Topic: Brake caliper adjustment screw?

[Tintop]

if 12 thou clearance from pad retracting, is too much, use the stock adjuster, and cut that in half (while in proper adjustment)

Just for clarification.   Upon brake release, the spring on the adjuster pushes the caliper assembly to the right .006.  The caliper seal retracts the piston .012, which leaves a .006 clearance on each side the rotor, for no drag.  Without the adjuster, the caliper wanders from right to left as the rotor alternately contacts the pads, over bumps, in turns, etc.

Now if you want easier tire changing on dual disc, or just don't want the extra hardware, leave em off..

I don't believe the front axle can reliably be registered laterally with zero tolerance upon reassembly after a tire change.  Lateral de-registration would affect the disk to rotor clearance, necessitating a readjustment of the caliper clearance adjuster.  So, if you do any planning ahead in your work flow, you can loosen the jam nut on the adjuster to give extra clearance between pads for the rotor, making re-install easier.   After wheel install, then re-adjust inside caliper pad clearance and lock down the nut.  A couple strokes of the brake lever should get the pads positioned for normal riding.

I do know this.. either way works..

Yes, either way works.  But, I think the way it was designed to work is better for street use.  Perhaps the weight saved (an ounce?) without the adjuster, spring and locknut is better for racing.  But, I'd like to see that demonstrated with differential lap times, before and after the change over.

Cheers,

Have to disagree here TwoTired.  Both the 550 and 750 front axle has shoulders on the 'nut' that goes on the left side.  Those shoulders align on either side of the fork leg.  Unless the axle spacers are re-installed incorrectly it will always position the wheel the same laterally.  As for just backing off the adjusters to faciliate wheel removal.  With dual disks this may be possible if the tire is the stock size.  However, if the tire / rim is oversize that will not create enough clearence for the tire to fit between the calipers.

[fastbroshi]

Eh Holes! I love it!!

[TwoTired]

Have to disagree here TwoTired.  Both the 550 and 750 front axle has shoulders on the 'nut' that goes on the left side.  Those shoulders align on either side of the fork leg.  Unless the axle spacers are re-installed incorrectly it will always position the wheel the same laterally. 

Yes, there are shoulders.  But, neither the the fork leg's receptors, nor the axles shoulders are made to zero tolerance or an interference fit.  So, it won't position within, .000 in.  And, it really doesn't need to be.  The less tolerance a part is made to, the more expensive it is.  So, there is a trade off between cost and necessity.

Further, the the axle nut screws on the axle and that seating surface too, is made to a non-zero tolerance.  These parts are all from a bin, and rarely perfect in every dimension to the drawing//specification.  You CAN get lucky, but it is no way assured.  That is the purpose of tolerances.  The external tolerance of one part can never exceed the internal tolerance of the part it is being fit into.  So, some are a bit sloppier than others.  If the wheel was off center even .010, it wouldn't effect driveability, but it would affect the caliper clearance.  Fortunately, the adjustment is there to adapt easily.

As for just backing off the adjusters to faciliate wheel removal.  With dual disks this may be possible if the tire is the stock size.  However, if the tire / rim is oversize that will not create enough clearence for the tire to fit between the calipers.

OK, I can see that, sort of.  Many changes can have an unforseen ripple effect which in turn requires still more changes/modifications.
But then, I don't see why you need oversize rims/tires, other than for ogling.
If you need to swing the caliper outward out of the way, you can remove the adjuster completely during the tire change.  Yes, it is an extra step, but so was the dual disk conversion, and the adjuster definitely has benefits for a street bike as I have explained.

Cheers,

[Tintop]

OK TT, I'll call it a draw.  Yes there are manufacturing tolerances to consider, and these will vary from part to part.  However, if I always assemble the same parts & wheel, the same way as originally fitted and aligned, it will always position the same.  And yes if you change a part you are back to square one.

Oh, and yes, my street 550 cafe's reversed caliper dual disks have the adjusters fitted.   Wheel removal is a PITA, but that's the trade off for the improved brakes.

[scottly]

For the SOHC4, the spring on the adjuster pushes the stationary pad away from the rotor .006 inch.  The square section seal in the caliper withdraws the piston and piston side pad about .012 inch.  This allows the rotor to spin free of the rotor when the lever is released.
Without the spring and adjuster, the brake will always have more drag and wear than without, provided the caliper piston and seal are in proper working order. 

A minor detail: The spring pushes the brake arm, NOT the pad, away from the rotor. The stationary pad "floats" in the housing, and is free to rub against the disc.

[754]

 EXACTLY..!!

 BOTH pads are on a radiused swivel pad, and can move in an arc..

