bending the frame rear loop

My rear loop is bent to the right about 3/8" and it keeps me from lining up the mudguard (and the license plate) with the centre of the tyre. Anyone got good ideas how I can bend it without resorting to damaging forces? (No hobot, I'm not going to use the 300 Win Mag) I'm assuming the powder coat will take it. I'm thinking if I could find a long bar, like maybe a digging bar or something even longer I might be able to pry it over if I could attach the frame to something like a tree or the 6' bucket on the tractor. Hmm, maybe a 10' 2x4 on edge and a come-along tied to a tree?

I've always thought it was bent and since I had the rear wheel off, I went ahead and pulled the mudguard so I could line up the wheel with the centre of the frame again since I got some new stainless adjusters for Xmas. That's when I really noticed it, it's pretty obvious.

Dave
69S

That's going to take some force and you haven't much available frame to resist the reaction forces. If the frame was stripped I would cut and reweld...

I might work the left and right separately, blocking it with wood and clamps and tweaking it over with screw force.

Take your time, think it out, what else you got to do?

pvisseriii said:

....what else you got to do?

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Install the new front shoes and sand them into shape. General cleanup from the summer grunge. Get some anodized slides and try them out. Make a new fuel (safer) harness. Re-paint the side panels, the left one got gas on it. See if I can fix the few dings in the tank without a complete paint job.

Dave
69S

WHOA! STOP! ALTO! Belay the Action. You have wrong assumption of what's being revealed.

The Whole Power Unit is built ~3/8" off centered to the LH side with the rear rim centered on power unit not the spinal tube or rear loop which is also centered on spine and stem. The rear fender can not line up centered over tire and spine at same time so pick one or compromise as one of the deep unspoken secrets of Commando-doom. This also shows up with accurate tire center parallel alignment.
You may respoke rim to center on spine and then can fit 120 or even 130 past chain.

Main rear loop issue is old age droop and fracturing.

Hobot may have a point, my frame seems to be off (about 3/8ths of an inch) and there is nothing I can do about.

I might work the left and right separately, blocking it with wood and clamps and tweaking it over with screw force.

Take your time, think it out, what else you got to do?

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In addition to all the stuff you have listed, if your frame is powercoated you might be adding "cleaning up the little chips of powercoat on the floor" to the list.

I guess I better start doing offset research (again) as I thought the rear wheel offset was supposed to center that wheel in the frame but not the swingarm.

Before you decide it is bent you should measure angles from the gusset back to points on the rear loop so that you are forming triangles, compare hypotenuses (spell check on that).
Russ

Norton made swing arm to center on power unit and rear tire to center in swing arm so after Archimedes and Pythagoras lines in the cement as lasers to crude a line I now forgo all tools but sticking a finger in gap of tire and swing arm at front to get them equal-ish by adjuster and feel, then nip up and fly perfectly fine with rear off set ~3/8" to LH of spine and front tire center. Tire alignment refinement is mostly a waste of time as what really matters is the drive chain alignment. R leg of swing arm is a bit cocked out to make it look like its centered on spine looking at its ends from the rear view.

I'm not talking about the cradle/engine/swingarm to frame alignment at all, just the frame itself. If I put a straight edge down the main tube, which I did to check for the rear wheel alignment to line up with the centre of the headstock, if you look carefully at the perpendicular ruler, the center of that part of the rear loop should be at 10 1/2", but it's more like 10 3/4" or so. I can clearly see the center of the rear of the loop is bent to the right about 3/4" and it shows up when I mount the mudguard and license plate. It even looks that way when I just look at the loop. Last year when I spoked the wheels, I centered the wheel on the main tube/headstock, so it's probably within 1mm of center on the frame tube, or as close as I can measure.

I know it's not important, but I would just like to straighten it out if I can. It may be a spring project when I can strap the bike to the bucket on the tractor. As far as the powder coating coming off, I just don't know. I did bend my header about 1/2" with a long piece of wood and nothing happened to the chrome. It's not a huge correction. I've bent things with paint and nothing happens unless you make large corrections.

Of course I could just live with it.



Dave
69S

That's a good idea ludwig. I'll think about it over the winter and see what happens in the spring. It's not like I have to take the bike apart to get to it.

Dave
69S

But don't forget the seat placement, you know, those little rubber bumpers. Make sure they are now / or / will after future bend, hit the frame. Then there is the little matter of the seat/ holddown / knob / thing a wha giggie, and it fitting after the bend.

Thee Olde Triangulated Trees & Chainblock Trick , Eh Wot . :?

Yes , measure up the cross brace / shock mounts . Obviously the spine if straight has them where they ought to be .
Doing a car , you uses the odd cut ( stump? round bit ) of a tree to vector the chain line .AND PADS , 10 x 2 planks ,
or bits of off cuts like that , all nice and snmooth .
Good Hemp Rope , or Nylon MAINSHEET , The one for the BOOM , nice and strong. And stand with the yeeth & delicate parts
out of the line of fire should something part . :lol:
Tieing on a brace / U shaped bit , to slip over where you tie o & a plank vertical at the rear loops / shock mount .

