Commando 750 SS Frame Spec

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Hunty

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Mar 25, 2013
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G'day
I have a 1971 Norton Commando 750SS that is in need of a new frame. I ma after some help identifying the correct frame for it as many commando frames I have looked at have all had minor differences. Apart form the obvious one of where the centre stand is. There are several differnces in holes that are drilled n the plate across the frame at the rear where things like the indicator relay bolt onto and also steering stops on teh front of the head tube. Does anyone have the definative answer as to what the frame came off the line like or know where I can perhaps start looking?

Many thanks
Piers
 
Hunty said:
I have a 1971 Norton Commando 750SS that is in need of a new frame. I ma after some help identifying the correct frame for it as many commando frames I have looked at have all had minor differences.
Click to expand...

According to Roy Bacon's info., 750SS production fell within the serial number series 145234 - 150723 (only a certain percentage would have been SS models) and there was only one frame part number (062002) listed for 1971, so it may be reasonably safe to assume the SS model had the same frame as other 1971 models from around the same period (unless anyone else knows better?) and the same frame part number continued for 1972.

Assuming any potential frame still has its original certification plate stamped with the 6 digit serial number then you'd need to look for a frame within the '71 -'72 series. A '73 750 (22xxxx) would be also be a close match but a pre -71 750 frame or an 850 (3xxxxx) frame would not be suitable if you are looking for an exact match to the original frame.

1971, 141xxx - 15xxxx
1972, 200001 - 21xxxx

Identifying a frame by serial number can never be guaranteed 100% accurate so you still need to satisfy yourself that any prospective frame is the correct item.
 
If you are looking for an exact match, you will need to find a 1971 frame. That frame has the side stand that mounts inboard of the outer frame tube and with a pin. Unfortunately their is a reason this design was only used for one year. The pin clips were easily lost and often caused the stand to jam into the pavement at speed! :shock: The factory (and now Andover and Old Britts) sold a weld on lug to convert these frames to later design sidestands.

If originality is not the most important, then go for a 1972-75 frame. These frames are interchangeable.
 
Ron L said:
If originality is not the most important, then go for a 1972-75 frame. These frames are interchangeable.
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Not exactly interchangeable, unless the (admittedly minor) difference in steering geometry between 750 and 850 frames is ignored?

Maybe better to find a replacement 750 ('71-'73) frame if possible?
 
Not exactly interchangeable, unless the (admittedly minor) difference in steering geometry between 750 and 850 frames is ignored?
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Which is why I said "interchangeable" and not "identical". If the 1 degree head angle difference on 850 frame is a concern you can always use an 850 triple tree. The significance of that 1 degree seems to be debatable by some. I don't have a dog in that fight as I have always matched the triple tree to the frame.
 
I have two 1971 S/S and the early one has the side stand lug on the outside of the frame so the skid plate will fit tight.The later one that I am working on now has no side stand and it never had one ,It has a centre stand that has a small skid plate that is removable.I have been told that this plate was something that was added but it looks factory.One of mine has a 21 inch front wheel and the other has a 19 inch In the tests for the early one they say it has the 21" wheel.I am away but will be at home in june if you need photos or for me to measure anything no problem.robertsfive@shaw.ca
 
Ron L said:
Which is why I said "interchangeable" and not "identical". If the 1 degree head angle difference on 850 frame is a concern you can always use an 850 triple tree. The significance of that 1 degree seems to be debatable by some. I don't have a dog in that fight as I have always matched the triple tree to the frame.
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Indeed, but perhaps not everyone would know that? Therefore "interchangeable" could easily be taken to mean identical-as no reference was given to the steering geometry or yoke/tree difference between 750 and 850 frames. :)
 
bwolfie said:
http://www.ebay.com/itm/1971-Norton-Commando-750-Stock-Frame-/251251450520?pt=Motorcycles_Parts_Accessories&hash=item3a7fc0e298&vxp=mtr
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That's an earlier '69-'70 frame, as it has the cross member for the "frame mounted" centre stand. The 139xxx serial number also dates to late 1970 production so it probably isn't a suitable replacement.
 
bwolfie said:
http://www.ebay.com/itm/1971-Norton-Commando-750-Stock-Frame-/251251450520?pt=Motorcycles_Parts_Accessories&hash=item3a7fc0e298&vxp=mtr
Click to expand...

