brakes

i know there is a million threads on this already, i have an 89 xj with shit abs i am going to swap in my 8.25 29 spline i have sitting around to replace my d35, and i want to replace the master/booster already, looking for the easyest bolt up swap parts, i hear the duel diaphram are beter but do i have to modify the pedel? i wanna buy parts this week so i am looking for the right answers, i have a 89 none abs proportion valve and valve to booster lines aswell

I think its the 96 booster that is a bolt-in. Others need some sort of linkage adjustment.

As I've ranted about before, this will NOT improve the brakes.

So just get an 89 master and booster and call it good?

My abs does NOT work at all

morgan320i said:

So just get an 89 master and booster and call it good?

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Uh, now you're getting me confused.

If your vehicle is an 89 with the single diaphram booster, locate a dual diaphram booster from a 96, along with the attached master. Should be a $50 part from the junkyard. The only fiddling you will need to do is bending the brake lines to fit the new master location. And you may need to remove/move your washer bottle.

U said does not improve braking.. Lol nevermind, im buying new, no junkyards close, 96 cherokee sport? Or grand

morgan320i said:

U said does not improve braking.. Lol nevermind, im buying new, no junkyards close, 96 cherokee sport? Or grand

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You can probably search the long story/details. You are changing nothing on the brakes themselves. The OEM brakes are marginal stock, substandard with any weight/tire increases (read unsafe). You want better braking performance you need to improve the calipers/rotors/pads.

The booster change simply changes the pedal effort vs. brake pressure. It will take less effort to get more braking from your stock (junk) brakes. You can get the same "braking" by simply stomping on the pedal harder every time. Many folks seem to believe that because they press less and get more pressure that it somehow means the brakes are improved. They arent, you're just getting harder braking out of the same junk.

That said, as part of this nutricious upgrade, changing the booster *along with the other upgrades* makes a better package.

My abs pump is bad so i have to slam on brakes with both feet to stop, i have been driving it this way for awhile, so any brakes will be beter lol

Shogun said:

You can probably search the long story/details. You are changing nothing on the brakes themselves. The OEM brakes are marginal stock, substandard with any weight/tire increases (read unsafe). You want better braking performance you need to improve the calipers/rotors/pads.

The booster change simply changes the pedal effort vs. brake pressure. It will take less effort to get more braking from your stock (junk) brakes. You can get the same "braking" by simply stomping on the pedal harder every time. Many folks seem to believe that because they press less and get more pressure that it somehow means the brakes are improved. They arent, you're just getting harder braking out of the same junk.

That said, as part of this nutricious upgrade, changing the booster *along with the other upgrades* makes a better package.

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This entire comment just wreaks of intelligence. Very nice.

Shogun said:

You can probably search the long story/details. You are changing nothing on the brakes themselves. The OEM brakes are marginal stock, substandard with any weight/tire increases (read unsafe). You want better braking performance you need to improve the calipers/rotors/pads.

The booster change simply changes the pedal effort vs. brake pressure. It will take less effort to get more braking from your stock (junk) brakes. You can get the same "braking" by simply stomping on the pedal harder every time. Many folks seem to believe that because they press less and get more pressure that it somehow means the brakes are improved. They arent, you're just getting harder braking out of the same junk.

That said, as part of this nutricious upgrade, changing the booster *along with the other upgrades* makes a better package.

Click to expand...

:huh::wstupid:

get a Wj booster and master from an online junkyard site like carport.com to start.
then get centric premium rotors and black magic pads, or that boostwerks 4 piston caliper upgrade that I read about earlier on here somewhere, big rotors, pads, and wilwood 4 piston calipers? or the WJ brake swap, I just did this, and already had the WJ booster and master, brakes are pretty sweet.

The wj is bolt on also? Booster/master?

Shogun said:

You can probably search the long story/details. You are changing nothing on the brakes themselves. The OEM brakes are marginal stock, substandard with any weight/tire increases (read unsafe). You want better braking performance you need to improve the calipers/rotors/pads.

The booster change simply changes the pedal effort vs. brake pressure. It will take less effort to get more braking from your stock (junk) brakes. You can get the same "braking" by simply stomping on the pedal harder every time. Many folks seem to believe that because they press less and get more pressure that it somehow means the brakes are improved. They arent, you're just getting harder braking out of the same junk.

