New Guy with a barn find

Sorry i diagree with Ron L if the guards are repaiable repair them as to my understanding the 69-70 guards are differant to 71 steel and 72+ later stainless and unobtainable , i am currently also doing a 70 and maybe i am lucky i have a good metal finish panel beater at my disposal who has been able to repair my arigonals, i have also been able to have my rusty rims replated spokes re zinked [ cadium plating is not available here now] i beleive in "do it once do it right" maybe if it takes longer due to dollers so be it but to me there is nothing worse than pulling it down later to finish it, to me its value is in its arigonality and yes i would stay with Amal's but deffernately fit an electronic ignition.
just my view Al

I guess if you're a stickler for originality re-chroming is the way to go. But what's the point? If it's been restored it's not original, is it? I'm with Ron, stainless steel and alloy. Given enough time, those expensive re-chromed parts will begin to take on a nice patina of rust.

I've got the same issue. Do I rechrome my fenders at $340, or buy stainless ones for a bit less, but the stainless ones, the front is a smidge larger which will require new stays, and the rear one I am not sure the holes are correct. I made the choice to rechrome.

Dave
69S

Sorry guys i dont want to sound like a moaner, i have a freind who has spent over $250 to bring a usable second hand guard into the country for his 69S as it had been fitted with a later model guard which would not alow the arigonal seat to fit properly.
just my view Al

Everything is pricey in Kiwi isn't it? It seems to me that a good metal worker could make the later one fit, but that gets into money too if you have to pay full rates.

Whatever else you do DON'T drill holes in the frame tubes (unless you're a well qualifed structural engineer)!

The frame is a fairly sophisticated structure, considering it was designed before NASTRAN and all the other clever programs. The existing welds and holes were very carefully designed to be in the lowest streesed areas so as not to introduce any stress raisers. If you absolutely must drill holes, drill them as close to the tubes' cetnerlines or adjacent to welded/brazed joints as possible.

After doing a lot of structural strain measurements on the frame when I was at N-V, I can categorically say that extra holes are definitely not a good idea! There may be some sound structural mod reasons for doing so, but please, don't do it just to tidy things up. Fatigue cracking and catastrophic failures may result.

I've seen a lot of folks drill the frame to install wires. Personally I avoid drilling and welding on a frame unless I have to. I've also seen choppers where the hole in the frame caused a crack to start. Commando frames I view as touchier than some frames, I guess the stress problems on the earlier ones make me think that.

frankdamp said:

Whatever else you do DON'T drill holes in the frame tubes (unless you're a well qualifed structural engineer)!

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Thanks for the advice but you should have told that to the moron who did it to my frame once upon a time. But that guy was intelligent enough to make sure the loads on the frame could never be significantly high - because he replaced the rear sus units with rigid struts and fitted an extra long Betor-Kawa fork thingie to give a rake somewhere in the region of 45deg. Just from pushing the bike I'd say that anything higher than walking speed probably won't work.

I'm really glad he didn't touch the engine and gearbox apparently.... ;-) :roll:

The existing welds and holes were very carefully designed to be in the lowest streesed areas so as not to introduce any stress raisers. If you absolutely must drill holes, drill them as close to the tubes' cetnerlines or adjacent to welded/brazed joints as possible.

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The holes in question were drilled in order to partially hide the wiring and the clutch cable (!). IMHO only an absoluty braindead lunatic can come up with this idea. Luckily they're placed at relatively unstressed areas as far as I can tell (and I'm a design engineer for automotive structures btw) and I'll actually check the whole stuff by means of a "clever program" - but that's not going to be NASTRAN as that's the worst GIGA snakepit I've ever worked with. I'll have a chat with our master welder and either have these holes welded up or just get a new frame from AN. they're reasonably priced IMHO.


Tim

Frank ,sorry to hijack the thread , but what is your opinion ( or others ?) about the crosstube some people ( like Kenny Dreer ) weld between the front down tubes ?
I have been thinking about this , but hesitate to do it . Maybe better a little flex than a crack ? .

Ludwig the crosstube seems to me a sensible modification. It was one of the improvements on the Commando frame made by Norton on their Thruxton Club Racer to be sold in the mid seventies. If it's welded properly why should it be prone to crack :?:
Holland Norton Works do this modification on their "Perfect Commando" as well:

There is room for argument on the term "perfect", but that is one gorgeous Commando, and good enough that i'd keep it if it were given to me!

Wow, Love the look of the bike VERY clean!

Hortons Norton said:

Wow, Love the look of the bike VERY clean!

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Too clean to be a real Norton

nortonspeed said:

Frank ,sorry to hijack the thread , but what is your opinion ( or others ?) about the crosstube some people ( like Kenny Dreer ) weld between the front down tubes ?
I have been thinking about this , but hesitate to do it . Maybe better a little flex than a crack ? .

Ludwig the crosstube seems to me a sensible modification. It was one of the improvements on the Commando frame made by Norton on their Thruxton Club Racer to be sold in the mid seventies. If it's welded properly why should it be prone to crack :?:
Holland Norton Works do this modification on their "Perfect Commando" as well:

Click to expand...

Ludwig I put one in because I like triangulations but I did shim my front iso as to put no stress on those thin downtubes
As I did more frame mods I cannot say what difference it makes but the bike HANDLES alas it also bibbert een beetje

look 79x100 it worked so when I see You next time we will have to taste that Witkap

ludwig said:

Frank ,sorry to hijack the thread , but what is your opinion ( or others ?) about the crosstube some people ( like Kenny Dreer ) weld between the front down tubes ?
I have been thinking about this , but hesitate to do it . Maybe better a little flex than a crack ? .

Click to expand...

I put a crosstube in my frame 20,000mi ago and rode over the Alaska Highway without cracking it. The idea was to make a small incremental improvement in the lateral stiffness in the downtubes for the front iso. The tubes have such thin walls and are so long that they can't be expected to do much to locate the front iso laterally. Using a headsteady that takes on some of that load goes a long way lessen what the front iso has to deal with.