p7 seatpost shim - removing

xtaffa

Dirt Disciple
Hi all, is there a safe and effective way of removing the - I think factory fitted - seatpost shim from my newly acquired 1998 p7?
 

mamadirt

GT Fan
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Lots of GT85 between shim and frame then dry off the inside and wear rubber gloves or latex dipped gardening gloves to gradually work it loose - easy for me though as I have small fingers 😉
 

xtaffa

Dirt Disciple
Right. Collective wisdom needed. Few days of multiple plus gas applications and niggling by hand and/or flat head, and this puppy isn't moving.

Looking down the tube there's a respectable layer of rust crust on the inside of the frame, so think this is corroded on.

Seatposts are one thing to get out, but a shim with sod all purchase is another.

I'd like to avoid caustic if possible, a) for downtime b) save my metallic paint from slop/spills, so thoughts on the following:

1) Use an internal bearing puller to lock in below shim and hit up with slide hammer.

2) Ask lbs to ream the shim from current 26.4 to 27.2. A lot of material to ream; can see a big labour bill and dirty looks after that, if they can do it at all.

3)Sheldon's dry ice crack shock method (+/-) the above..

Or is it really BB out, drain cleaner in time?


Thoughts massively appreciated.
 

old_coyote_pedaller

MacRetro Rider
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Not done this but I thought of using a tool similar to a headset cup remover.
Get a length of steel tube that will fit inside shim, cut 4 slots in it like headset tool, splay out then fit to end of length of rod so that splayed out end is facing up. Maybe if you can fit nut to other end of rod so you can put sliding weight on rod to make slide hammer.
Use in similar way to removing headset cups, push down past shim and pull upwards on rod, using it like a slide hammer probably best.
 

xtaffa

Dirt Disciple
Not done this but I thought of using a tool similar to a headset cup remover.
Get a length of steel tube that will fit inside shim, cut 4 slots in it like headset tool, splay out then fit to end of length of rod so that splayed out end is facing up. Maybe if you can fit nut to other end of rod so you can put sliding weight on rod to make slide hammer.
Use in similar way to removing headset cups, push down past shim and pull upwards on rod, using it like a slide hammer probably best.
Cheers for this, will get crayons out! I think this is what a blind puller does, but expensive/not sure lbs will have - and not sure any would reach down the 80mm or so needed...
 

xtaffa

Dirt Disciple
Right, after weeks of plusgas, agonising over caustic, and a call to local machine shop re. pulling, reaming etc., I followed said machine shop's advice and went down hacksaw route... sawed at slit and opposite, took 10-15min at most; hit first slice's lip with large flat screwdriver to pull away from wall, hit vertically down on it to drift away from stubborn corrosion at base, pulled out with narrow pliers, repeated lip bash on second slice, pulled away with narrow pliers again. Doneded. About 30-40min all told.

Owing to hooves rather than opposable thumbs, I put a tiny nick/cut into seat tube on expansion slit side right at top; that's the only collateral damage. Will fill that for peace of mind, wet and dry/wire wool then hopefully plastic shim winging its way from SJS should slot in tidily enough...


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enc

Kona Fan
Mine looked/looks plastic 🤔so left it in place... when I was polishing the frame
 
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