What brake fluid can I use with Wilwood brakes?

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Doosterfy

Doosterfy

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I have a complete Wilwwod brake system on my Duster. It's a Wilwood tandem master cylinder with wildwood discs with Wilwood four piston calipers on all four corners. I had a lot of issues with faulty brake line flairing when doing the install, and wet through quite a bit of Wilwood 570 brake fluid getting all the issues taken care of. Now I'm replacing the 1" bore master cylinder with a 7/8" bore one to get more stopping power. The problem with the Wilwood fluid is they only sell it in small little bottles and it's kinda pricey. I want to switch to a commonly available fluid I can buy at any auto parts store. I did a web search and I found one soured that says the Wilwood 570 is the same as DOT 3 brake fluid. It even says it can be mixed with it. Has anyone run DOT 3 with Wilwood brakes and did it work out? If not DOT 3, then what fluid? Remember I want to stick with fluid that's commonly available, thanks.
 
I think most would opt for the silicone fluid on an all new system (unless Willwood has some specific issue about it.)
 
I'd move up to Dot 5 myself , have used it in numerous cars over the last 20+ years with no problems at all
 
Even though the directions said not to with my wilwoods I ran dot 5. Never had any problem with them.
 
I'm having a problem with sticking caliper pistons on a truck that has DOT 5 (silicone) in it. Talked to a former brake engineer friend about it and he's heard of 5 not being compatible on occasion, even though it should be, and causing this type of problem. That truck is getting flushed of the 5 and I'll go back with DOT 4 or 5.1 (non-silicone).

Pretty much any non-silicone brake fluid will be compatible with the wilwood juice, but you may lower the boiling point. I'm partial to Castrol LMA.

Recall that non-silicone fluid will absorb moisture, silicone won't. Buying the large bottles of brake fluid is good for flushing a system, but don't leave one opened and partly used on the shelf. It will absorb moisture out of the air. This is not good because the moisture reduces the boiling point.
 
Only if the system isn't flushed bi-annually like we all do, right?
 
I would simply use DOT3. No need to try and reinvent the wheel.
 
DOT 4 and DOT 5.1 have progressively higher boiling points than DOT 3. This may be important depending on the use and service schedule.
 
Yeah. I understand all that.
 
For my own stuff I prefer DOT 4 simply because of the higher initial boiling point. I figure that by the time I remember to flush & replace it that the accumulated moisture will have brought it down to DOT 3 or so. I see that as better than starting out with DOT 3's BP in this coastal climate. If I lived somewhere where the relative humidity never got above, as a guess, 30% I might do different.
 
Thanks everyone. I'm going with DOT 3. It's a street strip car and I don't do any driving that will heat up the brakes all that much. The Wilwood 570 is $10 for a 12 ounce bottle. I can picture Wilwood buying DOT 3 in bulk and marking up the little bottles to rake in the cash.
 
Having worked for wilwood in a R&D role I'm quite sure that is not the case. The "570" is the fresh out of the bottle boiling point. Aren't going to get anywhere close to that with plain old DOT 3 fluid.
 
I used to have all kinds of weird sticky brakes when I first got my car out in the spring. Flushed system and put DOT 5 in and have not had any problems since. That was at least 10 years ago. Another problem I had was when I was going 80 for an hour Came up on my exit faster than I expected and when I hit my brakes had none. Brake fluid had boiled from the heat of the headers. That has not happened since and now I autocross it.
 
RustyRatRod said:
Here's all the different boiling points. There is not one that boils at 570*.

http://en.wikipedia.org/wiki/Brake_fluid#Boiling_point
Click to expand...
Not in a DOT standard, no. In a custom formulation, yes. How long does it maintain that BP? Dunno, depends on ambient humidity and service conditions.
Castrol LMA is my own choice for brake fluid. http://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/0027D9455250B6C780257AA900537025/$File/Castrol_Brake_Fluid_DOT_4_03742.pdf

I'm going to purge the Bronco of it's silicone fluid. It has two seized calipers and all of the rest of the system is normal. There have been cases where silicone has caused seal swelling when it should have been compatible. Pending evidence to the contrary that is what I'm blaming this problem on.
 
What I'm getting at, is most people will never push the limits of DOT3. So for them there's no need to spend lots of money on something like DOT5. Plus there's always the risk of mixing fluids, which you cannot to with DOT5. People see all this stuff and go nuts thinkin they need it. I sure wish I could invent something like that and get rich. People will buy anything thinkin they need it when they really don't.
 
The thing is that the boiling point isn't a static, fixed number. I suspect that this isn't well understood. The advertised BP for any given fluid is only good at the moment that you unseal the bottle. It starts a steady degradation from that point. How fast the BP lowers depends on how much ambient moisture there is in the air. It's been demonstrated many times that an opened, but capped bottle of brake fluid sitting on the shelf will pick up moisture form the air and lose it's original boiling point. Depending on the conditions around it and how long it sits there the BP can be drastically lower.

I agree that not everyone needs the highest BP that they can find. Road racers and AutoX'ers probably do, but drag racers usually don't and you have to be a really aggressive street driver to get anywhere close to needing it. I can hear it now, "yeah but I've faded my brakes before on the street." How old was that fluid? And more importantly did you flush the system ASAP after the fading?

They could make a brake fluid that doesn't absorb moisture, silicone for example. The problem with such fluids in moist environments is that then the moisture is free to move around in the system and can be much harder to flush out. By adsorbing the moisture the fluid is easily replaced and that removes the moisture from the system. AFAIC silicone is for collector and show cars that sit around mush more than they are driven.
 
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