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8.8 in..... break master and vacuum options?

3K views 37 replies 12 participants last post by  captainauti 
#1 ·
hello all again. i just finished the 8.8 with disc brake install. everything went great. my next issue to tend to is stopping. i hooked everything up to the stock setup that is in the heep. it is a 95 with stock braking for a 4cyl.
i took it for a quick ride, and it stops just the same as it always has...... like a$$. what can the fine people of JF recommend for break upgrades, do's and dont's.
1.the stock proportioning valve is in place...... should it stay, change?
2.its a 4cyl originally so maybe upgrade to the duel diaphram vac booster?
3.master cyl upgrades?

i hear of people locking up 37's, im running 33's, and its not the best stopper. it is off the road until it stops properly, so that is my next project.
thanx to all ...... again.:cheers2:
capt.
 
#3 ·
Mine stops awesome without special boosters or master cylinders.

I did remove the proportioning valve rubber washer but otherwise everything is stock.

I can lock up my 33's. I DO have new pads and new front rotors though. I also have it tuned perfectly with all new fluid. I would replace your pads and rotors and make sure you have it bled well. Otherwise you should be fine.
 
#4 ·
New pads and rotors. Bleed your entire system till all new fluid is in the lines and you should be fine. I just did my swap. And after replacing pads, rotors, and fluid mine stops better than a brand new car. I havent tried to lock them up yet, but with about 15% of the pedal pushed down. It feels like the rear end is almost locked up.
 
#5 ·
Jbolty...... I was thinking the dual diaphragm from the 4.0. What did you use?
Soonermatt.... What oring? Did you Try without removing it first? Was there an improvement?

I did change all the old fluid, all new parts up front and rear. Used the highest quality from napa. Just stops the same as before the swap. All air is out too.
 
#7 ·
Soonermatt.... What oring?
There's an o-ring in the proportioning valve. I guess it's a common mod; Google will describe it better than I could.

Did you Try without removing it first? Was there an improvement?
IDK. When I installed my 8.8 w/disc brakes my brakes were crap. The pedal went to the floor and I had to pump my brakes to get stopping power. I read all the threads about getting the bleeders on the top and actually bleeding the brakes correctly.

I THOUGHT I was doing it correctly and it still wasn't working right. So I pulled the o-ring and it didn't really make a difference.

After that, I debated buying a new master cylinder and as a last resort I just started cycling brake fluid through my system.

My mentality was that I would just act like I was flushing the system. So I hooked a bleeder line up from the right rear caliper into an old brake fluid bottle. I cycled through a cup of brake fluid which was about 20 pedal pumps. I did this for every caliper.

All of the sudden my brakes worked perfectly. The pedal would provide solid resistance at about 1/2 inch movement. Moving my pedal past 4 inches is impossible.

My fluid is completely clear and I can see the bottom of my master cylinder. When I go to brake, the jeep feels like it wants to roll over the front tires and the rears will lock up if I'm not careful. I had fun going out and "burning" my brakes in. I told my wife that she can feel free to drive the jeep like her little Honda. With the 4.88 gears and 4 wheel (new) disc brakes this thing stops and starts pretty nice.

So........without insulting you, I tend to believe that you haven't adequately bled your brakes.
 
#28 ·
what o ring are you talking about?

and i ordered all my parts from my local napa. not thinking, when they were delivered, i didnt look at the brand and i just saw the box..... it says cardone.:brickwall:brickwall:brickwall
now.... i think it might be bad? who had a bad cardone part, and what was the symptoms of a bad booster.
 
#8 ·
my fluid to is clear. all the way back. i have replaced all the lines. i bled the brakes with a vacuum pump, to be sure not to introduce any air.
dont get me wrong, it stops. it just doesnt stop as well as hear others here stop.
if the system drains, is there a chance of an air pocket developing in or around the proportioning valve?
 
#10 ·
so tomorrow i will be replacing front calipers, so every part from proportioning valve back is new. i am adding speed bleeders for ease of bleeding, and will try brakes again. if no better, id guess ill chang to the dual diaphram booster and newer plastic style master.
any input on changing the booster and master would be great. besides what the search came up with.
nate.
 
#11 ·
how about a brake booster and master from a tj? did they all have dual diaphrams? easy bolt up?
 
#12 ·
The most common swap is the dual diaphram booster from the 1995 6 cyl. But, they are just about impossible to find from anyone other than Cardone reman, and those suck. After having 3 bad ones in a row I gave up.

Now I have a 98 TJ booster but it took a fair amount of fab work from Mrblaine to get it working. The push rod is a different length and getting that exactly right is important. I've seen a few threads about welding on a threaded rod. No hard, but for sure not a bolt in deal.
 
#13 ·
I can get the master and booster from a 95 6 cyl at napa for under 200. it is two separate parts. is that the way to go?
 
#14 ·
two parts.

it's a pretty big improvement. Mostly a direct bolt in except the 95 master has metric fittings; they have the adapters at NAPA. Also, the fitting are on the opposite side, so you have a little plumbing to do.

Good opportunity to replace everything including all the hard lines and calipers and do a fresh clean fluid install.

Can't say it enough times to avoid the Cardone boosters.
 
#15 ·
Won't go cardone. Are the fittings diff from my 95 with 2.5?
 
#18 ·
Parts will be in next week. Added speed bleaders. Blead system twice more, and still the peddle goes half way before any response is noticed.I'm thinkin its a master cyl issue.
 
