Rear frame loop

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I have managed to align my rear frame loop to be central to the headstock & spine tube but am now looking at the height of it. Is it supposed to be parallel to the bottom frame tubes? The drawing I have found in this forum doesn't show definitely the angle of it when the bottom frame tubes are level. I fully expect it to need easing up after all those years of camping trips & youthful abuse!

Bob.
 

cliffa

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Hi Bob, "youthful abuse" oooh-errr. Anyway, there is a clearer image here:

http://www.rocbo.net/technique/norton_workshop/img/f/f04.gif

I reckon it should be parallel. If you can get a straight edge on the bottom of the bottom frame tube, according to that picture the distance between that extended line and the bottom of the loop toward the rear should total 514.32mm. So it you measure just behind the shock mount and it's that measurement it would be conclusive proof that it should be parallel. ( I don't think the 0.32mm will be important though :confused:)

Hope that helps,

Cheers,

cliffa.
 

Tornado

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My bike also has a drooped rear hoop...how did you ultimately bend yours back to centerline and how do you plan to bend it back to parallel with bottom tube if needed?

I'm thinking of something (heavy duty nylon strapping/2x4 wood etc) to bridge across top of frame just in front of shock mount top points to provide down force against which to push up from the hoop underside near the shock tops. The bridge could be strapped/bolted to my M/C scissor jack base under the bike. To provide the up force to the hoop...2x4 studs up to underside of the hoop close to the shock tops...maybe with another 2x4 across underside of hoop that the vertical studs abutt, to provide even force when the jack is expanded.
 
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It's very easy to bend back upwards a drooped rear loop. Frame upside down. Chunk o' wood under bend back point. Someone holds the head area and you push down on the end of the loop. Basically you do the opposite of what caused the bend. Cold of course.
 

Mr. Rick

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If the bike is not all pulled apart, I'd "just" remove the rear mudguard, and put a long stiff 2x4 under the loop and over the frame at the gusset where the rectifier is mounted. Wd that work?
 

Tornado

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Bike is fully assembled so no turning upside down to bend flat.
Concern I have for a pry lever as described is not bending each side evenly or not at the existing bend point. Would also need so way to hold rest of bike down against the lever up force.
Might work if I place a cross stud under hoop near the bend point and pry up against that.
 
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Thanks guys. Tornado. I bent it back to the centreline by clamping a piece of 2x2 box steel tubing to the rear loop & using an old sash clamp on the headstock to pull the box section over. A bit of heat in the shock mount areas & over she came.
I think to lift it up I shall clamp the frame down on my scissor lift with an additional clamp in the shock mount area & use a hydraulic bottle jack under the back end, spread across both tubes with a bit of wood. I cant see that a bit of heat will harm as it is only ordinary mild steel tubing, nothing fancy.
Cliffa. Rest assured that youthful abuse only consisted of too many passengers (2 or 3 at a time across rally fields), crates of beer etc. in my world!

Bob.
 

cliffa

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Thanks guys. Tornado. I bent it back to the centreline by clamping a piece of 2x2 box steel tubing to the rear loop & using an old sash clamp on the headstock to pull the box section over. A bit of heat in the shock mount areas & over she came.
I think to lift it up I shall clamp the frame down on my scissor lift with an additional clamp in the shock mount area & use a hydraulic bottle jack under the back end, spread across both tubes with a bit of wood. I cant see that a bit of heat will harm as it is only ordinary mild steel tubing, nothing fancy.
Cliffa. Rest assured that youthful abuse only consisted of too many passengers (2 or 3 at a time across rally fields), crates of beer etc. in my world!

Bob.

