Frame Tube Material .

Matt Spencer

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Jul 25, 2010
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BS.980 - CDSI

Rear Subframe .
From P.R. / Thruxton thread ; put as title so it jumps in your face in SEARCH .

So Comments on welding / repairing / straigtening and such like not unwelcolm .

Like Repairing Squashed Downtubes cause some chopper nut put highway pegs clamped there.
Or was it a Crash Bar that screwed them .

As you will .
 
I dont understand what youre asking or relating too - maybe thats why youve had no replys - Perhaps you could write a proper link to what we're to look at and reword you question?
 
I never buy chopper shit. Once they have been at it, I don't want it. 'Because I can' is never a good reason for doing anything - they are stuffed in the head.
 
So Cold Drawn Seamless tube.

So all those words mean is the Commando frame was made with common low carbon seamless drawn tube. Nothing special other than it not being seam welded.

Cheap and easy to weld with basic welding equipment.

None of your special Reynolds tube or bronze welding, just standard off the shelf commodity grade cold drawn tubing.
 
Pretty sure the one I was given that had tryed to go through a mercedes , was SEAMED tube . As I cut it up , and went . THATS SEAMED TUBE .

was a 70 roadster . so not Italian either . Just mild steel tube I though .

BUT .

If one were wondering WHAT the TUBE was . the FACTORY says its BS 380 . or the subframe anyyway . AS people previosly have aske " Wots the TUBE ' .
 
Matt Spencer said:
Pretty sure the one I was given that had tryed to go through a mercedes , was SEAMED tube . As I cut it up , and went . THATS SEAMED TUBE .

was a 70 roadster . so not Italian either . Just mild steel tube I though .

BUT .

If one were wondering WHAT the TUBE was . the FACTORY says its BS 380 . or the subframe anyyway . AS people previosly have aske " Wots the TUBE ' .
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Matt
Are you okay?
Your recent posts are even more fragmented & lacking in coherence than "normal".
 
I have a 73 850 frame in storage as well with some light crushing scars where a P.O. clamped either highway bars or an oil cooler to them way back when . Don't much know how to proceed so it keeps sitting in storage .
 
Cut and reweld a new section be the easy ways to fix once the welds been cleaned up and painted no one will know.
 
The Swedish organization for amateur built motorcycles don't accept anything else than cold drawn seamless steel tubes.
We built racing outfits frames from braced aircraft grade CroMo tubes.
Once had my poorly designed broken Harley flathead frame fixed by by inserting a 4" long plug into the tube and braced in place.
 
Metric or Imperial frame.

The wall thickness is probably somewhere in the 2mm+ range (0.080" +)
I used ER70 (T.I.G) for some light repairs and also to weld the springinator pad to the lower cross tube.

Frame Tube Material . Frame Tube Material .

Unless the tube was severely deformed small dents could be brazed.
You can also drill a hole and punch deformed area's outward, weld close the hole then metal work the OD.

I lengthened (to rotate the backing plate CCW) the brake torque arm on my Moto Guzzi (which some genius had beaten in with a hammer to clear the tyre perhaps).
It was easier to machine an insert that included a backing for the root run.

Frame Tube Material .

Instead of an internal insert (tube) a heavy washer insert (band) with large ID can be used around 3 mm thick.
That will allow a weld backing and alignment but not stiffen the joint excessively.
 
I've just cut the rear part of an Italian made 850 frame - and it has a seam - I've bought a length off Ebay (UK) of the same size to weld back on once I sort my tube bender out.
 
My mate uses in-line flux bronze welding in all his frames which includes the one I have. Flux cored nickel-bronze is OK. But if you are butt-welding pieces of tube together, you have a problem. If you fit internal sleeves,you increase the weight, but it might be the best answer. I would not do it with a steel weld, unless you can heat treat it afterwards.
 
If you use internal sleeves you might consider internally tapering the sleeve ends facing away from the tube. A non-tapered end internally can be a break point (stress riser) depending on the location of the tube you are replacing and the flex it is put under (that is, you may not need to do this, but have a look and analyze anyways). Good luck!
 
Your recent posts are even more fragmented & lacking in coherence than "normal".

Aus. has a avgI Q of 98 , therefore 20 % wouldve been classed as morons as well as of convict originality . 80 5 would be lower than 120 I Q. heir LA CK OF SOBRIETY IS ALSO redily apparent .

We assume the SS is alliance to Adolf lot ?? ' ROB ' Robb SS before he robs you ??

Sorry folksb . match imsolence with insolence . The entire countrys innebriates .

Frame Tube Material .

Frame Tube Material .

I suppose these explain the abnormalities , besides the genetic ones and alcoholism .
Frame Tube Material .

Then in Queensland they cut all the forests down , theyve all been out in the sun to long .



Hasta la vista​

 
Matt Spencer said:
Id think if you replicated it ( Frame , cradle , swing arm ) in chrome molly , it might start to steer better , at the limit . Raise the game , as it were .

https://www.motorcyclistonline.com/blogs/dick-manns-1970-daytona-200-victory-mann-machine/ Theyre pretty much antique nowadays .

But so is a Sopwith Camel .
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That is an interesting article. In America in the old days, there seems to have been a preference for high horsepower bikes and blasting down straights. My 500cc Triton had slight shorter stroke than the Daytona 500, and it would power on forever. So on a really big circuit , it was quick - but for normal racing, it really needed a 6 speed box. - Only one CR750 came to Australia. It was a full bit racer with four megaphones, so was really quick in a straight line. It is still owned by Bill Paterson Honda and Tony Caccioti used to ride it. I was talking to Tony a few years ago when he was racing one of Rex Wolfenden's 1100cc CB750 Hondas. He said Rex's bikes are better, and he had even achieved an improvement in handling. He said he remembered the CR750 and was apprehensive when he started riding Rex's bikes - but Rex's bikes are much easier rides. The last time I raced, I rode my Seeley 850, under and past the three leaders in a race, who were on Rex's 1100cc Hondas. They are fast down the straights, but not in the corners. Most Australian road race circuits are at least 50% corners. In corners Honda riders need to be very careful, they do not turn tight and accelerate through at full blast.
 
In the late 60s, early 70s - very few people had bikes which really handled. Even what could be done with a two-stroke in corners was limited. What Peter Williams and Gus Kuhn did with Commandos was different. When a two-stroke flashes past you as you go down a long straight, they have a psychological advantage which can knock your bum in, unless you are patient. With my bike, I must brake as I enter a corner, then I accelerate down the next straight from just inside the corner. The danger is, when the other guys get going again, they can move in front of you, as you leave the corner. When that happens, speeds are lower but the differential is big.
 
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