soft brakes

[iceman039]

My Brakes are quite soft compared to most other cars i have driven. do I need a brake tune-up, or is this just a characteristic of the svx because of the weight and undersized rotors? I would say my brakes take as much pressure as my half-ton gmc work truck takes to stop.

[msvx95]

Maybe you glazed over the rotors with too much heat....I'd say get new pads and get the rotors re-turned.

[bwb3]

This has been bothering me too. My '94 has less boost to the brakes compared to my '92. You have to stand on the brakes hard. And it has new slotted rotors. Maybe the calipers need rebuilding?
Gene

[msvx95]

maybe the brake booster isn't working properly....push the brake pedal a few times to eliminate the excess travel while the car is off.
Did you eliminate all the air out of the lines when you bled the brakes after installing the rotors?

[dcarrb]

If by "soft" you mean, soft pedal, I agree that's probably a power assist or hydraulic issue. Will the pedal hold steady, or eventually go to the floor?

dcb

[bwb3]

The pedal isn't soft, the breaks just don't grab hard. Was the same before the rotors. My mechanic thinks it might be the booster. It that a tough job? Fluid seems fine.
Gene

[immortal_suby]

flush the brake fluid out.
my brake pedal is hard as a rock. when it starts to feel soft I replace the fluid.

[Earthworm]

I flushed the fluid twice in my car following the directions from the FSM. My breaks require lots of pressure to stop the car but after a couple hard stops to heat up the (KVR Performance) pads they really start to bite.

[iceman039]

i think i will try new fluid, it doesnt seem like a major component issue, the pedal is just not as responsive as i would like. Also, when i am going slow, (only when brake is applied) there is a click from the rear right wheel. at first i thought it was something to do with the bearings, but i think its time for a brake overhaul. my abs light keeps coming on as well!

[Beav]

Vacuum boosters don't make soft pedals. Quick test: engine off, pump pedal several times to deplete vacuum reserve. Hold foot on pedal, about 5# force, and start engine. Pedal should drop, indicating booster works. Pretty simple.

Bad master cylinders don't make soft pedals. Falling pedals, pedals on the floor, frozen pedals, etc. could be master cylinder defects.

Bad brake hoses, that expand under pressure, can make a soft pedal.

Really cheap, soft rotors and/or drums can make for soft pedals. Over-sized drums can too.

Cheap, crappy pads can make for soft, spongy pedals and/or extended stopping distances. Some pads are so cheap - not inexpensive - (and believe me, I've seem some name brands straight out of the box do this) that you can actually see the friction material compress while someone stands on the pedal.

Loose caliper mounts and hardware can make for low/soft pedals as can loose/worn wheel bearings.

Physics, anyone? What's the difference between gases and fluids? That's right, fluids don't compress, gases do. Air in the brake fluid will compress and give a soft pedal. Caveat: heat a fluid past its boiling point and.....? Right again, it becomes a gas.

Brake fluid notes: DOT3 or DOT4 is more than adequate for anyone here on the highway. DOT5 silicone fluid is not compatible with DOT3 or 4, requires complete replacement of all rubber items in the hydraulic system, including ABS components and thorough flushing of the remaining steel components. DOT5 is NOT recommended for street use for one extremely large reason: It does NOT absorb moisture! Think about it... moisture is in the air, there's no getting around it. DOT 3 & 4 brake fluid is like any other petroleum based fluid, it's hygroscopic, meaning that it attracts and absorbs moisture. DOT 3 & 4 hold this moisture and disperse it throughout the entire system. Here's where it gets good: not all of the brake fluid in the system is subjected to the extreme high heat found in the calipers and wheel cylinders so the highly dispersed moisture has little effect on brake pressure because of steaming and compression. Now, in a DOT 5 system, any collected moisture eventually makes it way to the lowest points in the system, being that it is heavier and can't be absorbed and dispersed. So, what's the lowest/furthest points? The wheel cylinders and calipers, of course! Now you have a high concentration of moisture exactly where it will be exposed to the highest heat in the system and create the largest problem. DUH! What about race cars, you say? Well, they only get driven about 500 miles before they get new fluid and generally are chucked at the end of the season, so moisture in the fluid isn't an issue.

[oab_au]

Frozen calliper slides will produce inadequate braking, with a longer pedal travel. If the slides are stuck or frozen, the whole calliper frame will flex, to bring the outside pad to the disk, instead of the frame sliding across to the disk.

Harvey.

[Beav]

Yeah, what he said! ^^^

Or, both caliper slides freeze and the outer pad does no work at all.

[oab_au]

Originally Posted by Beav

Yeah, what he said! ^^^

Or, both caliper slides freeze and the outer pad does no work at all.

Yes there are a lot of good points, to opposed piston callipers.

Harvey.

[AFBeefcake]

I have soft brakes too. I have ss brake lines, KVR rotors and pads. Tonight I flushed the whole brake system. I ran about 2 quarts of fluid thought the system. Pedal is still soft. With the car off the pedal is nice and firm, but once I start the car the pedal becomes real soft until its almost at the floor.

Any one have any ideas I on what might be my problem?

[Earthworm]

Originally Posted by AFBeefcake

Any one have any ideas on what might be my problem?

I have the same carbon fibre pads. Try a few really hard stops and the brakes will work like they should. They only like to work well when hot.

They don't seem like an everyday brake pad.