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Discussion Starter #1
I had to change the front brakes pads on my 05 frontier KC 4x4 6 speed the factory pads lasted 99,850 miles. I replace them with Oreilly brand Brakebest ceramic pads. I didn't crack open any bleeder or anything just removed the MC cap compressed the caliper with a clamp installed pads and bolted everything back up. After I was done I pumped the pedal up with the engine off and it pumped up fine. Then I started the truck and the pedal was completely mushy I could press it to floor. The brakes grab about half way down and stop the truck but I can still press on down to the floor. The break pedal before the brake job were awsome you only had to press it down 2" and it was rock solid and you could never press it to the floor.

I went ahead and bleed and flushed the complete braking system with no improvement to the brake pedal.

The only thing I can think of is any internal master cylinder leak.

Any ideas?
 

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I had to change the front brakes pads on my 05 frontier KC 4x4 6 speed the factory pads lasted 99,850 miles. I replace them with Oreilly brand Brakebest ceramic pads. I didn't crack open any bleeder or anything just removed the MC cap compressed the caliper with a clamp installed pads and bolted everything back up. After I was done I pumped the pedal up with the engine off and it pumped up fine. Then I started the truck and the pedal was completely mushy I could press it to floor. The brakes grab about half way down and stop the truck but I can still press on down to the floor. The break pedal before the brake job were awsome you only had to press it down 2" and it was rock solid and you could never press it to the floor.

I went ahead and bleed and flushed the complete braking system with no improvement to the brake pedal.

The only thing I can think of is any internal master cylinder leak.

Any ideas?
Take your wheels off and recheck everything you did. Make sure the brake hoses are not pinched or twisted. Check the master cyl cap, make sure the rubber diagphram is still in there and is not cracked. Did you disconnect the modulator plug or other ABS (elec) control's?
 

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Discussion Starter #3
I took the wheels off and rechecked everything. All was good. No I didn't disconnect anything abs sensor or modules. I even re-bleed the brakes and there still spongy and soft.
 

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I took the wheels off and rechecked everything. All was good. No I didn't disconnect anything abs sensor or modules. I even re-bleed the brakes and there still spongy and soft.
Well, if everything looks good, then you may have a master cylinder that is bypassing internally. Disconnect the battery or unplug the ABS control unit before you remove the old master cyl.
 

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Did you replace or resurface your rotors? If not, your rotor's surface will have hills and valleys and your new pads will be completely flat. The brake pads will only be contacting the high spots on the rotor causing you to apply much more pressure than normal to stop.
 

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Discussion Starter #6
Did you replace or resurface your rotors? If not, your rotor's surface will have hills and valleys and your new pads will be completely flat. The brake pads will only be contacting the high spots on the rotor causing you to apply much more pressure than normal to stop.
No, I didn't resurface or replace the rotors. The rotors were in great shape. I have done hundreds of brake jobs and never had a pedal go from rock solid to spongy as hell just by put front pads on even if the rotors were a little imperfect.

I pressure bleed the whole brake system yesterday with no change in the brake pedal travel. I KNOW there is NO air in the brake system. The pedal is rock solid and feels great with the truck not running. There is no bleed off in the pedal holding pressure on it with the truck off but as soon as I start the truck you have to pressure the pedal half way down to stop the truck. Instead rock hard once stopped the pedal is spongy and I can push it to the floor.

I will drive the truck some more to see if the pads just need some more bed-in time.
 

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Discussion Starter #8
Could be bad calipers. at 100K i would definitely replace them.
I have took the brakes apart looked at the calipers there not leaking. There isn't much to a caliper to go bad except a leaking seal around the piston.
 

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Are you sure that the pads are mounted inside the brake pad brackets securely? I had the same sort of deal with my wife's quest, one side was hanging up and the van would stiop, but it was uber mushy. I took it all off and found out that the one end of the brake pad was not sitting correctly in the thin metal bracket. I put a little grease in there to aid in seating and then set it. That did the trick.
 

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No, I didn't resurface or replace the rotors. The rotors were in great shape. I have done hundreds of brake jobs and never had a pedal go from rock solid to spongy as hell just by put front pads on even if the rotors were a little imperfect.

