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Using heat on stuck/dimpled early CL77 fork tubes

blazesjake
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Using heat on stuck/dimpled early CL77 fork tubes

Post by blazesjake » Sat Dec 19, 2015 6:36 pm

Soi, I have the early style where the ability to use longer than necessary fender bracket bolts can dimple the sliders. i am wondering if anyone has had luck in using a torch to heat up the welded bosses to cherry red, then use a slide hammer to pull out the fork tube, thereby not damaging the tube or end components.

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G-Man
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Post by G-Man » Sun Dec 20, 2015 3:20 am

That could work, but may restult in distortion of the tube in that area. That's not a big deal as the sliding bush is much further down in normal operation.

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

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jleewebb
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exhaust expander

Post by jleewebb » Sun Dec 20, 2015 9:10 am

I used one of these on mine with some success.. http://www.autozone.com/test-scan-and-s ... e-expander ...heat would maybe have helped...I used a tractor jack to pull the tube out in the first place...
'62 CB77. "It's a rider."

blazesjake
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Posts: 12
Joined: Mon Nov 09, 2015 9:22 pm

Using heat on stuck/dimpled early CL77 fork tubes

Post by blazesjake » Sun Dec 20, 2015 9:27 am

Thanks for your reply g-man. In thinking of how honda made these sliders, I wonder if they went back into the sliders to align bore or ? after welding on the two mounting bungs and brake stay.I read the post on this subject from a few years ago, and did not see much conversation on this approach. If an torch brought the steel up to a dull red, lower than what the tube saw when it was initially welded, the metal should be soft enough where pulling the tube in slow movements might work. Alternatively, screwing a mounting bolt into the threaded bung and attaching a slide hammer to it, and then heating this same bung to dull red and pulling on it might be able to move the dimpled metal back. It would be a careful balancing act not to destroy the threads of the bung. But, like doing sheet metal work, many small lower impact blows are much better in shaping or moving metal.

blazesjake
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pipe expander

Post by blazesjake » Sun Dec 20, 2015 10:03 am

Thanks jleewebb for your reply. I think I saw your post from earlier-on this same subject. The tractor jack approach has got me to thinking that I have a t-post puller that I might use in the same fashion to separate them. I also have a exhaust pipe expander that I was thinking about using as you suggest. With light heat, I like this idea rather than dremel type removal of metal, if I can just move it back in place.

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G-Man
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Post by G-Man » Sun Dec 20, 2015 3:17 pm

One problem that I think you'll have is that the bronze bush will chill the very part your're trying to get hot as soon as you try and pull the fork stanchion past the dimple. I think that I just drilled straight through on one of my stubborn ones.....

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

blazesjake
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Joined: Mon Nov 09, 2015 9:22 pm

Test Summary

Post by blazesjake » Sun Dec 20, 2015 6:40 pm

G-man/ all
Well, not having had this construction apart I did not know what I might be dealing with. Here goes. I was in the shop, starting heating up the lower bung, and as I did so the internal spring pushed the slider out by about an inch. Yes!!!
From there, it became more restricted, and not knowing the construction materials on the end of the tube, all I could tell is that it was either differential thermal expansion of fork tube elements, or a distortion of the tube, that was causing the problem. Knowing that i was dead in the water, I turned off the torch and ceased operations. After things cooled, I went over to the shop press and gently pushed things back into the range of normal operation.
This front end has some nice looking collars which I would like to continue to use in this reconstruction/restoration, so I'll just mask and tape and use the current seals. I enjoy tinkering with old bikes, so I'll eventually get front end parts that can remedy this condition.

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