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Unread 11-12-2009, 05:12 PM   #1
Rupie25
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1977 CJ7 
 
Join Date: Sep 2009
Location: Atlanta
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Soft brakes?

With manual brakes, should they need to be pumped? First application of the pedal is pretty soft, I can still stop on the the first application of the pedal, but if I pump it once or twice the brakes are really strong. I have bled the brakes a couple of times. This is my first time with manual brakes and I don't have anything to compare to.

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Unread 11-12-2009, 09:28 PM   #2
jeepdaddy2000
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Should have a high hard pedal. First two most obvious procedures:
Bleed brakes.
Insure drum style brakes are adjusted.
There are plenty of writeups here on both procedures so take a sec and do a quick search if your unsure of anything.
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Unread 11-13-2009, 06:45 AM   #3
Mike Romain
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Air or poorly adjusted rear brakes or a loose front wheel bearing can all cause a low pedal on the first pump.

If the emergency brake pedal is really low, suspect the rear drum adjustment. (unless the cable was adjusted with the low pad adjustments, then you will need to adjust it to see if it needs it while backing off the cable to allow it to adjust. If the cable was adjusted with the low pad adjust, then the cable will be the pivot point for the shoes which will also cause a strange pedal before it breaks the cable end)

To check for a loose front wheel bearing, which pushes the caliper or wheel cylinder back in when you turn so the first pump has to refill it, you can rock the front wheel hard to feel for play or jack it up and wiggle the wheels to feels for play.

Then there is air. The combination valve on the frame below the master has a pin in the end under a grommet. This pin may need to be held from moving while pressure bleeding to get the air out of the combo valve and to allow free flow. There is a special tool for this or you can try to hold it with plumbers channel lock pliers or a hose clamp and a penny or anything you can make work. Mine gave me grief after one rebuild and many bleed attempts, had a spongy pedal that pumped up, so when I got to my first destination, (Finished the build the morning we left for a 10 day bush run) I opened up all the bleeders at once and just kept the master topped up for a whole bottle of fluid which got the air out thankfully. The best is to use a piece of hose on the bleeder nipple that goes into a jar with some brake fluid so air can't suck back in and to keep the mess down.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 11-13-2009, 10:54 PM   #4
Rupie25
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I put a new MC on and I did not bench bleed it. I just hooked up the lines and put fluid in. I'm now thinking I put air in the system around the Prop. valve. Bearings are new and tight, rear brakes are new and adjusted, and no leaks. I will check the Prop. valve. And try bleed again with the prop valve open or the pin pulled. Thanks for you help
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Unread 11-14-2009, 05:52 AM   #5
Mike Romain
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Quote:
Originally Posted by Rupie25 View Post
I put a new MC on and I did not bench bleed it.
Now you know why you have to bench bleed it. Anything else you now do is a waste of time, you have to take it off and do it right. It will not bench bleed in place on the jeep.

The pin on the combination valve mus be held 'still'. if you push or pull on it, you shut off one side of the brakes and it will never bleed.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 11-14-2009, 09:12 AM   #6
adamsclarke
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you can bleed the MC while it's on the jeep. Just unhook the lines and put a short piece of clear line on and route that back into the fluid in the MC. make sure the the clear line is submerged in the fluid so you don;t suck air back in. Slowly pump the brake while watching for all of the air to come out. It should bubble from the bottom of the MC and get all the other bubbles out from the lines. May take a little bit...but works well.
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Unread 11-14-2009, 10:22 AM   #7
Mike Romain
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Quote:
Originally Posted by adamsclarke View Post
you can bleed the MC while it's on the jeep.
The call it 'bench bleeding' for a reason. You have to have the Master level and it isn't close to level in the Jeep as well as some call for full strokes which the brake pedal can't give you.

Now if you can point it downhill or jack up the rear evenly you may be able to get it flat and if it is the kind of master that calls for short bleed strokes, you 'might' get away with it. If it calls for full strokes, then it has to come off.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 11-18-2009, 08:10 PM   #8
Rupie25
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I tried it while mounted jacked up the rear and it did helped. Still a little bit soft. When I get on the brakes I can lock up the rears, so I'm thinking I need to replace the proportioning valve (I converted the front from drum to disc). I think the air is in the valve, and the valve has some age to it, if I tinker with trying to reset it, I'll probably "brake" it. I'm thinking it's better to buy a new one.
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Unread 11-19-2009, 05:27 AM   #9
Mike Romain
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Figure it this way. When air gets trapped in the front end of the brake master cylinder bore and at the front of the rear reservoir seals it won't come out because the nose of the MC is up too high. You made it better by jacking up the rear end. Just think of how good it might get of the master was perfectly level, like on the bench in a vise.

I tried to fix a MC once that hadn't been bench bled and I use a level on the master to try and get it perfect. it was still off a bit to the side and we only had limited success. Gave up and did it right, it was faster than all the screwing around we were doing.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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