Soft Brake Pedal
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Braking response and pedal stiffness will always improve when replacing worn pads with new. With new pads, you push the piston back in, thereby reducing the amount of fluid in the piston chamber. The more hydraulic fluid in the piston chamber, pedal response reduces due to cushioning effects of having more brake fluid filling the piston chamber.
Another thing to note is that fresh brake pads will always feel responsive. But as they go through heat cycles, their effectiveness goes down. As the pads get old, they will become softer and less responsive. The change is so gradual that you will not notice it until you change brake pads again.
Oh, old fluid with moisture in it also causes bad pedal response and mushiness. Changing old fluid in many cases boost pedal response significantly. Again, the deterioration is so gradual that most people wouldn't notice it.
Another thing to note is that fresh brake pads will always feel responsive. But as they go through heat cycles, their effectiveness goes down. As the pads get old, they will become softer and less responsive. The change is so gradual that you will not notice it until you change brake pads again.
Oh, old fluid with moisture in it also causes bad pedal response and mushiness. Changing old fluid in many cases boost pedal response significantly. Again, the deterioration is so gradual that most people wouldn't notice it.
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From: By the sea, Tx
G35 sedan w/ too much money in mods
So is it bad to run with the MC almost completely full? Obviously as the pads wear the fluid level will drop over time.
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That is correct, brake fluid level is sometimes used as an indicator of pad wear level. When the brake pads become too worn, fluid level will become low, triggering the brake warning light. This method, however, is not always accurate because of timing of brake pad changes or flui being topped up in between pad changes.
It is not bad to run MC completely full or even above the full mark. The reason you don't want to fill the MC too high is because as the fluid gets hot, it boils and expands. This will cause an overflow as fluid expands in the reservoir.
It is not bad to run MC completely full or even above the full mark. The reason you don't want to fill the MC too high is because as the fluid gets hot, it boils and expands. This will cause an overflow as fluid expands in the reservoir.
Joined: Mar 2009
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From: By the sea, Tx
G35 sedan w/ too much money in mods
All good information and this is the technical advice I was seeking.
Thanks!!!
Well I have some feedback on my particular situation. Last week I replaced my 1/2 worn Hawk HPS pads with OEM. Mind you, I have never rolled on OEM, the car had some type of Duralast pads on when it was purchased. I replaced them with the Hawks last year and they felt OK but not what I expected.
The OEM were night and day different. Great initial bite and a more sure footed stop when you really mashed the pedal. ALSO, the pedal was rock hard on all presses of the pedal from the first to the 4th (if you pressed it that many times) However, the OEM pads have a lot of material on them so when I was all done the MC was virtually full. The fluid level filled the whole MC except for a bubble that covered about half of the top behind the cap. So I drained enough fluid to get to the "full" line and I'll be damned if the pedal didn't soften up noticeably. Not nearly as bad as with the Hawk pads, but definitely different than with the MC being almost completely full.
Now I want to go buy some fluid and fill the damn MC full again like it was but I don't know if that's bad for the brake system. Does anyone know the answer?
The OEM were night and day different. Great initial bite and a more sure footed stop when you really mashed the pedal. ALSO, the pedal was rock hard on all presses of the pedal from the first to the 4th (if you pressed it that many times) However, the OEM pads have a lot of material on them so when I was all done the MC was virtually full. The fluid level filled the whole MC except for a bubble that covered about half of the top behind the cap. So I drained enough fluid to get to the "full" line and I'll be damned if the pedal didn't soften up noticeably. Not nearly as bad as with the Hawk pads, but definitely different than with the MC being almost completely full.
Now I want to go buy some fluid and fill the damn MC full again like it was but I don't know if that's bad for the brake system. Does anyone know the answer?
Kinda curious to try and top off my fluid just to see if it changes anything.
Joined: Mar 2009
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From: By the sea, Tx
G35 sedan w/ too much money in mods
I was very surprised. Based on the post above you don't want the MC to be too full to allow for boiling, but I think I'm going to buy some fluid today and fill it back to the level it was at when I replaced the pads. That gives me a little wiggle room.
We use DOT 3 fluid correct?
We use DOT 3 fluid correct?
I was very surprised. Based on the post above you don't want the MC to be too full to allow for boiling, but I think I'm going to buy some fluid today and fill it back to the level it was at when I replaced the pads. That gives me a little wiggle room.
We use DOT 3 fluid correct?
We use DOT 3 fluid correct?
I've autoxed my mustang hard with fresh fluid and have never really had an issue with boiling the fluid. Then again, I bleed the brakes on that thing every 500 miles or so (summer of driving)
I use the valvoline synthetic fluid. It's dot 3/4 compatible and what I have put in my sedan. Just don't use dot 5 silicone fluid as it's not compatible.
I checked my fluid level and it's down from the summer, but I've suspected my rear pads are nearly done anyway. I'll grab some new front and rear pads and change them in the spring. Perhaps pressing in all 6 pistons and bleeding the fluid then might free up an air bubble.
Let us know of adding some fluid help. However I think if it does make a difference there is some other underlying reason. That just doesn't make sens
Last edited by Mustang5L5; Feb 1, 2011 at 05:20 PM.
Braking response and pedal stiffness will always improve when replacing worn pads with new. With new pads, you push the piston back in, thereby reducing the amount of fluid in the piston chamber. The more hydraulic fluid in the piston chamber, pedal response reduces due to cushioning effects of having more brake fluid filling the piston chamber.
Another thing to note is that fresh brake pads will always feel responsive. But as they go through heat cycles, their effectiveness goes down. As the pads get old, they will become softer and less responsive. The change is so gradual that you will not notice it until you change brake pads again.
.
Another thing to note is that fresh brake pads will always feel responsive. But as they go through heat cycles, their effectiveness goes down. As the pads get old, they will become softer and less responsive. The change is so gradual that you will not notice it until you change brake pads again.
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Joined: Mar 2009
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From: By the sea, Tx
G35 sedan w/ too much money in mods
Bought some Prestone dot 3 today and refilled the MC to the level it was at after the pad change and the pedal stiffened up noticeably again. Don't know why but I'm happy with my brakes for the first time in 2 years. Hope this works for other people.
Joined: Mar 2009
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From: By the sea, Tx
G35 sedan w/ too much money in mods
I'm working all day but will try to snap a pic when I get home. I'll post it up later. It's pretty damn full.
Joined: Mar 2009
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From: By the sea, Tx
G35 sedan w/ too much money in mods
Here's the pic. The drip down the side of the MC is not overflow from under the cap, it's left over from me not wiping down the MC after filling. As you can see I just have an air pocket on the back half and a firm pedal. 
Thanks,
If it ever stops snowing here in the northeast (AWD works very well BTW), i'll try that just for ****s and giggles and see if it makes a difference.
So you just topped it off, and nothing else? No bleeding? And it made a difference?
If it ever stops snowing here in the northeast (AWD works very well BTW), i'll try that just for ****s and giggles and see if it makes a difference.
So you just topped it off, and nothing else? No bleeding? And it made a difference?