Centering Brake Caliper
 

Bought an 86 Bianchi Sport SX this past week as a commuter bike. I live in Alabama, but found the bike on CL out in LA. I had a friend out there meet the seller, and take delivery of the bike. I paid DTLA to do an overhaul service, and to pack and ship the bike to me.

Nevertheless, the brake calipers are a problem at the moment. One pad on each of the calipers is rubbing the rim when the brake is disengaged. The calipers seem centered, and I have even attempted tightening them off-center to compensate away from the rubbing pad. However, when I tighten the brake for the first time after adjustment, the brake goes back to rubbing. Any ideas on how I can fix this? I am fairly handy with mechanical work...I have just never done my own bike repairs. So any advice would be welcome.

Brakes are Dia Compe (caliper says 400 on the back of one arm and 5M88432 on the other.

http://bikeforums.net/attachment.php...hmentid=469882http://bikeforums.net/attachment.php...hmentid=469883

Star washer behind brake, digging into the front of the fork crown? that will keep the brake center-bolt-spring-carrier centered .

you can then use a thin wrench on the flats provided in the spring carrier to hold it centered,
while you tighten the nut on the back of the fork.



And Level That Saddle ! :bang:

There is no star washer. It's the spring carrier, a plastic washer, the back half of the caliper, another plastic washer, the front half of the caliper, the dia compe steel washer, then regular nut followed by cone nut.

As as for the saddle, I have just unboxed the thing so I don't have everything dialed in. Nevertheless, I ride my saddle a bit forward tilted...because I am not a fan of impotence.

Nice bike! I suggest that before adjusting anything, lubricate the brakes a bit. I don't remember who I heard it from on this forum, but a tiny bit of oil or grease where the springs contact the caliper arms needs to be lubed so the springs slide nicely.

Thanks Gresp! I was stoked to find one in orchid.

I will definitely lubricate. any particular type of lube preferred for this sort of application?

One would think $150 in overhaul would take care of all of these things, no? That's why I need to learn to do his stuff myself. If I were working in a shop, no bike would leave with any sort of problem like this. I mean, after the brakes are applied and released, the pad on one side is in enough contact to seriously hamper free movement of the wheel. Is that not something the tech should have discovered and remedied? Sorry..just lamenting aloud the loss of quality service in the modern era...I can't remember the last time I paid someone to do work and it was actually done correctly.

If all else fails, my technique is to place a flat bladed screwdriver across the return spring next to the pivot on the side
of the caliper farthest away from the rim, and tap the screwdriver handle with a mallet or hammer using only
the amount of force required to shift the caliper into position.
I have done this for years, and some return springs actually have a notch close to the pivot possibly for this purpose.
However, using a wrench across the flats on the pivot close to the mounting point should do the trick...

The brake arms are not resting equidistant from the rim because the main/mounting bolt for the brake caliper is twisted. Simply pushing the brake arms into position does not work because you are not twisting the mounting bolt back into the correct position for it to hold the brake arms in the correct position.

You need to loosen the brake caliper mounting bolt before you try correcting it's position, loosening the nut or recessed nut on the back of the fork (not barely loose, I mean loose enough that the mounting bolt can turn, and you are not just twisting the parts that are stacked on the mounting bolt. Next, use a "third hand tool" to squeeze the caliper arms down to the rim and center them. While the brake arms are being held down on the rim, tighten the brake caliper mounting bolt without letting it twist out of position. Most brake calipers have a nut or other hex/wrench shaped part on it fixed to the mounting bolt that you can hold with a wrench while you are tightening the mounting nut or recessed nut to hold the brake caliper securely in position.

I recommend replacing diacompe single pivot sidepull brake calipers because they brake poorly. The brake arms flex, and they don't have the mechanical advantage of any Shimano dual pivot brake caliper.

Ronno, I have heard of that technique but have never been able to accomplish much with it. I think I am doing something wrong. :)

RoadGuy, your advice is solid. I was attempting to do this, but still having trouble.

I have now fixed the problem. The guy in this video (who is a trip!) shares a nice trick at 4:32:
https://www.youtube.com/watch?v=Fpc-R_BfpHU

It worked perfectly for me and now the bike is rolling and stopping real nice. After I fixed the brake, I noticed that my fork was a bit lose. So I had to tighten that up, then reset my headset. I am starting to wonder what exactly I paid that bike shop to do... :wtf:

I think what Fietsbob is saying is.. YOU NEED A STAR WASHER

:thumb:

A wise man once said, "Why should I pay someone else to @#$% my stuff when I can @#$% it up myself?" Applying this maxim over the years, I found that I could fix more and more things while messing up fewer and fewer things.

Great to hear the calipers are aligned now.

Just be aware that they go out of alignment often due to transport, bumping into something, etc.

Diacompe G, 500, 400, and their other versions of the single side pull are all like this. It's one of those quirks that you better learn to love and laugh off, or get some newer tektro(or other) dual pivots.

Preach!

Loosen the caliper from behind a bit using a hex wrench. Then the caliper can be held in place right behind the pivot of the clamp, using a cone wrench. Tighten the bolt in back with the hex wrench while keeping the brake in place in front.

The star washer between the front of the crown and 'fixed bolt' you hold with the cone wrench would help a lot if it is not already there.

Yeah, the front was a bit out of line after I rode today. So I adjusted it again. Since I know how to do it now, I will not mind it too much. That's just how some older things go. I have an older car that requires upkeep too...gives me something to do. :)

I just ordered a new seatpost for it...the one that came with it is a bit too short (220mm or so). I have long legs, and a shorter torso. I need a 300, but settled for a 350...in carbon...and Bianchi-branded:

Carbon Seat Post Bianchi 25mm with Adaptor to 27 2mm Black 194gr 300mm | eBay

My half-ass measurement looked to show the size needed at 25mm. However, it might need a shim to take it up to 26.6, which is the diameter I have seen quoted for the 89 Sport SX: Sheldon Brown's Seatpost Size Database

Might make the bike look a touch weird, but the longer vintage steel ones were very expensive (mostly campy). When I get the funds, perhaps I will switch it out for something metallic (titanium maybe?), to keep the more vintage look. It would be nice to cut a bit of weight. I bet it weights 27 or 28lbs or so right now.

Yeah, there's not a star washer at the moment. If the brakes require constant adjusting, I will definitely throw one of those on there. The fork doesn't have any marks in that area, so I don't think it has ever had a star washer on it.