Shimming FD clamp - help!

tbushnel · #1 08-03-2005, 11:23 PM

I have acquired a Panasonic lugged steel frame and wish to build it up with my early 90's Campy components that currently reside on another frame. My current FD is a braze on but using a shimano braze on / clamp adapter (current clamp ~35mm diameter). The seat tube on the Panasonic is something like 29.8 OD and the available clamp adapters are either 28.6 or 31.8mm diameter, so I will need to shim a 31.8.

I was planning to cut up a soda can and fashion my own shim. I was wondering if anyone had other ideas or is this the best way to go.
Thanks,
Ted.

dave thompson · #2 08-04-2005, 12:01 AM

Quote:

Originally Posted by tbushnel

I have acquired a Panasonic lugged steel frame and wish to build it up with my early 90's Campy components that currently reside on another frame. My current FD is a braze on but using a shimano braze on / clamp adapter (current clamp ~35mm diameter). The seat tube on the Panasonic is something like 29.8 OD and the available clamp adapters are either 28.6 or 31.8mm diameter, so I will need to shim a 31.8.

I was planning to cut up a soda can and fashion my own shim. I was wondering if anyone had other ideas or is this the best way to go.
Thanks,
Ted.

If you can't find the correct sized clamp, go to a hobby shop and buy some brass shimstock. It comes in different thickness.

Birddog · #3 08-04-2005, 08:23 AM

Old piece of inner tube might work too.

Birddog

Birddog · #4 08-04-2005, 08:24 AM

Old piece of inner tube might work too.

eddief · #5 08-04-2005, 08:30 AM

available. These were sliced so could be spread easily and then gently snapped onto the seat tube. Don't know who makes em but worked well for me.

Dave · #6 08-04-2005, 09:56 AM

You need material that's 1mm (.040 inch) thick. It would take 10 layers of coke can, which is .004 inch thick.

I'd look for plastic shim material, probably .020 inch and use two layers. You can get .040 inch plastic shim from www.mcmaster.com.

You may find a common 1 gal. plastic paint bucket to be close to .040 inch thick. The lids on plastic containers like cool whip, margarine and chip dip are about .020 thick.

Jeremy · #7 08-04-2005, 10:07 AM

This may sound wrong to you, but I would be very surprised if the seat tube on the frame you bought is actually a 29.8. Over the years there have been ft der clamps made in 1" (25.4), 1 1/8 (28.6), 1 1/4 (31.8) and 1 3/8 (34.9). There are non standard seat tube sizes out there, but they usually come with a braze on so that a ft der will work. The Panasonic frame that you have is almost certainly a 28.6. Sometimes the clamps seem a little tight but it seats properly when tightening. Take some calipers and measure the seat tube. If it truly is a 29.8, then you will have to fabricate a shim yourself out of some brass stock. As someone mentioned it is available at hobby stores. To calculate the thickness that you need take the OD of the seat tube subtract it from the ID of the clamp and divide that result in half. If you truly have a 29.8 seat tube, you will not be able to use the plastic shims available from bike shops because they are designed for an 1/8" difference in diameter. I hope this helps.

Jeremy

tbushnel · #8 08-04-2005, 10:30 PM

Thanks for all of the suggestions and good advice. Previously I had the LBS measure the ST diameter and it was 29.8. I purchased some calipers for myself and found that it was no less than 28.8mm on repeated testing clamping snuggly to the tube leaving a small line on the paint (trying to be as accurate as possible). This frame was reported to be never built up and the paint is new appearing. This frame was "custom painted by Panasonic" according to the decal. I wonder if the paint job was a little on the thick side or something.

I am torn between using the 28.6 clamp which would be snug, but it seems likely that the ST is in fact 28.6. Alternatively, I did find the brass shim material easily, so I could still shim the 31.8. I could also thin down the paint I guess.

Any last thoughts are appreciated.
Ted.

#9 08-04-2005, 10:42 PM

The frame is from the era of 28.6mm seat tubes. The extra diameter you measure is from the paint itself. Get thee a 28.6 clamp adapter.

For your information, that frame was from a time, I believe, when Panasonic had a quasi-custom program going. You could order the frame (though I can't remember if you could spec any tube lengths) with your choice of paint schemes and they would promise delivery in 3 weeks.

Jeremy · #10 08-05-2005, 09:29 AM

Quote:

Originally Posted by tbushnel

I am torn between using the 28.6 clamp which would be snug, but it seems likely that the ST is in fact 28.6. Alternatively, I did find the brass shim material easily, so I could still shim the 31.8. I could also thin down the paint I guess.

Any last thoughts are appreciated.
Ted.

Hi Ted,

Just use a 28.6 clamp. It will be fine. The clamp may compress the paint a little, but this will happen if you shim a 31.8 as well. Anyway, if you position the ft der correctly, the clamp will cover any deformation that MAY happen to the paint.

Jeremy

tbushnel · #11 08-05-2005, 06:39 PM

Thanks again. I finally picked up the 28.6 FD clamp from the LBS and it fit perfectly. I guess I should have just tried it first, rather than doing all that measuring. The up side of it is that now I know a bit more about typical ST diameters, I have a nice caliper to measure with which I always wanted, and if I ever need to shim anything I will be off to the hardware store for brass shim material.

I really do appreciate all the input. Maybe I'll post a pic of the finished build next week just for fun.

have a good weekend,

Ted.