ocs1667

I added a Jeep Grand Cherokee 1988 front diff Dana 44 with discs to the front and Ford 8.8 with discs to the rear of my 89 Cherokee.

I find that when I apply the brakes on a normal stop, the brakes work ok, nothing special. However when I apply them in a stop requiring a shorter distance because of going faster then 50 mph the stop seem like an eternity, another words am I going to stop. It fills like you have a trailer behind you and therefore you really have to think about stopping.

I have researched this problem and found I need a larger then the stock master cylinder to move a greater amount of fluid

My question is what master cylinder would you recommend I use.

Any advise would be very appreciated.
Dennis

Hopkins

I believe in 96 and up Jeep put a larger more powerful master cylinder in the XJ. You should be able to upgrade to one of those. No idea if it is a bolt on mod or not. Someone with more knowledge will chime in soon.

cruiser54

2 choices. a 95 to 96 XJ booster and master, or a 99 to 2004 WJ booster and master. I've done both and prefer the WJ swap.

WJ versus 95 to 96 XJ booster

Actually, the WJ booster is in some ways easier than the 95 to 96 XJ.

I've done both.

XJ, you don't have to mess with the firewall. No big deal anyway.
But, you have to move the washer reservoir. And, once the original booster comes out, the bracket inside the cab moves and makes it a bear to install the new booster.

WJ you have to bend the firewall lip, but don't move the washer bottle.
As an added bonus, the mounting studs of the WJ booster are a bit smaller and it's easier to get in.
Another bonus with the WJ is that it has FLEXIBLE lines from the master cylindere that make putting things together MUCH easier.

ocs1667

Thanks a lot for the info.

The "WJ" sounds like the way to go. V8?

Is the booster the same size close [width] as the existing one? I have Chevy V8 and room is tight.

Master cylinder has a larger piston that increases the PSI along with a larger reservoir.
Did you have any mech. problem with the pedal stroke due to the increase of fluid?

I looked up the booster mounts directly to the pedal, any problems there.

The flexible lines connect to the portioning valve with no additional work. Threads the same on portioning valve.

Any adjustment to the portioning valve.

Does the brake pedal feel like you have brake pedal and not the soft feel I have now. How far from top does it start to engage? 1/2 inch?
Thanks in advance Dennis

cruiser54

Booster close in diameter.
Booster rod must be modified to the profile of the 89 and diameter increased to accept 89 pedal bushings.
Lines from master to prop valve are metric. the ends must be changed at teh prop valve to American.
No adjustment to prop valve if using drum brakes in rear.

Pedal feel is excellent.

ocs1667

Thanks for the additional info.
I'll tackle it in January and let you know the out come.
Dennis

mentalbreakdown00

I have a 1995 xj, and didn't have to change anything, stops better than new... Even when I rebuilt the drums, it'll stop better now. I also didn't change the "proportioning" valve because in my honest opnion it's proportioned in the master anymore, and the valve is only for the brake light.... Has been for years..

cruiser54

You have the big booster.

And the prop valve DOES proportion the brakes. ALWAYS.

ocs1667

cruiser54

I asked if I needed to replace the proportioning because of the disc breaks on all 4 wheels now.

Should I get a new valve that's for disc's only, and not half/half

Your comment was no need to with drums in the rear.

May have missed my 1st request for info when I stated I have discs all the way around.

I still want to upgrade but do think proportioning valve would eliminate the current problem.

Any chance we could explore this over the phone? I could PM my ph.# to you and/or we could trade #'s

Dennis

mentalbreakdown00

Cruiser... I have had dozens off and apart in my life, and the only thing 99% have had in them is the safety switch for the light... IJS....

The only time I have ever needed to use something other than factory " combination" valve for a rear disc app was on my rx7, and my 89 stand where I was doing SCCA... I adjusted the backs to my liking for the constant stoppin/ slowing at higher speeds in turns.

cruiser54

You want the "guts" from a disc brake prop valve. 94 to 98 Grand Cherokee.

cruiser54

The light is ONE function.

The other is giving the rear brakes a "portion" of what the front are.

I too, have had Datsun Zs, LandCruisers, done track days etc. I have put adjustable prop valves on both of those.

That said, the guts of the 94 to 98 Grand Cherokee makes a difference when you convert a drum brake to disc brake in the rear. I tried it without, and then with, on my XJ.

hbracing13

I've done the wj swap vs using the 96 xj booster instead. Why didnt find any 96+ that looked decent but found a newly replace booster and just ordered a new master as all the reservoirs were broken off or the cap was missing.

I need to still to swap my guts as I've added rear disc but haven't yet and I did notice the differences with drums disc didn't improve much maybe when I swap I'll see the real difference.

cruiser54

The "guts" made a difference on my 88.

ocs1667

Cruiser 54
I Didn't want to drag this on forever. What do you mean remove the guts. I've asked several people who supposedly know about these things, and got a big blank look.

What year valve, and what do I do with it.
Thanks in advance for your help.
Dennis