Bent frame?

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
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Red Gauntlet
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Joined: Wed Aug 19, 2020 11:22 am
Location: Dorset UK

Bent frame?

Post by Red Gauntlet »

More saga with this piece of junk '65 G80CS that I bought, one of my friends noticed that the rear shocks are not vertical, so measuring the frame it is 9" from the inner flange of the shock mountings on the bike but on the spare bit of rear frame I have it is only 8&1/2" , the swing arm appears to be correct as the wheel fits ok, however the spare swing arm I have is only 8" I do think that is bent though, both rear frame parts measure 8&1/2" at the centre spar. Could someone guide me please as to the correct dimensions so I can get the gas axe out and do a bit of modification.
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Joker_Bones
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Location: DORSET UK

Re: Bent frame?

Post by Joker_Bones »

My 64 comp frame which has the swing arm with the double lugs for the bottom shock mount as yours does.

Measures...
8 3/4" between the rear loop top mounts.
8 9/16" between the swing arm inner lugs.
All fitted and tight.
Sort of makes sense, the lugs on the swing arm are thicker than the pressed sheet of the top mounts.

That's just how it is.
It looks okay from the back, difficult to say if the wheel and shocks are truly vertical and parallel but nothing alarmingly out.
Red Gauntlet
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Location: Dorset UK

Re: Bent frame?

Post by Red Gauntlet »

Excellent, thanks for the info, I will get to it this weekend, looks as if the frame is correct dimensionally anyway.
Cheers.
mdt-son
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Re: Bent frame?

Post by mdt-son »

Hi RG, please check your swinging arm for twist causing legs to be out of plane. If bent (and many S/A are, unfortunately - a result of a crash probably), the rear wheel will tilt to one side and creates the impression shocks are not vertical nor parallel. I discovered the S/A of my G15CS had a serious twist. They can be mended in a jig, but I chose to seek a replacement.

Top mounts of your spare subframe looks twisted.

- Knut
bitza
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Re: Bent frame?

Post by bitza »

Place a steel rule across swing arms then a small spirit level , should show if arms are bent .
Red Gauntlet
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Posts: 182
Joined: Wed Aug 19, 2020 11:22 am
Location: Dorset UK

Re: Bent frame?

Post by Red Gauntlet »

mdt-son wrote: Sat Jan 27, 2024 1:06 pm Hi RG, please check your swinging arm for twist causing legs to be out of plane. If bent (and many S/A are, unfortunately - a result of a crash probably), the rear wheel will tilt to one side and creates the impression shocks are not vertical nor parallel. I discovered the S/A of my G15CS had a serious twist. They can be mended in a jig, but I chose to seek a replacement.

Top mounts of your spare subframe looks twisted.

- Knut
[That rear frame is from a 1966 scrambler that has seen some considerable action RG]
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