Just finished my hydroboost swap and DAYUM. People are not bullsh*tting when they say 'don't put yourself through the windshield.' After years of little to no braking power, I almost hurt myself when road testing.

Like any project, got some little shtuff to work out. The Emergency Brake light in the guage cluster ('79 CJ7) is on.

Does anyone know what makes this light come on?

I don't think my brakes are dragging, I've checked and the emergency brake is disengaged, but the conditions for the light would help me troubleshoot.

Thanks,

-Zoomie

There is a switchattached to the parking brake pedal.
THe light also may comeon due to low fluid in the m/c.

The light is activated by one of 2 things. The first one is the switch on the back side of the e-brake peddle. The second is the 2 wires that go to the proportioning valve. So if you over-extened the valve the light will go on. I think you can just unplug either of the 2 plugs to see which one is the problem.

Brake pressure differential switch, or also known as rear bias control. Either way, it's the thing attached to the inside of the chassis rail right beside clutch housing. This is where the front splits into two lines, and the rear passes through. Since you've now changed lots of other parts, this remaining stock part doesn't match the system any longer. To do this properly you'll need to remove this part, then install an adjustable proportioning valve.

CP

dont be all putting a adjustable proportioning valve and shit on like the other newbie says. cause all you did was add a hydro boost not redo your entire friggen system
check the switches like the others said and work it from there
or just eliminate the light all together:flipoff2:
good luck

Why would he need to change the proportioning valve if he has not changed either the front or rear brakes. He only mentions he added a hydroboost system. This adds pressure to the system but does not change the bias front to rear. You should not have to change the proportioning valve based on the information he has given us. Unless you have insider information to his swap he didn't give us, I don't think it is appropriate for you to tell him to waste money on a bling bling adj valve that he doesn't need.

BTW :bling bling: should be a smiley that looks like massey with a shiney gold chain around its neck.

I agree with the :bling bling: !

It has to be at the bias/proportioning valve thing. I switched master cylinders to a 4 wheel disk with much larger bore and stroke than the stock CJ.

My question now becomes:

Is it messing with anything? I'm not leaking fluid anywhere, the brakes aren't dragging and the thing stops on a friggin' dime. I just don't want to be driving along and have the prop valve blow up on me and end up with no brakes! :eek:

I am sure it is fine. I would just pull the plug ot the top of the prop valve. If you are uncomfortable with that then maybe you should buy a new one.

Everyone jumping on me and it turns out I'm right. With that 4-wheel disk brake master the rears are probably getting too much volume/pressure ... the prop. valve switch turns on thinking that the system is now unbalanced. "Unbalanced" as compared to what Jeep intended, but with big tires and overall added weight it becomes difficult to determine how much rear bias you'll actually need. If you want to simplify then just remove the prop. valve and replace the front with a "T" and the rear with a F-F coupler ... since it won't be able to compensate anyway with all the volume you have now.

If you do any towing or find that the rears lock first then you'll need to add the bling-bling ... or put rear disks on to match your new system.

CP

Originally posted by CP8071
Everyone jumping on me and it turns out I'm right. ...
CP

Ah, but did we know this from the first post? No, so shut your trap newbie! Bragging rights are for the old timers only!:flipoff2:

Originally posted by DE Jeeper
So if you over-extened the valve the light will go on.

Should I be overly concerned about this if the prop valve doesn't leak?

The valve will eventually be swapped out for an adjustable, but I'd like to wait on that, if I can. Eventually I'll be going with Waggy shiz all the way around, but as of next week it's my DD again. But, if the valve is going to blow the first time I get on 'em on the road, I'll do it now.

I honestly don't know why the light is coming on even with all the new parts you have put on. I have only seen that light activate when you loose break pressue in the front of rear and the bias piece slides too far to one side. It should reset it's self when pressure is restored. If you are not leaking fluid and the breaks are fine I would not worry about it. The only thing, I think, that could happen is you loose the bias between the front and back. Since you have plenty of breaks with the hydro I would not worry about it.

Have you tried pulling the electrical plug to even check to see if it is the prop switch ot the the other one I mentioned?

Yeah, I pulled the bias plug - no light.

But now I have a much, much bigger problem. When I push the brakes, they tighten, but then never return. They just stay frozen.

I think I know what may be causing this. I had to make a pushrod out of a bolt between the booster and MC. In the booster it sits in kind of a cup. I think what might have happened is the MC returns a little slower than the booster and it slipped out of the cup - thereby not allowing the MC to return. I'll try to show you with stick figures -

[-I

That's the bolt sitting in the cup pushing the MC

[_I

That's the bolt falling out of the cup and not allowing the MC to return.

Anyway, ran out of daylight to open it up and see if this is what happened, but if it isn't what could be the cause of the dragging brakes?

-Air in the lines expanding as it heats? They were bled, and worked fine for about 10 hours

*shrug* Don't know much else about brake drag...