turning rotors?

i have pulsing coming from the front brakes, i think i have a warped rotor. i just bought a set off of ebay for $40 shipped. but worst case scenario, i need to have my originals turned, who does this? thanks!

 

i doubt anyone turns them. they are thin enough as it is. and a proper fitting machine probably doesn't exist.

lift the front tire off the ground and spin it by hand. see if the rotor is bent.

i had a v65 magna that i literally heated up the front brake rotors so bad you could see them glowing a mile away. (not on purpose though)

i rebuilt the entire front braking system with new seals. did nothing with the rotors. the rotors never gave me a problem. it had dual rotors.

 

Have somebody check the runout with a Dial Gauge.

Poor man's Dial Gauge.
Darning Needle
Gum Block Eraser.
Stick the Needle's eye into the end of the Eraser.
Hold the Eraser on the Caliper and touch the Disc like you are doing a Needle Drop on your favorite Record Album.

Rotate the Rotor.
Watch the Needle and Listen.

Oh, ... I almost forgot.
Who turns Rotor's?
A: Nobody!

 

They cannot be "turned" in the conventional sense. They can be very lightly GROUND, but it has to be done by somebody who has a Blanchard mill and the capability to do both sides at once.

I had one done (ground and drilled) and it works and looks great. UNfortunately, only a very small amount can be taken off (less than 0.5mm) so you have to start with a "true" rotor to begin with, one with only minimal gouges too.

Warped rotors have to be replaced, period. Out of spec on runout=dumpster food.

 

i did some research on the net, and found out what you guys beat me to. no grinding-goes below min. limit. so i'm hoping the new rotors will get rid of the pulsing/handlebar shake i have right now. i have new head stem bearings, and i've played with the torque on the stem nut, but it doesn't really change. i read on a different list that it could be the master cyl. anyone ever run across that?

 

Fix the warped rotor and go from there.

 

mine were warping. lot of judder when braking.

the fourth shop i took them to agreed to take them in. the other disc got machined down to 4,2 mm thickness but i will bolt it on anyway.

will post results when i eventually get it all together

 

oh noes my judder reduced a bit but it got more sharp.

i need to check them with a dial gauge.

my tire guy said my front wheel was warping a little when he was balancing my shinkos.

the machining shop i took my rotors for grinding said they had to grind also the side that bolts to the wheel on the rh side rotor.

i will take it off an run only the left rotor and see what happens..

 

A Wobble and Front-end Vibration can be caused by a number of problems.

The simplest Test youcan do is check the Air Pressure in your Tires and be vigilant about keeping the Air Pressure constant.

Wrench Check all the Nuts and make sure everything is tight.

Brake drag can be reduced by cleaning the Caliper Piston's Seal Channel of debris if the Rotors spin true.

Chamfering the Edges of the Pads reduces Right Angle Contact and lets the Rotor Spin without Squealing.
New Pads with Pre-chamfered edges will place less of the Caliper Piston pushed-out of the Caliper keeping the Piston in a position to retreat better when Hydraulic Pressure is relaxed.

Tire Wear can adversely impact how the Front-end trails on various surfaces.

 

thanks rick.


the issue was present already when i bought the bike. front end was juddering under braking. when not using the brake everything was fine.

i took a closer look and took the front end off.

i carefully rebuilt calipers and anti-dives. everything cleaned + new seals. calipers work very well, pads dont drag at all. im not that sure if the anti-dives work as they should, i need to play with the adjustment a little to see if it has any effect. i did make sure they operated well when i put them back together )the valve units spring was enough to force the actuating piston back up when no brake pressure was applied)

i measured my rotors with a dial gauge, they were warped. i took them for a grinding, and they told me they got them straight. currently i doubt that, i need to make sure with the dial gauge again.

wheel bearings were renewed.

i used a gsxr master cylinder with braking ss lines from m/c to calipers, oem brake lines from calipers to anti-dives.

tires are new shinko tour masters.

everything was tightened to specifications.

the front feels good, but when i apply my brakes they start to snap on every rotation of the wheel. meaning the problem persists, only its a more sharper snap than before. might be because everything is assembled more tight than before dunno

 

Put a "Severe" Chamfer on the Brake Pads. Look at the Factory chamfer that FERRODO puts on their Metallic Pads.

I cant put a pic with this because I am using a back-up computer.
If the Pads are Shuddering before they get a grip; a chamfer MIGHT help.

If those Disks are still way out of True, ... your only recourse will be to replace them.

 

just an update. i got a set of used rotors off of ebay. installed, and things are all good. thanks gentlemen!

 

thanks again rick,

i forgot to mention i did a good chamfer on the pads.
i investigated my brakes last night. i noticed that the right caliper is off its position somehow, only thing comes to mind is that the whole fork is rotated clockwise a little, because of poor machining of the front axle hole. or something.

seems that the beating the previous owner did to the caliper was for trying to compensate this fault. thread: http://xjbikes.com/Forums/viewtopic/t=25793.html

when i apply brakes my left caliper stays in position, and the piston is the moving part. on the right caliper the piston side pad is touching the rotor, not dragging, and when brake is applied the other side gets BENT towards the rotor, thus trying to rotate the whole caliper unit.

the only noticeable problem of this is the mentioned snap on the brakes once on every rotation, though im unable to see how this would be caused by this.


cheezy sorry for the total thread hijack

 

now im confused.

i had suspicions of my right rotor so i took off my right caliper, tied it to the fork and had a little test ride. for my amazement nothing changed. snapping continued.

well then i naturally put it back together and did the same thing with my left caliper. snapping was gone.

so it is my left rotor which is warped. its strange because the left side caliper is the one working properly.


i try to hunt for a used rotor and hope its straight.

btw theres a manufacturer in germany selling new oem looking rotors for 99 euros..