dougdunn

I bought a very sweet, all original Centurion Pro Tour and I am finally getting some time to spiff it up. It has Dia-Compe direct mount center pull brakes and they are not centered on the rims. I can't figure out what I need to do to center them. Anyone give me some pointers?

nlerner

I’d start with removing them from the mounts, thoroughly cleaning all of the contact points, and reinstalling with a dab of grease on the mounts. It’s possible you’re getting uneven spring tension, but I kinda doubt it.

steelbikeguy

and approaching the problem from another direction... have you verified that the rim is centered on the fork blades?

Steve in Peoria

nlerner

Ah, definitely check that first!

fietsbob

have you removed the brakes cleaned & re greased the pivots?


there are cable 'stirrups' that include setscrews to grip the transverse cable

to have it pull closer from one side than the other..

Dfrost 

And that the rim is properly centered on the hub?

Salamandrine 

Check wheel dish and measure the distance from the rim to the fork on both sides first. No point at all in adjusting the brake centering if the wheel or fork is off. More than likely, that is the problem. If the rim isn't centered, deal with that first.

If the rim is centered, first make sure the brake caliper is well lubed and not binding anywhere. Oil all pivots, the pin between the caliper, a the little pins where the springs contact the caliper arms. Actually take the brake of and apart, and grease the braze on pivots as well.

When you get to that point, it's basically like an old school cantilever brake. There's two things you can do, play with the straddle, and play with the springs. To play with the straddle hanger, try shifting it one way or another. This will change the centering point of the brake pads. You can encourage it to one side or the other by lightly bending down on the straddle wire. As mentioned, for extremes, use a modern Tektro straddle or equivalent that has set screws to hold position. To play with the spring, take the straddle wire and everything off. Pull out the brake pad that is in too far, twisting the caliper to overset the spring a bit. Be careful. You might have to loosen the pivot bolts. Try to avoid doing this if you can.

It's probably a combination of the wheel being off center, and pivots needing lube, maybe some straddle tweaking. Attend to that stuff first.

EDIT (again): looks like the spring plates are adjustable. But they are not.

madpogue 

Hard to tell from the pics -- is there one spring spanning between the two side? Or does each side have its own spring?

Salamandrine 

It should have individual springs. I'm pretty sure I see the end of an individual spring going into the braze on boss hole in the second picture.

randyjawa 

Let's assume the wheel is true and properly dished.

Center pull brakes work best when the cable frictions are minimal. Start with disassembly of the caliper. Clean it and lubricate each caliper. Grease pivots and also the area where the springs slide on the caliper arms.

Next, make sure that your yoke cables are clean and smooth. A piece of aluminum foil is the perfect tool for cleaning and polishing cables (old school). Ensure that there are no kinks in the yoke cable. Grease the yoke and cable contact area.

Install the brake and attempt to center it by pulling the lever tight. Snug up the mounting bolts on the calipers. If not centered, upon releasing the lever, you will have to loosen the mountain bolt and rotate the caliper in the appropriate direction. You might also have to smooth off the faces of the alloy mounting washers (they can become grooved making it difficult to realign the calipers)

Hope that is helpful.

Vintage_Cyclist

Each side has separate springs.

On my 1979 Pro Tour, the calipers were binding on the post/plastic bushing combination. I ended up taking them all off and sanded down the inside hole of the caliper that slides over the post/plastic bushing combination. Cleaned and greased. This corrected the condition completely. Also, inspect the plastic bushings themselves. Two of mine were a little cracked and frayed, which wasn't helping, so I cannibalized from the box of crap for replacements.





And the obligatory money shot.

Dfrost 

Weinmann 610 and 750 center pulls, likely available for cheap/free at your local coop, use red plastic bushings that are an exact replacement.

smontanaro 

While you have them apart, compare the two springs to make sure they match. You might need to bend one or the other to get them even.

Salamandrine 

So these have adjustable spring mounting plates? It looks like it in the picture. I haven't worked on one for 35 years. I forgot. If so that makes centering adjustment much easier.

madpogue 

+1; if those adjusters exist, that's the _right_ way to adjust any brake with two separate springs.

dddd

The spring plates are brazed on these bikes.

3speedslow

A little off the topic but if those same brakes are set up as centerpulls, what would it take to get them to be ready for canti mode?

Vintage_Cyclist

Not the Pro Tour. They plates slide onto the posts. One side of the post and corresponding plate is flat to keep them from turning. The front fork from my bike.



This is what the plates and springs look like.





As opposed to something like this:

madpogue 

Are there adjusters for the ends of the springs that engage the brake arms?

bwilli88 

Centerpulls whether stud mounted or regular cannot be setup as cantilevers.

Salamandrine 

OK, thanks for that. If there are flats to hold the spring plates, they are still not adjustable. That leaves tweaking the springs and straddle as the only way to change centering.

Probably still the wheel that's the issue.

Road Fan

The OP’s brakes look like conventional center pulls. What makes them “direct mount?” If they’re bolted to the frame and fork with a single center bolt you can loosen the nut and hold the entire caliper where you want it as you tighten it up.

The alignments, dish, true, lubrication, spring preload, straddle flexibility should be checked as well, bet depending on the immediate goal you can just turn them.

Or you could just buy a new frame ...

hokiefyd 

If you look closely, they're not bolted to the frame with a single center bolt. Each arm of the center pull caliper is mounted directly to fork studs without a center bolt, which is why the whole brake assembly can't simply be rotated.

Road Fan

duhhh, thanks, I looked too quickly!

Yeah, this adjustment could be complicated! I’d start with truing and dishing the wheel, then use the wheel to assess fork alignment, then mechanically overhaul the pivots and springs unless it’s actually new, then set the stationary shoe positions, then reattach the straddle and see if its bend is part of the problem.

unterhausen

I had this problem with some Mafac racers and had to bend the spring