anyway...after mating them to some levers i noticed that the return spring would rub quite hard against the spring retainer....i could feel it at the lever...not very smooth.
sure...i could grease or oil that point and make a mess of it....have road grit stick to it and then make it creak...or be lazy and put nothing on it....
but i've seen the modern calipers have a plastic sleeve over the spring ends.
so i removed the liner from a brake cable and slipped it over the spring tips. still fits in the retainer...almost frictionless movement...and no more grinding feel at the lever.
anyway...after mating them to some levers i noticed that the return spring would rub quite hard against the spring retainer....i could feel it at the lever...not very smooth.
sure...i could grease or oil that point and make a mess of it....have road grit stick to it and then make it creak...or be lazy and put nothing on it....
but i've seen the modern calipers have a plastic sleeve over the spring ends.
so i removed the liner from a brake cable and slipped it over the spring tips. still fits in the retainer...almost frictionless movement...and no more grinding feel at the lever.
Yep. The pair of brake calipers identical to yours that I just sold for $90 had no sleeve and were buttery smooth, if not stiff. In other words, they were strong with no stiction. They were in really good, almost new condition though.
I'd go the oil *and* sleeve route. Now that would be really smooth. -- Phil, Squid-in-Training
I used to have a set of those that I picked up really cheap about 15 years ago. I like your solution for lowering the friction. One thing I did with mine was to bend the springs in a bit so there wasn't so much preload... it helped a lot.
i thought of that...i'll ride them first and see how they opperate....if they bind a bit later...i'll add the oil for sure. it just seems a nice solution.
Phil said:
Yep. The pair of brake calipers identical to yours that I just sold for $90 had no sleeve and were buttery smooth, if not stiff. In other words, they were strong with no stiction. They were in really good, almost new condition though.
I'd go the oil *and* sleeve route. Now that would be really smooth. -- Phil, Squid-in-Training
that was my next question....why were the return spring preload soooo strong? was the old housing not lined? compared with a modern caliper, the things are like workout equipment.
did you bend them down by the tips or up higher?
Ron Ruff said:
I used to have a set of those that I picked up really cheap about 15 years ago. I like your solution for lowering the friction. One thing I did with mine was to bend the springs in a bit so there wasn't so much preload... it helped a lot.
that was my next question....why were the return spring preload soooo strong? was the old housing not lined? compared with a modern caliper, the things are like workout equipment.
I believe brake springs used to be much stronger because of friction in the cables, and because the levers had no springs.
- Frank Krygowski
The second, not the first. And a drop of oil does the trick without a plastic sleeve. Phil Brown
that was my next question....why were the return spring preload soooo strong? was the old housing not lined? compared with a modern caliper, the things are like workout equipment.
I believe brake springs used to be much stronger because of friction in the cables, and because the levers had no springs.
Friction in the cables was higher before lined cables became popular. Brake caliper springs needed to drag that cable back, and drag the lever with them. The friction made a strong spring necessary.
But the lack of brake lever springs may have been more important. Contrary to the old saying "you can't push a rope," it can help greatly if you do.
But you can push a rope when it is constrained by a housing.
Greg
-- "All my time I spent in heaven Revelries of dance and wine Waking to the sound of laughter Up I'd rise and kiss the sky" - The Mekons
All dual pivot brakes that I have looked at have such a plastic sleeve. Don't worry, that will also get full of road grit and cause a non-centered caliper return. The real solution is to make a return spring that doesn't have the stoooopid elephant ears, but rather coils around the center-bolt. Then there is no cosine error and sliding at the retention lug. I've designed such a spring but because I am not in the brake manufacturing business, you can't buy them.
Spring articulation is approximately at the center of the elephant ear.
I'm not sure what part of the spring actually yielded... maybe part of the coil or near there. I think I just grabbed the wire about half way from the coil to the tab and forced in each side until it yielded a little bit.
Old levers didn't have their own return springs, so the brake caliper had to do that on it's own. The lined housing I'm not certain about... I suspect that they weren't lined, though.
I used my old Campy calipers with "modern" Shimano levers and housing, and they seemed to work fine... good feel and plenty of stopping power. I have Ultegra calipers now (the Campys went when I sold all my bikes), but I don't see the point in having the extra leverage.
that was my next question....why were the return spring preload soooo strong? was the old housing not lined? compared with a modern caliper, the things are like workout equipment.
I believe brake springs used to be much stronger because of friction in the cables, and because the levers had no springs.
