The elusive master cylinger upgrade ???

[RCP Phx]

So after doing my WJ/KJ brakes, I have poor pedal travel. I spent most of the day(and night) reading all the different forums looking for some info on a larger MC that will fit a late model vac booster. I looked at over 500 MC specs and came up with some possibilities. Going to make some phone calls today! Not sure about the size needed but its a start. Just for reference here are the ratio's for factory parts with some different MC's. I'm leaning towards the 1-1/16" to start.

Using my 2000 with a 1" bore as a baseline.............
Front XJ caliper - 6.72/1 (x 2)
Rear wheel cylinder - (-).66/1 (x2)

KJ rear caliper - 3.77/1 (x2)

WJ front caliper - 3.77/1 (x4)

Here are some WJ/KJ #'s with different MC's...........

1-1/16" MC - 3.34/1 (x6)

1-1/8" MC - 2.97/1 (x6)

[Jeep Driver]

1" bore is sufficient. I takes no more fluid/travel to actuate two pistons than it does one.

[RCP Phx]

Originally Posted by Jeep Driver

1" bore is sufficient. I takes no more fluid/travel to actuate two pistons than it does one.

Wow!!

[techno1154]

Originally Posted by Jeep Driver

1" bore is sufficient. I takes no more fluid/travel to actuate two pistons than it does one.

My XJ have been fitted with the first generation WK '05 to '10 front rotors and calipers for almost a year. Several years ago I retro fitted the ZJ rear disc backing plate and the Ford Explorer calipers and rotors. There is no discernable difference in pedal travel. I am still using the original master cylinder which is 20+ years old.

According to my research, the above mentioned WK uses a 1.062" bore master cylinder. I do not know if it would fit the XJ brake booster. The WK2 2011 to ?? uses an even bigger bore master cylinder.

[Jeep Driver]

Originally Posted by RCP Phx

Wow!!

Spend a few grand on Brembos, then you can WOW me all you want.

[Jeep Driver]

FWIW to you...........


Just Saturday evening I bought a new MC for a '97ZJ to replace the '97ZJ MC I already have (strictly for appearance sake, there is nothing wrong with my current MC). I'm using a '04WJ booster.

I did this with the anticipation of doing the WJ knuckle swap in the Spring. NAPA currently has my MC with the Intrepid SS lines I was using. They are making my up a set of SS lines to the distribution block (no metering). Lines will cost me over $100.

I did not spend $200 out of ignorance nor stupidity.

My engine bay is completely stripped, painted, awaiting a my new engine.


One swap is '70 Corvette MC, 1 1/8 bore, you can look that one up.

[RCP Phx]

Neither the WK or a Corvette will fit a XJ booster. I find it hard to believe that after all these years and members this hasn't been resolved yet!

If push comes to shove, I'll build a "Fraken-cylinder" that fits!

[Jeep Driver]

The Corvette MC does fit.

No one said anything about a WK MC or booster.

Although the WK does have a version of the 8.25..........very little info found on them..........however, that would be a rear swap to look into.

Here is the GM swap- http://www.bsfab.net/?p=58

[cal]

It hasn't been resolved because its the solution to a problem that does not exist.

Going to a bigger bore just means you push the pedal harder for less distance with no change in braking performance. WJ's come with a 1" bore master and don't have problems, if you are having problems you need to figure out what is wrong with your car, not reinvent the wheel.

[RCP Phx]

It's a personal preference(nothing is wrong), but I don't care for it. The 1-1/16" bore should increase pedal effort and decrease pedal travel by about 12%! I prefer more input/feedback.

[ROKRWLR]

2001 Dodge 2500 MC is a 99% direct bolt in. You need an extended threaded adjuster in between it and the booster. I used a bolt with the head ground down to be round like the factory. Brake lines bolt right in with a little flexing.

This MC stops big 1 ton calipers with no problem. This might be too much for what you need? But it fixed me needing to pump the pedal to get enough fluid to my bigger calipers.

When I did this, there were a few threads around that include the Autozone part number.

wait... found it: ’99 + Dodge Ram 2500 (AutoZone #348202)

http://www.pirate4x4.com/forum/jeep-...ade-yj-tj.html

[yossarian19]

I think I used a '98 Durango MC, want to say it was 1 1/8 bore. Pedal feel was awesome but you definitely notice, too, that you have to push harder for the same brake performance. I'm with you on the preference for a stiff, low travel pedal

[madmax]

I'm running the 80s ford e350 master 1-1/8 bore. 100% bolt it aside from swapping fron fitting out

I have a wj swap upfront on a hp30 and a eb 9" with 11" f150 drum and 1-1/16 crown vic police wheel cylinders. I have great stripping power

[cal]

Originally Posted by madmax

I have a wj swap upfront on a hp30 and a eb 9" with 11" f150 drum and 1-1/16 crown vic police wheel cylinders. I have great stripping power

[RCP Phx]

Well the Dodge Ram 2500 uses a 1-1/4" MC, I haven't done any calcs for that because most said it's too large.

As for the Durango MC it is 1-1/16" so I will look into that one!