That said, as part of this nutricious upgrade, changing the booster *along with the other upgrades* makes a better package.

Click to expand...

I don't completely disagree, but let's imagine that max stock pressure is both feet and the pedal all the way down at the firewall. This will give X amount of pressure. Now with the upgraded booster the same pressure is achieved at 1" off the firewall (just as you stated, same braking with less foot effort). Now you have an additional 1" of movement. How does this additional 1" not create additional brake pressure?

morgan320i said:

The wj is bolt on also? Booster/master?

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not completly bolt on, some slight modification to the booster rod and you will need the hard lines from the WJ master to the prop valve, so you can cut and reflate them to use your prop valve fittings, but other than that, pretty much.

you could also go black magic for pads(and they sell centric premium rotors).

I think those pads won't work on his 89. I had the same issue with mine. Pre-90 (I think it's 90) knuckles and calipers are different. :sad1:

oh yah thats right , they dont do black magic for the pre 91 . nevermind, but you can go on rockauto and get centric premium calipers, rotors, and pads for like aorund 135$ shipped on all of it, then another 100$ on a WJ booster/MC from a JY, for around 235$ you would have some majorly improved brakes.

Are the centric premium calipers any different than stock? I'm in the same delema of what to do about my 89's brakes too. I already have the WJ booster/MC on the bench ready to go in but want to look at all my options. From what I've ready WJ knuckles are not exactly a "drop-in" swap so might be complicated for me.

HappySlappy said:

Are the centric premium calipers any different than stock? I'm in the same delema of what to do about my 89's brakes too. I already have the WJ booster/MC on the bench ready to go in but want to look at all my options. From what I've ready WJ knuckles are not exactly a "drop-in" swap so might be complicated for me.

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I think your 89 has the RENIX two piece knuckles and early style calipers? if so, you can upgrade to the later style one piece knuckles and late model calpiers real easy. It all just bolts on.

HappySlappy said:

I don't completely disagree, but let's imagine that max stock pressure is both feet and the pedal all the way down at the firewall. This will give X amount of pressure. Now with the upgraded booster the same pressure is achieved at 1" off the firewall (just as you stated, same braking with less foot effort). Now you have an additional 1" of movement. How does this additional 1" not create additional brake pressure?

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The Assumption is that with both the oem and the upgraded booster you can generate sufficient pressure to achieve lockup. This assumption goes away if you significantly increase vehicle weight or tire diameter (note my previous caveat).

So for simplicity we'll use your example; I lock the brakes at the firewall with oem, or I lock then at 1" off the firewall. whats that additional inch going to do for you?

There are two main things the booster/pedal arrangement can do for you; generate pressure and the pressure/effort/distance curve (how quickly and thus controllably that pressure is generated for pedal pressure and distance). The slower the pressure slope is the more accurately you can control the pressure to the calipers. This is important because "optimum braking" is not about locking the tires but getting as close to lockup as possible without 100% lockup (15% incipient skid).

In this aspect, the booster upgrade May indeed Not be an improvement because you will get to full lockup much quicker and thus May be more difficult to achieve optimum braking.

If your problem is insufficient pressure (weight/tire size) then the booster upgrade is warranted. In this case the curve is different due to the weight/size changes.

The other major component that drives performance is the caliper. Piston size and number of pistons dictate overall pressure reqd and the slope of the pressure curve. More/larger pistons will require more pressure (psi) but also lower the slope of the curve, in addition to applying even pressure to the pads over larger area.

So, it is my OPINION that BOTH booster and caliper upgrades will result in the most significant increase in braking performance. The biggest POS in the oem system is the caliper (once you can generate sufficient pressure). We havent even touched on rotors/pads/tires yet.

I would agree completely if I said "lock", but I said max pressure at the firewall. In fact I currently cannot lock the brakes at all on the street. So in my case if I can achive equal preasure at 1" off the firewall with an upgrade booster/MC then it seems to makes sense I will have additional braking.

So I think we agree for the most part, but some of the assumptions we're making about the test conditions are different.

Yes, they're two-piece knuckles so given what Lou said above I'll probably go with later model knuckles/calipers also. This will allow me a better selection of pads.