#21 ·
I tried all the same things bled it numerious times and still spongy and unresponsive, just got done with the E350 swap. I used a 1985 E350 van master cylinder Part # M2008 only 25.99 at O'Reillys and two fittings from Napa weatherhead part # 7828 1/4x5/16 and #7917 1/4x3/16. It stops great now just like Ripper mentioned some grinding on the ears of the master cylinder and some elongating of the mounting holes and it will fit like a glove. Bleed it and go enjoy your new braking.
 
#20 ·
e350 master here just gotta trim the ears down on the master and itll sit right in there, also it has different fittings on em. not hard to do at around 45 bucks total price. after bleeding like crazy my pedal still isn't really firm but i can lock up my 37s if i stand on it

edit: btw i have the 4 cyl booster still
 
#24 ·
soooo. i did everything like 5.7yj did, and still blah.
the only part that is not new is the proportioning valve.
blead the system 3 times and no air coming out. ran about 2 quarts through. pedal goes to the floor with ease stops like a freight train dragging a cinder block. i ran a clear tube off the speed bleader and no air coming out.
pedal can be pumped up pretty firm if i cycle the pedal rapidly. and it firms up hard with engine off. im at a loss.
 
#26 ·
captainauti said:
soooo. i did everything like 5.7yj did, and still blah.
the only part that is not new is the proportioning valve.
blead the system 3 times and no air coming out. ran about 2 quarts through. pedal goes to the floor with ease stops like a freight train dragging a cinder block. i ran a clear tube off the speed bleader and no air coming out.
pedal can be pumped up pretty firm if i cycle the pedal rapidly. and it firms up hard with engine off. im at a loss.
I'm at a loss too. The only way this could be possible is if you aren't bleeding it correctly or you have a hole or bulge in your system. If you have a leak you should see fluid. If the other....

This doesn't make sense.
 
#27 ·
the front seems to be diving according to my father when i stopped in front of the house. i dont have any leaks externally. the only other thought i have is that there are new pads, calipers, and rotors all the way around. maybe i need to get out on the road and heat them up to set them and burn off any oils on the rotors from packing..... never had that issue, but just thinking.


how about the rod going from the booster to the pedal, and adjustments on that maybe i didnt do? the pedal does hit the first resistance at about 1/4" of movement. then just goes steady to almost the floor where it seems to grab most, while standing on it.
 
#30 ·
the front seems to be diving according to my father when i stopped in front of the house. i dont have any leaks externally. the only other thought i have is that there are new pads, calipers, and rotors all the way around. maybe i need to get out on the road and heat them up to set them and burn off any oils on the rotors from packing..... never had that issue, but just thinking.

how about the rod going from the booster to the pedal, and adjustments on that maybe i didnt do? the pedal does hit the first resistance at about 1/4" of movement. then just goes steady to almost the floor where it seems to grab most, while standing on it.
I would try adjusting the rod out. You will know when it is too far out because it will make the brakes drag.
The suggestion about the ZJ prop valve is good too. They are pretty easy to find in yards. Just bring a pair of cutters and cut the lines. That way you will have the fittings too.
I know you said that there is no air but just to make sure get a vacume pump like this.
http://www.harborfreight.com/mityvac-vacuum-pump-39522.html
Most parts store stock either this one or one like it.
Take your bleeders out and wrap them with teflon tape. (this will keep you from sucking air through the threads)
The pump uses clear tubes so you can see if there is any air in the lines.
Tap on the calipers as you are doing it to make sure there is no air pockets trapped in them.
Hope this helps.
 
#29 ·
Okay, the rotors were cleaned of all shipping grease before install, right?
Also the pads need to be bedded. Do 10 easy stops from 30 to 0. And not any hard stops for the break in.
This is how I bed pads and shoes at my shop. Works great.
 
#31 ·
Okay, the rotors were cleaned of all shipping grease before install, right?
Also the pads need to be bedded. Do 10 easy stops from 30 to 0. And not any hard stops for the break in.
This is how I bed pads and shoes at my shop. Works great.[/QUOTE
yes cleaned off.

I would try adjusting the rod out. You will know when it is too far out because it will make the brakes drag.
The suggestion about the ZJ prop valve is good too. They are pretty easy to find in yards. Just bring a pair of cutters and cut the lines. That way you will have the fittings too.
I know you said that there is no air but just to make sure get a vacume pump like this.
http://www.harborfreight.com/mityvac-vacuum-pump-39522.html
Take your bleeders out and wrap them with teflon tape. (this will keep you from sucking air through the threads)
The pump uses clear tubes so you can see if there is any air in the lines.
Tap on the calipers as you are doing it to make sure there is no air pockets trapped in them.
Hope this helps.
the rod from the pedal to the booster? move it out so it lifts the pedal higher? the pedal is about maxed out all the way up. i am using speed bleeders. the have thread sealer on them from the factory, and have check valves in them to bleed without sucking air back in the system. and with the clear tube, clean clear fluid without bubbles is coming out.
im thinking the damn cardone part. might switch back to stock booster with the new master to see how that does. if it changes, im guessing bad part. cant believe i didnt look at the box. i ordered napas part not this crap.
 
#34 ·
I will be putting the stock booster back on later. See what happens then. If I stop better than now... I'll suspect a bad booster. Damn cardone crap.
 
#35 ·
but before i will be adding a residual pressure valve. just a thought from some hot rod guys with my symptoms... then back to a booster swap. grrrrr
 
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