1974 Commando frame issue

[TJBaker57]

didn't notice this until I had the engine out and began to clean the frame

Another question,,, when you were taking out the power unit,,,, did it seem like there was undue strain at the Isolastic mounts?

 

[jimbo]

Have you seen the size of the top tube 'spine' on a commando frame?

Wasco in the states is the only place I know, Richard is super knowledgeable with Commando frames

Wasco Frame Service

Motorcycle frame straightening and repair. Knuckehead, Panhead and Shovelhead restoration.

www.wascoframe.com

 

[Jonez69]

Another question,,, when you were taking out the power unit,,,, did it seem like there was undue strain at the Isolastic mounts?

No, not really.

 

[concours]

Another question,,, when you were taking out the power unit,,,, did it seem like there was undue strain at the Isolastic mounts?

A lot of this material has been covered. A quick search here on the forum. Will let you read and look at pictures for half the day.

 

[Tornado]

My 74 850 came to me with very similar down tube bends and conpressed areas. Presume highway or crash bars fitting at some point. I rode bike for many yrs, some 15k miles put on it under my ownership, never any issues. But it did always linger in back of my mind. When engine out work was done, i had the shop send it to a local frame guy who repaired the bends via cut/insertion of straight tubes/rewelding...and he put it on a commando frame jig to confirm all correct.
I believe Norman Whites restoration book describes how to deal with frame damage in this same way.

 

[ashman]

No throw it away and convert it to a Featherbed frame lol, no i have seen worse that that on frames and have straighten a few a British bike frames using home made jigs tie downs and a few car jacks and lumps of wood, best to straighten without using heat and stretching the frame a little over so the steel springs back, you might have to do it a few times to get it right.

Ash

 

[TJBaker57]

A lot of this material has been covered. A quick search here on the forum. Will let you read and look at pictures for half the day.

Will a search on the forum tell me if there is a lot of strain at the isolastic mount on the OPs Commando??

If there was a lot of strain there it may indicate a significantly bent frame.

 

[concours]

Will a search on the forum tell me if there is a lot of strain at the isolastic mount on the OPs Commando??

If there was a lot of strain there it may indicate a significantly bent frame.

Sorry, I read that one quickly and I thought it was the OP saying he had binding. My mistake.

 

[mdt-son]

Will a search on the forum tell me if there is a lot of strain at the isolastic mount on the OPs Commando??

If there was a lot of strain there it may indicate a significantly bent frame.

A "significantly bent frame" would be visible to the naked eye, and may call for a frame replacement.
I think some deformation could be absorbed by the rubber mounts - compression of rubbers is not a good measure for state of the frame.
The workshop manual has pictures with frame checking dimensions. I would go by them.

- Knut

 

[TJBaker57]

A "significantly bent frame" would be visible to the naked eye, and may call for a frame replacement.
I think some deformation could be absorbed by the rubber mounts - compression of rubbers is not a good measure of state of the frame.
The workshop manual has pictures with frame checking dimensions. I would go by them.

- Knut

I will try to explain what I was thinking.

In the manual the dimensions given for the distance between the front and rear isolastic mounting holes is 18.28".

Lets say as you are removing one of those isolastic mounting bolts that sucker is just stuck in there. As you finally force it out there is a bit of a clunk. You can see that there is no way you are getting that bolt back in that hole as it just doesn't line up. To me that would indicate perhaps that 18.28" specification is no longer met in this frame, perhaps due to the bends above the front isolastic mounting point.

 

[ashman]

I will try to explain what I was thinking.

In the manual the dimensions given for the distance between the front and rear isolastic mounting holes is 18.28".

Lets say as you are removing one of those isolastic mounting bolts that sucker is just stuck in there. As you finally force it out there is a bit of a clunk. You can see that there is no way you are getting that bolt back in that hole as it just doesn't line up. To me that would indicate perhaps that 18.28" specification is no longer met in this frame, perhaps due to the bends above the front isolastic mounting point.

Just bash the fu cker in, she be right lol

 

[Torontonian]

Just bash the fu cker in, she be right lol

I have a 73 850 frame with light crushing to both front tubes from a P.O. crash bar fitting . No bendings . I'm thinking filler will do it and repainting . History was "The Jumper " from Movie Production days . I worked in Movie Production for 6 years . Canada .

 

[TJBaker57]

I have a 73 850 frame with light crushing to both front tubes from a P.O. crash bar fitting

I cannot blame a previous owner for my little dents. I did that myself 50 years ago!! I have no intention of covering up these little scars. It's part of our shared history.

 

[Tornado]

I cannot blame a previous owner for my little dents. I did that myself 50 years ago!! I have no intention of covering up these little scars. It's part of our shared history.

So you are admitting to being a future Dreaded Previous Owner? Brave man!

 

[TJBaker57]

So you are admitting to being a future Dreaded Previous Owner? Brave man!

Well when this bike belongs to another,,, I won't be around anymore so I'm not too worried about that