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Soft Brake Pedal

1,281
3
Tulsa, OK
Several weeks ago I changed out my brake lines, pads, rotors, and fluid. I upgraded to StopTech SS lines, Carbotech xp 20/10 pads, new centric blank rotors, and motul rbf 600 fluid. Ever since then I have had a soft pedal, and the pedal travels much further before it grabs. The brakes work and I stop but something isn't quite right. I have bled the brakes myself multiple times with both a motive power bleeder and a pressure bleeder hooked up to an air compressor. I have also taken the car to my mechanic at a local ford dealership for him to bleed the brakes and he says everything appears fine.

Before I upgraded components I was using stock lines, stock rotors, HP+ pads, and Motul rbf fluid. My thoughts were that at the very least my pedal would retain the same feel after the switch but as I mentioned it is much softer. With some effort I can push the pedal to the floor while not moving with the car on.

Now for my question, is it possible that I have some air trapped somewhere in the MC? Or that there is possibly air in the ABS system? My next planned step is to take it back to my mechanic and have him bleed the ABS system. There are no leaks in the lines that I can see and I'm kind of out of ideas...

You guys have any thoughts on the matter? Anybody faced any similar issues?

Thanks.
 
did you let the MC run dry when you were changing the lines?
if so, there's a good change there might be air in the MC, like you mentioned. and if ABS activated after your install, there might be air in your ABS module as well.
Maybe you could try pushing fluid through the caliper to the master cylinder, if you haven't tried that yet.
 

ArizonaBOSS

Because racecar.
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Have the dealer put the ABS system on their power bleeder/actuator.

ALSO--how much pad do you have left? As the pads wear, the pedal travel will become longer prior to true engagement.
 
1,281
3
Tulsa, OK
I don't believe the MC ran dry when I was changing lines. I know I kept it full while we were bleeding the system.

I'm going to take it to the dealer next week and have them bleed the ABS. The pads were brand new when I put them on.
 
I'm sure you're smarter than I was when I replaced the standard lines with my Goodridge SS lines, so you've probably already checked this. The Brembo fronts have 2 bleeders per wheel, not one, and I spent about a half an hour trying to figure out why I had a soft pedal. As soon as I bled the inside bleeders, all was well :-[.
 

steveespo

Lord knows I'm a Voodoo Child
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Cookeville TN
Roadhouse
Bleed them the old fashion way, one person on the pedal one at the caliper. Start at right rear the LR, RF, LF. Open bleeder 90 degrees, push pedal down and hold, close bleeder and release pedal. Repeat until no air bubbles are seen in the bleeder hose. Also top off master cylinder after each wheel. Takes about 5 full strokes per wheel when changing lines, I took about 10 per caliper when I installed new dry calipers on the front. Like Athens said make sure to do both bleed nipples on the fronts. Check also for weeps at your new hose connections and that the bleeders are tight. A minuscule leak will give soft pedal, also would spray brake fluid so it's probably not that. If you still aren't tight, but it is improved go to an empty lot and try to engage abs a few times, then rebleed the system. I think it's just air in one of the calipers, I have removed lines 3 times and unless the pedal is pushed or the Master cylinder is bad fluid doesn't leak out of the open brake pipes more than a drip.
Keep us posted.
Steve
 
1,281
3
Tulsa, OK
Thanks for the heads up Athens7 ;) : I am aware that there are two bleeders per wheel on the front. Glad you were able to figure out your issue.

stevespo- Thanks for the response. I think I will try to bleed them as you described either today or tomorrow and see how that works. Then go try to activate ABS myself and bleed again if it's still soft.

I'll report back in the next day or so.
 
steveespo said:
Bleed them the old fashion way, one person on the pedal one at the caliper.

Good advise, I don't use any type of speed/power bleeders. On the fronts do the inside screw first, couple of pumps, then finish on the outside screws. On the last bleed at each wheel open the screw just a little bit, have the person in the car push hard and tell you when the pedal is half way down. At that point close the bleeder screw. Been doing this for years and I get a great firm pedal everytime right out of the box.
 
I agree with Steve on the bleeding, the old fashioned way is best. Above posts covered all the likely issues. I would suspect air in the master or the ABS system. Many new model cars have a Master cylinder that you cannot bleed properly in vehicle. ( you would think after 100 years engineers could figure this out)

have the dealer bleed the ABS and see if that helps, then start at the begining and do it all over again one step at a time.
 

PeteInCT

#LS-378 - So many Porsche's, so little time....
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2,848
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Connecticut
I agree on the manual bleeding also, I've never had a bleed done on my car by vacuum or pressure that was as good as the old fashion way. The pedal just doesn't get as firm.

That said, I do have Russell SpeedBleeders, and have never had a problem. Leaks, air in the calipers, or otherwise.
 
807
419
Pete,

Do your bleeders weep? I had the Russell bleeders and every single one wept slightly. This was after they were all torqued to spec and with the vehicle sitting on jack stands. I removed them all and put the factory bleeders back in. I have not had a problem since.

On topic, I also find that finishing the brakes with a manual bleed works best. If I do a complete flush, I will use a Motive power bleeder initially, and then go back and do a final manual bleed.
 
2012-Boss said:
Pete,

Do your bleeders weep? I had the Russell bleeders and every single one wept slightly. This was after they were all torqued to spec and with the vehicle sitting on jack stands. I removed them all and put the factory bleeders back in. I have not had a problem since.

On topic, I also find that finishing the brakes with a manual bleed works best.

Mine did only on the fronts and I chucked them because of that. However you are only the second other Boss or S197 owner that I have heard with the same issue.

Agreed
 

pufferfish

Supporting Vendor
1,094
66
Maryland
My speed bleeders started to weep after my last track day. I have no help for bleeding, so I bought a motive. Have yet to see how it compares to the ol fashioned way.
 
pufferfish said:
My speed bleeders started to weep after my last track day. I have no help for bleeding, so I bought a motive. Have yet to see how it compares to the ol fashioned way.

I don't have help either but I would rather ask someone for help at the track the morning I arrive then do these any other way. To beat a dead horse, the racing teams do it the old fashion way. I have been doing this way for years and it plain works, I have heard more then one story of problems with different types of speed or bleeding systems.
 
1,281
3
Tulsa, OK
Thanks again to everyone for all the advice! I bled the brakes the old fashioned way this evening and the pedal is significantly more firm. I went for a test drive and everything feels great. I activated ABS a few times and pedal became even more firm. I could probably stand to bleed one more time after that but it will have to wait until later this week or the weekend.

It's nice to have confidence in my braking again :D
 

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