Help Brake Help

[Rockhpr]

So after completely rebuilding my brake system during my frame off restoration my brakes still suck. I have new brakes, brake lines, proportioning valve, dual diaphragm booster and new master cylinder. With all of this my brakes still will only lock up on gravel. Bled system thoroughly. Not spongy just doesn't stop well. Any Ideas? Apparently I have more to learn about hydraulics.
Specs: 86 CJ7 4.0L from 96 XJ. 35" tires. Dana 30 front Dana 44 Rear.
Thanks

 

[coldair]

Astro van hydro booster! https://jeep-cj.com/community/threads/hydroboost-install-pics.7406/

 

[coldair]

Here is another one about the Astro van hydro booster. https://www.jeepforum.com/forum/f8/my-hydroboost-conversion-4356983/
One member you can talk to is gert I talked him into doing this he loves it. I have t been able to do this yet time isn’t on my side so my booster is sitting in storage waiting on me to install it.

 

[Manic Mechanic]

my only issue with that set up is that if you develop a leak u lose ur power breaks. i would start with the simplest. make sure your rear drums are properly adjusted. if that doesn't work think about changing them to disk you have large tires biggest thing most people don't think about is actually upgrading there brakes.

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[coldair]

Yes you do loose your power brakes BUT you dont loose all your braking. Do you worry about developing a leak in your power steering? If you're worried about leaks in a hydro boost system and not the power steering then maybe you should run a manual steering box and manual brakes. BTW a ton of manufactures use hydro booster and power steering at the same time.

 

[Manic Mechanic]

Yes you do loose your power brakes BUT you dont loose all your braking. Do you worry about developing a leak in your power steering? If you're worried about leaks in a hydro boost system and not the power steering then maybe you should run a manual steering box and manual brakes. BTW a ton of manufactures use hydro booster and power steering at the same time.

i do worry about it but more so since I off road and I have slid off a rock and hit the steering box hard enough to make it leak before

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[coldair]

I wheel pretty hard and dont worry about power steering leaks and not going to worry about a hydro boost leak. As long as you inspect your equipment before every outing you shouldn't have a problem.
As for hitting a steering box I dont know what to tell you maybe you should build a skid plate around your box.
I can tell you a hydro boost setup will give you way more braking power then any vacuum booster will.

 

[Rockhpr]

Thanks, I have considered adding rear disks. But I should still have ok braking up front. Even if I move my prop valve to full forward the front should lock up. They are only 35s and I have already upgraded the MC and Booster. Bled numerous times and rear is adjusted.

 

[Rockhpr]

If I add a hydroboost system can I still add ram assist on steering since they both use the power steering pump?

 

[coldair]

Yes you can run a hydro boost with ram assist. You might have to send the hydro booster in to have it ported. Or you can buy a whole kit from Vanco That already has the prot job done for you. http://www.vancopbs.com/category_s/68.htm

 

[CDT540]

I had a similar problem. I installed a after market vacuum brake booster kit a few years back and the brakes were great, huge improvement. Recently I had an issue with master cylinder and had to replace it. I don't usually use the shop but in this case I did. Since it was after market PB kit you couldn't just order a MC for an '83 CJ7. The word on the internet was the aftermarket brake booster kits uses a generic '80s corvette style MC. So that is what the shop put in. The brakes were awful, basically it felt like only the rear drums were engaging. In the end it was the wrong MC and it was plumbed incorrectly. Because the front discs move more fluid and more fluid is needed as the pads wear, the larger of the two MC chambers needs to go to the front and the smaller one to the rear. Mine was reversed so I think the rear pads were maxing out before I could move enough fluid to engage the front discs. Also, the size of the MC bore size makes a difference, I started with an MC with a 1 1/8 bore size but ended up using one with a 1 inch bore. It makes a difference in how much fluid id being moved. Specing the correct parts for these aftermarket PB kits can be really tricky, and at times it is trial and error.

 

[Manic Mechanic]

Specing the correct parts for these aftermarket PB kits can be really tricky, and at times it is trial and error.

you said a month full but have a good point. when I did my PB upgrade i installed a complete unit from a YJ using all new factory parts. Jeep stops on a dime and has no trouble locking up the tires.

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[Rockhpr]

I purchased the MC/booster kit as a unit. I am not sure what the bore is of the MC. That is something I was wondering about. Maybe getting a MC with a larger bore. I just would have to find one that would work. The reservoir size is the same for front or back on the MC I have.

 

[Belizean]

you said a month full but have a good point. when I did my PB upgrade i installed a complete unit from a YJ using all new factory parts. Jeep stops on a dime and has no trouble locking up the tires.

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MM you have drums in the back still ?

 

[CJ]

I purchased the MC/booster kit as a unit. I am not sure what the bore is of the MC. That is something I was wondering about. Maybe getting a MC with a larger bore. I just would have to find one that would work. The reservoir size is the same for front or back on the MC I have.

That is a dual drum MC not a disk / drum MC.

 

[Rockhpr]

It is listed as a Disk/Drum for 74 to 86 CJ. Dual Diaphragm with 1"bore.

 

[Manic Mechanic]

MM you have drums in the back still ?

yup. rear disc is my next upgrade

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[gert]

I did the hydro boost upgrade when I got my CJ on the road, initially the brakes really sucked, cold air convinced me to switch and man what a helluva difference I can lock up my 35s with ease I highly recommend it and it’s a cheap upgrade if your willing to fab a few parts your self, if not they sell the needed adapters on eBay


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[Rockhpr]

So those of you that have done the hydroboost setup, did you all use the astrovan setup? Did you get junkyard parts or purchase all new.

 

[Rockhpr]

The engine in my CJ is from a 96 XJ. The powersteering pump isnt very large. Does it provide enough pressure?