Frame check distances

Hi Guys
I have a 750 Commando frame that I think I have bent. Can anyone help me with the measurements I need to check this? Frame number is 141354 and I think is 1969.
Pete

Pete810 said:

Can anyone help me with the measurements I need to check this?

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Frame dimensions, pdf p.90
http://britmoto.com/manuals/Manuals/750_man.pdf

Pete810 said:

Frame number is 141354 and I think is 1969.

Click to expand...

141354 is more likely to be early 1971.

I think the most helpful thing I can offer is all's ya really got to aim for is easy enough assembly after bashing levering and wedging, which means that iso tabs at front and rear accept the iso mounts w/o much swearing and head steady can be bent and shimmed to sag neutral. Some run a tube thru the stem to check its cockeyed ness. Under spine tube can get bowed to one side and cradle plates can get bowed by flying hi sides, mostly by the launch than landing. Just running mostly straight on smack into something only bends the fork stanchions and maybe the yokes but like not survive one that bend the stem. All Commando have a slight arc in the main spine, like 1/8" low at ends by straight edge check. Swing arm are definitely a weak point in crash and impact loads and mostly shows up as unacceptance on putting the spindle back in.

Great info and advice thanks hobot and L.A.B.
Very much appreciated.
Pete

Any pictures ? ?

Get a large rubber sledge hammer & a Video . And HOLD IT DOWN . Still had all the teeth after a like episide . :lol:
Not that hard to straighten . Bottle jacks , 4 x 2 braces ( 2 x 4 in the U S ) and a solid doorway or two close concrette walls , Stairway ? . & patiance .Biggest factor .

most likely bent area is sagging rear loop. After discovering Peel was welded back on a bit droopy after powder coat, I put thick pad on cement and slammed the whole frame down on loop till eye ball pleasing lines again. Easiest reference point is empty crankcases in cradle w/o gearbox to guide ya on what to do next. Then shocks and swing arm cradle alignment for best chain sprocket alignment. Roll both stanchions together to get the best view of any bowing in them. Its mild steel frame that best responds to cold working, ie: plain brute force applied on wide enough cushioned area not to dent or crease the thin tubes. If front iso tabs are off to prevent mount insertion with only some determined bumping, you really got a hard one to fix. I needed to spread Trixies but nothing I did, 1/2" all thread spreader about to shear thread or wrench jaws off, plus heavy wood wedge and sledge hammering it barely gained a couple of mils even with the forces still applied when measured. I ended up cutting down the iso tube in 2 stages trial and error measuring once - but cutting twice so not to over do it accidentally. If it assembles decently then it'll handle decently I found, thankgoodness. Trixie got front destroyed by deer head on and then had rear shock torn out on hi side out of a Gravel drainage ditch log truck wedged us over the berm edge. Wiggled enough after had to get off to see why, then finish trip taking care as hinged so easy till new rubbers put in. Her under tube is like 3/8" off to LH, I think d/t it shattering my LH knee landing on it from hi side deer induced after knocking bike right out from under first. She is a dream boat to zoom around on, once good tires fitted and don't get LH drift I can detect and even no head shakes hands off, till lately as front tire getting wedge shaped. Still an un-tammed Cdo though so constant watching out to stay out of hinged zone that applies to all the best untamed Cdo's once pressed a bit too much in windy &/or lumpy leans. Can happen going pretty slow if conditions right and has nothing to do with straightness just innate with isolastic and spring tube chassis.

Thanks Matt and Hobot. It was a head on bingle into the back of a car. I straightened the forks and superficial stuff and reassembled some time ago. it went together OK but the handling is rubbish. Will check the dimensions from the Manual and report on progress.
Cheers
Pete