- Frank Krygowski
The second, not the first. And a drop of oil does the trick without a plastic sleeve. Phil Brown
All dual pivot brakes that I have looked at have such a plastic sleeve. Don't worry, that will also get full of road grit and cause a non-centered caliper return. The real solution is to make a return spring that doesn't have the stoooopid elephant ears, but rather coils around the center-bolt. Then there is no cosine error and sliding at the retention lug. I've designed such a spring but because I am not in the brake manufacturing business, you can't buy them.
Spring articulation is approximately at the center of the elephant ear.
I've got another set that were mounted on a bike and ridden less than 40 minutes (ie baarely used) that I'd sell for a price like that, if anyone is interested.
JT
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Old levers didn't have their own return springs, so the brake caliper had to do that on it's own. The lined housing I'm not certain about... I suspect that they weren't lined, though.
That's right. No nylon or teflon linings in the old days, just grease. I imagine the development of the lined cable housing was what allowed the weaker springs. But the springs on the levers themselves don't help the cable return significantly. They are very weak, and the cable is not held to the lever in a way that enables any push; the end of the cable would just stick out.
--
David L. Johnson
__o | As far as the laws of mathematics refer to reality, they are not _`\(,_ | certain, and as far as they are certain, they do not refer to (_)/ (_) | reality. -- Albert Einstein
so i removed the liner from a brake cable and slipped it over the spring tips. still fits in the retainer...almost frictionless movement...and no more grinding feel at the lever.
Great macro & lighting! What sort of equipment did you use? (I'm not inferring that the equipment is responsible for the great quality photo, just curious)
As for your Record upgrade, have you ridden it yet? Do you think it will stay in place, or work it's way off the stud?
Old levers didn't have their own return springs, so the brake caliper had to do that on it's own. The lined housing I'm not certain about... I suspect that they weren't lined, though.
That's right. No nylon or teflon linings in the old days, just grease. I imagine the development of the lined cable housing was what allowed the weaker springs. But the springs on the levers themselves don't help the cable return significantly. They are very weak, and the cable is not held to the lever in a way that enables any push; the end of the cable would just stick out.
The levers on at least a couple of our bikes are held in such a way that the brake lever springs push the cable. They have plastic clips that snap over the cable end, where it's anchored to the arm.
Try the experiment I described upthread. It's easy - I just did it in five minutes in my basement, using a 3/4" dowel, a string, and some large nuts as weights. The difference is easy to feel. Even easier if you do a 540 degree wrap angle, rather than just 180 degrees.
in this case...probably not...it's a base model Mavica (the ones that use 3.5" disks...i'm waiting for it to die so i can buy a new one) and the shade of my front porch.
for my needs...it's worked out so well....it's hard to justify getting a new one.
this is going on a bike that won't be done until Oct. 07. right now, i'm collecting parts to save the builder the time of having to track some of this stuff down.
john said:
Sal said:
so i removed the liner from a brake cable and slipped it over the spring tips. still fits in the retainer...almost frictionless movement...and no more grinding feel at the lever.
Great macro & lighting! What sort of equipment did you use? (I'm not inferring that the equipment is responsible for the great quality photo, just curious)
As for your Record upgrade, have you ridden it yet? Do you think it will stay in place, or work it's way off the stud?
Happen to have the SunTour GPX that features the same internal coil springs (each arm has its coil spring fixed to the center bolt)...always wondered why noone offers something like that these days..
in this case...probably not...it's a base model Mavica (the ones that use 3.5" disks...i'm waiting for it to die so i can buy a new one) and the shade of my front porch.
In any case great sharpness & depth of field. Using shade certainly did the job of delivering good lighting for your purpose. I wish most ebay & other net photography were as good. My daughter & her hubby both have Sony Digital cameras. I don't know squat about digital. I'm still using Canon film cameras & lenses. One of my lenses is a 50mm close up. I really enjoy doing macro photography.
On 22 Apr 2006 21:25:28 -0700, "Ron Ruff" <[email hidden]>
Quoted message said:
I'm thinking about getting some old calipers now... but my memory is foggy...
Are there any issues with leverage ratios using modern levers... and how do you deal with the nutted pivot bolt?
The nutted pivot bolt ? Why you just bolt it down on your vintage frame, of course. It's those recessed allen bolts that cause the real dilemma... they just don't work on a vintage frame! (Actually, I've swapped them with comparable brakes from the same period when there were both types. You can use bolts from an older set and just polish them a little. )
If you use the sleeve *and* oil, won't the sleeve tend to work it's way off ?
