Powerstop rotors and DOT 4 fluid?

[loudawg]

Hi all. I got some Powerstop slotted/cross drilled rotors with Axxis pads a couple of weeks ago, and I love them. However, I noticed that I can't even lock up my wheels anymore if I tried. I'm afraid that I may not be getting the full braking capacity out of my system, and in an emergency situation, that might be BAD! Powerstop recommends you use DOT 4 brake fluid, and I'm not sure what my 98 Eclipse GS came with, but I would think probably DOT 3. Is DOT 4 really that much better? I'm assuming it's just more dense, reducing the "sloppiness" or "mushiness" in the braking, and putting more force on the brakes before the pedal hits the floor. Also, I heard there is a DOT 5 fluid out. The cap says DOT3 or DOT4.

So my first question is. Does my car already come with DOT4, and if not, is there enough of a difference to make it worth flushing my system with it?

Second. If there is a big difference, could I use DOT 5 although it recommends only DOT 3 or 4? Thanks for any help and suggestions.

~Lou

 

[99redgst]

Dot 5 is a silicone based fluid and would require a complete flush of the system, it is usally not reccomened to use it unless specified. As you go up from dot 3, dot 4, ect. the boiling point of the fluid rise making the brakes less prone to brake fade. I wouldn't expect a world of difference but there should be a noticable difference.

 

[99redgst]

By the way your car has Dot 3 from the factory.

 

[loudawg]

I don't believe I have any fading problems. The problem right now is that I can completely floor the brake pedal, either instantly or gradually, and I can't lock up the wheels. There is plenty of fluid in there so it's not like it's running out or anything LoL. So would putting DOT4 in possibly enable me to get more force out of the brakes before the pedal hits the floor? It seems to me the problem is that there's either too much compression of the fluid (which of course is very little), there's too much play in the lines, or there's not enough travel in the pedal, so I"m not getting the full braking capacity out of the system.

~Lou

 

[99redgst]

Well I'd have to say you have a problem, sounds like air in the system. Do you bleed the brakes after the install? Although if you never removed the line somewhere or opened the bleeder screw, air should not have entered. As for a leak, it would have to be pretty small, or you would lose fluid quickly. Keep an eye on you fluid level, If it doesn't go down any in a few days I would rule out a leak. Contaminated brake fluid can cause a sloppy feel, did you know it is reccomened to flush you system every year or two, who really does this? Changing the fluid wouldn't hurt, If you have the money(not like DOT 4 is that expensive) and the time(and a willing helper) go ahead and do it. This would also get rid of any air in the system. If that didn't work, I would start looking for a leaking caliper or something.

 

[loudawg]

Great, I'll definitely flush it then soon. I need to do an oil change anyways, so I'll just do it all at once. Thanks for your help!

~Lou

 

[Omega]

Don't run DOT 5. As mentioned it is silicon based. It is TERRIBLY hydroscopic and requires regular flushing.

There isn't too much of a difference between 3 & 4. I would check other parts. Did you replace the pads? If so, they might not be bedded completely yet. You could also have dying flex lines.