I've been reading up on brake upgrades but I'm still a little confused. My brakes are completely stock, can I swap to the ZJ Master cylinder and get an increase in braking power? Any specific years? Also, is there a guide on getting WJ 2 pot calipers on my XJ?
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Brakes for a 1998?
- Thread starter XJ98Jeep
- Start date
Shogun
NAXJA Forum User
- Location
- Arizona Territory
The MC is not generating the friction to stop the vehicle. Why would that (alone) significantly increase braking peformance? It wont. You may get higher peak pressure, or faster onset rate, neither of which is a standalone good thing. You may get better modulation along the curve, which may be better.
Without a concurrent improvement in the calipers/rotors/pads you are polishing a terd. Bottom line is the stock stuff is junk no matter how you polish it. Junk it out, get good stuff and be done. The change is phenominal.
Without a concurrent improvement in the calipers/rotors/pads you are polishing a terd. Bottom line is the stock stuff is junk no matter how you polish it. Junk it out, get good stuff and be done. The change is phenominal.
Shogun
NAXJA Forum User
- Location
- Arizona Territory
Unless your problem is insufficient pressure, which I doubt, it alone will probably not increase braking peformance (ability to achieve optimum baking from the system and reduction in total braking distances and fade).
Now maybe with very large tires you may need increased pressure, but that is still probably not enough to improve perf. Think of it this way, does stepping on the pedal harder improve performance (see above definitions). Not necessarily. The cause of poor performance is not pressure alone, it is poor mechanics in the caliper, swept area, rotor quality, and inability to modulate said pressure to achieve optimum braking (15% insipient skid).
Lets say that every time you touch the pedal you get instantaneous full pressure at an amount double your present psi. Would that increase the perf? No. You would get uncontrollable, full wheel lock. Assuming you have sufficient pressure to lock the wheels (see above comment on very large tires), you must them be concerned with mechanical efficiency and ability to modulate the pressure. I am avoiding brake fade for now, another system efficiency issue. If you are not capable of generating sufficient pressure to achieve wheel lock, then a achange in booster/mc is only one part of improving total system performance.
Then we can discuss man/machine interface issues. Studys (mostly MB) show that in general people do not achieve sufficient pedal input to get full braking when needed (even when forwarned), thus we are seeing systems (again mostly MB) that increase pressure themselves when it is determined that the driver needs heavy braking, called something like "panic" braking. A new booster/mc may assist in achieving faster, heavier braking, but again, that is mostly an interface issue. The wheel brakes cannot perform better than they are capable of, ultimately (assuming you can get there already). But you may be able to extract better total performance by better pressure modulation.
The factory calipers are poor mechanical devices. The dumb blade that is supposed to slide smoothly cannot due to the flexing of the frame and subsequent "divots", which then serve to bind the smooth operation of the caliper. A single piston caliper makes it difficult to have even pressure along the length of the brake pad, which can cause binding, poor/incomplete friction over the swept area, and pressure spikes. Generally, the more pistons, the smoother and more even the pad pressure distribution.
Uh, thats probably enough to digest for now.
Now maybe with very large tires you may need increased pressure, but that is still probably not enough to improve perf. Think of it this way, does stepping on the pedal harder improve performance (see above definitions). Not necessarily. The cause of poor performance is not pressure alone, it is poor mechanics in the caliper, swept area, rotor quality, and inability to modulate said pressure to achieve optimum braking (15% insipient skid).
Lets say that every time you touch the pedal you get instantaneous full pressure at an amount double your present psi. Would that increase the perf? No. You would get uncontrollable, full wheel lock. Assuming you have sufficient pressure to lock the wheels (see above comment on very large tires), you must them be concerned with mechanical efficiency and ability to modulate the pressure. I am avoiding brake fade for now, another system efficiency issue. If you are not capable of generating sufficient pressure to achieve wheel lock, then a achange in booster/mc is only one part of improving total system performance.
Then we can discuss man/machine interface issues. Studys (mostly MB) show that in general people do not achieve sufficient pedal input to get full braking when needed (even when forwarned), thus we are seeing systems (again mostly MB) that increase pressure themselves when it is determined that the driver needs heavy braking, called something like "panic" braking. A new booster/mc may assist in achieving faster, heavier braking, but again, that is mostly an interface issue. The wheel brakes cannot perform better than they are capable of, ultimately (assuming you can get there already). But you may be able to extract better total performance by better pressure modulation.
The factory calipers are poor mechanical devices. The dumb blade that is supposed to slide smoothly cannot due to the flexing of the frame and subsequent "divots", which then serve to bind the smooth operation of the caliper. A single piston caliper makes it difficult to have even pressure along the length of the brake pad, which can cause binding, poor/incomplete friction over the swept area, and pressure spikes. Generally, the more pistons, the smoother and more even the pad pressure distribution.
Uh, thats probably enough to digest for now.
I do see what you're saying, but I can put my brake pedal on the floor without locking my 33's up, so i do think I need more pressure on the pads/shoes. Along with what I've heard about the WJ 2 pot calipers, that should at least make my brakes useable.
Shogun
NAXJA Forum User
- Location
- Arizona Territory
Hmmm, I thought the 98 had the dual-diaghram booster which should generate sufficient pressure. My 89 single-diaghram did not with anything larger than stock tires, the upgrade to 96 dual handled 31s fine.
Remember you can cheat by slamming the pedal (very quick pressure onset rate) to get wheel lock, not correct, you need to generate the pressure via a controlled increase in pedal pressure (I know not your problem).
I have not worked with the WJ calipers but do not trust that they are high quality equipment, given the track record. I upgraded to Bosch calipers and the increase in performance was superb. Better "performance" than just the booster upgrade, which only served to get me in the game. (now running very heavy 32s)
Remember you can cheat by slamming the pedal (very quick pressure onset rate) to get wheel lock, not correct, you need to generate the pressure via a controlled increase in pedal pressure (I know not your problem).
I have not worked with the WJ calipers but do not trust that they are high quality equipment, given the track record. I upgraded to Bosch calipers and the increase in performance was superb. Better "performance" than just the booster upgrade, which only served to get me in the game. (now running very heavy 32s)
Shogun
NAXJA Forum User
- Location
- Arizona Territory
They are from the ford exploder, made by Bosch. Requires machining the knuckle. I got the Vanco system, best bucks I have ever spent. I had a hard time believing that ford could do anything well, but these brakes Work. I usually drive BMW/Audi and will stack these brakes up against them any day.
Bottom line is for under $1000 and a couple hours easy labor, you can have superb brakes. You spent that much on tires.
Bottom line is for under $1000 and a couple hours easy labor, you can have superb brakes. You spent that much on tires.
Shogun
NAXJA Forum User
- Location
- Arizona Territory
No. The Bosch/exploder brakes are included in his kit.
I think there is a thread on it if you search, or just hit the website.
I think there is a thread on it if you search, or just hit the website.
- Location
- Hammertown, USA
On your 98, you already have the better master/booster. The upgrade is a WJ master/booster, not ZJ, and its good pre 1995.
You're best bet will be to pony up and contact Vanco PBS for a brake upgrade, or do a WJ conversion (the Vanco is comperable in stopping and much easier/cheaper).
You're best bet will be to pony up and contact Vanco PBS for a brake upgrade, or do a WJ conversion (the Vanco is comperable in stopping and much easier/cheaper).
