Disc brake iissues
|
Posts: 31
Threads: 10
Joined: Aug 2019
Here I go again, after getting the "won't go" problem resolved, ran into another. I also converted the rear brakes to disc and having issues with them. Brakes are real soft, have to pump them up 3-4 times to get them to work. Had it up to 5 or six but after adjusting the calipers with spacers for alignment, it got a little better, but there is too much space between the rotor and pads. We also adjusted the piston out some which helped but still have to pump up them up. Not real sure what to do. We did power bleed the brakes also. Have a new master cylinder with a proportioning unit on it.
Posts: 1,330
Threads: 34
Joined: Feb 2015
I've never tinkered with aftermarket rear disk brakes. Do you have the correct master cylinder for rear disk and front disk brakes? Disk brake calipers usually require more fluid volume flow than the wheel cylinder on drum brakes. It's odd that the pistons pull back so far after releasing the breaks.
On stock calipers there is a square cut O-ring that seals the caliper piston to the caliper. During brake application, as the piston moves a little, the square cut O-ring deforms slightly, then when the brakes are released the deformed square cut O-ring returns to its normal shape and pulls the piston back. As the pads wear, occasionally the piston will need to move further than the square cut O-ring can deform and the piston will slide past it a little and basically self adjust.
Posts: 3,119
Threads: 92
Joined: Jan 2010
I agree with 69 Mach1. You shouldn't have that much distance between the pads and rotor. And once they moved out to the disc's they should stay there, and only pull back enough to loosen their grip on the rotor. approximately .030 or thirty thousandths of an inch. Think like 2 match book covers. so if they are pulling back an 1/8th inch or more? That's not a good thing. If all else works, then you might make a phone call, or two, and see if all the parts are correct for the rear kit that was installed. Hope it helps.
JTS
Posts: 31
Threads: 10
Joined: Aug 2019
(08-19-2019, 03:39 AM)1969_Mach1 Wrote: I've never tinkered with aftermarket rear disk brakes. Do you have the correct master cylinder for rear disk and front disk brakes? Disk brake calipers usually require more fluid volume flow than the wheel cylinder on drum brakes. It's odd that the pistons pull back so far after releasing the breaks.
On stock calipers there is a square cut O-ring that seals the caliper piston to the caliper. During brake application, as the piston moves a little, the square cut O-ring deforms slightly, then when the brakes are released the deformed square cut O-ring returns to its normal shape and pulls the piston back. As the pads wear, occasionally the piston will need to move further than the square cut O-ring can deform and the piston will slide past it a little and basically self adjust. I drive a truck for a living and when I get home hopefully on Friday, will do some more checking and hopefully resolve the problem. There was a new master cylinder and proportioning valve put on it , so seems kind of strange to have this problem. Thanks for the info and will let you know!!!
Posts: 31
Threads: 10
Joined: Aug 2019
(08-19-2019, 06:49 AM)JTS71 Mach1 Wrote: I agree with 69 Mach1. You shouldn't have that much distance between the pads and rotor. And once they moved out to the disc's they should stay there, and only pull back enough to loosen their grip on the rotor. approximately .030 or thirty thousandths of an inch. Think like 2 match book covers. so if they are pulling back an 1/8th inch or more? That's not a good thing. If all else works, then you might make a phone call, or two, and see if all the parts are correct for the rear kit that was installed. Hope it helps.
JTS
Thanks JTS for the info, we are going to get back at it this weekend and there will be some phone calls made before then. I am wondering as you are if I have the wrong "stuff". Will also let you know what we find out.....thanks again!!!!!!
Posts: 1,330
Threads: 34
Joined: Feb 2015
It crossed my mind that the other thing that causes a caliper piston to retract too far is a warped rotor. In your case they would have to be unusually severely warped. But maybe something else is causing them to not run true.
Posts: 31
Threads: 10
Joined: Aug 2019
I want to thank you all for the info. I did get the problem resolved.....I hope. A friend found a You Tube video to see if it might help and seems it did. In it, it showed and with the audio, disconnect the caliper from the mounting bracket, put it on the rotor, then remove the e brake bracket from the caliper and also the cable, then turn the nut under the bracket in until there is no play. Well as I said, so far so good. I even drove it most of last weekend....lol Thanks again !!!!!
