KJ rear disc brake???

RCP Phx · Nov 9, 2016

I've got the best pads/rotors out there, but this is only going to get wosre when I do the WJ brakes!

I'm getting a headache thinking about all this, since my stroke my "shoulder calculator" doesn't work so well!

The data I'm using now is.......

2000 XJ-
MC 1"bore
Front calipers 2.595" x 2
Rear cyl(s) .8125" x 2

2004 KJ-
Rear calipers 1.890" x 2

2004 WJ-
Front calipers 1.890" x 4

I'm also looking at the end play with a c-clip axle installation.

I see now that the Ford Explorer use a 1-1/16" MC ?

lazyxj · Nov 9, 2016

My 2001 XJ has Vanco dual 48mm pistons calipers, up front, and ZJ disc on the rear.
The pedal has travel but firms well, once the play has been taken up.
Tried a 1-1/8' and 1-1/4" MCs but the pedal pressure became too high for my wife to use.
https://www.flickr.com/photos/lwade/3419228732/in/album-72157616348032595/
The 1-1/16" MC maybe the sweet spot, with adequate piston volume without exceeding the brake booster's capacity to keep the needed pedal pressure to a reasonable level.

I see where Blain, from Black Magic Brakes, now includes a 1-1/16" MC, along with some of the Vanco front brake kits.
http://shop.blackmagicbrakes.com/VANCO-Super-16-Big-Brake-Kit-w-Master-Cylinder-BBK-OS16M.htm

Let us know how it works out if you use the 1-1/16" MC. I would like a higher pedal too.
Anyone know what 1-1/16' MC fits our XJs?

Jeep Driver · Nov 9, 2016

lazyxj said:
My 2001 XJ has Vanco dual 48mm pistons calipers, up front, and ZJ disc on the rear.
The pedal has travel but firms well, once the play has been taken up.
Tried a 1-1/8' and 1-1/4" MCs but the pedal pressure became too high for my wife to use.
https://www.flickr.com/photos/lwade/3419228732/in/album-72157616348032595/
The 1-1/16" MC maybe the sweet spot, with adequate piston volume without exceeding the brake booster's capacity to keep the needed pedal pressure to a reasonable level.

I see where Blain, from Black Magic Brakes, now includes a 1-1/16" MC, along with some of the Vanco front brake kits.
http://shop.blackmagicbrakes.com/VANCO-Super-16-Big-Brake-Kit-w-Master-Cylinder-BBK-OS16M.htm

Let us know how it works out if you use the 1-1/16" MC. I would like a higher pedal too.
Anyone know what 1-1/16' MC fits our XJs?

The new MC in your pics, which one is that? part number?

RCP Phx · Nov 10, 2016

I am going to look at the 1-1/16" Ford Explorer as a possible donor!

Desert4x4 · Nov 11, 2016

I also have to agree that the KJ parking brakes are pretty weak.

Stock XJ parking brake setup is stronger.

KJ discs are better with foot brake though of course.

RCP Phx · Nov 14, 2016

I just got back from week of camping, the braking power is a little better but the ability to dissipate heat is much better(I tow a 3500# trailer), I almost burned them to the ground 10yrs ago coming into Telluride!

lazyxj · Nov 14, 2016

Jeep Driver said:
The new MC in your pics, which one is that? part number?

The photos of the MCs were taken 7 years ago. I don't have them anymore and do not have the part numbers available.
I originally found all the MCs and their dimensions on Rock Auto.

RCP Phx · Nov 15, 2016

lazyxj said:
The pedal has travel but firms well, once the play has been taken up.
Tried a 1-1/8' and 1-1/4" MCs but the pedal pressure became too high for my wife to use.
https://www.flickr.com/photos/lwade/3419228732/in/album-72157616348032595/
The 1-1/16" MC maybe the sweet spot, with adequate piston volume without exceeding the brake booster's capacity to keep the needed pedal pressure to a reasonable level.

What vacuum booster did you use?

RCP Phx · Nov 15, 2016

I did some calculations this morning, it looks like I should lose about another 1/4 of the travel with a harder pedal. The calcs with a 1-1/16" MC look very promising!

Matt in Ohio · Nov 30, 2021

Old thread I know but I am thinking about this now and this all kinda discourages me.

How about a explorer axle or a rubicon axle?

RCP Phx · Dec 1, 2021

I don't know what's discouraging, if you read my follow-up threads you would see they have been working great now for years and I will never change back.

The other axles will act the same way until you get everything working "together".

KJ rear disc brake???

RCP Phx

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