This is the third season now with my Crossfire and first time this issue has occurred. Before this the pedal was very responsive favoring almost aggressive. Your problem is absolutely something that can be fixed.

 

Biggest problem with brakes after a vechicle has been sitting is rust on the rotors, longer it sits, the more builds up, and enough the dust and build up on the pads, till it gets work off.
example, mine has been down over a month while I have been working on a single aluminum driveshaft from the 2 piece steel, now I have no more flex discs and not more center carrier bearing.
but the rust has built up on the rotors thicker, and first drive, had to push hard on the brake and petal went alot farther down, due to having to push alot harder on the petal, but after easy driving on my back roads, going easy on brakes not to heat or much pressure, just doing a self cleaning, while doing some light testing brakes kept feeling better and better, now, good as they where before, throw you in the windshield.

you can also get a test gauge and take out a bleeder, and screw the test gauge in the bleeder to test pressure and for bleed off.
power assisted brakes can build pressures upto 1400 psi.

 

Circling back on this. I did this and found the brake pedal to be very firm and what I consider normal when the car is turned off. When running however the pedal goes back to being soft. Do those finding indicate what might be wrong between air in the lines or master cylinder? Brake fluid level is very normal and no signs of leakage.

 

The only thing that changes is the ABS system is turned on and I suspect that the control unit takes up the fluid but if it is full this should not matter. Is the cause of the problem air in the ABS system?
What one person calls a soft pedal another may say is fine. We have no way of comparing two or more cars if they are not side by side.

 

 

Please post the solution!

 

Yes, would love to hear a solution for this everlasting problem. Where do you get the gauge that is referred to that measures the pressure in the brake line. I guess that could tell us if we have a master cylinder that has a bleed off problem at the seal, or if a brake caliper is having a bleed off problem. Let me know about this. A firm pedal, like that on the American made cars and the Japanese imports is what I feel is desirable. My wife has a Subaru and the pedal on that barely moves and the pedal starts getting firm. I had a Chev. HHR until recently and the brake's were great on that car, too! Very nice brake feel!

I solicit any helpful information.

Jim

 

 

As said before, the spongy soft brake pedals can be solved with a bleed/flush with new DOT4 fluid. Many have had this occure with old fluid. Try it, least expensive and least troublesome solution!

.

 

 

My 05 roadster has been sitting several months and I am experiencing the same "soft pedal" issue that you have been discussing. I have tried the "pumping while not running" approach, and haven't seen any appreciable improvement. I am going to try bleeding the brakes next. My question is what fluid to use. Should I go ahead and pay the extra money for the MB dot 4 plus, or will off the shelf dot 4 from one of the parts stores be safe to use? Here is the spec from the manual:

Brake Master Cylinder Use brake fluid approved to MB 331.0, or a DOT 4 brake fluid with: minimum dry boiling point (ERBP) 500°F (260°C), minimum wet boiling point (WERBP) 356°F (180°C), maximum viscosity 1500 mm2 /s, conforming to FMVSS 116 and ISO 4925.

Standard dot 4 specs show lower minimum ERBP (230C) and WERBP (155C). Is this really going to make a difference?

 

donsxfire - I bought my brake fluid from Rob at Needswings. The reason being that I was also buying other brake parts at the same time. His is a dot 4 fluid and since it was recommended by him, I felt safe. He has both the "race" fluid and the "street" fluid. Of course, get the "street" fluid.

An open question for all here. Has anyone replaced the master cylinder with a new one, not a rebuilt, and noticed any improvement? Has anyone replaced the calipers and noticed any improvement? Like 180 said, he, and a lot of us, have replaced the fluid and bled the system only to find no appreciable improvement. I didn't think of it until 180 mentioned that the gauge wouldn't help, but I agree with him. I don't think it will reveal what we are looking for. I'm one who just refuses to say "that's the way it is". There has to be an improvement somewhere. If American, Japanese, and other European cars can have a good brake pedal feel, we can too! It might take all of us to find the answer but we have to keep trying. I put "Wildwood" calipers on a street rod, two in fact, and was very happy with their performance over run of the mill calipers. I also used their complete brake system on a race car. Wonderful brakes!

If anyone has some more ideas, lets hear them.

Thanks,

Jim

 

Thanks for the feedback Jim. I looked up the fluid from your dealer, and it exceeds the temp specs, so it should definitely be OK. FYI to everyone: Ebay has the Mercedes Benz dot 4 plus fluid, 1 liter for $15, free shipping, and a free bottle of windshield washer fluid. I'll probably go with that, just to be safe. I'll report how it works out.

 

 

Hey Dave, in the future if you are making a joke, enclose the text like this : <JOKE>This a joke</JOKE>

 

HaHa. Got it. I'll be sure to check the label. Based on what I have read in this forum, my next step should be bleeding the brakes and replacing the fluid. Am I on the right track? I am relying on your experience to help me solve this problem.

 

 

Thanks for taking the time to describe the basic procedure. I have found the detailed procedure on the forum. It's very good. I'll also check the pads when I have the wheels off and post the results on this thread. Just waiting for the fluid to show up.

 

My solution has been to replace the brake lines with stainless from Brake world and super grippy pads from DiscItalia, followed by a thorough bleed starting at rt rear, lt rear rt front etc. Maybe not perfect but acceptable.

 

Thanks Jeff. I just talked to a German Import specialty garage near me. They specialize in European Imports, particularly Mercedes and BMW. They told me that to do the job properly they have to use a scan tool to properly bleed the brakes. They said that's the only way to COMPLETELY CLEAR ALL FLUID from the system. I've never heard of that before but I'm not a German car Specialist. This shop comes highly recommended and I guess that all one can do is try them once and see. If it's a rip, I can sure let a lot of people know. If it's good, I can also relate my experience here. I will keep everyone posted on the results. It may take a week or more because they are busy enough that I can't get in for a week. Hope that's a good sign.

Jim