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  #1  
Old September 4th, 2019, 07:06
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azupcountry azupcountry is offline
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Different brake pedal feel after booster replace

2 weeks ago the brake booster failed on my 96 classic 4wd (no ABS 4.0 247k miles) while commuting home on I-4. Fortunately the stop and go traffic allowed me to feel the brake performance diminishing and hear the whistling get louder. I was able to exit and take surface roads/handbrake the last 10 miles.

FYI when the booster goes the brakes might as well be blocks of wood.

Replaced with a NAPA part without having to disconnect lines from the master cylinder.

Now, before the brakes start biting there is a bit more pedal travel. It is not soft, does not get worse and there are no leaks. I have tested on back streets by locking up brakes in forward and reverse as well as normal braking.

Is the difference in pedal travel/feel simply due to parts differences? Will bleeding the system make any difference?

Also, recently replaced rear drums/brakes but did not bleed.

Thanks!
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Old September 4th, 2019, 18:57
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lazyxj lazyxj is offline
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Re: Different brake pedal feel after booster replace

When replacing either the master cylinder or booster, the booster's push-rod needs to be adjusted to the specified clearance.
Too much clearance will cause a low pedal.Too tight or no clearance can cause a gradual brake lockup.
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01 Sport, Russ Pottenger 4.6, AW4, 4" lift, 33 X 10.50 KM2, 4.56-8.25 TruTrac, D-30-E-Locker with alloy shafts, Hidden M8000 winch, Vanco front and ZJ rear disc brakes, Frame stiffeners, Lots of armor, Towing baseplate. http://www.flickr.com/photos/lwade/c...7603770130683/
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Old September 5th, 2019, 02:37
tech1001 tech1001 is offline
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Re: Different brake pedal feel after booster replace

x2.
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  #4  
Old September 5th, 2019, 05:51
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cruiser54 cruiser54 is offline
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Re: Different brake pedal feel after booster replace

Yup.

And adjust your rear brake shoes.

You'll need to disconnect the lines from the master cylinder to check the clearance anyway.

NEVER a bad idea to bleed your old crappy brake fluid out. It goes bad over time.
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Old November 2nd, 2019, 21:42
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azupcountry azupcountry is offline
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Re: Different brake pedal feel after booster replace

MJcruiser54 had it...crappy fluid. Crappy enough to cause my drivers side caliper to lock up last Friday.
Removed, cleaned the smudge out of the caliper, and bled a bottle and a half of fluid.
Pedal is firm and now all of the new brake hardware works a lot better. Thanks everyone!
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Old November 2nd, 2019, 22:11
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cruiser54 cruiser54 is offline
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Re: Different brake pedal feel after booster replace

I like to use a turkey baster and suck all the fluid out of the master. Clean the reservoir if you can, with NO chemicals. Lint free rag to get the goop out. Add fresh fluid. Bleed brakes using the correct procedure. Should do this every coupla years or so.

Same thing with power steering. Same procedure for emptying the reservoir. Use the correct fluid though. No bleeding to be done.
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Old November 7th, 2019, 07:08
md21722 md21722 is offline
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Re: Different brake pedal feel after booster replace

I like to change the brake fluid & coolant every 2 years. I also change the thermostats every couple of years to minimize the risk of them failing closed, failing open, or hanging somewhere in the middle. If fluids haven't been done in a while then more frequent changes should be considered because the new fluid will start cleaning things up.

For brake fluid, if you have that plastic reservoir and its got a lot of residue in it, the new fluid will start cleaning it up and leaving it in suspension. If the reservoir isn't cleaned or replaced this can go on for quite a while. The old metal GM style ones were a lot easier to clean.
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Old November 7th, 2019, 10:26
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lazyxj lazyxj is offline
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Re: Different brake pedal feel after booster replace

With several vehicle to flush every two years or so, I bought a power flusher to ease the process of single handed flushing.
If you work by yourself most of the time, it's time saver.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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Both XJs are still Real XJs http://www.naxja.org/forum/showthrea...hlight=real+XJ
01 Sport, Russ Pottenger 4.6, AW4, 4" lift, 33 X 10.50 KM2, 4.56-8.25 TruTrac, D-30-E-Locker with alloy shafts, Hidden M8000 winch, Vanco front and ZJ rear disc brakes, Frame stiffeners, Lots of armor, Towing baseplate. http://www.flickr.com/photos/lwade/c...7603770130683/
1997 Country, Mostly stock, 2" lift, Engine mods, NP242, Towing baseplate
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