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Discussion Starter · #1 ·
82 cj7 4.2 engine w/ front power disc brakes. trying to wrap up the little things after finally getting it running. Several issues along the way have been fixed with all of your help and nearing the end of the restoration and after finally getting it running but not completely drivable yet for any distance I noticed that the brake pedal doesnt feel right.. not good pedal. I have replaced cylinders and shoes in rear and adjusted to a good point which I know is where the pedal feel comes from so this leads me to my ? along the way it has been discovered that I had recd the CJ with the wrong master cylinder/booster set up and had to replace the booster to accommodate the TBI conversion when I discovered the existing master cylinder is for 4 wheel disc brakes so I left it in place because it did not bypass when brakes applied but now wondering if I need to get correct cylinder for front disc brake car? Could that have an effect on the pedal feel? AND does it look like the brake line diameters off the current master cyl look correct or was that changed also by previous owner? See pics of mc and the set up when i got the cj
, thanks Mike

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You may want to trace those brake lines and check out the Combination Valve and yes, you can get a different feel with a disc/disc master.

It is a common practice to fit a residual pressure valve in the rear line, which stops the brake linings from relaxing all the way whilst driving. This sharpens up the rear brakes. Some masters have them already, but they can also be purchased to fit in the port.

The rear brakes are usually fed by the front port on the master cylinder in a stock CJ. The feed is down a larger 1/4" tube to the Combination Valve and out to the rear. I see what looks like a 3/16" on the front and 1/4" on the rear in your blurred photo. This may be a feature of this particular master cylinder, that the rear brakes are on the rear port. I just mention this as you may be scratching your head later if you get a new master.

The disc/drum master will have different size reservoirs to compensate for the amount of fluid movement needed. They are very cheap.

Then the Combination Valve itself is also a proportioning valve and the model you need depends on the type of front brakes. You may want to check this.

The last thing I would check is the clearance between the rear of the master cylinder piston and the pin that sticks out from the booster. The clearance should be a few thou, a 1/4" will make your brakes spongy.
 

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Discussion Starter · #3 ·
You may want to trace those brake lines and check out the Combination Valve and yes, you can get a different feel with a disc/disc master.

It is a common practice to fit a residual pressure valve in the rear line, which stops the brake linings from relaxing all the way whilst driving. This sharpens up the rear brakes. Some masters have them already, but they can also be purchased to fit in the port.

The rear brakes are usually fed by the front port on the master cylinder. The feed is down a larger 1/4" tube to the Combination Valve and out to the rear. I see what looks like a 3/16" on the front and 1/4" on the rear in your blurred photo. Have you got them switched?

The disc/drum master will have different size reservoirs to compensate for the amount of fluid movement needed.

Then the Combination Valve itself is also a proportioning valve and the model you need depends on the type of front brakes. You may want to check this.

The last thing I would check is the clearance between the rear of the master cylinder piston and the pin that sticks out from the booster. The clearance should be a few thou, a 1/4" will make your brakes spongy.
the way you see the lines is the way I recd the jeep. The smaller line (front reservoir) goes to the rear port on the pro valve. Should that front reservoir have also a 1/4" line to pro valve? so I probably need to replace pro valve also. Also looking at the rear connection at MC there is an adaptor to accommodate the line. Tells me the whole thing was changed out at some point. Never heard anything of a residual valve on the brake line. Thats a new one for me. I am going to change out MC and pro valve so PLEASE tell me the correct line diameter from MC to valve for the front reservoir i.e. rear brakes. thanks Mike
 
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