 NO matter what anyone says, if the caliper seal retracts, say .012.. that is 12 THOUSANDS of an inch.. to those not in the know.. that is the thickness of 3 or 4 hairs off your head..
 So  the adjuster, set right can center that.IT DOES NOT..CANNOT prevent the pads from swivelling and touching..
 Its 12 thou.. at best you can center it.. does not mean it will stay there if brake expands in use.. Not everyone is capable of adjusting it properly..
 So ask ask you....... do you feel lucky ...........PUNK....
 
............at your wrenching skills..
.. or are you just anally going thru the motions while telling yourself you are doing something worthwhile.....

 You decide, its your ride..

[Anti-Johnny]

How is this screw intended to be adjusted. Not knowing how it works until now, I assumed that my squeaky brake was the result of the shop tightening this too much after putting my new tires on. I tried loosening it and tightening it some and cant tell a difference.

[MCRider]

How is this screw intended to be adjusted. Not knowing how it works until now, I assumed that my squeaky brake was the result of the shop tightening this too much after putting my new tires on. I tried loosening it and tightening it some and cant tell a difference.

A few definitions: The "live" pad, the one pushed by the piston is the A pad, the dead pad is the B pad.

Loosen the lock nut on the adjuster and turn the screw clockwise. Now you'll have clearance for the B pad. Push on the caliper so the A pad goes into the caliper a bit. Make sure the whole set up swings free on the pivot pin of the caliper mount. If not, you'll need to disassemble and clean the pivot. Use some waterproof grease on the pin and reassemble.

Get a 6 thou feeler gauge and put it between the B pad and the disc. Turn the screw counterclockwise drawing the b pad towards the disc until the gauge can be withdrawn from the pad/disc with the slightest of resistance. Hold the screwhead and tighten the lock nut. Pump the brake lever so the A pad comes into contact with the disc. Squeeze a little more and you'll see the B side draw into the disc. Release the lever and the spring will push the B pad away from the disc 6 thou and the A pad will retract into its housing a few thou. The wheel should spin free with the slightest sound of pads dragging.

[Anti-Johnny]

How is this screw intended to be adjusted. Not knowing how it works until now, I assumed that my squeaky brake was the result of the shop tightening this too much after putting my new tires on. I tried loosening it and tightening it some and cant tell a difference.

A few definitions: The "live" pad, the one pushed by the piston is the A pad, the dead pad is the B pad.

Loosen the lock nut on the adjuster and turn the screw clockwise. Now you'll have clearance for the B pad. Push on the caliper so the A pad goes into the caliper a bit. Make sure the whole set up swings free on the pivot pin of the caliper mount. If not, you'll need to disassemble and clean the pivot. Use some waterproof grease on the pin and reassemble.

Get a 6 thou feeler gauge and put it between the B pad and the disc. Turn the screw counterclockwise drawing the b pad towards the disc until the gauge can be withdrawn from the pad/disc with the slightest of resistance. Hold the screwhead and tighten the lock nut. Pump the brake lever so the A pad comes into contact with the disc. Squeeze a little more and you'll see the B side draw into the disc. Release the lever and the spring will push the B pad away from the disc 6 thou and the A pad will retract into its housing a few thou. The wheel should spin free with the slightest sound of pads dragging.

Thanks MCRider! Ill be hunting down that gauge in the morning. I plan on rebuilding my caliper this weekend so this is good to know. My brake didnt start squeaking until I started messing with it, and so now I get to figure out what I did.

[MCRider]

How is this screw intended to be adjusted. Not knowing how it works until now, I assumed that my squeaky brake was the result of the shop tightening this too much after putting my new tires on. I tried loosening it and tightening it some and cant tell a difference.

A few definitions: The "live" pad, the one pushed by the piston is the A pad, the dead pad is the B pad.

Loosen the lock nut on the adjuster and turn the screw clockwise. Now you'll have clearance for the B pad. Push on the caliper so the A pad goes into the caliper a bit. Make sure the whole set up swings free on the pivot pin of the caliper mount. If not, you'll need to disassemble and clean the pivot. Use some waterproof grease on the pin and reassemble.

Get a 6 thou feeler gauge and put it between the B pad and the disc. Turn the screw counterclockwise drawing the b pad towards the disc until the gauge can be withdrawn from the pad/disc with the slightest of resistance. Hold the screwhead and tighten the lock nut. Pump the brake lever so the A pad comes into contact with the disc. Squeeze a little more and you'll see the B side draw into the disc. Release the lever and the spring will push the B pad away from the disc 6 thou and the A pad will retract into its housing a few thou. The wheel should spin free with the slightest sound of pads dragging.

Thanks MCRider! Ill be hunting down that gauge in the morning. I plan on rebuilding my caliper this weekend so this is good to know. My brake didnt start squeaking until I started messing with it, and so now I get to figure out what I did.

