Mounting the controls on the handle bars

I’m restoring my 75 Mk3 850 and I am having some problems determining the correct size bolts that hold the left and right controls to the handle bar (the bolts that hold the 2 halves together). The best that I can tell is that the parts diagram is wrong. I have 3 bolts on the right side control, 2 look to be 10-32 x 1 and the other one looks to be a 8-36 x .875, but not sure on this. The left side has 4 bolts that look like they could be 8-36 x .875 but not sure.

Anyone have any info on what the bolts should be, any where to get them, or what part number they would be.

Chuck

ChuckW said:

I’m restoring my 75 Mk3 850 and I am having some problems determining the correct size bolts that hold the left and right controls to the handle bar (the bolts that hold the 2 halves together). The best that I can tell is that the parts diagram is wrong. I have 3 bolts on the right side control, 2 look to be 10-32 x 1 and the other one looks to be a 8-36 x .875, but not sure on this. The left side has 4 bolts that look like they could be 8-36 x .875 but not sure.

Anyone have any info on what the bolts should be, any where to get them, or what part number they would be.

Chuck

Click to expand...

Hi Chuck,
On my Mk3 the r/h "switch" halves are held together by 3 crosshead screws of differing lengths, in the parts book the number is 06-2488 for 4 on both right and left units but the left units screws are definitely smaller in dia., which as you say does not compute!
I have had a look in an earlier parts book , (I know the switch units may be different!!, but.....,), they give 2 diferent parts numbers for different switch screws, they are , as for Mk3, 06-2488, (4 screws), and 06-2241,(4 screws), if you go to this address....http://www.britishonly.com/estore/searc ... rames.html , it will open up a window and there is a box called "part mumber search" and another next to it with a drop down list, just put the part number in and drop list to Norton and hit the "go" button this should give you the correct size of screw you need, I use it when I am stuck for screw or bolt size.
Hope this helps
Robert

ChuckW said:

I have 3 bolts on the right side control, 2 look to be 10-32 x 1 and the other one looks to be a 8-36 x .875, but not sure on this. The left side has 4 bolts that look like they could be 8-36 x .875 but not sure.

Click to expand...

They seem to be metric M4 & M5.

Mine are ALL different! I wanted allen bolt replacements from Oldbritts, but none would fit. Ella there says that Aparently towards the end of production Norton would just stick any bolt they had handy in there.

Captain B said:

Ella there says that Aparently towards the end of production Norton would just stick any bolt they had handy in there.

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That's a bit doubtful I think, as I'd expect the switch units to have been supplied by Lucas to the Norton factory as complete assemblies with the screws included?

I think it's far more likely that the fine screw threads in the units probably stripped sometime in the past and the screw holes were then retapped by a previous owner, or some of the screws were lost and just replaced with whatever the PO had handy?

The screws are original to the bike.

Right side has 3 screws: Two have the same dia. and one is smaller.
Major Dia. .190, TPI 32, Length 1.0 and 1.25
Major Dia. .152, TPI 36, Length .875

Left side has 4 screws.
Major Dia. .152, TPI 36, Length .875

So what we have is a total of 7 screws made up of 2 different thread sizes and 3 different lengths. The parts books list only one size 06-2488 10-24 x 5/8 which they are NOT 24 TPI.

MK3 850 7-1975

LAB, with the above info could they be M4 and M5 screws. Did Norton use metric on the bikes?

Any help would be very much appreciated.

Chuck

First, I am no expert on thread sizes much less on the Norton, but it has been my experience that Lucas used a lot of BA size screws and nuts, I think it was used a lot in electrical and telephone equipment in the UK. The 2BA screw is real close to a 10-32 which is close to the .190/32 you have. The others, I don't know. I used to think the Nortons had some Metric on them, but found out that none were, mostly UNF, UNC, BA, BSW, and even BSC. There are endless varieties. Check out this link, you may find what they are exactly but will not be easy without the proper measurement tools, but then finding what you need is another issue. You may be reduced to re-tapping them to something you know fits, especially if you want stainless or socket heads. BoltDepot has good prices on SS UNF/UNC/Metric.

http://www.motalia.co.uk/Html/Charts/thread_charts.html

Dave
69S

Pretty sure no metric was using on the Commandos.

