005" preload on the main bearings so I would say they expect .003"-.005" expansion of the cases when hot. If the rod journal isn't centered to the cylinder bore like when I got it and it was .03" to one side it shows up where the piston touches the head on one side after being revved to 11000 rpm. Once I shimmed it to center the piston touches more equal side to side and rings last longer. So yeah to what X-file said.

 

[fatmatt]

Re: New Norton owner, 74 850, Help!

I assume there's more to it than that.

If they are good and capable welders of aluminium, possibly not.

Welding crankcases and alumium bits on bikes etc has been around for near a century or so.
Providing they degrease thoroughly, and preheat the cases, all should be good.

Aircraft welders do this sort of stuff every day.
Don't let someone practice on your cases if they have to re-learn how to successfully weld aluminium though.

Dropped the case off at my friends this evening. He's pretty confident it should be no problem. He was asking about the quality of the casting, i.e. how dirty is the alloy. He was explaining the difference in impurities between an old school VW motor which is relatively clean and very easy to work w/ versus a newer Jetta he had recently relocated a motor mount in to assist a guys quest to go lower and showing me the voids that are created when the impurities burn out. Hopefully I'll be back in business this weekend and ready to test assemble the motor in my new ebay engine stand.

 

[Rohan]

Re: New Norton owner, 74 850, Help!

Dropped the case off at my friends this evening. He's pretty confident it should be no problem. He was asking about the quality of the casting, i.e. how dirty is the alloy. He was explaining the difference in impurities between an old school VW motor which is relatively clean and very easy to work w/ versus a newer Jetta he had recently relocated a motor mount in to assist a guys quest to go lower and showing me the voids that are created when the impurities burn out. Hopefully I'll be back in business this weekend and ready to test assemble the motor in my new ebay engine stand.

Have fun !
Tell us how it goes - with a pic or 2...