New project, but missing VIN plate
- Thread starter GraemeH
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No, they no longer supply it so AN offer "(USE 06.4080 + 06.4078) (AS A PAIR)" except they're currently out of stock.
Yes nearly as it's the upper yoke you need as you have the correct lower yoke.
The different yoke sets use different bearings so you might want to check those.
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Yes, apparently you can.
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Note that the fork offsets are different which is why it important to fit the yokes in pairs.
I got given a gearbox from a fire sale and took it apart yesterday. It is in great condition inside. It doesn't appear to be a commando box given the number, but the only difference I noticed to far is that the kickstart spring does not go round a peg, but into a hole in the casing.
Can I transfer all the innards to my Commando box since that has the correct number, or is there some other difference that I missed?
Can I transfer all the innards to my Commando box since that has the correct number, or is there some other difference that I missed?
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As your frame is a 1971 Commando 750, finding a top yoke 06.1915 should be the preferred solution.
They turn up on Fleebay quite often. You can put an ad in the Classifieds section on this site as well.
- Knut
In principle you can. A new mainshaft is needed of course, and I suggest you replace the layshaft for the scrolled version. Most of the gears were improved throughout Commando production and some gear pairs had slightly different ratios. Compare each gear tooth count with what you have. Also needed is a new type kickstart spring, and probably a new kickstart shaft.
The latest type sleeve gear is of better design than the previous versions (replace with corresponding layshaft gear).
- Knut
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The 4th and 3rd gear tooth forms (and/or gear quality) were changed during early Commando production so those two gear pairs are not the same.
Is this gearbox pre-commando though? Any idea what bike and age, given the number and where it is stamped? (N25121)
I checked the gears - they are identical (at least I see no difference), as is the layshaft, but the mainshaft is quite different - the one from 25121 is 23.6cm long opposed to 24cm for 144531. So I am thinking I could just replace my rusty gears with the ones from 25121, keeping the longer mainshaft.
Another question: I believe the bushes in layshaft 3rd and mainshaft 2nd should be a loose fit and revolve within the gear. Mine don't. Should I replace them?
Mainshafts different but gears the same:
Layshafts and gears look identical:
I checked the gears - they are identical (at least I see no difference), as is the layshaft, but the mainshaft is quite different - the one from 25121 is 23.6cm long opposed to 24cm for 144531. So I am thinking I could just replace my rusty gears with the ones from 25121, keeping the longer mainshaft.
Another question: I believe the bushes in layshaft 3rd and mainshaft 2nd should be a loose fit and revolve within the gear. Mine don't. Should I replace them?
Mainshafts different but gears the same:
Layshafts and gears look identical:
Bushes need to be fixed to the gears wheels. Your bushes could be worn, check bores.
Gearbox is from a pre-1962 Norton, either a single (Model 50/ES2) or a twin (500/600).
Short mainshaft is for AMC's single row clutch. Long mainshaft is for the Commando clutch. It looks rather beaten. I would replace it if I were you.
Layshafts differ, look closely. I recommend using the layshaft off the Commando gearbox.
- Knut
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Yes.
As I already mentioned, 3rd (from 133488) and 4th gear (from 128646) pairs can't be unless they've been replaced with the later Commando parts.
Correct.
The gears in the pre-Commando box all seem pretty new - certainly not dating from 1962. So I assume they have been upgraded at some point. So I'm thinking of using all the cogs from there and ditching my rusty chipped ones.
Knut - you say look closely at the layshafts - I honestly see no difference. Can you give me a clue what to observe please?
Knut - you say look closely at the layshafts - I honestly see no difference. Can you give me a clue what to observe please?
You are in luck if your gear wheels have been replaced. Please look for any "RS" markings, if there are any, ditch the gear wheels. Those gear wheels are *potentially* lethal.
Re. layshaft - unless it has been replaced too, the old ones didn't have the spark eroded lube track for the 3th layshaft gear wheel and roller bearing encircled below.
- Knut
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Soak cumbustion chambers in degreaser, then evaporust to convert the rust and then re-assess. I assume the remnants of the pistons are siezed, if so I would do the same there and then use Kroil and heat to try to break rings free. As long as they are not at bdc, I would use hydraulic pressure as the last resort.
Thanks iikevelos, I managed to get the combustion chambers clean with lots of elbow grease and steel wool/scotchbright. I think the metal I was seeing was simply where someone had attempted to drill out a stuck spark plug. There was no real sign of seizure, but due to the hole in the spark plug, the whole barrel was rusty. I am now waiting to hear if it's salvageable, though I guess it can be sleeved...
Since I am still waiting on motor and gearbox, I started some of the cycle bits. Some PO had powder coated the swing arm, including the insides of the bushes:
New Vernier isolastics are on order:
And I cleaned up the mount and the head steady ready for painting. Actually - should such items simply be given an enamel paint coat or should they be powder coated for more durability?
Since I am still waiting on motor and gearbox, I started some of the cycle bits. Some PO had powder coated the swing arm, including the insides of the bushes:
New Vernier isolastics are on order:
And I cleaned up the mount and the head steady ready for painting. Actually - should such items simply be given an enamel paint coat or should they be powder coated for more durability?
Coming back to my yokes: I finally managed to get a matching top yoke on ebay, stamped with NM 061917 to match my existing bottom yoke 061916. Got them both nicely powder coated, only to realise while trying to insert a stanchion, that the bottom one is bent way out of line:
Nicely finished:
Quite obviously bent yet I didn't notice it before:
I guess it must be pretty hard to get it back into exactly the correct shape. Or is there a technique for this? Preferably one that won't ruin my nice new finish.
Nicely finished:
Quite obviously bent yet I didn't notice it before:
I guess it must be pretty hard to get it back into exactly the correct shape. Or is there a technique for this? Preferably one that won't ruin my nice new finish.
marshg246
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I've never been able to straighten a Norton bottom yoke. To be sure it's bad, put both tubes in, no top yoke, and tighten the pinch bolts, then measure the distance between at the top and bottom, and check that they are exactly in line - I use a piece of plate glass to do that.
Also, using the two tubes, be sure that they are straight.
