Brake Problems: What Could It Be?

All, I've always had weak brakes and think they should be much better based on what others say. I've got a '76 CJ-7 with 11" drums all around. I had 31's, then 33's, now

35's on the rear (might do a turn-around back to 31's 15 years later) and I've seen very little difference 'tween 'em all; always weak. I've changed master cylinder, wheel cylinders, drums and the whole works. I've bled them by gravity, pedal pressure and vacuum pump too. Still, WEAK; to the point that I have to stand on it as hard as I can to get a wheel to lock up in the rain if I'm lucky. I don't think there's a blocked line and everything's practically new minus the proportioning valve. Could the valve be the culprit from the start? Or, should I look for something else? If somebody has a troubleshooting scheme, I'd really appreciate it. Regards, Jim "Comin' Through!!!" Drinkwater
Reply to
James Drinkwater
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Duff servo perhaps ? Do you have decent manifold vaccuum ?

Dave Milne, Scotland

Reply to
Dave Milne

That's my thought. The OP doesn't say if it's an assisted system or not. But bad vac or a leaking booster can sure make braking difficult.

Blocked lines are easy. If fluid comes squirting out when you bleed by pedal, then your lines aren't blocked.

The proportioning valve is a solid brass doodad and hardly ever fails. When it does it usually just leaks out the end. Do make sure that both front and rear brakes are being applied and the proportioning valve isn't stuck on just front or rear. (some are tricky when bleeding brakes and have to be locked down with a clamp)

When it comes to brakes it might be worth the money to have a decent local shop look them over. And I'm not talking midas. I'm talking a shop with real mechanics. (long story)

Reply to
DougW

Reply to
Will Honea

That sounds like any CJ I have ever driven.....

My 86 has front disks and power brakes, an old tenant had an 85 with standard brakes and they both act as you describe.

I had to lock mine up the other day due to some brain dead moron pulling a u-turn in front of me and hit the pedal hard enough to blow one of the front steel lines....

I have heard of folks using a larger MC, maybe a caddy one?

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

How about something like

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are aftermarket options to fit a vac assisted boost Just make sure the lines are up to the increased pressure. :)

Reply to
DougW

Sorry for the omission. It has standard brakes (no booster). I talked to a professional mechanic the other day who has extensive experience with off-roading and the kind of issues we all deal with. He said I can try "hollowing out" the proportioning valve to see if that has a dramatic effect on braking. Now, I know what you're thinking, "You might as well just replace the valve." Might as well but maybe this can prove the issue while I wait for a new part. I don't think it'd be unsafe and, worse case, would just improve braking somewhere. Not so sure 'bout the benefit of boosters or larger master cylinders. Sure, it'd be easier on my foot, but it still doesn't address the gripping power does it? Or does it? Whattaya think? Explain to me the repositioning of the proportioning valve pin reset to neutral.

Regards, Drink

"DougW" wrote in message news:0e92h.93479$ snipped-for-privacy@newsfe19.lga...

Reply to
James Drinkwater

Reply to
L.W.(Bill) Hughes III

can try "hollowing out" the proportioning valve to

The proportioning valve acts as an emergency cut-off should the front or rear brake lines spring a leak. Taking the guts out is dangerous.

address the

The booster replaces standing on the brake and adds significantly to the available hydraulic pressure.

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That is why when adding a booster to a standard system you have to upgrade the flex lines and double check all hard lines. I installed one on a friends pickup and the first time he tested it, it blew a bubble in the flex lines.

Reply to
DougW

Reply to
James Drinkwater

You're driving on front drum brakes with a foot that is used to disks. Drums were always weak, and worse when wet. You should consider converting the front to disks -- find a donor axle and it should be a bolt-up job.

-- "I defer to your plainly more vivid memories of topless women with whips....r" R. H. Draney recalls AFU in the Good Old Days.

Reply to
Lee Ayrton

Thanks Bill, Maybe you can help me out understanding the interchange; which is what's stunting my progress. I'd like to get off-the-shelf brake parts that'll interchange: master/slaves, booster, REAL quality shoes, etc. But, I'm concerned I'll have fits with bolt patterns, rod length, fittings, and hidden pitfalls. Most parts shops run out of gas after, "What kind of car is it for?":) Drink '76 CJ-7 standard brakes

11" drums x 4
Reply to
James Drinkwater

Reply to
James Drinkwater

You don't need to swap axles or even a have working donor axle, you just need the parts from the mounting brackets outward. Any CJ (5 or 7) disk brake donor from 1976 through `83 should bolt up, but `79 and up will be better for parts availabilty. Don't forget to include the proportioning valve (located on the inner frame rail below the driver's left foot), and consider dropping the extra money on preformed stainless brake lines. Really, you'll be happy to didn't try to bend them yourself.

Article on your Dana 30 front axle: .

Dana 30 disk brake conversion how-to:

Good luck.

-- "I defer to your plainly more vivid memories of topless women with whips....r" R. H. Draney recalls AFU in the Good Old Days.

Reply to
Lee Ayrton

Yep. There is an orifice in there that sets the pressure ratios.

There are mods, but I don't reccomend doing them.

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I still think the best aproach is a disc conversion and adding a booster.

Reply to
DougW

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