Atlas Crankshaft Assembly

I received a crankshaft fixing kit from RGM and was finally getting around to installing it after having had the journals ground. The kit which was identified for all engines pre 212,278, which mine is. My crank when I took it apart had 4 bolts and two studs. The studs were the two lower ones joined by the tab washers. The new kit is all studs and nuts but the tab washers aren't long enough to connect the two lower studs. Anybody have and experience with this? RGM has another kit for engines post 212,278 but very clearly say that the two kits are interchangable. So why have two kits?

jms said:

So why have two kits?

Click to expand...

The difference besides bolts and studs (which they say the pre kit has) seems to be the thread, 26 TPI and 24 TPI UNF.

Perhaps if the new studs (which they say is the later kit) match the original length and diameter fasteners the plates could be reused.

750's including Atlas 06.7120 Nut Bolt kit. https://andover-norton.co.uk/en/shop-details/16921
850's up to 74 Stud Nut kit 72-74 06.7094 https://andover-norton.co.uk/en/shop-details/16907/crankshaft-stud-nut-kit-750-850-1972-1974
Both should work but the thread pitch is different , and W/w or AF wrench size for the later.
But pay attention to the stud lengths on the later as two are longer for the bottom with the plates. And two Nuts are longer and they go to the top.
Edit: I am wrong here, see Post #4 with Greg's comment. It's good to check the Andover Drawing section.

Any longer nuts go to the top or TDC location.

my 72 combat had 06.7120 kit.

CanukNortonNut said:

But pay attention to the stud lengths on the later as two are longer for the bottom with the plates. And two Nuts are longer and they go to the top.
Any longer nuts go to the top or TDC location.

Click to expand...

I'm fairly sure you're wrong. The two longer studs go at the top and besides clamping they align to the two halves along with the pin at the bottom - they are a very snug fit in the holes. The two longer nuts go at the top with them.

You are correct. My bad. The two longer studs belong with the Longer Nuts, Which go to the top. That way you can centre punch them. I just use blue loctite.

Thanks Greg. good catch.

Ok thanks everybody. To clarify RGM sells two kits. One kit is 4 bolts, 2 studs, 2 long nuts, and 4 regular nuts. That’s what I ordered and took off my crank. The other kit that they sell is 6 studs, 2 long and 4 short, 2 long nuts and 4 short.
what was packaged up in error and sent to me was 4 long and 2 short studs, 2 long nuts, and 4 regular nuts.

They are great at shipping fast but not so great answering Email.

Here’s the question, given that two of the studs are long when they should be short, it means that I can’t center punch in a normal way so is loctite red sufficient? Also what torque value should be used? Thanks all

jms said:

Ok thanks everybody. To clarify RGM sells two kits. One kit is 4 bolts, 2 studs, 2 long nuts, and 4 regular nuts. That’s what I ordered and took off my crank. The other kit that they sell is 6 studs, 2 long and 4 short, 2 long nuts and 4 short.
what was packaged up in error and sent to me was 4 long and 2 short studs, 2 long nuts, and 4 regular nuts.

They are great at shipping fast but not so great answering Email.

Here’s the question, given that two of the studs are long when they should be short, it means that I can’t center punch in a normal way so is loctite red sufficient? Also what torque value should be used? Thanks all

Click to expand...

Most cranks I take apart are not punched and definitely don't have red locktite - if you feel you must, use blue.

Just use the two extra long studs at the bottom and bend the tab washer over - before people jump, it is called a tab washer and the workshop manual says to bend it!!! Do not re-bend it (use a new one)! The long studs may be difficult to get in as the long studs are supposed to be very tight in the holes.

This is for Commandos, but much of it should be good for Atlas: https://www.gregmarsh.com/PDFDocs/Norton Commando Torque.pdf Do be careful to not use the torque meant for 3/8" bolts/studs when to you have 5/16"!

You could trim the stud with a file or if you have a lathe and take it off on the stepped side or the longer threaded side. I don't think it is really necessary. but use the long ones at the tab washers as Greg suggested. The tab washers are about 0.035" thick X2.
I would use Loctite 243 (blue) as it is designed to be in an oil environment as opposed to 242 blue. Red Loctite you would need heat to take it apart again and it could be you. That tab washer also captures the dowel pin from moving anywhere so they are important that you use them. Just pre bend them slightly with pliers so you can hook a screwdriver under them to get at them with a channel lock or punch and turn the nut so one flat faces the tab.
If You use a crowsfoot 1/2" with your torque wrench, but make sure you calculate the difference. https://www.tekton.com/blog/how-to-accurately-use-a-torque-wrench-with-a-crowfoot-wrench
You should be fine.
Cheers,
Tom

Thanks all