RADBMX.CO.UK
Technical & Reference Section => Tech and Restoration => Topic started by: 750Rush on March 17, 2012, 02:27 PM
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Well, I thought it felt slightly heavy when I bought it, but now I know why.
After filling the seatpost with coca-cola and letting it sit for the morning, I attahed the stem to it, them the forks to the stem and with some more WD40 had a good old twist (it was very stiff) this is what I found:
(http://www.radbmx.co.uk/archive/albums/w265/750Rush/P1050981.jpg)
(http://www.radbmx.co.uk/archive/albums/w265/750Rush/P1050989.jpg)
(http://www.radbmx.co.uk/archive/albums/w265/750Rush/P1060003.jpg)
(http://www.radbmx.co.uk/archive/albums/w265/750Rush/P1060004.jpg)
(http://www.radbmx.co.uk/archive/albums/w265/750Rush/P1060005.jpg)
Nothing like a big iron rod to make a super light race bike :-\
So much for what I thought would be a nice blue rental seat post too.
The seat post was twisting off the iron bar. I've tried to twist the iron bar out with some molegrips on it, but it won't shift. My question is, how the heck is it stuck in? I know there is a small crack on the frame where the seatpost inserts, but wouldn't it have been easier to weld that back up?
Any help or advice would be much appreciated as I have already paid far too much for this bike as it had a cracked rear tuff and now this :-[
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I would hazard a guess that you have a seat post stuck in there and someone has hammered the bar down into it to hold the post on the top
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How do I get it all out?
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you could try welding a bar on top of post forming a "T" then put it in a vice and try turning it :daumenhoch:
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You need to get a big slide hammer,
Drill and tap the end of the bar,screw a bolt in there,and attach it to the slide hammer :daumenhoch:
get someone to hold the frame and get hammering :daumenhoch:
looks like this
(http://www.radbmx.co.uk/archive/albums/x241/LOUSHARDWARE/CT1054-1.jpg)
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flip it over and stick the rod in a bench vise, do it up FT and give the frame a twist, and/or caustic the rest out :-\
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I might suggest some thing else before you try that lot - right see if this makes sense
The original owner has a renthal seat post but wants to take it out - snaps it off down in the seat tube - some clever bloke says you never get it out, but if we get another seat post the same, we can then cut it down and stick a rod of metal between the two to join them together ~ with enough new seat post down the seat tube it will stay they as the metal rod is holding both in - lock it down with a seat clamp and hey presto your ready to go !
i would suggest trying the caustic soda route
i had a renthal post stuck and they do seem to weld/bond them selfs in well - take a little while to do but might be the best way and not twist the frame in any way
if the bottom bit of seat tube is renthal, then it might melt out and the iron rod will brake/drop out and you will then have a clear empty seat tube to use
it's just a thought before you twist the frame or try to drill out ?
what do you lot think ?
cheers B ;)
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JESUS :shocked: ive seen a few stuck post threads but that is the worst by far :wtf: good luck mate hope you get it sorted :daumenhoch:
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they do come out - in the end ;D
(http://www.radbmx.co.uk/archive/albums/tt183/ELEVENTEENBENDYCAT/SNC10613.jpg)
(http://www.radbmx.co.uk/archive/albums/tt183/ELEVENTEENBENDYCAT/SNC10616.jpg)
(http://www.radbmx.co.uk/archive/albums/tt183/ELEVENTEENBENDYCAT/BMX/SNV11190.jpg)
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It's ok getting the metal bar out but then how do you get the rest of the old seat post out :-\
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the causic sode eats the alloy metal and dissolves it - it just turns to a mush that you have to wash out ever so oftern and put some more stuff in with hot water - in the end it's all gone
takes time, but is a good way if you are not sure that you don't want to damage it or know how to drill it out !
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the causic sode eats the alloy metal and dissolves it - it just turns to a mush that you have to wash out ever so oftern and put some more stuff in with hot water - in the end it's all gone
takes time, but is a good way if you are not sure that you don't want to damage it or know how to drill it out !
That's the only way then or a machine shop to drill it out
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I've just got back in. Many thansk for the advice. Where can you but caustic soda from, B&Q?
Will it damage the chrome if it spills?
I suppose the tube will need re-chroming anyway once I can find someone to weld it?
Sorry for all the questions!
