Crankshaft studs

Nourish

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Dec 2, 2009
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I've just received a pair of the longer NA crankshaft studs and they're not as tight a fit as in the Hemmings video. The threads are nothing special - especially not under a magnifying glass. They're cut not rolled, so if I should wish to make some myself to obtain a light intererence fit what should I make them out of?
 
So often, in the supply chain today, "new" isn't "better".

Just went through it this week, OEM parts for a Japanese CNC turning center.

🗑️😡
 
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Yours is an 850?

Then

andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk

On the last crank I put back together there was burnt oil deposits behind the cheek flanges and on the flywheel, I removed this before reassembly in case it was causing a misalignment. I also needed the pattern they made to match the cheek to flywheel as the crank came to me in pieces and the flywheel unmarked.
 
Nourish said:
I've just received a pair of the longer NA crankshaft studs and they're not as tight a fit as in the Hemmings video. The threads are nothing special - especially not under a magnifying glass. They're cut not rolled, so if I should wish to make some myself to obtain a light intererence fit what should I make them out of?
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You should be able to get them in with great finger pressure or light tapping. If they go in easily, don't use them! I only use the AN sets - they have always been correct. I'm no metallurgist, and am only guessing, but I think those two are special steel. You can always write AN and ask - they normally answer questions quickly.
 
kommando said:
Yours is an 850?

Then

andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk

On the last crank I put back together there was burnt oil deposits behind the cheek flanges and on the flywheel, I removed this before reassembly in case it was causing a misalignment. I also needed the pattern they made to match the cheek to flywheel as the crank came to me in pieces and the flywheel unmarked.
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Yes, thank heavens for those stains. I've had the same issue!
 
3/8"

I found the pre Mk3 5/16" stud kits to be of average quality and the low cost reinforced that.
 
Time Warp said:
3/8"

I found the pre Mk3 5/16" stud kits to be of average quality and the low cost reinforced that.
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Thanks, that’s what I thought.

So the easiest fix for the OPs sloppy studs would be using mk3 studs and drilling / reaming to suit.

FWIW the studs on a Maney crank are ‘mallet fit’ tight.
 
I think if you look at the RGM page you will note a different amount of torque for the early v late
studs. Don't ask how I found out about this.
 
These are Andover Norton studs and they drop in but still a better fit than RGMs. It would be much easier to make some studs that are a better fit than try to machine out for mk3 studs.
 
You
marshg246 said:
You should be able to get them in with great finger pressure or light tapping. If they go in easily, don't use them! I only use the AN sets - they have always been correct. I'm no metallurgist, and am only guessing, but I think those two are special steel. You can always write AN and ask - they normally answer questions quickly.
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why would you think they are different?
 
Nourish said:
You

why would you think they are different?
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Different color, different feel. I may well be wrong, but a simple email can tell you.

If they are not a snug fit, then I'm confident that someone before you opened the holes. To be clear, only the top two are a tight fit.
 
I find AN very protective over their products - unlikely to tell me what material to make my studs out of!
 
If you want to make your own then start with some 8.9 grade hi tensile bolts but you also have 10.9 and 12.9 with higher strength.

www.marshfasteners.com

What Are The Different Grades Of Bolts?

Knowing the different grades of bolts and their tensile strength can help you choose the right type for your application.
www.marshfasteners.com www.marshfasteners.com

Go for the next metric size up with the unthreaded shank longer than the Norton stud and ground to size, cut off metric thread and hex head and get some one to roll the threads on both ends.
 
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Crankshaft Bolts (2012)

Guys, after joining this forum and saw alot of http://www.accessnorton.com/commando-crankshaft-porn-t8365.htmlI want to try order the bolts from ARP for my norton crankshaft, and they are asking for measurement, is this the correct size for the diameter right the unthreaded part are 0.375" not...
www.accessnorton.com www.accessnorton.com
 
Nourish said:
I find AN very protective over their products - unlikely to tell me what material to make my studs out of!
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On average, I ask a question about once a month and get an answer 100% of the time so I've not found that to be true.

If I understand right, you have RGM studs that are definitely too small in diameter and AN studs that are not to your liking on fit and want to make larger diameter studs. If the AN studs are a snug slip fit, you're good - they do not need to be an interference fit! Heavy finger pressure or light tapping is what you should want. I'm confident that if the two long AN studs are loose that someone opened the holes in the crank. If that's the case, I'm also confident that Ashley or Simon will be helpful if you explain the problem.

technical@andover-norton.co.uk
 
Nourish said:
Yes the AN studs fall in . Ok I'll contact them👍
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Once you figure it out, you may be able to make a little money on thicker studs if they don't have another solution. However, I have a crank on the shelf that was opened up but I think the cheeks and flywheel were done separately so it still may be out of whack even with thicker studs.

Of course, if you have a lathe (or between center test stand), you could assemble with what you have, check/true, and then run a reamer (or drill) through to get them aligned and to a known size.

I just looked it up - I've installed/sold 21 of the AN sets and with the exception of the one just mentioned I've found the fit right on all I've installed and have had no customer complaints.
 
Get your undersized studs copper plated on the shank but not the threads. Use emery cloth to size them to a finger press fit.
 
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