Orange P7 Shimmed seat tube problem

[Spibblo]

Building has commenced on my 1997 P7 frame, having spent time removing the lacquer, polishing nickel and adding new decals- looks ace. As per title though I'm having a problem getting the seatpost in. It goes in about 2.5 inches then just gets stuck. I have several posts, two original orange and a new one all in the right diameter 26.4. All doing the same so it's not the post but something wrong with the shim, which is the original Orange one. I have filed it inside to make sure it's free of any corrosion etc. I have tried another post which is .2 mm less diameter and that goes in ok but obviously that's not going to be suitable. Any ideas whats happening.. has something got between the frame and shim to narrow it? 2.5 is not enough post in the frame, it doesn't clear the welds on the top tube..

 

[hamster]

I had a similar problem and found that the shim had also acquired surface corrosion and needed a good tidy up inside and out. It seemed to have built up quite a thick layer of surface corrosion. My seatpost went form very sticky to smooth (with a film of grease on the post).

 

[rwm1962]

Have you tried sliding the shim to the top of the seat post & then inserting them together? If the seat tube is corroded where it starts to stick would be a clue. I'd go for a USE shim myself as they don't corrode & react with the steel seat tube.

 

[Spibblo]

Re:

Thanks guys.. is taking the shim out easy or evil? I sound negative, sorry. I think I know the shim may need to come out but not done it before. I actually have a spare shim I could use if all goes wrong getting the current one out.

 

[rwm1962]

I've mangled one that had corroded to the frame but squeezing it together at the top freed it enough to waggle it out.

 

[enc]

Re:

i tried (admittedly not too hard for fear of nreaking it) and failed to remove the shim on my P7 which looks to be made of plastic.
fortunately, my post goes in and out easily enough.
Have you tried shining a light inside the tube to see if all is clear?

 

[hamster]

Re: Re:

Thanks guys.. is taking the shim out easy or evil? I sound negative, sorry. I think I know the shim may need to come out but not done it before. I actually have a spare shim I could use if all goes wrong getting the current one out.

I dreaded removing the shim, but actually it was not difficult. A good dose of Plus-Gas a day beforehand definitely helped. PlusGas is amazing stuff. Squirts of it over 2 days and I removed an 18 year old exhaust manifold on Saturday, no bother. Bolts turned smoothly with no undue force.

The problem on mine was the corrosion between the shim and the frame which made up the extra thickness.

 

[Spibblo]

Re:

Thanks for replies.
I did have a look inside but will have another look with better torch. I think it's ok feels smooth. It's probably as Hamster experienced, corrosion between the shim and frame causing it to narrow. Water and debris must work it's way in through the slits in the shim. I don't have plus gas only gt85. I'll make a start with that while I try and get some plus gas.
I'll let you know how it goes, well I hope :shock: