Yes, another brake question - 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 Wrangler Forums > YJ Wrangler Technical Forum > Yes, another brake question

Rough Country Deals at JeepHut.comSave at JeepHut on Smittybilt Soft topsUp to $75 Cash Back on Your ARB Fridge Freezer Purchase

Reply
Unread 02-04-2013, 08:26 AM   #1
mntbkrguy
Member
 
mntbkrguy's Avatar
1994 YJ Wrangler 
 
Join Date: Oct 2002
Location: Washington, DC, VA
Posts: 246
Yes, another brake question

Background:
94 YJ, 8.8 swap w/disk brakes. Master Cylinder out of an old Mercury Grand Marque, stock proportioning valve with the o-ring removed.

Symptoms:
1) When first started I hit the brakes and it takes a while to slow to a stop so I usually hit the brakes a few times when I first start moving to warm them up (figure of speech).
2) Once warmed up the brakes are touchy, if I press to hard the jeep nose dives and I have been wearing my front pads down quick. I need to replace the pads and rotors this week.
3) The pedal goes all the way to the floor, when I replaced the Booster about a year or so ago I adjusted the push rod to the point where I think that is the point where the pedal stops.
4) when I really need to stop and have the foot to the floor it seems to take a longer distance than I feel comfortable stopping.

I have bled the brakes many times with little improvements. The last time I used a hand vacuum pump to pull fluid up to the master from the passenger front and got just a few little bubbles from the front which I think may have been stuck in the proportioning valve which helped a very little.

I have read every post I can find and it seems like everyone has had different results. I am ready to put in a ZJ Proportioning valve when I change the brake pads and rotors, I have also considered a 95 booster.

I can deal with the touchiness, and the soft brake pedal but what really has me concerned is the short stopping distance and it taking time before the brakes really start working after initial startup.

Any experienced input would be a huge help, Vancopbs, any suggestions.

__________________
Mntbkrguy
1994 YJ 4.0
8.8 rear, 35's
mntbkrguy is offline   Reply With Quote
Unread 02-04-2013, 08:45 AM   #2
SeanB95YJ
Registered User
1995 YJ Wrangler 
 
Join Date: Nov 2009
Location: Schenectady, New York
Posts: 1,185
This is what I did back when I had my XJ and swapped to rear discs....

4-wheel disc MC (which you have already)
dual diaphragm booster (you mentioned new booster, but didn't say if it was stock replacement or upgraded dual)
removed stock prop valve completely
ran front directly from MC through a T fitting to each of the front wheels
ran the rear through an adjustable prop valve I bought from Summit Racing
bled/flushed system fully
initially had the prop valve fully open (full flow) and took it to a deserted shopping center where the town dumps all excess plowed snow (after it's melted, there's lots of sand on the pavement)... did some slow test runs SLAMMING on the brakes locking up the tires... kept making prop valve adjustments (reducing flow) until the fronts would lock BEFORE the rears did

on 33s I swear it stopped better than most cars on the road

Good luck
__________________
[FONT="Comic Sans MS"][COLOR="Blue"]Sean B. - Schenectady, NY - 95 YJ, 350/700r4/NP241, JB Shorty SYE, 8.8 rear, 2" BDS, 1" homebrew shackles, Daystar 1" BL, TJ flares, 35x12.50 General Grabber AT2 on 15x10 Bart D-Truckers, Polyshield polycarbonate windshield, HD over/under crossover steering
[/COLOR] [COLOR="Red"]swap/build thread: [url]http://www.jeepforum.com/forum/f22/after-almost-4-years-finally-my-own-build-swap-thread-1542284/[/url][/COLOR][/FONT]
SeanB95YJ is offline   Reply With Quote
Unread 02-04-2013, 09:24 AM   #3
mntbkrguy
Member
 
mntbkrguy's Avatar
1994 YJ Wrangler 
 
Join Date: Oct 2002
Location: Washington, DC, VA
Posts: 246
I have the stock booster and thought about upgrading to the dual. I haven't heard of removing the proportioning valve for the front that is a different idea. I looked at the adjustable valves for the rear it sounds like you have had good luck with that. That may be back on the list.
__________________
Mntbkrguy
1994 YJ 4.0
8.8 rear, 35's
mntbkrguy is offline   Reply With Quote
Unread 02-04-2013, 09:37 AM   #4
jbolty
Moderator
 
jbolty's Avatar
1990 YJ Wrangler 
 
Join Date: Jun 2007
Location: San Diego, CA
Posts: 15,699
I did the 95 booster swap a couple years ago and had a lot of problems; low pedal mostly. I adjusted the push rod, swapped the master and bled gallons of fluid. Turns out to have been a bad booster. I got three in a row that were defective rebuilds from Cardone. Eventually mrblaine made a custom bracket for me and put in a 98 TJ booster. With that and EBC pads in the front I can stand the jeep on its nose with the brakes. Never touched the proportioning valve. Not long after this the black magic pads came out and I have some experience with those and highly recommend.
__________________
.
"The right to be heard does not necessarily include the right to be taken seriously." —Hubert Humphrey
.
If you live within wheeling distance of San Diego county, click here
jbolty is offline   Reply With Quote
Unread 02-04-2013, 09:58 AM   #5
NHfireYJ
Web Wheeler
 
