Rear Disc Brake Help - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Rear Disc Brake Help

Savvy/Currie Aluminum Control ArmsROCK BOTTOM prices on LIFT KITS at Rockridge4wd!! WANT TO December Specials at Jeephut.com

Reply
Unread 07-14-2013, 12:06 PM   #1
gup
Registered User
1985 CJ7 
 
Join Date: Jan 2012
Location: Jenison, MI
Posts: 11
Rear Disc Brake Help

Issue
• After trying to bleed brakes and getting fluid at all wheels. The rear calipers don’t move at all. Is there something I am missing that would stop these from moving? I just received the axle with these brakes from a local shop that built the axle for me and need advice.

Jeep information
• 1985 CJ7 – Chevy 350
• Stock front Disc brakes
• 8” Dual Diaphragm Power brake booster unit.
• Master cylinder, 1” bore
• Stock proportioning valve

New additions
• New Rear Disc Brakes (Calipers/Discs/Pads from 1998 Ford Explorer)
• Ford 8.8 axle cut to width.
• Braided lines from Calipers to Steel lines then to rear brake hose.

__________________
1985 CJ7 - Chevy 350 - Edelbrock 4 brl Offroad - Hedman Headers - SM456 4 Speed - Ford 8.8 Rear Axle 3.31 Gears - Yukon Grizzly Locker - Rear Disc - 8” Dual Diaphragm Power booster - Twin Stick - Fiberglass Tub - Total Lift 5.5" (2.5" Suspension, 2" Body, 1" Shackle) - 35 x 12.50 Baja Claws.
gup is offline   Reply With Quote Quick reply to this message
Unread 07-14-2013, 12:16 PM   #2
jeepwhore
Hair puller xtraordinaire
 
jeepwhore's Avatar
1984 CJ7 
 
Join Date: Jun 2006
Location: Kamloops, BC
Posts: 3,206
Rear disc conversions seem to be hit and miss. Some have no problems, some have nothing but. Could be you need a residual valve. Might want to search the forum. There are several rear disc threads that might have a solution for you.
__________________
'84 CJ-7: Yota axles (spartan locked front, e-locked rear) 4" BDS, 1" Daystar & 3/8" shackle lifts, 35" X-Terrains on steelies, YJ Tub & family roll bar, heater blower upgrade, 4.2L w/MC2100 & Team Rush, Warn 8274. Rebuilt 4.2/4.0 hybrid, AX15 and twin sticks/clocking ring waiting to go in.

The advertised position for a topless, dirty jeep girl has been filled......by my wife. Thanks to all that applied.
<------------and yes, that is her.
:-D
jeepwhore is offline   Reply With Quote Quick reply to this message
Unread 07-14-2013, 04:28 PM   #3
gup
Registered User
1985 CJ7 
 
Join Date: Jan 2012
Location: Jenison, MI
Posts: 11
Thanks JH. (couldn't bring myself to calling you your full name)

So is a "residual valve" the same as a porportioning valve? And by looking at them there are tons of options. Is it advisable to go after market and adjustable?
__________________
1985 CJ7 - Chevy 350 - Edelbrock 4 brl Offroad - Hedman Headers - SM456 4 Speed - Ford 8.8 Rear Axle 3.31 Gears - Yukon Grizzly Locker - Rear Disc - 8” Dual Diaphragm Power booster - Twin Stick - Fiberglass Tub - Total Lift 5.5" (2.5" Suspension, 2" Body, 1" Shackle) - 35 x 12.50 Baja Claws.
gup is offline   Reply With Quote Quick reply to this message
Unread 07-14-2013, 04:48 PM   #4
BESRK
GROUND POUNDER
 
BESRK's Avatar
1980 CJ5 
 
Join Date: Nov 2002
Location: Newport News, VA
Posts: 12,279
The residual valve is actually inside the master cylinder. It simply maintains a set amount of pressure in the rear brake system (IIRC, it's about 10lbs for a typical drum brake). The residual valve is there to help apply some pressure to counter the rear brake shoe springs when they retract. It minimizes the distance the shoes need to travel before they engage in the drum. That helps keep a nice firm brake pedal with "comfortable" travel.

On a typical rear disk setup, the brake pads don't have any sort of spring system trying to retract them.. usual residual valve for a disk setup is about 2lbs.

I'd verify that your getting pressure in the rear line coming out of the master cylinder. If so, next point of blockage would be the proportioning valve. Maybe crack the rear line coming out of the proportioning valve while someone depresses the brake pedal. If you have pressure at the proportioning valve, next stop is back at the rear axle lines and calipers.

Also, if you let the master cylinder go dry, you may have to bench bleed it to get good pressure/flow from it again.
__________________
'80 CJ5 w/AMC360, T176, D44 w/Detroit 4.56, RE 4" YJ lift and 35s..

Ground Pounder Fab


Lower 2

Guardrail

Down Schoolbus

Slickrock Tellico

Save

Crozet

More Crozet
BESRK is offline   Reply With Quote Quick reply to this message
Unread 07-14-2013, 05:00 PM   #5
waterdowg
Registered User
1984 CJ7 
 
Join Date: Mar 2009
Location: nj
Posts: 2,248
Quote:
Originally Posted by gup View Post
Issue
• After trying to bleed brakes and getting fluid at all wheels. The rear calipers don’t move at all. Is there something I am missing that would stop these from moving? I just received the axle with these brakes from a local shop that built the axle for me and need advice.

Jeep information
• 1985 CJ7 – Chevy 350
• Stock front Disc brakes
• 8” Dual Diaphragm Power brake booster unit.
• Master cylinder, 1” bore
• Stock proportioning valve

New additions
• New Rear Disc Brakes (Calipers/Discs/Pads from 1998 Ford Explorer)
• Ford 8.8 axle cut to width.
• Braided lines from Calipers to Steel lines then to rear brake hose.
How did you bleed then?
waterdowg is offline   Reply With Quote Quick reply to this message
Unread 07-14-2013, 07:13 PM   #6
gup
Registered User
1985 CJ7 
 
Join Date: Jan 2012
Location: Jenison, MI
Posts: 11
So hopefully I can answer the questions you guys gave me while trying to help me. About 3 momths ago I purchased and installed the following:

http://www.ebay.com/itm/74-86-JEEP-C...item4174dea341

I then bench bleed it prior to installation. It helped but I had drums that were bad on the back so I assumed it was just that. Then I did the axle swap with disc brakes on the rear.

I bleed those starting with the farthest wheel. Helper pressed the pedal while I released the bleeder letting air out...repeat all wheels while refilling the resevoir between.
__________________
1985 CJ7 - Chevy 350 - Edelbrock 4 brl Offroad - Hedman Headers - SM456 4 Speed - Ford 8.8 Rear Axle 3.31 Gears - Yukon Grizzly Locker - Rear Disc - 8” Dual Diaphragm Power booster - Twin Stick - Fiberglass Tub - Total Lift 5.5" (2.5" Suspension, 2" Body, 1" Shackle) - 35 x 12.50 Baja Claws.
gup is offline   Reply With Quote Quick reply to this message
Unread 07-15-2013, 09:17 AM   #7
dg6772
Registered User
1986 CJ7 
 
Join Date: Feb 2011
Location: Muskegon, Michigan
Posts: 1,694
Does the m/c have 2 equal reservoirs? Are you sending enough fluid to the rear brakes, as discs use more fluid than drums do.

Dave in Muskegon
dg6772 is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools






Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.