Page 1 of 2

Changing disk brakes

Posted: Thu Aug 18, 2005 10:53 am
by eugeart
I just bought the GSX 750 and I didn't like the look of the pads from what I could see and the rear rotor is is scored a little. I've turned rotors and not turned them in the past with cars- the jury is still out. Since its the rear and isn't used much I'd decided to just change the pads.

Wow, alot o'meat on those rear pads- virtually identical to the EBC sintered that I bought. Hmm, I'll take those back and get my$30. The rear squeaks but at least I know its not worn pads, just a rough rotor that will have to be replaced or turned eventually.

Turned my attention to the front double disk. I'd figured these things out by now (the rear was a minor learning experience) and checking them should be little problem. Wow, these are almost gone and they'll have to be replaced.

What I learned: remove the plastic top cover to expose pads and pins.

Rear- at least with this katana undoing the top two bolts breaks the caliper apart, but this releases brake fluid and a tiny round gasket that I was just lucky to see lying there. I put that all back together before continuing and took a new approach. Undo the bottom bolt and lever up the caliper, bleed a little to release pressure. Remove the two cotter pins slide out the retaining pins and the pads can be removed. Installation is the reverse and bleeding may be required to fit the new pads in the caliper and on the rotor. Bleed once back on if neccessary.

Front- same as the rear except the two bolts that hold the caliper to the forks must be removed. I found the front to have more pressure than the rear so I had to bleed the brakes to get the new pads in. Installation reverse of removal.

I'm sure there is a better way and I'd like to know it.

Turning the rotors to a smooth finish would be nice but if replaced in time I feel that brakes work just fine without turning.

Posted: Thu Aug 18, 2005 11:32 am
by 9000white
you dont have to bleed any fluid out to change pads--take a screwdriver and push the old pads apart then install the new ones. if the master cylinder is full to the top and wont let the fluid return to reservoir take the top off and take a paper towel and soak up some of it.

Posted: Thu Aug 18, 2005 11:44 am
by TechTMW
You're not supposed to turn Motorcycle disks either ... (Most places won't do it) They're already thin and brittle ... turning them is just asking for trouble.

Posted: Thu Aug 18, 2005 12:02 pm
by eugeart
Thats what I thought about the disks. Ideally, in my opinion rotors should last a very long time for the typical rider if they pay attention to the pads. As it is on my test ride the redone brakes perform flawlessly. I suppose they'll be broken in at some point and then I'll make my final judgement. The squeak in the rear is gone too- how I managed that I don't know.

Yeah, I was a little ansy about bleeding etc... on cars I use a giant C-clamp and a piece of wood to push in the calipers' pistons. This time the pads had worn so much that I couldn't get both new pads in at the same time so I had to let some pressure off. Each caliper has four pistons and I'd push one in with a screwdriver and the other would push out and there was no way I was getting a clamp the size I had to work.

All in all it was pretty easy. I've found that if one is methodical and careful the task isn't too bad.

Posted: Thu Aug 18, 2005 1:33 pm
by 9000white
i had a disk turned one time on a Virago because of .013 warp.they kept it a week and charged me $47.00.

Posted: Sat Aug 20, 2005 11:13 am
by bigswifty
You're not supposed to turn Motorcycle disks either ... (Most places won't do it) They're already thin and brittle ... turning them is just asking for trouble.
They probly didnt literally turn the discs.
i think it would actually be better to grind motorcycle rotars on a blanchard, or even a big surface grinder....quick operation and no hassle setup.

the service limit on mine is .280, and they're about .330 now. So i would guess that they could be machined ONCE.

Posted: Sat Aug 20, 2005 5:55 pm
by iwannadie
eugeart wrote:Thats what I thought about the disks. Ideally, in my opinion rotors should last a very long time for the typical rider if they pay attention to the pads. As it is on my test ride the redone brakes perform flawlessly. I suppose they'll be broken in at some point and then I'll make my final judgement. The squeak in the rear is gone too- how I managed that I don't know.

Yeah, I was a little ansy about bleeding etc... on cars I use a giant C-clamp and a piece of wood to push in the calipers' pistons. This time the pads had worn so much that I couldn't get both new pads in at the same time so I had to let some pressure off. Each caliper has four pistons and I'd push one in with a screwdriver and the other would push out and there was no way I was getting a clamp the size I had to work.

All in all it was pretty easy. I've found that if one is methodical and careful the task isn't too bad.
im about to change my rear pads and ive been reading about bedding them in. seems like a very important step ha, shouldnt just jump on and ride like normal or you can screw your brand new brake pads up. maybe doesnt matter to you but i use my rear brake just as much as the front ;)

Posted: Sat Aug 20, 2005 6:19 pm
by eugeart
Yes you should use them both in conjunction. Obviously though the front handles 75% of the load. They should wear out twice as fast.

Too much applied preesure to rear brake when coming to a stop has been proven to make your bike unstable. That is why the rear will kick out to the right if too much rear brake is used at the wrong time. It physics man. Not only that the resistance of the drive train to the rear wheel is what keeps you upright in a sense- like a gyroscope as well as slowing you down. Lock up that back wheel and a novice or even accomplished riders could lay it down coming to a simple low speed stop. Its all physics.

For regular stopping I use the front brakes liberally with a touch of the rear while downshifting. Right before I am about to stop and then only then do I pull in the clutch and maybe a little more of the rear cause that rear wheel helps me keep upright.

Emergency stops are another kettle of fish though ideally they should be handled much as above I suppose

Posted: Sat Aug 20, 2005 7:13 pm
by iwannadie
eugeart wrote:Yes you should use them both in conjunction. Obviously though the front handles 75% of the load. They should wear out twice as fast.

Too much applied preesure to rear brake when coming to a stop has been proven to make your bike unstable. That is why the rear will kick out to the right if too much rear brake is used at the wrong time. It physics man. Not only that the resistance of the drive train to the rear wheel is what keeps you upright in a sense- like a gyroscope as well as slowing you down. Lock up that back wheel and a novice or even accomplished riders could lay it down coming to a simple low speed stop. Its all physics.

For regular stopping I use the front brakes liberally with a touch of the rear while downshifting. Right before I am about to stop and then only then do I pull in the clutch and maybe a little more of the rear cause that rear wheel helps me keep upright.

Emergency stops are another kettle of fish though ideally they should be handled much as above I suppose
i didnt mean to sound like i was telling you to use your rear brake more. you should be worried though if you didnt properly bed in your new pads. if you dont do that right then your back brake becomes Alot less effective(from what ive read).

as for the rear brake, i use mine often without touching the front brake so i think the wear balances itself out a bit so that im not replacing the front twice as often as the rear.

Posted: Sat Aug 20, 2005 7:55 pm
by eugeart
Sorry if I sounded a bit pompous there. I originally thought the rear was worn. It turned out to be the front so I only replaced them. The rear I left alone. I've babied these brake for about 150 miles or so, and they work well. I'm impressed with the EBC sintered. They were $30 each side after tax. I could redo all four disk drakes on my car for $30. And tires- don't even get me started. Oil? Costs the same as a car or more with a decent filter. Who said bikes were cheap?