Author Topic: brake pedal goes to the floor!! (Read 2737 times)

yotatough · « **on:** Dec 24, 2009, 07:00:09 PM »

I'm swapping axles in my runner (97 2wd) after I did the rear axle and got the lines all hooked up and bled, the pedal can be pumped up to stiff then it drops to the floor ( pump, pump, pump stiff, hold and drop to floor)

its not leaking fluid anywhere, its been bled over and over, it did sit for a little while during the swap, I'm being told that it may be the master cyl. but before I messed with it it had very touchy, and very good breaks, I'm not sure where else to look.

I knew the pedal was going to be a bit softer with the bigger axles, but it should still hold pressure, its puzzleing me.

79coyotefrg · « **Reply #1 on:** Dec 24, 2009, 07:31:59 PM »

it does indeed sound like your master cylinder is letting fluid to bypass the piston I HIGHLY recommend Marlins master cylinder,

fade · « **Reply #2 on:** Dec 24, 2009, 07:42:40 PM »

Did you cross thread any lines? how did you bleed your breaks did you start with the farthest away? maybe your bleeder valves are open a lil? My guess though would be the master cly sounds like that issue. I've always had problems with those things..

yotatough · « **Reply #3 on:** Dec 25, 2009, 12:08:28 AM »

dose a master just up and quit like that?

thanks guys.

yotatough · « **Reply #4 on:** Dec 25, 2009, 12:14:32 AM »

Quote from: 79coyotefrg on Dec 24, 2009, 07:31:59 PM

it does indeed sound like your master cylinder is letting fluid to bypass the piston I HIGHLY recommend Marlins master cylinder,

will it fit on my 97??

Cheesemaker · « **Reply #5 on:** Dec 25, 2009, 07:23:36 AM »

OOPS · « **Reply #6 on:** Dec 25, 2009, 10:45:03 AM »

"...This is from the FSM and it works great..."
1. Drivers side rear
2. Passenger side rear
3. Passenger side front
4. Drivers side front
5. LSPV (Load sensing proportioning valve)

toyotanner · « **Reply #7 on:** Dec 25, 2009, 12:18:06 PM »

sounds like a master cylinder to me if it was sitting for a while it might have been worth a bench bleed...

yotatough · « **Reply #8 on:** Dec 25, 2009, 01:14:44 PM »

it only sat for a few weeks, and I didnt unhook the lines untill this week. I think its gotta be the master,

like I said it will pump up to stiff, then it drops to the floor, if it was air in the line wouldent it stay spongy and not loose pressure?

OOPS · « **Reply #9 on:** Dec 25, 2009, 01:49:56 PM »

Nope, air compresses, fluid does not. It may be the MC if you bled them like I posted.

TOY087 · « **Reply #10 on:** Dec 25, 2009, 02:13:52 PM »

check brake buster

yotatough · « **Reply #11 on:** Dec 25, 2009, 02:19:03 PM »

Quote from: OOPS on Dec 25, 2009, 01:49:56 PM

Nope, air compresses, fluid does not. It may be the MC if you bled them like I posted.

I understand that air compresses, but would it pump up hard then loose pressure like I discribed? (loosing pressure without lifting the pedal, pump, pump hold, losses pressure.

yeah I've bled it just that way a few times now, so I'm gonna assume its the master.

unless theres somthing I'm overlooking

Larryb · « **Reply #12 on:** Dec 25, 2009, 02:42:38 PM »

Any visible signs of fluid leaking at any of the wheels cylinders, calipers, master cylinder or any where in between? If not it sure sounds like the MC unless you have some sort of restriction or blockage in one of the lines not allowing it properly bleed out.

yotatough · « **Reply #13 on:** Dec 26, 2009, 07:03:22 PM »

Well I installed a new master and it didn't fix the problem. I adjusted the rear brakes and it's a little better, I think I need to drive it to see how it feels, I might just throw in a full size master. We will see

Cheesemaker · « **Reply #14 on:** Dec 26, 2009, 07:51:36 PM »

Who did you get the master from and what size??

yotatough · « **Reply #15 on:** Dec 26, 2009, 08:54:48 PM »

its new, stock 97 toy runner. I believe its 1"

yotatough · « **Reply #16 on:** Dec 26, 2009, 08:56:48 PM »

I forgot to mention I'm running dana axles 44 up front 60 in rear. thats why I said I knew it would be a litte softer, just didnt expect it to feel this bad, also I havent driven it yet so I have no idea what it will feel like on the road.

Cheesemaker · « **Reply #17 on:** Dec 27, 2009, 08:17:04 PM »

Did you replace all the brakes on the axles or did you use what came on them? There have been members that have had the same problems and they used the old stuff, and once they got all new parts it was all good.

yotatough · « **Reply #18 on:** Dec 28, 2009, 09:36:04 PM »

I replaced all the front with new stuff, the rear I was gonna leave for a little bit, I adjusted them and that was all I did to the rear,

I got a 1 1/8" master from a 84 chevy 1/2 ton, gonna see if it makes a dif. or not, if not I will try to run the booster from the chevy as well.

I'll get the lines hooked up tommorrow. and have a verdict by then.

yotatough · « **Reply #19 on:** Dec 30, 2009, 09:55:50 PM »

well I havent driven it yet but the pedal feels sooo much better now with the chevy master installed in it. I'll keep you all posted when I test drive it.

thanks for your support!!

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