The switchgear was made by Lucas and not Norton, and I believe Lucas started the change-over to metric fasteners reasonably early on, as they supplied electrical parts to the British car industry which was already "going metric".

The smaller diameter screw threads could be 3BA or number 8?

3BA is .1610" x 34.8 tpi. Number 8 is .164" x 36, and 4mm .157" which is nearer to your measurement of .152" and standard (coarse) metric M4 x 0.7 pitch works out to be 36.28 tpi.

However, .190" is too big to be 2BA (.1850" x 31.7 tpi), and a standard screw from a R/H switch unit would not screw into my 2BA thread gauge, it was also slightly over the nominal 10-32 diameter at .192" instead of slightly under as I would have expected, so it could be 10-32 or it could be M5, as 5mm is .196" and M5 has a standard (coarse) pitch of 0.8mm, which works out to 31.75 tpi. So I can't say for sure, but I can say that both M4 and M5 screws do seem to screw into the threads in the MkIII switch units easily enough.

swooshdave said:

Pretty sure no metric was using on the Commandos.

Click to expand...

What about...

Spark plug threads?
Spin on filter thread?
Veglia instrument mounting stud threads?
:wink:

[Edit]I nearly forgot the MkIII rear brake master cylinder to casting thread!! :roll:

Thanks to all for your help. I will try the M4 and M5 today and let you know how they work. I think that we all can agree that the parts books are wrong again.

Chuck

Les, the M4 and M5 screws worked fine.

I was unaware that metric was used so I never looked to see if one would fit and that cost me a lot of time and frustation. In no time I was able to get some nice stainless allen bolts at the local Sears store and I also picked up a metric thread gage.

Thanks again for your help.

Chuck

ChuckW said:

I was unaware that metric was used so I never looked to see if one would fit and that cost me a lot of time and frustation.

Click to expand...

I agree, as metric fasteners are not what you'd expect to find on a Norton! :wink:

L.A.B. said:

swooshdave said:

Pretty sure no metric was using on the Commandos.

Click to expand...

What about...

Spark plug threads?
Spin on filter thread?
Veglia instrument mounting stud threads?
:wink:

[Edit]I nearly forgot the MkIII rear brake master cylinder to casting thread!! :roll:

Click to expand...

I said, "Pretty sure" not "Damn sure". :mrgreen:

Hi all,

I just made an assembly list of the stainless fasteners needed for the Mk3 controls, based in part on information in this thread. Parts are listed in Group 24 and 25 of the Mk3 Spares List but as mentioned above, the entries are partially wrong and certainly incomplete. I hope the short list below will put the record straight.

Gr. 25
Item P/N Qty
(21) 14-0105 1/4" x 28 tpi UNF x 1" Pivot screw, lever, front brake (1)
(22) 14-0401 1/4" x 28 tpi UNF locknut (1)

Gr. 24
Item
(15) 06-2235 1/4" x 28 tpi UNF x 7/8" Pivot screw, lever, clutch. (1)
(16) 14-0401 1/4" x 28 tpi UNF locknut. (1)
(20) 06-8074 M5 x 44 mm. Master cyl to switch block, right. (4)
(21) 06-8107-M5 Spring washer for M5 screws. (4)
(19) 06-2488-1 M5 x 32mm. Screw for switch block underside, right. (1)
(21') 06-8107-M5 Spring washer for M5 / 1/4" screws. (1)
(19) 06-2488-2 M5 x 25mm. Screw for switch block underside, right. (1)
(21') 06-8107-M5 Spring washer for M5 screw. (1)
(19) 06-2488-3 M4 x 22mm. Screw for switch block underside, left and right. (5)
(21) 06-8107 / 00-0190 Spring washer for M4 / 3/16" screws. (5)
(29) 99-0226 1BA x 9/16". Screws for choke lever clamp. (2)
(27) 06-7977 / 12-607 (2BA -xx?) . Pivot screw for choke lever. (1)

Regards,

Knut