Master Cylinder Resevoir Question

atomicflatulenc · 06-03-2009, 05:19 AM

Which resevoir is for the rear and front? My original thought was that the rear of the MC (closest to the firewall) was for the rear brakes of the jeep.

Mike Romain · 06-03-2009, 05:27 AM

Nope, they mess with your brain. The larger rear one is for the front brakes and the smaller front one is for the rear brakes.

atomicflatulenc · 06-03-2009, 05:35 AM

I knew they were messing with me.

I did a YJ conversion from Ebay and the outlets of the new MC didn't match. So I did what any newbie would do, I switched them. Back then my rears would always lock up first.

Two years later, I tweeked my rear axle tubes and found a replacement that had disc brakes. Did the research and found that a new MC and prop valve were in order. Now I'm having difficulty getting it to all go together.

The Corvette MC has a deep resessed hole in the MC and the pushrod won't work with it. There was a little machined piece that slid into the YJ conversion from Ebay. It's diameter is a little too big. Going to the machine shop to get it sized down to fit today.

Second issue is with all the lines going to and from the MC and prop valve. Can't get all the right sized do-hickies sorted out.

Mike Romain · 06-03-2009, 05:45 AM

When the lines go from the master down to the prop valve they also pull a fast one by crossing in route.

Please enlighten me about your swap. My new master has blown out all over the place, out the cap out the end, it is a POS so I need another.

atomicflatulenc · 06-03-2009, 06:03 AM

The rear disc was a conversion that uses 82 thunderbird rear discs with a built in parking break. They are gonna be a PITA to bleed since the bleeders are on the bottom of the calipers.

I'm used STU's write-up for the prop valve. Picked up the front brake output splitter from NAPA since the ZJ prop only has one output and splits at the ABS.

Found the 72 corvette MC is for disc/disc and has been used for the jeep disc/disc conversion, just need to work out the crap with the hole in the MC.

The vacuum booster is a dual diaphram from a YJ. Cost way too much on ebay for what I got. We are playing with all the adjustments to get better play and to keep my brake lights from flashing. The pedal wasn't returning high enough to keep the brake lights off.

**rixcj** · 06-03-2009, 06:21 AM

Quote:

Originally Posted by atomicflatulenc

The vacuum booster is a dual diaphram from a YJ. Cost way too much on ebay for what I got. We are playing with all the adjustments to get better play and to keep my brake lights from flashing. The pedal wasn't returning high enough to keep the brake lights off.

There's a metal tab that makes contact with the button on the brake pedal. The tab can be bent for different situations.

I just did the YJ conversion on my jeep, and it's great. I had very good CJ power brakes to begin with, but they're much better now. More like newer car power brakes than CJ power brakes.

I kept the frame mounted proportioning valve, so I had to get creative connecting the lines, which had different size fittings...

Rich

Mike Romain · 06-03-2009, 09:20 AM

Quote:

Originally Posted by atomicflatulenc

The rear disc was a conversion that uses 82 thunderbird rear discs with a built in parking break. They are gonna be a PITA to bleed since the bleeders are on the bottom of the calipers.

Oops, there is a right and left caliper. When on the wrong side, the bleeder is on the wrong way or down.

Quote:

We are playing with all the adjustments to get better play and to keep my brake lights from flashing. The pedal wasn't returning high enough to keep the brake lights off.

I have found that the brake light switch can back off a bit causing that. It recently happened to me during a frame swap and new wiring harness install. I had to reach up under and get the switch back in deep enough.

foggybottombob · 06-03-2009, 09:39 AM

I put 87-89 Nissan 300 ZX calipers on my CJ rear dana 44 axle using a bracket made by a local guy. These calipers have a built in e-brake connection. The guy who made my brackets did the same thing with a slightly different bracket for his AMC 20 and I have yet another bracket to do this for my XJ dana 44. I used 95 geo tracker rotors and some slightly longer Dorman wheel studs. I have all the part numbers written down if anyone is interested in any of this. I stayed with the original CJ prop valve and that works fine with these parts since the calipers have such a small piston.

The left bracket is for the XJ D44 and the right bracket fits a scout D44. I don't have a picture of the AMC 20 bracket.

atomicflatulenc · 06-08-2009, 05:34 PM

Quote:

Originally Posted by Mike Romain

Oops, there is a right and left caliper. When on the wrong side, the bleeder is on the wrong way or down.

If I switch the calipers around to get the bleeder on the top, then the parking brake cable won't work right. The tab that the funky connector goes into will be wrong.

atomicflatulenc · 06-08-2009, 05:38 PM

Does it really matter which resevoir is the closest to the firewall. The brakeline that comes fits the firewall side of the MC is also the right thread for the rear input on the proportioning valve.

Do the internals of the MC make it so the front and rear brakes are applied in any kind of order? Or is that just controlled by the proportioning valve?

atomicflatulenc · 06-09-2009, 09:59 AM

Bump...

Does it matter which resevoir is plumbed to the front and rear brakes?

foggybottombob · 06-09-2009, 12:33 PM

What little I know about it is that the reservoir going to the disk is usually bigger because the calipers typically take more fluid to operate than a drum brake wheel cylinder. Otherwise, I think the differences in brake line pressure are handled by the proportioning valve.