rear brake issue

[Locomotive]

I replaced my rear pads and discovered 2 pistons were stuck. Removed the caliper and removed each piston. Had a little gunk to remove from each piston and now it works great. After i replaced the pads i have noticed that they seem to grab and slip a little. Very noticable especially when using the rear to slow down at high speed. Never had this happen with the old brakes. Dont know if the rotor is bent or the brake pads need to set. Any ideas?

[Squidley]

You mention "Grab and Slip" 1st thing that hits me is did you get all the air out of the system? If it was a worn or warped rotor you would feel the petal pulsate. Did you go with diferent material pads than you previously used also? Just trying to get a clearer picture of what you got

[Locomotive]

bone stock pads and still bleeding off air

[mtman]

Did you flush all the old brake fluid out of the rear system? You might have some gunk in the rear system that's plugging up those tiny holes and not letting the full pressure get where it needs to

[Squidley]

John,

I see that your on an '86, dont know if you knew about the linked brakes. If you have air in the rear, more than likely it's in the left front too as that is part of the rear petal brake system. The 1st gens can be a bear to bleed, I have done many of them. You might have to bleed that entire system to get it working right. Also there is a bleeder up by the steering head bearing that leads to the front caliper. Check that out as well and try to bleed it from there.

[Locomotive]

Well I have bled the brakes many times and i do not have any air in the system. Still have the grab and slip issue. Only thing i can think of is maybe it is the composition of the new pads. Different brand that what i had origionally but the material looks the same. Never had this issue with the old set of brakes so i doubt i have a warped rotor. 2 pistons were sticking but i was able to break them free and popped all of them out for a cleaning. The seals were still good and leak no fluid at all.

[rhncue]

Well I have bled the brakes many times and i do not have any air in the system. Still have the grab and slip issue. Only thing i can think of is maybe it is the composition of the new pads. Different brand that what i had origionally but the material looks the same. Never had this issue with the old set of brakes so i doubt i have a warped rotor. 2 pistons were sticking but i was able to break them free and popped all of them out for a cleaning. The seals were still good and leak no fluid at all.

 

By "grab and slip" do you mean that the brakes are pulsating when applied? If so, then one rotor is warped and you usually can see where as there will be a little color change or even a little rust on that rotor. Since the pistons were froze chance are that those pads were not making contact on the rotor so no pulsating was felt.

 

If the slipping is not a pulsation but actually slipping, then it is because of new pads not seated yet on the glazed rotor. A little time and use will cure.

 

Dick

[CptKirk]

Had an issue with my 87 when I got it. Stuck pistons caused increased pressure on one side of the rotor which is a two piece affair.

 

The unequal pressure caused the rivets to let go and the two piece rear rotor could chatter and move independent of the hub (laterally).

 

If your bike has a two piece rotor/hub assembly have a boo at how solid the rivets are that connect the rotor to the hub you may find that they are loose and allow the rotor to wobble side to side much worse than a heat warped rotor.

 

The one I garbaged would rattle like a kids toy yet the previous owner was driving around on it.

 

Pretty sure you know that ANY brake fluid on the rotors or pads will cause a grab and a lockup.