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#847357 04/28/21 2:45 am
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Hi all,
BSA fettling took a back seat for long while. Trying to get my rear in gear for the nice weather.

I always wanted to replace the nuts on the rocker cover with domed/acorn nuts. Wondering if there is a good source out there anyone can recommend.
I've don't see much in the searches on the usual brit bit suppliers websites, but maybe a phone call is warranted.

I've notice that a metric M6-1.0 nut seems to fit the rocker bolts decently, but not perfect. A touch sloppy. Does anyone know if these are a specialty thread? The BSA parts book doesn't clarify those details.

Any advice is much appreciated.
Cheers!
Dennis


'67 BSA Lightning
'04 Triumph Speed Four
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First, suggest you at least download a parts and repair Manual then you would know these bikes were never metric. What thread depends upon what year. early bikes would be BSC thread and later SAE. '70 parts book clearly states 1/4" BSC for the domed nuts.

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What bike is it?


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Sorry, folks. Left out that key information.

1967 BSA Lightning

I do have a parts and repair Manual, however, they don't mention the specs for any of the bolts.


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Thanks Dennis,

In that case its as Dave said, 1/4 Cycle thread is for all those studs on the rocker box. (the stud end going into the aluminium is BSF)

From 69 they started giving bolt/nut specs, although some items like cylinder head remained the same. others changed from BSF/CEI to UNC/UNF.

The centre studs originally were acorn nuts and the outer 4x were standard open nuts. but nothing stopping you fitting acorn nuts all round (I have)


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71’ A65 823 Thunderbolt (undergoing restoration)
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You could look up the part 68-0137 on this database:

http://www.gregmarsh.com/MC/FastenersList.aspx

Last edited by Nick H; 04/28/21 12:17 pm.

1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
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That's a great link. Thanks Nick.

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Correct nuts are 1/4" x 26 tpi (BSF/CEI as stated above), one side flat (i.e., the bottom side is not beveled at the corners). British Tools and Fasteners has them, in stainless steel if you wish. They also have the domed nuts, as go on the center two studs, but I think domed nuts on the sides would look "funky" (just my opinion).

As to wrench size, sometimes the aftermarket nuts are 7/16" SAE (for the benefit of us Yanks), but if they stick with the original spec, you will need a 1/4" BS (or 3/8" Whitworth) wrench to turn them. British Tools and Fasteners also sells BS/Whitworth wrenches, but you can probably find them cheaper online. Kokens are good for medium-priced tools.


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Thank you, all, for the information and links. Searching the Brit Cycle and other sites with the parts Manual number wasn't turning up anything.

Currently I have some german helmet spike nuts holding the cover down. They look stupid. So domed or not, anything will be more appropriate than those.

https://images.app.goo.gl/ecHARroMUCsRjBnE8


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Originally Posted by Dennis Yurcik
Thank you, all, for the information and links. Searching the Brit Cycle and other sites with the parts Manual number wasn't turning up anything.

Currently I have some german helmet spike nuts holding the cover down. They look stupid. So domed or not, anything will be more appropriate than those.

https://images.app.goo.gl/ecHARroMUCsRjBnE8

Sounds like you share my taste in hardware, LOL!

I buy most British hardware by type, size, and thread form (as opposed to part number). To that end, British Tools and Fasteners also carries a comprehensive set of British and metric thread gauges.


Mark Z

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Those “German helmet” spike nuts are perfect for holding your pie in place to warm through on the rocker box, a bit of lock wire wrapped around them and your good to go wink

Just ask Kent Shaun.


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71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
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Mark, get rid of any of that "spike" crap that's on your bike.

There are enough hazards in motorcycling without adding more to the bike itself.

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Originally Posted by Irish Swede
Mark, get rid of any of that "spike" crap that's on your bike.

There are enough hazards in motorcycling without adding more to the bike itself.

I think you misunderstood my post. Dennis said the spiked bolts looked stupid, and I agreed.


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Just use half a dozen 1/4 BSF Allen bolts with fibre washers, job done.

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Originally Posted by NickL
Just use half a dozen 1/4 BSF Allen bolts with fibre washers, job done.


Allen Bolts... you heathen laughing


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68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
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68’ D14 trials (undergoing transformation)

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Originally Posted by NickL
Just use half a dozen 1/4 BSF Allen bolts with fibre washers, job done.

Forgive me if this is approaching OCD territory, and I'm sure you've heard it before, but: The advantage of studs and nuts over bolts is that you're not unscrewing and screwing into the aluminum every time you remove the cover.


Mark Z

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Stick some helicoils in there then. Even M6 eh?

BTW, how often do you remove the rocker cover on your bike?

OCD doesn't come into it, it's practicality that's important, BSF stuff is hard to find and stupidly expensive these days.


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