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post #1 of (permalink) Old 02-09-2004, 08:56 PM Thread Starter
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brake questions

hi there

just wondering what others have done to beef up their brakes to better stop the big tires. rear discs...what else has been done?

also...i thought i read something about having to "center" the proportioning valve when bleeding. how exactly is that done (i ran new brake lines).

by the way...it's an 82/85 CJ7

thanks
patrick
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post #2 of (permalink) Old 02-09-2004, 09:16 PM
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Re: brake questions

Rear disc is great.... not sure it's good with big tires.

Should help.

</font><blockquote><font class="small">In reply to:</font><hr />
i read something about having to "center" the proportioning valve when bleeding.

[/ QUOTE ]

Sounds like a 4wd.com "Tech Tip"

Somewhere (sorry that I can't find it) I saw a tool exactly for that. It was a small thing that clipped onto the proportioning valve while bleeding. Looked like it depressed a button (detent) on the side.

But then again I have never had one of those and don't think that it's very hard to bleed brakes if you just consider where the air is trapped.

Good Luck
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post #3 of (permalink) Old 02-10-2004, 08:24 PM Thread Starter
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Re: brake questions

hi there

my understanding of the proportioning valave is that it's function is to control the amount of pressure going out each line. because each line is of a different length, the pressure from the master cylinder must then be split differently to the different lines.

is that the correct understanding?

if it is...how do i adjust it so that i don't have all my braking power going to the front drivers side tire...er something like that.

thanks
patrick
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post #4 of (permalink) Old 02-10-2004, 08:45 PM
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Re: brake questions

This was posted a couple days ago.
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post #5 of (permalink) Old 02-10-2004, 08:55 PM
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Re: brake questions

Here is an article on the subject, pointed out in a previous thread by CJ7Taz
look here

Here are a couple of threads about brakes/bleeding.

Rear discs not working!

Proportioning valve

Brake bleeding question. No brake pedal at all!

The BBS Search will give you lots more.

Good Luck
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post #6 of (permalink) Old 02-10-2004, 09:58 PM
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Re: brake questions

I just realized that there are two other posters on this thread. I was thinking it was the same person replying to himself. [img]images/graemlins/thud.gif[/img]
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post #7 of (permalink) Old 02-10-2004, 10:02 PM
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Re: brake questions

</font><blockquote><font class="small">In reply to:</font><hr />
I just realized that there are two other posters on this thread. I was thinking it was the same person replying to himself.

[/ QUOTE ]

That's OK, I often talk to myself seems to be the only way to get the answers I want. [img]images/graemlins/blush.gif[/img]

I'm the one with CJ on the end.
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post #8 of (permalink) Old 02-11-2004, 08:07 AM
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Re: brake questions

You misunderstand the purpose of the proportioning valve, which is understandable because it's misnamed. It doesn't proportion pressure; it limits pressure to the back brakes.

Drum brakes work at much lower hydraulic pressure than disk brakes. The proportioning valve limits the maximum pressure to the back. Otherwise they would lock up while the fronts are just starting to work.

There might be a true proportioning valve out there, but I've never seen one. The common way to proportion front and rear hydraulic pressure it to use separate master cylinders actuated by a beam between them. The pedal linkage pushes on the beam, and the F/R ratio is adjusted by moving the linkage contact on the beam. It's standard race car stuff, and usually has a knob in the cockpit turning a screw that moves the contact point back and forth.
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