‘70 Commando Roadster rebuild in GA

[BusDriver330]

Cheers All,
For decades I have admired the history of Brit bikes, even made a pilgrimage to the the museum and what’s left of Brooklands.

Last fall I was lucky enough to find a few specimens for rebuild and chose a 1970 Commando 750 Roadster. Mileage in the 4 digits, mostly complete numbers matching 12/69 build. A Canadian import, I believe.

Although my first Brit bike build, I have resurrected a few Japanese bikes, still working a 1971 Yamaha 250 Enduro, a 1966 Dream 305 and also build 600/1000 Kawi race bikes. A little experience, but not much Brit experience! And the Brit way has already bitten me a few times.

That said, I have an appreciation for the expertice I’m reading about and and appreciation for those taking on the same task I have embarked on.

Hopefully I can gain more insight from the knowledge bank here without making too many mistakes. Thanks in advance for patience thrown my way, a 61yr old Brit beginner.

Photos to follow (if I learn how).

 

[BusDriver330]

As purchased last fall ‘18

edit- okay first mistake... photo upload

First step:

 

[blaisestation]

Very nice to start with ,Enjoy the journey !

 

[Mwood7800]

I would weld a tab on for updated kickstand.

 

[o0norton0o]

You should know that the 70 year model has some unique differences from later models, so when you do searches for certain topics you may find answers to questions that are not applicable to your bike. I have a '70, so I am giving you the heads up. There's a lot of subtle differences.

You should read Pete's rebuild: https://www.accessnorton.com/NortonCommando/1970-commando.26609/

I'm sure I gave Pete a list of things that are "must do's", like kegler clamps on the swingarm tube, reed breather of some sort, etc. Read his thread and you'll see all the special issues to address for your bike.

 

[BusDriver330]

Very nice to start with ,Enjoy the journey !

I enjoy the mechanical details, but you pushed the right button!

It’s about a ‘journey’... this Brit bike. It started many decades ago for me.

 

[BusDriver330]

I would weld a tab on for updated kickstand.

Ugh!

Now you tell me. My friends at Procryo Coatings down here did a great job prepping and powder coating.

Keep it coming.
Thanks

 

[BusDriver330]

You should know that the 70 year model has some unique differences from later models, so when you do searches for certain topics you may find answers to questions that are not applicable to your bike. I have a '70, so I am giving you the heads up. There's a lot of subtle differences.

You should read Pete's rebuild: https://www.accessnorton.com/NortonCommando/1970-commando.26609/

I'm sure I gave Pete a list of things that are "must do's", like kegler clamps on the swingarm tube, reed breather of some sort, etc. Read his thread and you'll see all the special issues to address for your bike.

Brilliant. Thanks for the link. I am certainly not inundated with ‘all the volumes of information’ needed to make sense of this 12/69 build and matching up the parts list.

I had the low mile engine rebuilt with new hardware, Pazon ignition, and a ‘breather’. The frame mods escaped my initial study, damn it.

I anxiously look forward to reading through Pete’s build.

 

[Bob Z.]

I would weld a tab on for updated kickstand.

Let me throw out this thought:
Instead of modifying this original frame, how about finding a used newer version with the factory center stand and side stand updates.
Then the original frame could be preserved and the new frame could have a replacement VIN plate installed with the same 6-digit number. Future owners could decide to use the original unmodified frame or the later (better) frame.
I'm at the point in my life as a long time Norton owner where I can appreciate the original (but maybe flawed) specs, but understand the upgrades.
Somebody has to keep the original vintage specs!

 

[o0norton0o]

The early frame has a 27 degree steering head and less offset in the steering yokes to give a good trail number. Before combining frames and yokes of different models, the new resulting trail number should be calculated and understood.

I have an early frame and both stands work fine to this day. Last year I did replace the bolt on part of the side stand because the pivot had gotten sloppy, but it still worked. The early side stand is short, so you need to be concious of the bike's posture when you use it. Other than that, I've never had a problem with it.

If anything, I would say make sure the "wings" that support the fuel tank are welded on good. They can break off from supporting the weight of the tank IF a person doesn' get a foam block between the tank and the frame's main tube to take the weight off the wings... so much little stuff to know...

 

[BusDriver330]

Let me throw out this thought:
Instead of modifying this original frame, how about finding a used newer version with the factory center stand and side stand updates.
Then the original frame could be preserved and the new frame could have a replacement VIN plate installed with the same 6-digit number. Future owners could decide to use the original unmodified frame or the later (better) frame.
I'm at the point in my life as a long time Norton owner where I can appreciate the original (but maybe flawed) specs, but understand the upgrades.
Somebody has to keep the original vintage specs!

Good suggestion. But the frame is nearly flawless and would be a shame not to use it in the build from my perspective early in the process. I don’t plan on a lot of thrashing about and would also appreciate the originality.