NHfireYJ's Avatar
1994 YJ Wrangler 
 
Join Date: Dec 2009
Location: Seacoast NH
Posts: 2,390
Running the same set up as you, (O ring still installed) No issues at all, on 35's
__________________
BETTY...94 SE, Golen Stroker 4.6, RE 4" lift, 1" booms rear, 1/2" booms front, 1" BL, 35 12.5 15 GY MTR's Kevlar on 15 x 8, AA SYE w/ Woods shaft, D30 Aussie, 8.8 w/ LSD, 4.10, Smittybilt front and rear bumpers, Wildbuilt rock sliders, Cutom tire carrier w/ Jerry can, Hi-Lift, Smitybilt 8000lb winch, Ammo can consol, VHF & CB radio, Herculined, Neoprene seat covers, Hard /soft/ bikini tops.

HUMMER INTAKE. Click here.. http://www.jeepforum.com/forum/f12/h...style-1257285/

FEBRUARY 2013 YJOTM
NHfireYJ is offline   Reply With Quote
Unread 02-04-2013, 03:33 PM   #6
JeeperDon
Patience, Grasshopper
 
JeeperDon's Avatar
1993 YJ Wrangler 
 
Join Date: Jan 2005
Location: Albuquerque, NM
Posts: 6,410
OP, to me your '1)' item is screaming air-in-line. I just added the axle with discs and nothing else but a good bleed. My brakes were fine before and are fine after, with zero differences in any particular press at any time. On any brake work done right with good working parts, the overall stopping performance may be different as you play with MC's, prop valves, and boosters, but it should never change from stop to stop. You said you did the air, and I'm not saying you don't know what you're doing, but to me it's an air issue.
__________________
'93 YJ, '02 GM 4.3 Vortec V6, SOA, dual ARB's, 8.8+D30(w/WarnHubs), 4.88 gears, 35" BFG KM2's, AX15, 15x7 wheels, NP231+4:1+SYE+2LO, York OBA, Warn M8000, no top or doors Apr-Oct.
Member and Web guy: New Mexico 4 Wheelers My Truck Page on NM4W Site
JeeperDon is online now   Reply With Quote
Unread 02-05-2013, 07:47 AM   #7
mntbkrguy
Member
 
mntbkrguy's Avatar
1994 YJ Wrangler 
 
Join Date: Oct 2002
Location: Washington, DC, VA
Posts: 246
JeeperDon I think you are correct although I have no idea how that could be so after all the effort I have put into bleeding the system.

I have just ordered new rotors premium pads a tee for the line and adjustable proportioning valve. I saw an adjustable one a while back but it was expensive so I kind of gave up on that but after seeing them for only $35 on Summit I figure that is the best way to eliminate one of the biggest parts of it. I also think replacing the pads and rotors will make a huge difference since they are looking pretty rough. obviously I will have to bleed the whole system again and another temptation is to use a homemade version of this.
http://www.motiveproducts.com/

It is really just your typical garden sprayer with a plate to force fluid through the system.

I will keep an update if anyone wants to know how it all ends up.
__________________
Mntbkrguy
1994 YJ 4.0
8.8 rear, 35's
mntbkrguy is offline   Reply With Quote
Unread 02-05-2013, 08:08 AM   #8
JeeperDon
Patience, Grasshopper
 
JeeperDon's Avatar
1993 YJ Wrangler 
 
Join Date: Jan 2005
Location: Albuquerque, NM
Posts: 6,410
A caliper may be hanging up too. Also look for the little notches in the brake hanger, where the pad notches hit the hanger. There is not stainless steel cap there on a YJ as on other vehicles, so the hanger gets wear notches. I had that and recently welded the notches up and ground them smooth.
__________________
'93 YJ, '02 GM 4.3 Vortec V6, SOA, dual ARB's, 8.8+D30(w/WarnHubs), 4.88 gears, 35" BFG KM2's, AX15, 15x7 wheels, NP231+4:1+SYE+2LO, York OBA, Warn M8000, no top or doors Apr-Oct.
Member and Web guy: New Mexico 4 Wheelers My Truck Page on NM4W Site
JeeperDon is online now   Reply With Quote
Unread 02-05-2013, 08:16 AM   #9
TSEJEEPERS
Registered User
1993 YJ Wrangler 
 
