Rear brake rotor getting hot
Intermediate
Joined: May 2012
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From: Aubrey Tx
So Far since my last post, I have rebuilt the Master cylinder and completely blew out the brake lines again. I saw something floating around in the master cylinder that didn't look right just before I pulled her down for a look-see and rebuild. I didn't really see signs of wear or anything but I already had this available to me so I did it. I regreased the pistons with piston grease and all seems to be well there so far. I figured if I couldn't re-assemble it by hand it was wrong so I just did it til it felt right. Re-installed the new brake shoes and I am currently bleeding them as we speak. I will re-test it when I get it back together and get back with ya'll. Damned this is frustrating...
Last edited by Hedghawg71; Sep 3, 2012 at 03:31 PM.
Intermediate
Joined: May 2012
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From: Aubrey Tx
I have been told by a couple of folks the brake pads always make contact. Is this true? And why doesn't my front ones? Would a performance machine setup do the same? because if it doesn't I am going this route. I had PM on my old Shovelhead and I don't remember any of this mess.
Intermediate
Joined: May 2012
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From: Aubrey Tx
I did re-grease the pins too. I used alcohol to clean it all up, blew everything out with an air compressor andre-assembled it all. As far as the bearings I will give them a look over in the next few days to see what is going on there and get back with ta'll on this. My wife is about to go nuts not being able to ride this week and I ain't far behind her on it. ;-)
Stage I
Joined: Apr 2019
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From: Northern Kentucky
2010 Fatboy Lo rear brake rotor hot
I have replaced the rotor, brake pads, caliper, rear brake line and bled the brakes and its still getting hot. It doesnt appear the pads are retracting. Any help would be greatly appreciated!
Seasoned HDF Member
Joined: May 2008
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From: South Carolina
You should have started a new thread, but too late now..
Have you rebuilt the master cylinder?
Are you sure the caliper is riding in the correct position relative to the rotor?
Have you rebuilt the master cylinder?
Are you sure the caliper is riding in the correct position relative to the rotor?
Last edited by Dan89FLSTC; Apr 13, 2019 at 06:19 PM.
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Joined: Sep 2008
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From: San Diego, CA
I have been told by a couple of folks the brake pads always make contact. Is this true? And why doesn't my front ones? Would a performance machine setup do the same? because if it doesn't I am going this route. I had PM on my old Shovelhead and I don't remember any of this mess.
There are no springs to retract the caliper pistons. They use a square cut seal on the piston, that pulls it back, just a very slight amount, when hydraulic pressure is released. This movement is not visible to the human eye. Most experts I've talked to, believe that even with the retracting motion of the square cut seal, the pads may still make very slight contact with the rotors....
There can be problems when the brake pistons stick and or there is an issue with the square cut rotor seals....
I copied this explanation of how the piston/square cut seal works from an article on Auto Repair by Jim Miller. Don't know the guy, just googled the issue to get an explanation, more eloquent than I could write...
"A round, square cut, “O” ring seal is contained in a groove cut into the caliper bore and provides a seal for the caliper piston. A dust seal is placed around the lip of the caliper piston at the brake pad contact area and is secured in a groove on the outside of the caliper bore. A hydraulic seal is maintained through contact of the caliper piston surface with the caliper seal. The caliper seal also provides two other functions in the disc brake caliper. It acts as a brake return spring to maintain correct clearance between the brake pad and the rotor. The caliper seal is able to do this because of its placement in the groove cut in the caliper bore. The seal groove is cut slightly wider than the caliper seal. When the automotive brakes are applied, the piston slides forward in the bore, moving the caliper seal against the edge of the seal groove. This causes the seal to distort in the same direction as the movement of the piston. When the brakes are released, pressure is removed from the piston and the distortion of the caliper piston seal causes it to pull the piston back slightly and create a small amount of clearance between the brake pads and the rotor."
Hedgehawg71- In your particular case, it sounds like you've properly cleaned the caliper, piston bore, and pistons..... I would suggest you double check that you've put the seals in the proper place, and that they fit properly.... get a service manual if needed to check your reassembly....
Good luck with the repair....
Last edited by hattitude; Apr 17, 2019 at 09:57 AM.
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