|
|
|
|
| Author |
|
|
Registered
Join Date: Apr 2000
Location: Kansas City
Posts: 1,675
|
How Much Should Disc Brakes "Drag"
Recently completely rebuilt parking brakes on my '70 911E. All looks and works well, but I began thinking about caliper drag. After adjusting the parking brakes, I put the transmission in neutral and manually rotated the rear tires by hand. They rotate fine, but they certainly don't "spin". I can hear an audible "drag" of the brake pads on the rotors (the actual brakes, not the parking brake shoes).
Wondering how much "drag" is normal when no pedal applied and rotating "freely". I guess I am just paranoid about a parasitic drag of the pads on the rotors. Is there a good way to determine whether the calipers are retracting appropriately when in free wheel position? Thanks, JA
__________________
John - '70/73 RS Spec Coupe (Sold) - '04 GT3 Last edited by Jandrews; 11-23-2013 at 09:52 AM.. |
||
11-23-2013, 09:46 AM
|
|
|
Registered
Join Date: May 2008
Posts: 2,948
|
The rear wheels will always be harder to turn because of the axle/CV joint assemblies, the differential, etc. If you want to know if you have caliper/pad drag, remove the rear wheels, take out the locking pins for the pads, and then attempt to remove/slide each pad. If the pads move, you're good. If the pads are tight/very tight, you have calipers in need of resealing, or you have brake fluid hoses in need of replacement. The hoses should be replaced every ten years/100K miles, whichever comes first. Your hoses will be dated so you can verify when they were made. Faulty hoses allow fluid to flow to the caliper under brake pressure, but close down internally and restrict return flow when the brake pedal is released.
__________________
Keep the Shiny Side UP! Pete Z. |
||
|
11-23-2013, 11:05 AM
|
|
|
Registered
Join Date: Apr 2000
Location: Kansas City
Posts: 1,675
|
Thanks Peter!! You are exactly the guy who I hoped would chime in, and you were first!! I replaced my hoses years ago, but not sure how many years ago. I will check the dates on them. And then that "pad pin pull test" is EXACTLY what I was looking for....something to see if I am good or not!
Many thanks, and what a great asset Pelican is to make experts like this available to us "common" men! JA
__________________
John - '70/73 RS Spec Coupe (Sold) - '04 GT3 |
||
|
11-23-2013, 11:19 AM
|
|
|
Registered
Join Date: Aug 2008
Location: sectors R&N, SE Pa
Posts: 3,117
|
wow - this is great. I have a similar issue with the front, and the hoses were updated and the lines have been bled. I think I am do for a re-sealing.
__________________
Dan '87 Targa Carrera 3.2 - Fabspeed Cat Bypass, M&K Muffler, SW Chip Venetian Blue |
||
|
11-23-2013, 01:41 PM
|
|
|
Registered
|
if you can turn them without strugling theyre probrobly fine. if they were to fully release you would have a spongy peddal. if they dont pull or get hot then youre good
__________________
82 SC , 72 914 |
||
|
11-23-2013, 02:31 PM
|
|
Porsche
1972 porsche 914
