Retrobike Forum Index

It is currently Tue Dec 06, 2016 9:36 am

* Login   * Register * Search  * FAQ



Post new topic Reply to topic  [ 71 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7, 8  Next
Author Message
 Post subject:
PostPosted: Wed Jan 23, 2013 1:04 pm 
Dirt Disciple

Joined: Wed Jan 23, 2013 12:54 pm
Posts: 28
Location: Bedfordshire
Apologies for resurrecting a bit of an old post, but did the BB survive the process in the end? I'm about to do this to an old Specialized Hardrock I have as the hacksaw method has failed, I don't have a BB tool and even if I get hold of one, I'm expecting it to be a bit of a sod to remove!

Cheers


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jan 23, 2013 1:27 pm 
Devout Dirtbag
User avatar

Joined: Mon Jan 07, 2013 8:36 pm
Posts: 144
Location: Balls Deep
Love the swearing and the excited tone of voice!!

Wondering wether this method would work on seized bottom bracket cups?? :lol:


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jan 23, 2013 2:55 pm 
Retro Guru
User avatar

Joined: Sun Mar 14, 2010 2:33 am
Posts: 2922
Location: daaan saaaf
Quote:
Wondering wether this method would work on seized bottom bracket cups??


Steel cups in a steel frame - no.

Steel cups in an aluminium frame - yes, but not the way you want. :D


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jan 23, 2013 7:45 pm 
Retro Guru
User avatar

Joined: Fri Jan 13, 2012 2:28 am
Posts: 1057
Location: Near Gatwick
Matt87 wrote:
Apologies for resurrecting a bit of an old post, but did the BB survive the process in the end? I'm about to do this to an old Specialized Hardrock I have as the hacksaw method has failed, I don't have a BB tool and even if I get hold of one, I'm expecting it to be a bit of a sod to remove!

Cheers


You could saw the seat post off, cork the open end, flip the bike over and put the caustic though a bottle bolt hole. once you have thinned the post down a lot the ring the cork is in should come out easy.

I recently removed the remains of a seat post that had been hammered down the tube, I took pictures while I did it and video. I will sort some out if any interest.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jan 23, 2013 7:46 pm 
Gold Trader
Gold Trader
User avatar

Joined: Fri Apr 29, 2011 3:34 pm
Posts: 1576
Location: Haydock
xerxes wrote:
Quote:
Wondering wether this method would work on seized bottom bracket cups??


Steel cups in a steel frame - no.

Steel cups in an aluminium frame - yes, but not the way you want. :D


Lol.. Can just imagine..

Hello I need this bottom bracket out this frame.

Few weeks later.. Here is your bottom bracket sir...;)


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jan 23, 2013 10:12 pm 
Dirt Disciple

Joined: Wed Jan 23, 2013 12:54 pm
Posts: 28
Location: Bedfordshire
integerspin wrote:
Matt87 wrote:
Apologies for resurrecting a bit of an old post, but did the BB survive the process in the end? I'm about to do this to an old Specialized Hardrock I have as the hacksaw method has failed, I don't have a BB tool and even if I get hold of one, I'm expecting it to be a bit of a sod to remove!

Cheers


You could saw the seat post off, cork the open end, flip the bike over and put the caustic though a bottle bolt hole. once you have thinned the post down a lot the ring the cork is in should come out easy.

I recently removed the remains of a seat post that had been hammered down the tube, I took pictures while I did it and video. I will sort some out if any interest.

Might be worth a go if I can get a funnel, would have to use something other than a cork to bung the end though I think, there's several slits running down the length of the post from where I sawed it so presumably it would run down these and around the cork. It'd be nice to know if the bb housing was sealed from the seatpost on the bike, then I wouldn't have to worry about taking it out, or trying to pour caustic into the tiny bottle cage bolt hole!

Would definitely be interested in those. How many times did you refresh the caustic soda solution, and over how long?


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jan 24, 2013 2:23 am 
Retro Guru
User avatar

Joined: Fri Jan 13, 2012 2:28 am
Posts: 1057
Location: Near Gatwick
The seat post had been cut off and hammered down the tube, picture one isn't brilliant but you can just make out the top of the old seat post.

The cork is a bit of 19mm silicon hose with an expander in one end. An old head bolt and a few bit's of scrap plus a bit of threaded tapered scrap did the job. The cork just needed tightening by hand to seal, Picture two is clearly the cork.

The funnel is a bit of brake pipe, a scrap of tube and an old syringe. The brake pipe is ground to a taper, wrapped with ptfe tape and screwed into the bottle bolt hole, screwed in gently as it just has to stay in place[no threads were harmed in the **** of this seat post]. The syringe is taped to the top tube, I just poured the caustic in to the syringe. Picture three and four show the funnel.