I pressure bleed the whole brake system yesterday with no change in the brake pedal travel. I KNOW there is NO air in the brake system. The pedal is rock solid and feels great with the truck not running. There is no bleed off in the pedal holding pressure on it with the truck off but as soon as I start the truck you have to pressure the pedal half way down to stop the truck. Instead rock hard once stopped the pedal is spongy and I can push it to the floor.

I will drive the truck some more to see if the pads just need some more bed-in time.
When you pushed the caliper pistons back into the their bores, you may have bottomed them out. Remove the caliper and take out the pad above the pistons. Put in a thinner piece of wood in the pads place. Just hang the caliper over the rotor, and have someone depress the brake pedal. Watch to make sure the pistons move. Sometimes crud builds up on the piston and or the piston bore, and will not allow the piston to move once it goes past the piston seal. If the pistons won't move, replace the calipers. If all works ok, you may have unseated a check valve in the actuator module, when pushing the pistons back into their bores, forcing the fluid back to the master cyl. Disconnect the battery, have someone press down on the brake pedal and crack all the lines, one at a time. See if that helps.
 

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i literally have the exact issue. still havent found a fix for it to this day. pedal goes to the floor when its on, but when the trucks off its fine.
i replaced all 4 rotors and pads, and from the first time i turned the truck on it did it, and after bleeding all 4 corners and now having braided lines up front with the tswap it still is doing it.

the truck does stop, but it doesnt feel safe at all. if i would have known this was going to happen i would have just left the warped rotors and shitty pads on there.
 

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Brakes are weird. I replaced the front pads and rotors on my other non-Nissan car last weekend. Same thing as you - pedal felt fine with the car off but sank to the floor with the car on. I found a tiny amount of fluid on the front wheel that I thought may have been brake fluid, so I reseated the piston and checked the brake line. Never saw any leaks after that...but no change. Bled the system. Still no change. So I just drove it...and over the course of maybe 150 miles, the problem worked itself out and the pedal feels totally normal now. I still can't figure out why it was so soft or how it fixed itself.

I hope you get it sorted out. My car definitely didn't feel safe either... It sure took a lot more effort to get it to stop. How many times did you bleed the system after you installed the braided lines? While I was researching my issue, I read that you sometimes have to bleed 2 or 3 times to get all the bubbles out.
 

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after the replacement of lines i bled them twice, and they felt 100% the exact same as just after the pads and rotors.

so im kinda at a loss on the bubbles since i did nothing to open up the system when i did pads and rotors. the only reason im so concerned now over when i changed the brakes is because on the trails i was pushing the pedal to the floor. i feel i had all the brake power i suppose it just was mushy all the way down.
 

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after the replacement of lines i bled them twice, and they felt 100% the exact same as just after the pads and rotors.

so im kinda at a loss on the bubbles since i did nothing to open up the system when i did pads and rotors. the only reason im so concerned now over when i changed the brakes is because on the trails i was pushing the pedal to the floor. i feel i had all the brake power i suppose it just was mushy all the way down.
mine feels that way too and i havent touch the brakes on my 2012. also after a specific point its meshy/spongy to the floor. dealer said its normal. brakes have plenty of stopping power and will lock up to stop till the ABS kicks in.
 

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mine feels that way too and i havent touch the brakes on my 2012. also after a specific point its meshy/spongy to the floor. dealer said its normal. brakes have plenty of stopping power and will lock up to stop till the ABS kicks in.
It's not normal for the pedal to be totally soft and just sink to the floor. The brake pedal on my truck feels a little mushy compared to other cars, but I don't think that's what Andy is describing.
 

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It's not normal for the pedal to be totally soft and just sink to the floor. The brake pedal on my truck feels a little mushy compared to other cars, but I don't think that's what Andy is describing.
mine is mushy, but doesnt sink to the floor.
 

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your pads suck, seriously. unless youpushed old fluid with debris in the MC and damaged the bore your pads suck. over the years Ive put pads on for people they bring etc. Everytime Ive delt with this its a pad issue. Did you "BED" the pads in properly? otherwise Ide change them. Best pads Ive delt with over the years for Not doing this are OEM's and EBC. Akebono suck. 3 times Ive taken them off for customers for this exact issue. You could stand on the brake and they wouldnt grip enough to activate the ABS. And delt with this with the BEST store pads too.
 

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My experience with EBC has not been good, they just don't last. I use only OEM pads now. Give that a try
 
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