David Jenkins
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| posted on 22/5/08 at 10:19 AM |
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Separating things glued together with PU
As the title says, really.
When I get my bike carbs sorted I want to remove the GRP air intake that's currently sitting on my aluminium bonnet - I plan to replace it with
a much shallower aluminium bump.
Trouble is, in a mad fit of insanity when I was building the car, I fixed it with PU and pop-rivets - I think the theory was that the PU would stop
it buzzing or rattling... as if I could hear it anyway!
I don't want to trash either the bonnet or the bump, so does anyone know a way of 'undoing' PU sealant?
cheers,
David
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02GF74
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| posted on 22/5/08 at 10:27 AM |
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For PU i have used a knife to cut it off as well as a dremel with a slotted reamer - both are quite time consuming.
there may be a chemical means like the silicon sealant remover stuff or paint stripper perhaps? Not tried that so it may not work.
Or applying heat to melt/burn it? again not tried it.
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indykid
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| posted on 22/5/08 at 10:43 AM |
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a snap off knife is good for such a job as you can work it in along the join and the blade is long and flexible. keep it well lubricated with water or
wd40 and it stops the blade jamming.
i cut a PU'd on back panel off an indy once.........never again though!
it's not a fun job but the end result is rewarding.
tom
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RazMan
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| posted on 22/5/08 at 10:47 AM |
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Cheese wire might do the job
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Duncan_P
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| posted on 22/5/08 at 11:05 AM |
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That was my initial thought as well, or how about one of those wire saws (if you can find one thin enough)
quote:
Originally posted by RazMan
Cheese wire might do the job
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David Jenkins
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| posted on 22/5/08 at 11:09 AM |
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quote:
Originally posted by 02GF74
there may be a chemical means like the silicon sealant remover stuff or paint stripper perhaps? Not tried that so it may not work.
Or applying heat to melt/burn it? again not tried it.
Chemical strippers would probably wreck the GRP... heat too.
I might try cutting it first.
Got to sort the carbs though, before I tackle this!
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iscmatt
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| posted on 22/5/08 at 11:53 AM |
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Another piece of advice with doing this is that it will be time consuming but don't try to do it quickly, accept it will take a long time and do
it slowly, take you time!! I'm sure everyone here has tried to do a job/finish off quickly and regretted it due to making a small job an
expensive repair job.
Also when removing PU from bodywork, once the air take is off, a finger nail is a good tool for scraping off PU, won't scratch the bodywork,
though again, time consuming and also you end up with a bit of a sore thumb 
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Bluemoon
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| posted on 22/5/08 at 12:18 PM |
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As it's an ali bonnet, I wonder if nasty brake fluid would do the trick, something must desolve PU I would guess brake fluid might...
Dan
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chrsgrain
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| posted on 22/5/08 at 12:31 PM |
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Yup, brake fluid is the thing - found out it ate PU by accident! 
Chris
Spoing! - the sound of an irony meter breaking...
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Mix
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| posted on 22/5/08 at 02:39 PM |
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Hi
Piano wire, cheese wire, guitar string, will all work far better than trying to use a blade. You should be able to push the wire through the joint
using a pair of pliers and then gently pull it around the joined surfaces. Not sure how you would remove the residue though.
Mick
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David Jenkins
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| posted on 22/5/08 at 02:53 PM |
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quote:
Originally posted by Mix
Not sure how you would remove the residue though.
Not too worried about that, as long as it doesn't end up all lumpy. I plan to fit the replacement hump in the same location, so it'll be
covered.
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eccsmk
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| posted on 22/5/08 at 03:11 PM |
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i have some of the wire left from having a new windscreen fitted
if i can find it i'll send it to you 
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pewe
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| posted on 22/5/08 at 03:20 PM |
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Screwfix do Sealant Remover for silicone and Acrylic - don't know if it'll touch PU though.
They also do Foam Eater for PU foam @ c.£10 a pot though.
B&Q should also do it.
Cheers, Pewe 
[Edited on 22/5/08 by pewe]
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charlierevell
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| posted on 22/5/08 at 04:15 PM |
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I used a decent and very sharp snap off blade type knife. You can stick the blade out a long way and use its flexibility... might need a few blades
for the whole job to keep them sharp.
PU seems to stick very well until you free a corner and twist it.... then its not tooo bad!
An alternative to a nail is a surf board wax comb... sharp plastic edge that wont damage the GRP.
Tango orange is an 'IN' colour!!
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