Join Date: Dec 2003
Location: Morton IL
Posts: 4,925
I am running somewhat the same system is you.
I did install the 95 booster and a proportioning valve from a 4 disk GrandCherokee at the same time as the master though.
If I remember right don't you have to change the lines on the master?
They are switched on the Marquis master. (front and back)
I also had a few problems with one of the lines going into the master. (leak)
As always make sure your bleeders on the calipers are on top and start with bleeding the passenger back first.
You may want to tap on the calipers the same time you are bleeding them. Sometimes air will get trapped in them.
__________________
93 YJ SOA 2" springs front, XJ springs rear w/main leaf added, High pinon 9 inch rear detroit locker front Dana 44 ARB 4.56 Gears, 36 inch Irok tires too much to list. www.mijc.org
TSEJEEPERS is online now   Reply With Quote
Unread 02-05-2013, 08:16 AM   #10
kjg26
Registered User
1993 YJ Wrangler 
 
Join Date: Jul 2003
Location: North of Atlanta, Georgia
Posts: 1,812
I swapped discs brakes from a 98 grand cherokee into my 93. I swapped a 95 booster and master cylinder and 97 grand cherokee prop valve and it stops wonderfully. Locks up 33s.
__________________
Black 1993 YJ 4.0, 5 Speed
Slowly but surely getting better and better. Trailer build soon!!
kjg26 is offline   Reply With Quote
Unread 02-05-2013, 12:04 PM   #11
87TPIYJ
Registered User
1987 YJ Wrangler 
 
Join Date: Feb 2009
Location: Jacksonville, Florida
Posts: 768
Quote:
Originally Posted by jbolty View Post
I did the 95 booster swap a couple years ago and had a lot of problems; low pedal mostly. I adjusted the push rod, swapped the master and bled gallons of fluid. Turns out to have been a bad booster. I got three in a row that were defective rebuilds from Cardone. Eventually mrblaine made a custom bracket for me and put in a 98 TJ booster. With that and EBC pads in the front I can stand the jeep on its nose with the brakes. Never touched the proportioning valve. Not long after this the black magic pads came out and I have some experience with those and highly recommend.
Not to hijack the thread but can you post a pic of that bracket you had made for the tj booster? Did the bracket keep you from having to cut and extend the plunger?
__________________
87 YJ, 350 TPI, NV3500, NP241C, 35x12.50x17, SOA, 8.8LSD Warn 9.5XP
87TPIYJ is offline   Reply With Quote
Unread 02-05-2013, 12:25 PM   #12
mntbkrguy
Member
 
mntbkrguy's Avatar
1994 YJ Wrangler 
 
Join Date: Oct 2002
Location: Washington, DC, VA
Posts: 246
JeeperDon, another great suggestion I will take a look
__________________
Mntbkrguy
1994 YJ 4.0
8.8 rear, 35's
mntbkrguy is offline   Reply With Quote
Unread 03-25-2013, 09:24 AM   #13
mntbkrguy
Member
 
mntbkrguy's Avatar
1994 YJ Wrangler 
 
Join Date: Oct 2002
Location: Washington, DC, VA
Posts: 246
Here is the update. I decided to go with the adjustable rear proportioning valve and T off the front. So far so good, I took the jeep up tp Rousche Creek for a weekend with my club and felt a lot more compfortable. I think in the long run I could use a little extra power from a dual diaphram booster will help but being able to stop facing down a very steep grade in 4x4 low without my foot mashed to the floor gives me a lot more confidence.



__________________
Mntbkrguy
1994 YJ 4.0
8.8 rear, 35's
mntbkrguy is offline   Reply With Quote
Unread 03-25-2013, 03:34 PM   #14
zeus87gn
Automotive Neurosurgeon
 
zeus87gn's Avatar
1987 YJ Wrangler 
 
Join Date: Sep 2006
Location: Houston, Texas
Posts: 2,407
Quote:
Originally Posted by mntbkrguy View Post
3) The pedal goes all the way to the floor, when I replaced the Booster about a year or so ago I adjusted the push rod to the point where I think that is the point where the pedal stops.
Classic symptom of a master cylinder with bad seals
Did you get a rebuild from the store or a used one from a yard?
__________________
Handicapped license plates are not for mentally handicapped people -

"Man has not yet evolved an inch from the primordial slime that spawned him." Mark Blankfield, Jekyll & Hyde... Together again

Holley Carb thread
zeus87gn is offline   Reply With Quote
Unread 03-25-2013, 06:23 PM   #15
87TPIYJ
Registered User
1987 YJ Wrangler 
 
Join Date: Feb 2009
Location: Jacksonville, Florida
Posts: 768
Quote:
Originally Posted by mntbkrguy View Post
Here is the update. I decided to go with the adjustable rear proportioning valve and T off the front. So far so good, I took the jeep up tp Rousche Creek for a weekend with my club and felt a lot more compfortable. I think in the long run I could use a little extra power from a dual diaphram booster will help but being able to stop facing down a very steep grade in 4x4 low without my foot mashed to the floor gives me a lot more confidence.
I can't even explain how much better the dual booster is!
__________________
87 YJ, 350 TPI, NV3500, NP241C, 35x12.50x17, SOA, 8.8LSD Warn 9.5XP
87TPIYJ is offline   Reply With Quote




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.