15 replies to this topic

[BlueJay73]

Just flushed the brakes in the '99 I am building. Used ATE Gold, which is a  DOT 4 fluid.

After finished, noticed on the master cylinder cap to use DOT 3 fluid.

Any thoughts?

Should I re-flush with DOT 3?

Thanks,

Jim

 

[Jeff Wasilko]

That should be fine. It's DOT 5 you don't want to use.

[Steve Scheifler]

My recommendation would be to save a lot of money and run the Valvoline "synthetic" stuff available everywhere and cheap. At least in our 1.6s there is zero problem with boiling even less than fresh fluid, and even at a track that absolutely melts down a set of Carbotechs. If you keep the cap on it will last a bunch of weekends with just an occasional bleed, and if you insist on pointless frequent flushes anyway it will save you a bunch of $$.

Opinions to the contrary always welcome.

[BlueJay73]

Thanks for the info. I Googled DOT 3 vs DOT 4 and everybody pretty much says they're interchangeable except that 4 has a higher boiling point than 3.

Thanks for the heads-up on the Valvoline synthetic "stuff." I'll check it out.

Funny, you're not afraid of stirring the waters up with that "pointless frequent flushes" comment!

I've seen 20 page threads on the necessity, or lack of, for bleeds/flushes in a track car--after every event, every other event, SRF once a season... .

I wouldn't be surprised if this touches one off.

[Jeff Wasilko]

I use wilwood 570 and bleed occasionally throughout the season (a season's usually 25-40 days for me). Usually once at the start after the car sat for the winter and a few more time between then and November.

 

I like the wilwood since it comes in 12 oz bottles, which is basically the size of the reservoir. It's cheap (about $6 a bottle shipped from ebay).

[Tom Hampton]

I've used Castrol LMA for years without any issues---based on Dave W's book.  Its cheap, and it works.  In 5 years of using it, I've never had *any* brake fade, or other evidence of fluid failure.  I flush the system at the beginning of the year, and run a bottle through the system (including the clutch) every event or two as part of my pre-event preparation.  Even that might be excessive---but, my annual brake fluid expense is below the financial noise floor, so I can't see the point in trying to optomize it further. 

 

I'm pretty light on the brakes, maybe that will change somewhat as I move up in the pack.  But, so far this season that has not been the case (despite dropping several seconds per lap).  Then again, only one of the tracks that I frequent has multiple threshold braking zones from 4th to 2nd gear (Eagles Canyon)---I always run a bottle through the system before this track.  More often then not, I seem to be trying to find ways to brake less in the effort to go faster.

[SaulSpeedwell]

My recommendation would be to save a lot of money and run the Valvoline "synthetic" stuff available everywhere and cheap. At least in our 1.6s there is zero problem with boiling even less than fresh fluid, and even at a track that absolutely melts down a set of Carbotechs. If you keep the cap on it will last a bunch of weekends with just an occasional bleed, and if you insist on pointless frequent flushes anyway it will save you a bunch of $$.

Opinions to the contrary always welcome.

 

Agree.  Castrol DOT4 (formerly known as LMA) and Valvoline "synthetic" and good ole Ford Heavy Duty DOT3 are all fine.  I've never "boiled" fluid in one of these cars. 

[SaulSpeedwell]

Just flushed the brakes in the '99 I am building. Used ATE Gold, which is a  DOT 4 fluid.

After finished, noticed on the master cylinder cap to use DOT 3 fluid.

Any thoughts?

Should I re-flush with DOT 3?

Thanks,

Jim

 

 

ANECDOTAL:  I used ATE Blue and Amber (TYP 200) for years with zero problems in the brakes.  I like switching from blue to amber to know when I can stop bleeding.  BUT ...  I have failed more clutch slave cylinders than anyone I know, and the ATE fluids turned my MityVac lines into glass. 

 

I started putting cheap DOT3 in the clutch hydraulic, and my failures stopped. 

[Jeff Wasilko]

Audi folks generally hate the ATE fluids in clutches as well.

[Killian]

I've read a few folks say that if you use part of a bottle of fluid, to discard the rest after a month, as it's absorbed too much water (hygroscopic).  Wouldn't I then have to fully flush my system after a month, because it too has absorbed too much water?  How is my brake system sealed better than an air tight container? 

[Steve Scheifler]

It isn't unless the person who told you that doesn't put the cap back on the bottle. I'll admit to discarding a partial bottle if it's been many months or opened many times, but more often I demote it to clutch-only use and discard the last one I labeled that way.

[SaulSpeedwell]

It isn't unless the person who told you that doesn't put the cap back on the bottle. I'll admit to discarding a partial bottle if it's been many months or opened many times, but more often I demote it to clutch-only use and discard the last one I labeled that way.

 

Thus the reason everyone should ignore the brake fluid "dry" boiling point spec unless you are bleeding every session or week and throwing fluid away.  Because the other 98% of us are ALWAYS at the "wet" boiling point.

[davew]

We have Blackhawk in our back yard. It is the hardest track in the country on brakes. Right Kyle and Mike? We bleed a couple squirts every night at the track and run a bottle during our in shop reprep. I use exclusively Castrol LMA in our SM's. LMA stands for "Low Moisture Absorbing" and is now refered to as Castrol GT.

 

We use the quart bottles, because of the quantity we go through. If you use the pint bottles, just finish the bottle every use. I was taught to label the date the bottle was opened and discard for race use after a month.

 

I was also taught to use the same fluid in the brakes as you use in the clutch. No chance to mix up the fluids this way. Remember some fluids are not compatable with each other, and should not be mixed.

 

dave

[Ron Alan]

So if you neglect the brakes and rarely bleed(change)and keep dumping out of the same bottle for 4 years...what is likely to happen?

[wheel]

At the very least, you will have a sponge for a pedal, when they get hot.

[Steve Scheifler]

Few people have more experience with these cars than Dave so you can't go too far wrong giving his advice some weight. But Dave, we are probably of the same generation and even IF what we were taught way back when was gospel, a lot of things have changed. I could probably spend over $100/weekend on brake fluid and then report the typical "no problems" that I hear from people who habitually overkill, but what does that mean? Tossing out a tightly sealed bottle of GTX after a month is just silly. If it sat open for too long on a humid day then toss it now, otherwise it is 99% as good as it was a month ago and better than what's in the car. Or better yet, switch to something that is plenty good enough, cheap, and available everywhere. If you race somewhere it isn't good enough, do a full flush for that place, and only then consider expensive fluid that's not readily available.

Bleeding a bit each event to move fresher fluid to the caliper is not a bad idea, but overdoing it can have risks as well. How many times do you loosen and tighten a bleeder before making a mistake and over or under tighten it, or introduce air by accident, or whatever? Each time you pop the cap off to do that you also let more moisture in. Can you determine that trade-off?

There are countless things we *could* do every weekend, or even every session, but we don't because it isn't necessary and isn't without risk. We could also spend as much as our wallet will tolerate on lots of "better" products that don't have any real benefit "just be be safe", but is recommending that really a help to the budget racer? I do a lot of things just because I can, but I generally know which ones are likely pointless and don't necessarily recommend them.