Hi Brent,
i would like to buy this frame but the seller dont permit me to write: please, could you kindly ask to the seller if he can sell me and ship to italy?.
Thanks.
Piero
 
L.A.B. said:
bwolfie said:
http://www.ebay.com/itm/1971-Norton-Commando-750-Stock-Frame-/251251450520?pt=Motorcycles_Parts_Accessories&hash=item3a7fc0e298&vxp=mtr
Click to expand...

That's an earlier '69-'70 frame, as it has the cross member for the "frame mounted" centre stand. The 139xxx serial number also dates to late 1970 production so it probably isn't a suitable replacement.
Click to expand...

Hi Les,
i have two 1971 with 134xxx and 135xxx serial number but both have the new frame with cross member ahead.
Why this frame has a 139xxx VIN?.
Ciao.
Piero
 
pierodn said:
Hi Les,
i have two 1971 with 134xxx and 135xxx serial number but both have the new frame with cross member ahead.
Why this frame has a 139xxx VIN?.
Ciao.
Piero
Click to expand...
Piero, please understand. 134xxx, 135xxx, and 139xxx you do not want and are old. Frames with cross member to mount centerstand are NOT new.

Your 71 frames and the frame on the Ebay are older than 71 even though they say different.

Do you have a tag with numbers on the frame neck to take a picture to show us?

Again, frame on Ebay (251251450520) you no want. Bad, frame is "Pezzo di merda".
 
I wouldn't think it would matter much which frame you obtained as long as you don't use the combination of head angle and fork yoke offset which gives you maximum instability , i.e. minimum trail and minimum head angle.
 
pierodn said:
L.A.B. said:
bwolfie said:
http://www.ebay.com/itm/1971-Norton-Commando-750-Stock-Frame-/251251450520?pt=Motorcycles_Parts_Accessories&hash=item3a7fc0e298&vxp=mtr
Click to expand...

That's an earlier '69-'70 frame, as it has the cross member for the "frame mounted" centre stand. The 139xxx serial number also dates to late 1970 production so it probably isn't a suitable replacement.
Click to expand...

i have two 1971 with 134xxx and 135xxx serial number but both have the new frame with cross member ahead.
Why this frame has a 139xxx VIN?.
Click to expand...



I cannot explain that. It may be just another of those strange inexplicable Commando mysteries. All I can say is those two serial numbers (134x & 135x) do not fit into the generally accepted sequence of events regarding the serial number timeline if they both have the forward mounted cross member instead of the frame mounted centre stand cross member.

134x/135x should date from around the late '69 to early '70 production period. What are the date codes?
 
acotrel said:
I wouldn't think it would matter much which frame you obtained as long as you don't use the combination of head angle and fork yoke offset which gives you maximum instability , i.e. minimum trail and minimum head angle.
Click to expand...

Hi Sir,
I dont interest to buy the older frame but i would understand if the older has a different yoke angle than 1971 frame and other differences ( not the rear cross member, center and side stand that i know).
Ciao.
Piero
 
" I wouldn't think it would matter much which frame you obtained as long as you don't use the combination of head angle and fork yoke offset which gives you maximum instability "

Thought that was the 71 Frame . :? at least the ' roadster ' etc chrome headlamp mount 750s ?

Unless you want a fully Std. Spec. machine , Id go for the best condition one you can get , structurally .
Faded grotty original paint wouldnt be hideing anything . 74 on or so has the higher rake & subframe
reinforceing shock mounts , so dont sneeze at a 850 one but tryn grab the triple clamps too .

This is the Autobahn version . For scrambling & tearing up alleys & go cart tracks the toeyer ones probly better .
For desert raceing youd use the 850 or early type bunny ear / triple clamps , so as maintain way through the sagebrush .

:mrgreen:
 
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