A while back I bled my old fluid out and put in some fresh DOT 4 brake fluid.

Is that OK, since the cap on my reservoir says to use DOT3?

I noticed my MC reservoir leaking after an autocross event, but I think it had leakage problems before because I could see where the fluid had trickled down the side.

 

what is the difference in the two?

 

As far as I know and don't hold me too it: DOT 4 has higher boiling point and is thinner viscosity than DOT 3. DOT 3 is more "oil" based and DOT 4 is a more corrosive fluid (like hydraulic fluid (jack oil) vs ATF). I have heard if you use DOT 4 in a system designed for DOT 3 you can possibly damage seals. Is this like using GL5 (lack of Zinc additive) oil in a tranny that is ment for GL4? I'm not sure, but if Mazda recomended DOT 3 and hasn't released any service bulletins stating DOT 4 is safe, I'd stick with DOT 3...

Most importantly: Have you noticed if your brakes feel "mushy" or your brake lines more flexible? Any unusal leaks besides at the M/C? If it starts seeping from all over and your brakes feel mushy I'd change it ASAP. I'm waiting to change mine when I get some new SS lines...

 

They feel very stiff (minus the damn M/C leak), and I didnt notice any leakage when I did my pads.
Which the fluid had been in for about 1500 miles.

Yes, DOT 4 has a higher boiling point, which yields more performance.
But the TII braking system is so elaborate to begin with I might just be hurting myself with the DOT 4.

Well, when I change the M/C I'll swtich back to DOT 3.

 

I have the simular braking system (GXL) and I've noticed mine is a little mushy. I'm not sure if the previous owner used DOT 3 or 4, I used 3 when I changed my pads. I bled my brakes very well and used clear tube to see the bubbles and make sure I had steady fluid (no bubbles). I think power brake bleeders cause more harm then good. I've never had them work right.

 

Just use Ford DOT 3 brake fluid. It has the highest boiling point of any DOT 3 or 4 brake fluid (about 550 degrees I believe). One guy I know uses it in his BMW 2002 race car and he swears by it. I've got it in my car now and there are no problems with it. You can get it at any auto supply store. Check it out and see for yourself!

 

anything water soluable is fine. Higher the rating the better .

 

What alot of people dont take into account is that brake fluid absorbs water over time, I believe that sythetics like dot 4 and 5 dont absorb as much water as well as having the higher boiling point. Any of the dot 4 and 5 bottles I looked at say that they meet dot 3 specifications and it works just fine in my 7.

 

on the subject of breaks, does anyone know where I can pick up a pair of stainless steel braided lines? for a 88se

 

http://www.howstuffworks.com/question451.htm

http://www.shotimes.com/SHO3brakefluid.html

 

Check out this website.
http://www.k2rd.com/Online_Catalog/StainlessLines.htm

Keep in mind. If you have a vigerous state inspection they might ask if your upgrade is DOT approved. You would have to show that or not pass. Here are DOT approved lines.

http://www.rx7.com/cgi-local/2catalog.cgi?cat=1&part=5


I do not know the difference between DOT and non DOT.
However, on the rx7.com website they said the lines have a removable protective covering. I believe that maybe the reason.

James

 

I believe the owner's manual says to use DOT 3 or 4 brake fluid. Hopefully you have nothing to worry about.

 

Use DOT3 or DOT 4 that is approved in DOT 3 systems, should say on the bottle, but DO NOT USE DOT5 SILICONE FLUID!! It's used mainly for classics and other non-driven vehicles for mostly storage purposes. If you do use it, you'll notice a much more squishy pedal feel because it compresses. Trust me on this, I know.

 

Oh, stupid me. I remembered that the bottle of DOT 4 I bought said it's safe for systems requiring DOT 3 fluid.

Too bad I just put in fresh DOT 3, damn.

Yes that is true, I used Ford DOT 3 in my old Honda.
The reason it's better because Ford has such shitty brakes that it needs really good fluid to compensate. LOL!

 

the higher the number the newer it is.... when the car was made dot 3 was the newest. that is why it says dot 3. since then dot 4, dot 5, and dot 5.1 have been made. dot 5 is %100 different and in no way can be used. but 3, 4, and 5.1 are all interchangable.

 

Ford Spec Dot 3 is great stuff (I can attest that it is incredible under race conditions) but it has to be changed substantially more frequently then other stuff.

 

Dot 4 is good for s/s lines it has the same boling point as dot 5 but doesnt eat rubber bushings