Posts: 3,119
Threads: 92
Joined: Jan 2010
Cool Glad to hear you fixed it. There's always answer, sometimes it's easier then others, but there is always an answer. Good Luck with it.
JTS
|
Possibly Related Threads… |
Thread |
Author |
Replies |
Views |
Last Post |
|
Brake booster/servo hose length |
mach71 |
7 |
3,005 |
08-23-2022, 09:40 AM
Last Post: JTS71 Mach1
|
|
Brake pedal adjustement |
tanataur |
24 |
51,986 |
11-07-2013, 10:17 PM
Last Post: tanataur
|
|
Parking Brake Warning Light - Wiring |
crendave |
1 |
9,767 |
04-10-2012, 10:19 PM
Last Post: ohiomustang
|
|
brake booster/tach question |
paul cass |
4 |
16,010 |
01-04-2012, 03:27 AM
Last Post: JTS71 Mach1
|
|
Rear Brake locking up???? |
TFFTR1 |
10 |
30,636 |
01-24-2011, 11:45 AM
Last Post: don29163
|
Users browsing this thread: 1 Guest(s)
|
Latest Threads
|
What's One More Iron In The Fire!
Last Post: fram lee666
03-18-2024 06:21 PM
» Replies: 125
» Views: 238138
|
"Jacobra"
Last Post: JTS71 Mach1
06-30-2023 11:13 PM
» Replies: 86
» Views: 150924
|
My old Queensland Ambulance
Last Post: JTS71 Mach1
06-30-2023 11:08 PM
» Replies: 5
» Views: 1702
|
New member from San Jose, CA
Last Post: JTS71 Mach1
05-09-2023 08:39 AM
» Replies: 12
» Views: 3964
|
Saving Seatbelts
Last Post: Jim
02-19-2023 10:23 PM
» Replies: 2
» Views: 9113
|
Sourcing new wheels
Last Post: JTS71 Mach1
01-25-2023 02:34 PM
» Replies: 1
» Views: 2003
|
Shaker Air Filter
Last Post: JTS71 Mach1
01-08-2023 02:24 AM
» Replies: 3
» Views: 1467
|
1971 Mach 1 parting out interior parts -...
Last Post: ylwhrse
12-22-2022 01:38 PM
» Replies: 0
» Views: 640
|
Painting
Last Post: Rare Pony
12-14-2022 06:24 PM
» Replies: 2
» Views: 1970
|
WELCOME ALL NEW MEMBERS INTRODUCE YOURSE...
Last Post: JTS71 Mach1
08-31-2022 01:36 PM
» Replies: 82
» Views: 157067
|
1970 mach 1 matching numbers
Last Post: Kstweeter
08-31-2022 10:31 AM
» Replies: 1
» Views: 1087
|
Brake booster/servo hose length
Last Post: JTS71 Mach1
08-23-2022 09:40 AM
» Replies: 7
» Views: 3005
|
New Member
Last Post: JTS71 Mach1
08-20-2022 11:18 AM
» Replies: 2
» Views: 1501
|
smooth window operation on 70 Mach
Last Post: CUSTOMMISER
08-15-2022 12:10 PM
» Replies: 2
» Views: 1482
|
Blinkers on solid
Last Post: busted21
08-09-2022 03:58 AM
» Replies: 14
» Views: 8728
|
Blinkers on solid when lights on.
Last Post: JTS71 Mach1
08-08-2022 12:06 PM
» Replies: 1
» Views: 1720
|
351 cj running hot
Last Post: busted21
08-08-2022 12:13 AM
» Replies: 5
» Views: 3410
|
Major Winter projects
Last Post: JTS71 Mach1
07-09-2022 05:12 AM
» Replies: 49
» Views: 21298
|
Happy Fathers Day!!!
Last Post: JTS71 Mach1
06-20-2022 02:34 AM
» Replies: 0
» Views: 1686
|
1969 Raven Black 390 Looking For
Last Post: mason1958
06-11-2022 09:48 AM
» Replies: 10
» Views: 15088
|
|
|