Bicycle Mechanics - Campy top tube cable clip screws?

The Campy 649 brake cable clips... anyone know what the screw threading is on these? I was going to replace the screws on mine with some stainless, but can't figure out the threading. Not M3, not 4-40. The thread looks to be a bit coarser in pitch than an M3, but about the same diameter. The hardware store I was at did not have any M3.5.

From old catalogs, they show the nut as a separate piece, but mine are captive. I'm not sure I've ever seen any that aren't. I posted this on C&V, but no one seemed to know.

I can't help, but I agree those are a strange size. If they are M3.5, they'll be hard to find, especially in stainless. Have you tried taking one to a bolt supply store?

If it's m3.5 there are some out there.

http://www.microfasteners.com/catalog/products/METMSPPS.cfm

Thanks. Yes, I know a number of places that I can order M3.5 from, but wanted to confirm the threading before I did so.

Why bother trying to identify the size. Bring the clip to the hardware store and have at it trial and error. Whatever fits is right, but 3 of them.

That is what I did (took one of the screws to the hardware store). Nothing they had fit (M3, 4-40, etc.) Since nothing they had fit, I have to resort to figuring out what it is unless I want to order anything possible. In this case it would seem to either be down to M3.5 or it is something with an odd pitch or whatever. The screw would start just a touch in an M3 nut... almost like it is the correct diameter but a coarser thread pitch.

OK. I assume you still have a screw from one of the other clamps. Start with a ruler and count the threads over an interval, both metric and inch, and get a good estimate of the pitch. If you have a caliper you can get a diameter and see it it's metric or inch.

With the pitch and major diameter, see if you can find a near match among the threads listed here (http://mdmetric.com/thddata.htm) Be aware that you may not have precise measurements, so if you find something that seems close, that's probably it.

They are 3.0mm diameter, and the pitch and diameter are the same as a Campy drop-out adjusting screw. I don't have a pitch gauge here, or I would check them. I think they are .8

They are 3.0mm diameter, and the pitch and diameter are the same as a Campy drop-out adjusting screw. I don't have a pitch gauge here, or I would check them. I think they are .8

Definitely nor .8 which is the same as a water bottle screw 5x.8, but if it's 3mm it's likely an M3 coarse with a .5mm pitch (3x.5mm).

I have a Lambert from the early '70s with top tube brake cable clips. They are copies of the Campy clips, although I do not know if the bolts are the same. THe bike did have some odd parts.

Anyway, I removed one of the clips and measured the bolt. The major diameter is 0.107 inches, which is about 2.75 mm. If I counted correctly, the pitch is 40 tpi or 0.63 mm. So, I checked the bolt charts and the bolt is smaller than a M3. I tried a M3 which will just start in the nut, but only about one turn. The bolt is not as large as a 4-40, but the pitch is almost correct.

Recently, I put the Lambert back together for trainer duty. I found I had lost one of those clip screws. IIRC, I managed to force a 4-40 screw in the nut. That might work for you if you need to replace the bolts. I also noticed that Campyoldy has a set of 3 clips for about $20.

Good luck.

Edit: After reading aixaix's post, disregard this post if a M3 bolt will go through the non-nutted side of the clamp.

If you're talking the 70's era part, I measured mine at (within my sem) 3 x 0.6. You might try posting the question to the C&V subforum.

They measure 3.06mm according to my calipers. I haven't counted threads yet. A 4-40 will thread into them, but is loose. Might work though, as they will tighten up. I have the original screws (have been using these for 30+ years), so will go with them if I can't find anything else. I will probably buy a spare set of these (and a 626 cable guide) as they do tend to break over time from flexing to go over the tubes.

Always good to have a few spares, but I bet the originals will last another 30 years.

The screws are 3mm .5 pitch.

^ Hmmm. A std. M3 at a hardware store should be coarse (not fine), which is 3mm x 0.5mm pitch I think? I'll have to take a clip in and try a screw rather than trying one of my screws in a nut. Perhaps the nut I tried had gotten mixed up. The display thing they have for checking threading did not go below M4 (or 6x32 for US).

For what it's worth, drop-out screws and Campy N.R. (and likely many other) derailleur limit screws are the same size & pitch. Of course, I am assuming that the Campagnolo cable strap screw I measured (owned since new, BTW) is the same as yours. McMaster.com should have what you are looking for, though you might end up with 22 spares!

Unfortunately (?), my bike has Campy vertical dropouts, so I can't check that. I'll take a clip to another hardware store and check their M3s.

is there a source for Campy drop out adjusting screws? Mine are bent.

is there a source for Campy drop out adjusting screws? Mine are bent.

For originals try yellow.jersey.org or Branford Bike. Otherwise buy the longest 3x.5 screws you can find and even if they don't reach through you can adjust them from the axle side and once set they'll stay put.

^ Hmmm. A std. M3 at a hardware store should be coarse (not fine), which is 3mm x 0.5mm pitch I think? I'll have to take a clip in and try a screw rather than trying one of my screws in a nut. Perhaps the nut I tried had gotten mixed up. The display thing they have for checking threading did not go below M4 (or 6x32 for US).

Find a Fastenall store. They have M3 in stainless and sell the bolts by the piece. I bought a few to replace the limit socket head screws on my Campy front derailleur limit screws.

^ Thanks for jogging my memory, I'd forgotten about those places (Fastenal). Went to one at lunch today, and while they didn't have any M3 in stock to try, he tried the screw in his threaded thread gauge and it would not even start. On the thread pitch gauge he had, it was closest to the .7mm pitch (gauge did not go any finer than that). It did fit a 5-40 though, so I had him order some stainless button allen head ones which will be there tomorrow.

For originals try yellow.jersey.org or Branford Bike. Otherwise buy the longest 3x.5 screws you can find and even if they don't reach through you can adjust them from the axle side and once set they'll stay put.

Yikes! $25!!!
Gotta love Campy!

^ Thanks for jogging my memory, I'd forgotten about those places (Fastenal). Went to one at lunch today, and while they didn't have any M3 in stock to try, he tried the screw in his threaded thread gauge and it would not even start. On the thread pitch gauge he had, it was closest to the .7mm pitch (gauge did not go any finer than that). It did fit a 5-40 though, so I had him order some stainless button allen head ones which will be there tomorrow.

Fastenal is a great place to look for that kind of stuff.

Who would have thoguht a 5-40 would fit. Just a little larger than 3mm.

Got the screws today (stainless hex button head) and they fit fine, go figure. I wouldn't recommend that anyone assume theirs also take 5-40. These came with the brakes from an LBS back in the early '70s, probably '74, and are chrome plated, not the later stainless steel that I believe they switched to. Thanks for all the helpful comments.