It's a wonder these last as long as thay have. Old Britts make strengthening support brackets, which I think are well worth adding if you are doing work in that area anyway.

http://www.oldbritts.com/38_200001.html


Cheers,

cliffa.
 

jug

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It's a wonder these last as long as thay have. Old Britts make strengthening support brackets, which I think are well worth adding if you are doing work in that area anyway.

http://www.oldbritts.com/38_200001.html


Cheers,

cliffa.
Adding these to my frame while the engine is out. Also putting 2 threaded bungs in the frame loop to mount the rear fender directly to the loop, doing away with the ineffective rubber mount (using vibration insulation between the loop and fender). No more cracked tail lamp ferings for me.
 

KiwiNeill

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Mr Rick

same as the method I used, heating beyond the shock gusset area and easing it up with a pipe, adjusting each side to make it symmetrical, looks better with slight uplift from level too.
All easily done with one person, bike complete and on centre stand, sounds like Bobolink did similar thing in a different way but works OK.

Dropped hoop looks even worse on Production racers, spoils the lines of the bike.


Can,t insert a pic directly from ipad via a url unless someone knows a way. I don,t use icloud.
 

Tornado

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Mr Rick

same as the method I used, heating beyond the shock gusset area and easing it up with a pipe, adjusting each side to make it symmetrical, bike.
Can,t insert a pic directly from ipad via a url unless someone knows a way. I don,t use icloud.
How do you stop the bike lifting up with this method? Seems prying with a lever arm under hoop and over the center spine cross plate
will lift bike up easily, no?

For adding pics from a file on your device, you must be a VIP member (small membership fee applies)...then your pics can be hosted by this site. Otherwise you can upload them to some other site that permits image linking. Like
PBASE.com or many others...then just copy/ paste the pic link address into the box that opens when you click the "image" button (looks like a landscape portrait, next to smiley face button) at top of the text entry area.
 

Tornado

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My plan of attack for the drooped hoop:
Take 2x4 of 2-3' long. Place it on top of a bottle jack which is a top of the bike spine gusset, block of wood/rubber mat beneath jack for stabilty/frame protection. Align the 2x4 with spine. Lash the forward end of 2x4 to the spine with high load Spectra or Vectran line out of my sailboat box of spare bits. This stuff can take ~2000 lbs at 3mm diameter...so 4 or 5 wraps around spine and 2x4 should be fine. Similar lashings at rear end of 2x4 above and further rearward of the
hoop bend points...the 2x4 is now a lever arm being pushed upward by the bottle jack and the weaker hoop sections will be the bits moving upward as force builds.
No net forces applied to bike vs gravity or suspension, so no need for external straps etc.
 

KiwiNeill

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Tornado
I used the last of my industrial sized oxy/acetylene cylinders with a big tip to preheat a 4" section of the hoop on both sides by the shock mounts (old shocks fitted)
Position the pipe to take the weight enough so bike doesn,t fall off the centre stand, around 200lb on the rear of my Mk3, then heat the 4" sections equally so they are a nice cherry red until you feel the steel bending gently upwards, check both sides equal. You don,t need a white heat! Only enough to bend the hoop, but a large source of heat works best.

Right click to select photos from PC/ipad library then left click to insert, like on my ipad email would be better for lazy people like me.
 
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If none of the above works , try using mind bending energy. Spoons and forks have been bent by pure concentration . Focus intently without interruption. Use the FORCE as an assist.
 

Tornado

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Tornado
I used the last of my industrial sized oxy/acetylene cylinders with a big tip to preheat a 4" section of the hoop on both sides by the shock mounts (old shocks fitted)
Position the pipe to take the weight enough so bike doesn,t fall off the centre stand, around 200lb on the rear of my Mk3, then heat the 4" sections equally so they are a nice cherry red until you feel the steel bending gently upwards, check both sides equal. You don,t need a white heat! Only enough to bend the hoop, but a large source of heat works best.
Sounds like a reasonable approach...but does the heat damage the frame paint and what precautions are needed to prevent damage to other frame attachments?
 

Tornado

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If none of the above works , try using mind bending energy. Spoons and forks have been bent by pure concentration . Focus intently without interruption. Use the FORCE as an assist.
We'll have to start calling you Ure Geller...

 
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