Winding up the chain block , you get it all tensioned off , sureptitiously . Once the tensions on , GO EASY . its fairly light .

Mostly common sense and lines of sight / force vectors . Loop over & under shold stop you twisting it , insted . :lol: 8)

But spend plenty of time visualiseing the proceedure as you set it up .A narrow alley , a few boxes & a bottle jack could
do it to, TECNICALLY you work out which order of events occured ,and reverse it to avoid stretching / distortion .

Free , its just a bit of light One In. Tube . Not a great deal of force is required . But caution as to not TWIST where its
supported etc doing it . Hence the planks as jig to SPREAD THE LOAD , get a concentration , thats where it goes/ moves .

Use a string line from down the spine & a plumb bob to check it all first .

Shoot maybe you could just alter the clip that hold the fender enough to slide it over a bit, then put the tail light fairing back over it. We are talking about getting a quarter of an inch?

Russ

Dave,
Theres a number of ways to do this, none particulary easy but do-able. If you don't cut n shut, then applied force by pressing or pulling the section of frame has some warnings - what ever you do, the sideways movement must happen rearwards of the upper shock mounts. A very rigid compressive brace inbetween the shock mounts is a must and a solid immovable support to the side that the frame section is being moved toward. Another brace in-between the mid-section of the rear loop would also be a good idea to transfer the applied load to the opposite tube, otherwise the side with the applied load could buckle. On a BSA frame I used a plumb bob off the rear dangling just above the wheel centre to indicate the movement and when to stop. Don't be surprised that when you release the load the bugger springs back a fraction!

You could use a hydraulic jack mounted horizontal to press, or use a winch strap and 2 Ton "come-along-winch" like a Tirfor to pull. But in any case,the bike must be very rigidly supported on the side you are correcting.

Mick

hoot maybe you could just alter the clip that hold the fender enough to slide it over a bit, then put the tail light fairing back over it. We are talking about getting a quarter of an inch?

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Oh sure, take the easy route. Big deal, anyone can move a fender over a quarter of an inch. The beautiful, Zen, well engineered, breathtakingly executed, and, dare I say it, personally satisfying way is to move the bike.

Gelignites quickest , but requires some experiance . :lol: :shock:

Speaking of which , a three foot length of 6 x 2 pine , and giveing it a judiciously applied ' Big Whack ' would be enough
to shift it .
The Hydraulic Jack is incemental , take it a iota past , so it ' comes back ' to neutral , even if you have to push it back .

rvich said:

Shoot maybe you could just alter the clip that hold the fender enough to slide it over a bit, then put the tail light fairing back over it. We are talking about getting a quarter of an inch?

Russ

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No, we're talking about 3/4" and when you get the mudguard on, it's even more. It's quite apparent with the license plate and the rear wheel. I'm glad everyone is thinking on this one, but it's going to wait 'til spring when I can get the bike mounted on something that won't move. There's no way I can do it in the shop. Plus I need to talk to the powder coater and see if the coating will take the stress.

I put a carpenters framing square on the plate at the rear of the main tube and it's pretty obvious that the right side is sprung towards the right compared to the left side. For all I know it came out of the factory like this, but I did buy it with 4K on it, so it's not new to me.

I like the idea about bracing the parts that may incur stress while trying to bend it, but I'm betting if I can strap it in the bucket of my JD2020 tight enough and get a 'come-along' attached to the rear of the loop it will co-operate. I realize it will probably spring back a bit, I've had a bit of experience doing these sort of things. I'll report back in March. I'm just not going to worry about it this winter and it doesn't affect the riding, just looking at it from the rear.

Dave
69S

Smart man Dave...........Measure twice, cut once.

Ugh. The photo reveals the loop R of center of spine and tire sure enough. I've corrected that plus a droop on past Peel when frame was naked by slamming it down on carpeted cement floor, really hard, a number of times.

Best bet is slice it off just behind the shock mounts and find make two pins solid or tube to bang in couple inches forward of the joint and bang the loop on a couple of inches of pin sticking out while also banging it to centeralize. Holes made a couple/3 places on either side of joint to tack the pin in solid then seam filled in then grind back to hardly tell. This will not stress your mind or rest of the frame and scenery and will greatly stifle a dragging tail syndrome and is pretty easy quick task compared.
This is how Peel got backed ups, leveled up centered. For real cargo I also fit Z plate struts, which double to back up hard bags of which you could only fit one d/t hiding the high side pipes : )

Could also just lay in on side blocked at the shock area and padded over loop and jump up and down on it.

Well my first thought was to take the 20lb sledge to it, but that would put a dent in it. So I'm going to take it slow. As before, I'm going to mull over 'til spring, it doesn't keep me from riding or improving.

Dave
69S