You're welcome, if you turned the screw and couldn't tell a difference, its likely the thing isn't swinging freely on the pivot pin. You shhould see the B pad move away from the disc immediately as you turn the screw.

[TwoTired]

How is this screw intended to be adjusted. Not knowing how it works until now, I assumed that my squeaky brake was the result of the shop tightening this too much after putting my new tires on. I tried loosening it and tightening it some and cant tell a difference.

A few definitions: The "live" pad, the one pushed by the piston is the A pad, the dead pad is the B pad.

Loosen the lock nut on the adjuster and turn the screw clockwise. Now you'll have clearance for the B pad. Push on the caliper so the A pad goes into the caliper a bit. Make sure the whole set up swings free on the pivot pin of the caliper mount. If not, you'll need to disassemble and clean the pivot. Use some waterproof grease on the pin and reassemble.

Get a 6 thou feeler gauge and put it between the B pad and the disc. Turn the screw counterclockwise drawing the b pad towards the disc until the gauge can be withdrawn from the pad/disc with the slightest of resistance. Hold the screwhead and tighten the lock nut. Pump the brake lever so the A pad comes into contact with the disc. Squeeze a little more and you'll see the B side draw into the disc. Release the lever and the spring will push the B pad away from the disc 6 thou and the A pad will retract into its housing a few thou. The wheel should spin free with the slightest sound of pads dragging.

Thanks MCRider! Ill be hunting down that gauge in the morning. I plan on rebuilding my caliper this weekend so this is good to know. My brake didnt start squeaking until I started messing with it, and so now I get to figure out what I did.

You're welcome, if you turned the screw and couldn't tell a difference, its likely the thing isn't swinging freely on the pivot pin. You shhould see the B pad move away from the disc immediately as you turn the screw.

Not quite.  The spring does not necessarily push the piston side pad back, especially if the seal is distorted or the piston sticking.  To set the stationary pad, back off the adjuster so it will allow the arm to swing inward, then push on the caliper against the rotor to force the piston pad back into the bore.  (Beware the fluid is going back up to the master.)  Now set the fixed pad clearance to rotor at .006 in, lock down the adjuster and recheck clearance.  Readjust if necessary so that after lock down, the inside pad still has .006 in clearance.  Depending on how far in you pushed the piston previously, it will take a pump or two of the brake lever to get it back into ready position.  This assumes the caliper is clean of all foreign sludge or hardened brake fluid and the piston isn't too badly pitted, which distorts the seal and diminishes piston/pad retraction.

Cheers,

[crazypj]

With dual disks this may be possible if the tire is the stock size.  However, if the tire / rim is oversize that will not create enough clearence for the tire to fit between the calipers.

 Totally agree with this
 I ran Dunlop TT100's almost exclusively on 550, 4.10 x19 on WM3 rim.
It wasn't possible to get wheel out without removing caliper bolts both sides and 'splitting' calipers and letting all the air out to get it between mounting bolts
 Without the adjusters it's a right PITA to get wheel back in as one or the other would always swing' into wheel.
 I also noticed the brakes didn't seem as 'tight' with the adjusters removed so I guess the pistons do retract when riding.
 I used adjusters and re-set pads every few thousand miles (although pads were usually worn out by 4~6,000 miles)

[TwoTired]

BOTH pads are on a radiused swivel pad, and can move in an arc..

I guess you also threw away that nylon ring that keeps the pad in line with the rotor, too?

Nothing like throwing away parts because you don't understand what they are for.

It is 6 thou clearance not 12 thou.
Yes, a small portion of pad can/could contact the rotor.  But, it ain't the whole pad as the caliper swivels back and forth on its pivot.

But, it's ok, I "get it" that you just don't/can't "get it".  Do what you like.  I just hope beginners and those who wish to understand, will choose science and engineering over speculation.

Be Well!

[754]

 This is what I tested feel free to list how many miles you tested yours.
 BTW the finned calipers  probably,did not use the plastic washer.

 I ran 2 discs drilled by me with calipers turned around. -3 lines I assembled myself. Later on I chromed the MC and calipers and cut the adjuster mounts off prior to chroming. No ill effects observed.. no noticeable drag if coasting..you can hear if they are dragging.
 Perhaps some of you enjoy the spongy feel of stock lines opposed to the firmer feel of  hardlines,, but I prefer the harder feel, and 2 finger braking, and the ability to easily chirp the front tire at 60mph..
 I ran mine for at least 20 thousand if not 30 or more, with no noticeable ill effects..

 You can put your time into fine tuning many areas of your bike, I prefer to concentrate on power and gas mileage..

  Keep in mind, if you adjust the brake incorrectly, it can drag, there are many things you can do to your bike that will make a bigger difference.. your choice..