Are the flaws that disastrous to warrant changes for safety? Thanks

 

[BusDriver330]

The early frame has a 27 degree steering head and less offset in the steering yokes to give a good trail number. Before combining frames and yokes of different models, the new resulting trail number should be calculated and understood.

I have an early frame and both stands work fine to this day. Last year I did replace the bolt on part of the side stand because the pivot had gotten sloppy, but it still worked. The early side stand is short, so you need to be concious of the bike's posture when you use it. Other than that, I've never had a problem with it.

If anything, I would say make sure the "wings" that support the fuel tank are welded on good. They can break off from supporting the weight of the tank IF a person doesn' get a foam block between the tank and the frame's main tube to take the weight off the wings... so much little stuff to know...

Purchased the kit for tank mounting, was vigilant as I’ve purchased metal tank for it.

I’ll post a pic of the upper and lower yoke and maybe you can identify what I have and if changes should be made. I’ve acquired a few modern bearings and shields for the head. Hoping I can pin down a good setup, even if I have to acquire new yoke.

 

[BusDriver330]

I would weld a tab on for updated kickstand.

Mwood, I took a look at my side stand and noticed the back half of side stand mount ‘is’ welded.

Was that your concern or can you refer me to a picture of a proper setup for safer use? Thanks

 

[NPeteN]

The old stand uses a wimpy cylinder with two circlips to hold/pivot the leg, prone to failure. If you can find a suitable bolt to use instead, that may work if it's to late to weld.

Frank (oOnortonOo) helped me a lot with my bike, lots of good advice in my thread from all over the forum.

 

[L.A.B.]

Purchased the kit for tank mounting, was vigilant as I’ve purchased metal tank for it.

A reinforcing plate or later Commando coil bracket bolted beneath the tank brackets using the existing holes strengthens the tank brackets.

I’ll post a pic of the upper and lower yoke and maybe you can identify what I have and if changes should be made. I’ve acquired a few modern bearings and shields for the head. Hoping I can pin down a good setup, even if I have to acquire new yoke.

The yokes, which I assume are the ones that came with the bike and shown in your first photo are correct for that frame.

040122 is the casting/foundry number found on the majority of Commando gearbox casings and isn't significant.

 

[BusDriver330]

The old stand uses a wimpy cylinder with two circlips to hold/pivot the leg, prone to failure. If you can find a suitable bolt to use instead, that may work if it's to late to weld.

Frank (oOnortonOo) helped me a lot with my bike, lots of good advice in my thread from all over the forum.

Ah, so the frame mount mod rids you of a less than adequate pivot design. Any pictures of your fix?

 

[BusDriver330]

A reinforcing plate or later Commando coil bracket bolted beneath the tank brackets using the existing holes strengthens the tank brackets.




The yokes, which I assume are the ones that came with the bike and shown in your first photo are correct for that frame.




040122 is the casting/foundry number found on the majority of Commando gearbox casings and isn't significant.

I’ll rummage the Andover site for the coil mount. From my modern race builds(heavy tanks), I see the wt. distribution centered near the top section of the frame near the head. I have an image of a support mount over the top of the spine utilizing the existing hardware for mounting the tank front section. I’ll post if I engineer something. Thanks

*edit-disregard my ‘image’ of a tank mount mod, I see in Andover the later models have a ‘fixing strap’ to accomplish this.

Yes.
The yoke pic was original to my purchase, bottom was not very pleasing to the eye, so I ordered replacement. Hopefully no issues to mate the old upper yoke.

Sorry. Wrong picture

Question on the swing arm clamps. Is the key objective to prevent deformation of the housing of the swingarm bushing? Just a reinforcement of a skinny metal tube? Thanks

 

[BusDriver330]

Concentrating too much on the content and not the contributors.

Thanks for the replies Bobz, oOnortonOo, L.A.B., Pete and Mwood

 

[BusDriver330]

I also noticed a front brake system upgrade from one of our appreciated parts providers. Anyone upgrade their drum brakes with this mod?

edit- 06.3410, https://andover-norton.co.uk/en/shop-details/16081/front-drum-brake-stiffening-kit

 

[L.A.B.]

I’ll rummage the Andover site for the coil mount. From my modern race builds(heavy tanks, I see the wt. distribution centered near the top section of the frame near the head. I have an image of a support mount over the top of the spine utilizing the existing hardware for mounting the tank front section. I’ll post if I engineer something.

Here's the later coil mounting bracket.
https://andover-norton.co.uk/en/shop-details/15885/coil-mounting-bracket-06-2231-06-2490-

When bolted to the tank brackets they can't sag (and then break) although a piece of sheet steel or alloy achieves the same.

Question on the swing arm clamps. Is the key objective to prevent deformation of the housing of the swingarm bushing? Just a reinforcement of a skinny metal tube? Thanks

The swingarm spindle can become loose inside the cradle tube (as it is held in place by one small central bolt) which can result in swingarm play that affects handling. The Kegler mod. clamps the spindle tight within the tube.