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Caustic will only damage non-ferrous metals... :daumenhoch:
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should be ok on chrome - but as you say re-chrome or a paint will be on the cards
you can get it on ebay - maybe ask other members which they like best
does take a bit of time - but works
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Yeah good advise bendy. Caustic soda mixed up strong. Remember to be gloved up etc and away from kids as it is nasty stuff. You will need to do it in a well ventilated area as well. Be patient and the alloy post will break up leaving you with the steel rod which be loose. :daumenhoch:
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Many thanks everyone. Some project this is turning out to be :2funny:
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wouldn't be as fun if it was too easy >:D ;)
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Yeah good advise bendy. Caustic soda mixed up strong. Remember to be gloved up etc and away from kids as it is nasty stuff. You will need to do it in a well ventilated area as well. Be patient and the alloy post will break up leaving you with the steel rod which be loose. :daumenhoch:
Caustic ain't gonna eat up a solid iron / mild steel bar anytime in the next 20 years, surely? :shocked:
Alien blood is what you need! :daumenhoch:
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glen sorry Rich ;D if the iron rod is in the rethal alloy post at the bootom of the seat post tube, it will come out easy ;)
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Will this stuff from Homebase work?
http://www.homebase.co.uk/webapp/wcs/stores/servlet/ProductDisplay?langId=110&storeId=10151&partNumber=799726
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Yes thats the stuff :daumenhoch: Definately go for dissolving the ally seatpost from around the bar and seatpost tube ;) Use wam water 4 the caustic and do it where u can keep it walm if u can ;) I use a blow torch 2 reheat mine when its gone cold . This will b slowly slowly catchy money time tho ::) Don't expect it 2 work in minutes. wash out the mixture after a day and refill etc .
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Took about 3days or so for mine to dissolve .. Worked really well :daumenhoch:
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is the post that's stuck in there definitely alloy and not steel?
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Find in a couple of years when it's not shifting that much ;D
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I've no idea, but it's got to be worth a go. I don't want to keep it as it is because it's so dam heavy!
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burner weight ;D
well hopefully it is as i said - the cut in the top half of the seat post, should mean it had to slip over the metal tube and the metal tube should be hammered into a old bit of renthal post which is welded it's self into the frame - so hopefully it will desolve out and drop ;)
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I put some caustic soda granuels in the post with some boiling water and left it for the night. It hardly took any of the mixture as is seems solid about 1cm down into the frame. It fizzed a bit, but no frothing like in you Bendy's pic. I emptied the few drops this morning as I didn't want my kid to touch it today. I'll have a look when I get home tonight, but I think it might need machining out or something more severe :'(
I have thought of getting in there with a small drill bit to see if they welded the iron rod in its central position within the frame tube. I thought I could drill small holes around it and try to get some more caustic mixture in underneath and around. If I can get enough drilled holes in there, it may weaken it enough to come out?
If it does come to machining it all out, and then getting it welded, can anyone recommend anywhere that could do it?
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Yeah drill some holes around it if you can get a drill in to do it. Then the caustic. An impregnate it more. :daumenhoch:
This is very much a waiting game. So patients is the word.
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the person or people who did this deserve an awards for being muggy c**tS !
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Is there a hole into the seat tube from within the bottom bracket shell?, if so, you could try doing the caustic treatment from that way, might get a bit more in.
MM
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Nope, there isn't.
I'm getting the drill out tomorrow :10_2_12:
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(http://3.bp.blogspot.com/-GKXj_CVNjPo/Tf0yb_1gFKI/AAAAAAAAAD8/JkVyMZOVqeA/s1600/NukeOrbit.jpg)
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get it fully drilled out mate , but get a specialist do it .. be a sad day if you popped a hole through the seat tube :-[
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I'm going to have a go with ting drill bit over the Easter weekend.
I've just donated money for a site supporter tag to give me some good luck!
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Phil commented earlier ..He s your man for the job
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It takes time for it to happen - slowly slowly catchy monkey - it will work, give it plenty of time - put it as a side project ;)
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The iron bar is out!
Having clamped it in my shed vice nothing happened. I took it to my brother-in-law and his vice is much sturdier, and after filing some flat edges, the bar came out in his vice with a bit os pursuasion and wd40. It was 10-11" long and screwed into the remains of the other hald of the renthal seat post.
We drilled the middle of the renthal out a bit, and are going to have a go at getting that out with a slide hammer, failing which I'll revert back to the caustic soda option now there is room to put solution down the tube.
Result!
Anyone know of a good place to get the frame and forks re-chromed?
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Congrats mate - result :daumenhoch:
Carl "In2bmx" has a decent chromer he uses ;)
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:daumenhoch:
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Nice one, sounds like you nailed the hardest bit. :coolsmiley: