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Unread 03-22-2012, 12:47 PM   #1
RubyCJ
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CJ7 Power Brakes - sort of

I know this is another thread about power brakes but I have to post.

Ever since owning my 1986 (258) and adding power brakes 10+ years ago I have not had good brakes. Pull up on the steering wheel, stand on the pedal and slowly come to a stop. Over time I replaced:
* Rear wheel cylinders, drums and shoes (3-4 times) and adjusted the brakes
* Front calipers, rotors and pads (3-4 times)
* 3 complete sets of power brake boosters with brackets and MC
* New hoses on front and rear
* 3 proportion valves (latest is a new coming with the new booster kit.
* This weekend replaced the front hard lines from the proportion valve
* Filed out the grooves in the caliper brackets

Have 18" on the vacuum line - coming from the intake manifold
Checked to be sure the caliper bleeders are high (correct side)
Good brake pedal 1/2 down from top and hard
Bled brakes - rear first and front last.
Rear (shoe/drum) brakes are doing the stopping work and I can sometimes get one to skid on loose stone
Front pads (disk) do wear down and are replaced.
Pedal has about 1-1/2" free motion at top before contacting resistance.

Only strange thing that happens is the brake pedal will not return completely to top (noticed when brake lights stay on) after using 5+ times. I can pull the pedal up with my foot and feels like something is holding it down about 1". Not stuck more like held back. I put an extra spring on the pedal but it still happens.

I actually took a booster/MC system from a different CJ and put it on mine - no difference. Put my booster/MC system on the other CJ and stopped great.

I also wonder about bench bleeding the MC by using the pedal in the Jeep?

Please save my sanity and the guy in front of me with some ideas!

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Unread 03-22-2012, 01:40 PM   #2
Dngrs1
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35x15.50-15 tires? Try putting some 31x10.50-15's on and see if that makes a difference. Just a thought.
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Unread 03-22-2012, 07:44 PM   #3
1980tallcj7
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I messed around with crappy brakes for a couple years...manual, yj booster with various MCs, back to manual, finally broke down an bought one of these , http://www.summitracing.com/parts/TFF-2131NB/
works like a charm. Maybe it'll work for you too.
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Unread 03-23-2012, 07:41 AM   #4
RubyCJ
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Quote:
Originally Posted by 1980tallcj7
I messed around with crappy brakes for a couple years...manual, yj booster with various MCs, back to manual, finally broke down an bought one of these , http://www.summitracing.com/parts/TFF-2131NB/
works like a charm. Maybe it'll work for you too.
Thanks, I have tried 3 different new boosters and MC assemblies with the same poor results. Appreciate the thought though.
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Unread 03-23-2012, 07:48 AM   #5
RubyCJ
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Quote:
Originally Posted by Dngrs1
35x15.50-15 tires? Try putting some 31x10.50-15's on and see if that makes a difference. Just a thought.
I have a set of 35*12.5 BFG's on her now for general riding. This is just so irritating. I have rebuilt 3 CJ's and don't have issues. Swap parts and test out back and forth.
Irritating!
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Unread 03-23-2012, 10:29 AM   #6
LT1CJ7
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Hydroboost
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Unread 03-23-2012, 11:59 AM   #7
waterdowg
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How have you been adjusting the rear brake shoes?
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Unread 03-23-2012, 09:17 PM   #8
RubyCJ
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Quote:
Originally Posted by waterdowg View Post
How have you been adjusting the rear brake shoes?
I turn the adjusting screw that expands the shoes until I hear / feel rubbing on the drum, as I am turning it. Using the slot in the back side of the backing plate and a special screwdriver.
Once set close I take the Jeep to a hard surface and back up at speed and apply the brakes hard. Do this 3 or 4 times. This helps to set them and also adjusts them closer.
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Unread 03-23-2012, 09:20 PM   #9
RubyCJ
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Quote:
Originally Posted by LT1CJ7 View Post
Hydroboost
Very tempting. After the $$ I spend replacing parts over and over, I could have bought it already.
Is it really better than a normal operating vacuum booster ?
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Unread 03-24-2012, 08:57 AM   #10
82JeepCJ7
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Have you seen the mod where you re drill the mounting holes for the booster mount and move it all up 3/4"? You have to move the hole where the rod from the pedal mounts down 3/4" also. It effectively increases the "arm" when applying pressure to the MC.

I did this mod back in 1995 and it helped mine a lot. It will almost stand on its nose when you hit the brakes.
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Unread 03-24-2012, 09:11 AM   #11
Jack61
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Quote:
Originally Posted by RubyCJ View Post
Very tempting. After the $$ I spend replacing parts over and over, I could have bought it already.
Is it really better than a normal operating vacuum booster ?
I think maybe you have a problem with the proportioning valve. I have been running 35s for longer than I can remember and with the vacuum booster it always stop okay but not great. A few years ago I found a GM hydroboost on ebay for $100 and installed it and let me tell you this Jeep stops right now with less effort.
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Unread 03-24-2012, 01:54 PM   #12
CjinPA
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Your never going to stop fast with 35s and a factory CJ power brake set up. I can remember putting 35" boggers on my CJ and driving it. I had to plan far in advance to stop. It was scary to drive. You can swap in a YJ power brake booster and master cylinder to get better braking. You can swap in a dual diaphragm brake booster and master cylinder from a six cylinder 95 YJ wrangler and you will be amazed at how much braking power you will have, or you can go the hydroboost route. But stop wasting your time and money with the CJ set up.

I will explain why the YJ system is much better than the CJ set up.
The push rod on the CJ power brakes is canter levered so you only get a portion of the force you apply to the brake pedal transfered to the brake booster.
Here is a picture of the CJ power brake push rod.


In a YJ Wrangler the push rod goes directly in to the brake booster so you get 100% of the force applyed to the brake pedal transfered to the booster.


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Unread 03-27-2012, 07:42 AM   #13
RubyCJ
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Quote:
Originally Posted by 1980tallcj7 View Post
I messed around with crappy brakes for a couple years...manual, yj booster with various MCs, back to manual, finally broke down an bought one of these , http://www.summitracing.com/parts/TFF-2131NB/
works like a charm. Maybe it'll work for you too.
Thanks, I have purchased 3 different new dual diaphragm with MC assemblies over the last 10 years with the same poor results. Kept putting the older assembly on other CJ's during build ups. Funny thing is they work great on the other Jeeps. Even with same tire size and disk / drum setups.
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Unread 03-27-2012, 07:51 AM   #14
RubyCJ
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Quote:
Originally Posted by Jack61 View Post
I think maybe you have a problem with the proportioning valve. I have been running 35s for longer than I can remember and with the vacuum booster it always stop okay but not great. A few years ago I found a GM hydroboost on ebay for $100 and installed it and let me tell you this Jeep stops right now with less effort.

Thanks but I have tried 3 different new ones with same results.
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Unread 03-27-2012, 08:04 AM   #15
RubyCJ
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Think I will look into the direct push rod YJ mod.
Thanks 82jeepCJ7 and CJinPA

Has anyone had problems with the hydroboost setup?
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