Commando Frame rake repair info needed

baz · Feb 14, 2017

Rohan said:
I'm curious why they could get to 27 degrees, but not 28 ?
That is only a very small increment....

The local frame guy here has a frame jig that is a large open steel cube, nearly a tons worth, that he can clamp and hold frames in - and uses a variety of hydraulic and chain adjustments etc that can push pull and drag frame bits in all directions. He is Harley trained to do this, but has adapted it to do about everything and is very in demand.
His queue of girder forks requiring attention would make most old bike makers blush...

actually one degree is quite a bit to move on a motorcycle frame ,but I would still want it spot on personally especially if using 850 yokes

Rohan · Feb 14, 2017

So it was OK to move it 5 degrees, but not that very last one !!
Getting it back where it came from is the order of business for frame repairers ?

Reminds of the story of the gent who set up as a frame 'repairer', and had a whole rush for one particular model.
Ages after, when he was long gone, folks finally got these things ready to assemble, they discovered that the kinks taken out of the frame were there for a reason !!

baz · Feb 14, 2017

Rohan said:
So it was OK to move it 5 degrees, but not that very last one !!

If that's what the experienced frame straightener says then "yes" the last one degree could be too much on a damaged frame

Myford · Feb 15, 2017

Your frame must have passed mine on the way out. mine was being checked just before yours. They tweeked mine a bit. 5 mm twist to the swinging arm and headstock off centre line and twisted. Like you i thought they were a great firm doing a great job. Because i only live 8 or 9 miles away they even collected it.
Terry

gunnag · Feb 16, 2017

Getting it back where it came from is the order of business for frame repairers ?

Although I agree with this statement, I guess that sometimes its not practical or indeed safe to pull the frame back all the way. I can only be guided by their experience and knowledge and other than finding a new frame that good enough for me. What effect the 1 degree difference will make, I dont know, though I'm told it will make bike steer quicker.

Your frame must have passed mine on the way out. mine was being checked just before yours

Yes they mentioned they were doing a few Commandos at the same time prefer to batch them up. Seems that they get quite a few Commando frames in to repair, so clearly have some expertise in them.

baz · Feb 16, 2017

gunnag said:
Getting it back where it came from is the order of business for frame repairers ?

Click to expand...

Although I agree with this statement, I guess that sometimes its not practical or indeed safe to pull the frame back all the way. I can only be guided by their experience and knowledge and other than finding a new frame that good enough for me. What effect the 1 degree difference will make, I dont know, though I'm told it will make bike steer quicker.

Your frame must have passed mine on the way out. mine was being checked just before yours

Click to expand...

Yes they mentioned they were doing a few Commandos at the same time prefer to batch them up. Seems that they get quite a few Commando frames in to repair, so clearly have some expertise in them.

sounds like they know what they are doing, just keep in mind that the 750 frame was 27 degree rake with parellel yokes and the 850 frame 28 degrees with de raked yokes cheers baz

Bernhard · Feb 16, 2017

gunnag said:
Hi Steve,
I asked a similar question and the answer is something like the following:-
- the frame is rigidly secured in place in the jig using clamps and frame distortion/accuracy is then determined by taking measurements at varyious reference points
- Where the rake needs pulling out, a temporary yolks are fitted into the headstock using the upper and lower bearing seats as reference points, a long steering stem bar with a pointed end is passed through the temporary yolks and the pointed end is measured against a ruler on the jig
- Heat is applied to the frame in varyious positions as needed to make it pliable and then several tons of force is applied from the base of the steering stem lower bearing hole.The top bearing is prevented from moving forward by a stop bar. Several pulls may be needed to get the required rake angle.

Have a look at This video from about 10 mins 36 secs onwards. This essentually uses the same process but uses a cold pull to adjust the metal.

Interesting on how different owners of the Motoliner jig apply their own technique to frame straighten. When I smashed my bike into the side of a car the headstock was bent back to one side, they removed the complete forks and with the engine still installed in the frame which they insistenced upon, they put a 2 inch diameter bar into the headstock and hit the bar with a sledge hammer until it was right :shock: :?

But I must stress that this was not a Commando frame-each bend requires a different technique.

Commando Frame rake repair info needed

baz

Rohan

baz

Myford

gunnag

baz

Bernhard

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