I mix caustic by temperature/feel, it doesn't want to be to hot, otherwise it will boil when it meets the ali. Because I videoed some of this I stuck a thermocouple in the caustic, to see how hot I was mixing it[just trying to be flash] about 50º with the caustic in it was about what I usually mix it to. The water had come out of my dehumidifier and was whatever the temperature was a few weeks ago.

I poured 100CC in to the seat tube, I poured it in at about 4pm. The seat tube got hot but stayed touchable, it was still hot a few hours later[still doing something]. It had started cooling down when I went in for dinner at 7pm so I left it overnight. The next day I emptied the tube and scraped the clag out of the tube with a welding rod. Then I re-corked it and filled it with cold water to flush as much of the crap out as I could. Picture five is what it looked like when I drained the seat post, what you see in the seat post is the clag, which scraped out with an old welding rod bent into a loop.

I mixed another 100CC of caustic. This time I mixed it a bit hotter, after measuring the temp I figured I was doing it a bit cold;-) I mixed it and the temp was 70º. I poured it in and it boiled and steamed out of the other bolt hole, damaging one of the stickers;-( Oh well not the end of the world. I poured a bit of cold water in to bring the temp down, only 10 cc or so. It still felt hot a few hours later and I gave it another few hours then drained it. I scraped the clag out of the tube with an tube with my trusty old welding rod and washed it with fresh water. I had some black clag in the lin bin I had drained it into, but no seat post anywhere.

I twisted a welding rod and some rag up, like a bottle brush and with a cordless drill I gave the tube a clean. I poured some lanolin/white-spirit
in the tube to stop it rusting. Picture 6 is the clean seat post

I would have to guess at the amount of caustic used, I would guess less than a few hundred grams. When mixing the caustic I just sprinkle a little in the water and then swirl the water around till the caustic is dissolved. If you chuck in too much it will boil and climb out of the pot, if your holding it it will burn your hand, I know from past experience. So you just sprinkle a little in.


Attachments:
seatpost001.jpg
seatpost001.jpg [ 24.71 KiB | Viewed 342 times ]
seatpost002.jpg
seatpost002.jpg [ 29.67 KiB | Viewed 342 times ]
seatpost003.jpg
seatpost003.jpg [ 30.4 KiB | Viewed 342 times ]
seatpost004.jpg
seatpost004.jpg [ 37.91 KiB | Viewed 342 times ]
seatpost005.jpg
seatpost005.jpg [ 25.79 KiB | Viewed 342 times ]
seatpost006.jpg
seatpost006.jpg [ 16.79 KiB | Viewed 342 times ]
Top
 Profile  
 
 Post subject:
PostPosted: Thu Jan 24, 2013 9:23 am 
Dirt Disciple

Joined: Wed Jan 23, 2013 12:54 pm
Posts: 28
Location: Bedfordshire
Cheers for taking the time to post all that, really helpful stuff! I'm thinking that's the way I'll do it, just need to get some bits together to make a similar funnel device, and something to bung the end as the top of the post is such a mess. Wondering if plasticine might be worth a go...?


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jan 24, 2013 10:52 am 
retrobike rider / Gold Trader
retrobike rider / Gold Trader
User avatar

Joined: Sat May 09, 2009 11:46 pm
Posts: 3924
Location: East Riding of Yorkshire
I took the bottom bracket out to do my Richter and it made it all pretty easy.

I'd suggest you change the caustic soda pretty regularly, as it reacts pretty rapidly at first, but soon slows a lot as the concentration of caustic soda decreases.

If I remember correctly I ended up using one 500g container of caustic soda which cost about £1.50.

There's a few more details here:
http://www.retrobike.co.uk/forum/viewto ... 1&start=15
and a video here:
http://youtu.be/-dYnSVVDxrE

I wasn't bothered about the paintwork, but it would have been relatively easy to take more care and do it without any going on the paintwork.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jan 24, 2013 8:52 pm 
Retro Guru
User avatar

Joined: Tue Nov 23, 2010 9:00 pm
Posts: 392
I tried it upside down with the tube through the bottlecage hole technique, but after cutting the seatpost couldn't seal it properly so it all just ran through, didn't hang around long enough to melt much.

Best technique I found (shown in the vids on previous page) was just to fill the thing up, didn't have any affect on the BB, though clearly if you've got any aluminium parts on it they'll die of death.

All good fun eh what what?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 71 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7, 8  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: boswell, Google Adsense [Bot], Joe_Rides, M-Power, makster, raidan73 and 40 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

About Us

Follow Retrobike

Other cool stuff

All content © 2005-2015 Retrobike unless otherwise stated.
Cookies Policy.
bikedeals - the best bike deals in one place
FatCOGS - Fat Chance Owner's Group

Powered by phpBB® Forum Software © phpBB Group