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How to spread the seat post clamp

#1 2013-03-30 6:59am

webdevkit
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How to spread the seat post clamp

I am trying to re-install the original seat post and seat clamp on my late-80's GT Performer.

The post goes into the down tube no problem, but when I put the seat post clamp onto the down tube, it pinches the tube enough to make it either really difficult or impossible to push the seat post in.

I've tried a few things I could think of to spread the seat post clamp a little, but I am still having a lot of difficulty getting it in.

Now, I am aware the chrome plating may have increased the size of the post, but I can clearly tell that the clamp, once it is on, is the reason for the difficulty.

Are there any tricks that I can do to spread the seat clamp a little bit to prevent it from pinching?

I've tried twisting a flathead screwdriver in it, but it only spreads it enough to the get the clamp onto the tube.  Another thread mentioned using a nickel or quarter and the bolt, but I don't think it applies, or I just don't understand their directions.

I'm already disappointed to have chipped some of plating off my clamp, so I just want to figure out a way to do this without causing more damage.

Thanks.


10 01 11

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#2 2013-03-30 7:27am

kaosGT
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Re: How to spread the seat post clamp

I've had good luck using a small pry bar and flat tip screwdriver, wedge them in and squeeze like a set of pliers
http://i532.photobucket.com/albums/ee323/DATSKAOS/207C4B0B-6734-470A-B991-3C9E8F0E38EA-14992-00001B1506B63385.jpg

You can also use a set of snap ring pliers or a set of spreaders shown in this pic..
http://i532.photobucket.com/albums/ee323/DATSKAOS/5643F18D-926A-427E-9CDA-7933E435F57C-14992-00001B1524190613.jpg

Use tape on the tips of tools to protect the finish, if the clamp is polished or chromed, maybe heat it up a little with a propane torch to make the spreading easier..Good Luck

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#3 2013-03-30 7:30am

KU Dude
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Re: How to spread the seat post clamp

Look into a set of spreader-nose pliers. Looks like needle-nose but when you squeeze the handles, the jaws move outward. Less damage to your work. Use battery post spreader pliers for the tube if you need. Hope this helps.

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#4 2013-03-30 7:35am

webdevkit
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Re: How to spread the seat post clamp

Thanks a lot.  I think I will take a trip up to the hardware store.


10 01 11

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#5 2013-03-30 7:44am

sharpbbb
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Re: How to spread the seat post clamp

or CV joint clip pliers maybe good.

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#6 2013-03-30 8:34am

wired
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Re: How to spread the seat post clamp

Great tips.  Just added to the Best of Restoration thread...

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#7 2013-03-30 9:55am

XJguy
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Re: How to spread the seat post clamp

Although the above procedure will work I suspect they will leave a mark.

You want to use something that will either spread the force, like a very wide screw driver or chisel, or a plastic, or wood wedge to hammer in, while keeping the outside safely against a folded up towel.


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#8 2013-03-30 10:54am

stonie
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Re: How to spread the seat post clamp

Remove the bolt.
Re-install the bolt from the opposite direction.
Stick a penny in the slot, then tighten the bolt against the penny.


That should open the clamp enough for the install, if it still doesn't
fit then the clamp is too small.

wink


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#9 2013-03-30 11:02am

Jeno007
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Re: How to spread the seat post clamp

stonie wrote:

Remove the bolt.
Re-install the bolt from the opposite direction.
Stick a penny in the slot, then tighten the bolt against the penny.


That should open the clamp enough for the install, if it still doesn't
fit then the clamp is too small.

wink

Theres no threads in that clamp. If its a potted clamp, theres a good chance it will crack when you try to spread it if you go more than a millimeter, so be careful.


Anything is negotiable.

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#10 2013-04-05 12:31am

Northland_Rider
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Re: How to spread the seat post clamp

Would using a stem and tightening it up so that it spreads it out from the inside out. Should work ok to and no marks?

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#11 2013-04-05 7:05am

webdevkit
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Re: How to spread the seat post clamp

Just realized I never posted an outcome to this post.

I borrowed a couple of pry bars, similar to what kaosgt posted above, and it worked flawlessly.  I taped the ends of them and it did not create any more damage.

It was proving a little difficult to pry and insert/adjust the seat by myself, so I needed an extra set of hands, but the bike is coming along very nicely now. On to the brakes!


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#12 2013-04-05 8:54am

Coco
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Re: How to spread the seat post clamp

XJguy wrote:

Although the above procedure will work I suspect they will leave a mark.

You want to use something that will either spread the force, like a very wide screw driver or chisel, or a plastic, or wood wedge to hammer in, while keeping the outside safely against a folded up towel.

I've used wood wedges or shims. No damage to the soft aluminum this way.

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#13 2013-04-05 9:12am

Jeno007
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Re: How to spread the seat post clamp

MrSlayer wrote:

Just realized I never posted an outcome to this post.

I borrowed a couple of pry bars, similar to what kaosgt posted above, and it worked flawlessly.  I taped the ends of them and it did not create any more damage.

It was proving a little difficult to pry and insert/adjust the seat by myself, so I needed an extra set of hands, but the bike is coming along very nicely now. On to the brakes!

Good deal, glad it worked out. smile


Anything is negotiable.

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#14 2016-10-21 8:37pm

Jmack
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Re: How to spread the seat post clamp

Grab a hammer and bang it as hard as you can


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#15 2016-10-21 10:09pm

BRICKOS2
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Re: How to spread the seat post clamp

Dirty recommends some of these as well...

http://cdn.skim.gs/image/upload/v1456338236/msi/beer-bucket_hzzqv1.jpg

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#16 2016-10-25 5:30pm

esw
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Re: How to spread the seat post clamp

You could simply install the post to the height you want it, then put the clamp on.

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#17 2016-10-27 2:43am

detroitjohnny
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Re: How to spread the seat post clamp

http://i532.photobucket.com/albums/ee323/DATSKAOS/5643F18D-926A-427E-9CDA-7933E435F57C-14992-00001B1524190613.jpg

I never thought about a piston ring spreader.  That's an awesome idea, I will be using on my next build.  Thanks!!


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#18 2018-04-21 9:04pm

Murph80
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Re: How to spread the seat post clamp

I'll have to look onto a piston ring spreader, sounds expensive.  Small pry bar and a screw driver sounds more my speed.  Thanks!!

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