Footrest hanger - ARP hardware

robs ss · Mar 12, 2023

Has anyone installed ARP hardware (studs & 12-point nuts) to fix the hangers to the z-plates?
A 10 pack of ss 5/16" x 24 nuts is part # 400-8331
I can't find a suitable stud though (5/16" x 24 one end and 5/16" x 18 the other).
Anyone able to help?
Cheers

gortnipper · Mar 12, 2023

Why do you need studs with different thread forms on either end? Couldnt you just have studs with the same on both ends?

robs ss · Mar 12, 2023

gortnipper said:
Why do you need studs with different thread forms on either end? Couldnt you just have studs with the same on both ends?

Yes - could do.
The z-plates have the coarse (18) thread as standard.
I believe in using a finer thread with nuts, where possible. Reduces the probability of loosening.

YING · Mar 13, 2023

robs ss said:
Yes - could do.
The z-plates have the coarse (18) thread as standard.
I believe in using a finer thread with nuts, where possible. Reduces the probability of loosening.

Rob,
I use the factory studs and flat washers along with the ARP 12-point nuts and haven’t had any problems.
Mike

robs ss · Mar 13, 2023

YING said:
Rob,
I use the factory studs and flat washers along with the ARP 12-point nuts and haven’t had any problems.
Mike

Thanks Mike - I may do that yet.
I currently have the CNW ss button head allen screws but am wary of constantly loosening/tightening them into the alloy to get onto the primary (belt tension check, clutch clean, etc)
So, I'm going to go back to stud/nut configuration.
Asked AN what their threads were for these studs and got a leery reply from Simon Amos asking why I wanted this information.
I will buy elsewhere.

L.A.B. · Mar 13, 2023

robs ss said:
Asked AN what their threads were for these studs and got a leery reply from Simon Amos asking why I wanted this information.

UNC x UNF.
The nuts for the (x5) studs are "5/16" UNF".

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The 5/16" thin nut for the set screw (x1) is UNC, thus so should the inner ends of the studs.

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The stud also has the Unified identification (one turn of thread removed from the outer end).

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(Early Commandos without the Z-plate mounted Zener and earth/ground ring terminal would have had 6 studs and nuts.)

YING · Mar 13, 2023

robs ss said:
Thanks Mike - I may do that yet.
I currently have the CNW ss button head allen screws but am wary of constantly loosening/tightening them into the alloy to get onto the primary (belt tension check, clutch clean, etc)
So, I'm going to go back to stud/nut configuration.
Asked AN what their threads were for these studs and got a leery reply from Simon Amos asking why I wanted this information.
I will buy elsewhere.

Rob,
The factory studs I have are coarse threads going into the Zplates with fine 5/16-24 for the nuts that hold them on. I use red loc-tire on the threads into the plates so they stay there and don’t have the tendency to come out every time I want to check the primary.This has worked for me for quite some time
Mike

robs ss · Mar 13, 2023

Jared from ARP just got back to me (very helpful!)
The stud I need is Part# AG1.700-12G (see diagram below)
Available in chrome moly or stainless - I'll go the bling route.
Cheers

L.A.B. · Mar 13, 2023

robs ss said:
The stud I need is Part# AG1.700-12G (see diagram below)

According to the ARP stud drawing, the fine thread end of the stud is 5/16" - 24 UNJF (3A).

robs ss said:
A 10 pack of ss 5/16" x 24 nuts is part # 400-8331

The SS 400-8331 nuts appear to be UNF, therefore, they could be tight on UNJF studs and I'd guess an increased chance of galling as they're SS.

Unified National J Series vs. Unified National

www.ring-plug-thread-gages.com

"PRODUCT COMPATIBILITY
UN Bolt into UN Nut = No problems.
UNJ Bolt into UNJ Nut = No problems.
UN Bolt into UNJ Nut = No assembly problems; functional problems are possible.*
UNJ Bolt into UN Nut = In most cases an interference fit at the thread minor diameter; functional problems are possible.*"

robs ss · Mar 13, 2023

L.A.B. said:
According to the ARP stud drawing, the fine thread end of the stud is 5/16" - 24 UNJF (3A).

The SS 400-8331 nuts appear to be UNF, therefore, they could be tight on UNJF studs and I'd guess an increased chance of galling as they're SS.

Unified National J Series vs. Unified National

www.ring-plug-thread-gages.com

"PRODUCT COMPATIBILITY
UN Bolt into UN Nut = No problems.
UNJ Bolt into UNJ Nut = No problems.
UN Bolt into UNJ Nut = No assembly problems; functional problems are possible.*
UNJ Bolt into UN Nut = In most cases an interference fit at the thread minor diameter; functional problems are possible.*"

Thanks for that Les - I'll check with them.
I would assume the nuts are compatible (why wouldn't they be?) but the table for the nuts only states 24TPI
Cheers

Che

L.A.B. · Mar 13, 2023

robs ss said:
I would assume the nuts are compatible (why wouldn't they be?) but the table for the nuts only states 24TPI

I don't know. I just noticed "UNJF" on the drawing. I can't see the need for the outer end to be UNJF as the inner is normal UNC.

robs ss · Mar 13, 2023

L.A.B. said:
I don't know. I just noticed "UNJF" on the drawing. I can't see the need for the outer end to be UNJF as the inner is normal UNC.

ARP just confirmed the studs are UNJF because the threads are roll-formed and that the nuts, although UNF, will fit fine.
Cheers

gnolan · Mar 14, 2023

The only difference between a UNF internal thread and a UNJ internal thread is the minor diameter. 5/16-24 UNF is .267 - .277, UNJF is .2719 - .2799
The larger minor diameter of the UNJF is to assure clearance for a UNJ external thread, which has a controlled root radius.
If the 2 components assemble easily by hand, there will be no problems.

mean gene · Mar 14, 2023

Little late but in USA automotive industry used oil hardened exhaust studs with different thread pitch. These are what I have been using for added safety and strength. 5/16 nf and 5/16 nc with a flanged nut. I think Doorman was the supply company.

robs ss · Mar 15, 2023

Bought the ARP ss hardware - $28AUD per stud/nut (includes shipping from US then to me) - not cheap but good stuff.
The AN route would be $9AUD but not in the same class.

L.A.B. said:
The stud also has the Unified identification (one turn of thread removed from the outer end).

Les, do you think that indication is still something we can trust today?

L.A.B. · Mar 15, 2023

robs ss said:
Les do you think that indication is still something we can trust today?

Good question and the answer is probably not, because the identification likely only applied to British-manufactured studs where Unified replaced the original British Standard thread studs.

The cylinder base studs are one example where the studs were changed during Commando production.
AN seems to continue the tradition because their Unified studs have the identifier...

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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

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

...whereas their BS studs do not...

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

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

...except for these two where they seem to have got the stud pictures mixed up!.

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

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

RoadScholar · Mar 15, 2023

Why not just use an ARP bolt?

Best.

Dan1950 · Mar 15, 2023

gortnipper said:
Why do you need studs with different thread forms on either end? Couldnt you just have studs with the same on both ends?

While fine threads hold better in steel or cast iron, aluminum holds better with coarse threads. It is very common to have studs with one end coarse and one end fine thread when aluminum is involved.

robs ss · Mar 15, 2023

RoadScholar said:
Why not just use an ARP bolt?

Best.

I have something similar already (not ARP though)
I don't like repeatedly loosening/tensioning into the alloy z-plates (primary side multiple times per year - clean clutch, check belt tension...)
as it will IMHO be slightly damaging the threads with each job.
I think studs are preferable for this application.
Cheers

robs ss · Mar 26, 2023

The ARP hardware arrived today.
The studs were, as I expected, too long so I shortened them from 1.7" to 1.4", including reducing the length of the domed end by 0.05"
Just hacksaw, bench sander and polishing wheel.
The dome is actually very handy in guiding the hanger on.
Here's the original and shortened length:

Installed studs with a bit of blue (243) and completed install:

Here's the heads of the button head bolts after about a dozen remove/refit cycles.
The hex keys are the right size but that many cycles of 25-30 ft.lb is hard on a small hex. The 12 point ARP nuts will handle the duty much better - plus it's steel on steel instead of steel on aluminium.
Cheers

Footrest hanger - ARP hardware

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1974 MK II Roadster