Replaced rear rotor and pads - Weak brakes & hot rotor

[ReSTored]

Breaking in new brakes the Gatekeeper post, above, applies. However, it sounds like you have other issues.

If you have slammed on your brakes and then your rear rotor may be hot for a minute or two (so to the front rotor(s)). If in normal use your fronts are cool to the touch, but the rear is hot then the rear brakes are dragging and your rear brake piston(s) may be fully or partially seized. Best thing to do is to pull the wheel off, pump the brake pistons out using the rear brake pedal, then remove the caliper and then clean everything up using brake cleaner and high # grit sandpaper + change out the brake fluid as well. You might be able to do this properly without new piston seals or new pistons, depends what condition they are in. If you don't get this addressed you may ruin your new rotor and pads + have poor braking capability as well.

After the caliper is attended to clean off the rotor with a 3M type abrasive pad and brake cleaner and you're good to go.

 

[Krime]

Breaking in new brakes the Gatekeeper post, above, applies. However, it sounds like you have other issues.

If you have slammed on your brakes and then your rear rotor may be hot for a minute or two (so to the front rotor(s)). If in normal use your fronts are cool to the touch, but the rear is hot then the rear brakes are dragging and your rear brake piston(s) may be fully or partially seized. Best thing to do is to pull the wheel off, pump the brake pistons out using the rear brake pedal, then remove the caliper and then clean everything up using brake cleaner and high # grit sandpaper + change out the brake fluid as well. You might be able to do this properly without new piston seals or new pistons, depends what condition they are in. If you don't get this addressed you may ruin your new rotor and pads + have poor braking capability as well.

After the caliper is attended to clean off the rotor with a 3M type abrasive pad and brake cleaner and you're good to go.

Interesting. Haven't had the chance to take thinks apart again, so this morning I applied some brake cleaner to the discs in the interim. Nothing changed, but I thought I'd do a test – I rode the bike on the 404 until I hit traffic and pulled over, making sure to not use any rear brake whatsoever from the time I'd left my house until then. Felt the rear rotor and it was very slightly warm. Not hot, but a bit warm. This tells me that it is dragging very slightly, and would explain why it takes so long to cool down after they getting hot from using the brakes. So looks like I'll need to do more than just the rotor + pad clean/sand down.

 

[boyoboy]

Interesting. Haven't had the chance to take thinks apart again, so this morning I applied some brake cleaner to the discs in the interim. Nothing changed, but I thought I'd do a test – I rode the bike on the 404 until I hit traffic and pulled over, making sure to not use any rear brake whatsoever from the time I'd left my house until then. Felt the rear rotor and it was very slightly warm. Not hot, but a bit warm. This tells me that it is dragging very slightly, and would explain why it takes so long to cool down after they getting hot from using the brakes. So looks like I'll need to do more than just the rotor + pad clean/sand down.

I don't understand your reasoning. cleaning the rotors after pads have soaked up the contaminants won't help. the only way to fix this is to skim off the now glazed part of the pads completely.. this is a couple or more days since the problem started. I would have cleaned the rotors and skimmed off the slippery brake pad material in, oh, about 40 minutes or less the same day. a slightly warm brake rotor is not an indication of a sticky caliper. The only problem is how the brakes were fixed in the first place (in my opinion, respectfully).

 

[bitzz]

If operating correctly the pads are held against the rotor to keep the rotor clean, so there should be some drag.

That new rotor had cutting fluid on it when you bought it. You need to clean it off. It probably said something to that effect on the packaging.

Why do people that know nothing about brakes find it so hard NOT to screw with their brakes.