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spongy brake feel and long brake pedal travel

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Old 05-15-2007, 06:04 PM
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0utlier
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Default spongy brake feel and long brake pedal travel

I've gone through the list and read what I could find on this problem. First, the brakes work, but the pedal travel seems a bit long before you really get into the brakes. I can easily push the brake pedal past the gas pedal and get really close to the floor before getting into the real meat of the brakes.

1. I thought it could be air in the lines so we bled the brakes. That didn't help.

2. After bleeding didn't help I assumed the master cylinder was giving up the ghost so we put on a new master cylinder and re-bled the brakes. That didn't help either. Same brake pedal travel as pre-new master cylinder.

What else could it be? Or is this type of brake pedal travel normal? I don't remember the brake pedal travel being so long, but maybe I've just become super sensitive. Thanks.
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Old 05-15-2007, 06:24 PM
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Whats the condition of the brake pads and fluid? are you using DOT 4?
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Old 05-15-2007, 06:44 PM
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The brake pads have plenty of life left in them. I'm using ATE super blue brake fluid which is new.
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Old 05-15-2007, 06:59 PM
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Originally Posted by 0utlier
The brake pads have plenty of life left in them. I'm using ATE super blue brake fluid which is new.
Good..........are you using the power bleeder?

If so, why not flush the system once more making sure you bleed the master cylinder.

How are the rubber lines?
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Old 05-15-2007, 07:13 PM
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I had the same thing with my '89 and it turned out to be very small leaks in the piston seals of the calipers. They were big enough to cause the pedal feel to be bad, but small enough that you could not tell that there was a leak until both front wheels were removed.

Good luck.
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Old 05-15-2007, 07:16 PM
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The new MC has a bleeder valve and we're bleeding the brakes the old fashioned way by pumping and holding. The system has been flushed twice now and we're as confident as you can be that there is no air in the system. The lines seem to be fine. We're not losing any fluid. It's very strange indeed.

The brakes seem to work fine, it's just the pedal travel seems too much. Panic braking from 60 to 0 seems to be fine, it's just a long pedal travel down.
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Old 05-15-2007, 07:23 PM
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Does your pedal sink while braking or is it just long travel? My '88 feels a bit funky too and I will be looking into it once I get the car back from the paint shop.
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Old 05-15-2007, 07:48 PM
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Interesting to see if someone finds out more on this.
My pedal is also soft and with long travel, after changing out the pads and rotors front and rear.

I have assumed changing the fluid and bleeding can improve things, but may be this can be caused by grease on the pads?
The manual states that no grease must be applied to the area in contact with the pistons, and also to renew the damper plates, which I did not do.
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Old 05-15-2007, 08:01 PM
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Hi Scot, some random ideas-
Sometimes it's necesarry to 'bench bleed' the master cylinder, the idea is to cycle the fluid right at the fitting on the master cylinder itself. Sometimes you just get air pockets somewhere up there and within the master cylinder and no amount of conventional bleeding will help. I've seen odd cases when I had to take a master cylinder off the car, bench bleed it and put it back on.

Another rare possibilty for long pedal travel is when the calipers aren't well centered or crooked in some way from part swapping, the application of the brake will clamp the caliper but if it's not able to rest in that position it will relax and you have extra pedal travel to take up slack nest brake application.
Getting theoretical along those lines. although not your case, is on a race car that has loose wheel bearings or a flimsly spindle. Cornering forces will push one side of the caliper in and next time the brakes are needed alot of pedal travel will be required to move the pistons back out, that's when a floating caliper might be handy.
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Old 05-15-2007, 10:03 PM
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It is possible to adjust the travel of the brake pedal...mine also has quite a bit of slop at the top of the travel and is spongier than I would like....but I attribute it to worn pads, track days & a "loose" setting on the brake pedal....there is a section in the WSM that shows how to adjust it (but of course I haven't looked yet)
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Old 05-15-2007, 10:18 PM
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Move seat forward.
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Old 05-15-2007, 10:26 PM
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Originally Posted by Okv
My pedal is also soft and with long travel, after changing out the pads and rotors front and rear.
Hmm... changing the pads and rotors is what fixed mine. Pads were half worn. Rotors were worn out.
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Old 05-16-2007, 04:07 AM
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When you say that you are bleeding by "pump and hold" are you opening the bleeders on both a front and a rear at the same time? Just opening a single does not allow full travel of the master cylinder, sometimes trapping air.
Also, when pushing back the caliper pistons to replace pads, crack the caliper bleeder screw(s) to prevent pushing fluid back into the ABS system.
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Old 05-16-2007, 11:13 AM
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I was actually doing the pump and hold, but I'm pretty sure he was just bleeding a single bleeder at a time. We'll go back and try doing both at the same time.
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Old 05-16-2007, 11:48 AM
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Scott..........given that your using the manual bleeding method I'd strongly recommend getting the power bleeder.

This tool makes bleeding the brakes little effort and ensures a perfect job every time. Plus its a one man operation; no sense in using up your brownie points with the wife when you don't have to.
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