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PostPosted: Fri Dec 21, 2012 1:52 am 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
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Joined: Sun May 25, 2008 11:03 am
Posts: 18207
Location: Sunny Glasgow
My tuppence worth is to as said soak it in cleaner then wire wool or a file to get a good look at the problem.If it is splitting then it might only be a matter og a bit of welding and dressing off. :?


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PostPosted: Fri Dec 21, 2012 2:09 am 
Old School Grand Master
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Location: The Home Of Mountain Biking, And All Great Things.
Were you planning on a complete respray?

What is it anyway?

Without cleaning that area up a little it is hard to guess what is happening.

If you were planning on a respray I would go ahead and put a torch on it once you have tried soaking it a few days.


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PostPosted: Fri Dec 21, 2012 9:13 pm 
eBay Outing Master
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Joined: Sat Nov 21, 2009 3:53 pm
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I would scrape away the paint at the very top flat end, not the tube itself just the top to see if it is a shim or collar then with the paint exposed if it is a shim then you will be able to plusgas the whole shim from the top and lube,soak and let rest a few days for a few times and try again


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PostPosted: Sat Dec 22, 2012 9:55 pm 
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Joined: Wed Feb 20, 2008 12:21 pm
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Location: Lost in Translation
It's a reinforcing sleeve, commonly seen on mtb seat clusters. The sleeve and tube haven't been joined correctly, and that's led to this crack.

The bike is an MBK Ranger Hi-Tech:

http://www.retrobike.co.uk/forum/viewto ... ?p=1765755

What to do? I think I would start by cutting out as much of the post as possible, then going in with a reamer and/or caustic soda. The crack could probably be filled with braze, but I don't think it's likely to be a problem in the long term, and it would be a shame to lose the original paint.

In any case, it's a £15 frame. It probably makes more sense to recycle it than pay for a repair.


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PostPosted: Fri May 03, 2013 8:09 pm 
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Joined: Sun Jan 29, 2012 12:38 pm
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Location: High Wycombe, Chiltern Hills
Just a quick update on this project...!

I eventually tried the caustic soda method by pouring the solution in through hold in the bottom bracket. It fizzed, got hot etc and I left it for a few days rinsed and repeated a few times. As there appeared to be a lot of solid seat post in the frame I'd thought I'd give it some assistance with a drill...

A few broken drill bits later I decided to pass it on to my old man who works in metal fabrication. He assured me he'd have the hardware to drill through anything...

He fixed the frame up to a machine, but he could only drill about 2-3 inches down into the post until he hit something else that was too hard to drill through. Could this be some kind of residue left behind from the caustic soda?

As expected, loads of black liquid stuff came out when I rinsed the frame through after using the caustic soda. Just wondered if anyone else had seen something like this before?

Thanks!


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PostPosted: Fri May 03, 2013 9:33 pm 
retrobike rider
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Location: Manchester
Caustic Soda won't make anything harder. It will leave behind the other elements that are in the alloy, that's what the black stuff is. Again, it won't be hard.
If its only 2-3" down then you should be able to see it with a powerful light. Was the frame definately lined up? The drill could have been hitting the frame and with it being a harder material feel like it wasn't cutting it? No offence to your dad :)

We all love a good mystery on here so take a picture with your camera flash on and post it!


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PostPosted: Fri May 03, 2013 9:38 pm 
retrobike rider / Gold Trader
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Joined: Mon Jun 22, 2009 11:09 am
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Location: Devon
Rampage wrote:

We all love a good mystery on here so take a picture with your camera flash on and post it!


True


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PostPosted: Fri May 03, 2013 9:55 pm 
Retro Guru

Joined: Sun Jun 20, 2010 4:39 pm
Posts: 1455
did your father's ream hit the top bottle cage boss?
i had this with my rockhopper. i used an airsaw with a full length hacksaw blade, and sawed the post along it's entire length, then inserted a drift through the hole in the bb shell, the one the cable guide screw uses. smacked the drift and out she came.....took about an hour. and at times, i did get bored sawing the post, but all the time i saw swarf falling out the frame, i told myself "there's less metal to cut through now" :D


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PostPosted: Fri May 03, 2013 10:23 pm 
Retro Guru
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Joined: Sun Jan 29, 2012 12:38 pm
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Location: High Wycombe, Chiltern Hills
I had tried drilling a hole horizontally into the post through the slot below the seat pin clamp. I could barely make a mark with the drill as the metal was so hard. This was the same area that my Dad could drill down to before the drill got stuck.

It seems like the area where the seat post goes from solid to tubular is made of some unworldly substance, impenetrable by even the toughest drill! :shock:

I'll try and get some pics to see if anyone has any ideas.

I might try another dose of caustic soda, just to see if it reacts with the post again.


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PostPosted: Sat May 04, 2013 12:09 pm 
Gold Trader / MacRetro rider
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Joined: Thu May 06, 2010 10:05 pm
Posts: 5644
Location: Aberdeen
There's not the remnants of an earlier (stuck) seatpost wedged further down the seattube is there? Saw this before on a frame I bought, previous owner had got most of the stuck post out but given up on the remainder and just rammed the new post in anyways.


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