Cratecruncher

I recently purchased a pair of Universal Model 61 calipers off feeBay for a restoration project.

The calipers look pretty nice with no sign of trauma but I can't seem to get one of the lugs to budge. So far I've tried penetrating oil and a heat gun. Using needle nose pliers at the base of the cable I can't get the lug to rotate. I feel if I could get the cable lined up with the slot I can tap it out with a drift. Before I take it to the drill press I thought I'd ask the community. Though I've been doing my own cars and motorcycles for years this is my first bicycle since I was a kid.

thumpism 

Make sure the slot the cable moves in is not crimped and restricting the cable's movement. I've seen that before.

Andrew R Stewart 

I have seen plenty of center pull caliper arm end holes, for the straddle cable ends to fit in, that have a piece broken off. Likely from someone trying to remove the cable end and finding out how brittle some older Al parts can be. If you must try tapping the end do so with the hole's outer surround on the bottom. The other side's split surround is especially easy to bend. Also the cable end will have the steel cable strands balled up in the end button's casting. A drill will tend to drift about some when it contacts those strands.

I might try clamping the button end in a vice, trapped between two "anvils" that only touch the button end and not the caliper arm hole. This way the efforts to get the button end to loosen and rotate slightly in the arm's hole is not stressing the cable or the arm. Andy

Cratecruncher

Thanks for the replies guys. It helps a lot! The caliper arm doesn't have any signs of damage and the slot is exactly the same as the other. The cable is free to move back and forth in the slot. It appears as though the lug is just too big for the hole. The idea of capturing the lug in a vice is interesting. My only concern is making the lug even bigger by smooshing it. It looks like the lug is cast aluminum and I really dread drilling in to a tootsie roll with a hard center! I will practice drilling on the free lug and see if it's even possible. If I can make a hole I can tap a bolt thread. If I can screw in a bolt I can get a wrench on it. If the tap breaks...

Andrew R Stewart 

I read your post as the cable button end (the lug) was frozen in the arm's hole as in not even spinning. Given my new understanding I suggest continuing to work/rotate the cable button end within the arm's hole until you cant stand it then with the complete ring side of the hole against a hole drilled through some non marring material (hard wood?) to accept the button end and start pressing before any tapping. Andy

dedhed

have you tried any penetrating fluids yet?

thumpism 

You could also try driving a drywall screw into the cable end so you have something to lean on when giving it muscle.

JohnDThompson 

That is particularly true for those old Universal calipers, which I suspect were cast rather than forged.

Cratecruncher

Yes, this is my altered plan of attack before risking buggering up an expensive tap. I'll start with a good quality sheet metal screw and vice grips. The risk here is that the fastener snaps off or it's cone-shape expands the lug (button) making it even tighter in the bore. The button looks like it's cast aluminum and inspection under some magnification reveals it cracked and that is why it is too big for the hole. I guess the good news is it didn't fail catastrophically approaching a busy intersection!

SJX426 

@Cratecruncher - The Caliper is cast and will not bend but will break. Do your work gently.

flanso 

If the caliper is steel and the cable end aluminum, caustic soda.

Cratecruncher

Thanks for all the responses everyone. I wanted to update the thread with my results. I started a dimple in the center of the button with a sharp nail, then enlarged it with a hand drill and tiny bit on both sides. Next I used the drill press to drill down into the button from each side using a cheapo 1/8" twist drill. The surfaces of the button flaked away - very brittle stuff. Once through the center I just flexed the wire back and forth and the button continued to crumble. Just after the photos wer taken I took one final tug on the last wire strand still holding and the rest of the button shattered into 100 tiny pieces. The caliper cleaned up real nice and is ready for 1000 more miles of faithful service.



The moral of the story is that these old center-pull cables seldom get replaced when people do a cable job. But they are a critical part of the brake function and need to be inspected and replaced if there's any doubt. The surface of the stuck button was marbled with tiny flake-like cracks in the metal and was way past it's expiration date. The new caliper will be replacing the Weinmann 610 on my Italvega Nuovo Record so it matches all the other brake hardware that came on the bike. I have a thread going HERE if anyone is interested.

Andrew R Stewart 

Great follow up! Andy