The elusive master cylinger upgrade ???

R

RCP Phx

NAXJA Forum User
Location
Phoenix,Az
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 said:
1" bore is sufficient. I takes no more fluid/travel to actuate two pistons than it does one.
Click to expand...

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.
 
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.
 
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!
 
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.
 
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.
 
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...am-2500-master-cylinder-mc-upgrade-yj-tj.html
 
Last edited:
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
 
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
 
madmax said:
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
Click to expand...


icelands_stripping_ban.jpg
 
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!
 
Historically a lot of folks, including me, used the Ford E350 master cylinder and added a dual vacuum booster for the older XJ's/
 
I have a buddy that ran the e350 master in his zj with a stock dana 30 and a 8.25. I run the 98 durango master and xj double diaphram booster on my dana 34 with 78 bronco calipers and a ford 8.8. Needed the slightly larger bore to move enough fluid for the front calipers.
 
I picked up a 98 Durango MC this evening. It is truelly a direct fit, I measured everything with a calipers and it all matches. I won't bleed the system till tomorrow when there's some good light!
 
Well it's been about 10 days and the system is awesome. The travel is lessened and the pedal effort shows no sign of being harder than stock. If I can find a "direct" replacement I might try a 1-1/8" bore!
 
Update... last night I did install a 1-1/8" bore MC from a 2000 Durango. It barely fits under the hood (clearance to the cap 3/16") and you have to grind/clearance the prop valve bracket because of the larger MC body. I will bleed the brakes today and report back on the change.
 
You must log in or register to reply here.

Similar threads

n1ywb
Brake performance
Replies
12
Views
1K
cruiser54
C
B
Caliper/cylinder compatibility.
Replies
14
Views
1K
LEVI_KING
L
blondejoncherokee
WJ Master Upgrade
Replies
9
Views
2K
Talyn
Talyn
B
98xj 5.3 swap (the poverty method).
11 12 13
Replies
248
Views
64K
kastein
kastein
TORX
Oregon Trophy Challenge 2014
Replies
5
Views
2K
NW-ZJ-SCOTT
NW-ZJ-SCOTT
Back
Top