Brake fluid puking out of master cylinder on track

[93cobra]

Hi guys, finally went out yesterday on track with my car. It wasn't a very hot day, but after each session I had to clean brake fluid from the apron and from the reservoir. I have always had this issue since the car was new, and I believe it's been discussed before about the master cylinder being overfilled from the factory. I have had it happen on the street, and changed the cap, but since I lowered the fluid level 1/4" below max I have not experienced it on the street. There was another boss at the event and he did not experience this, but he recently had his brake fluid changed to dot 4. Is it possible my master cylinder reservoir is bad, or is the fluid really getting that hot? Thanks

 

[F.D. Sako]

This is a common problem. I fill mine just a tad over the min mark, and haven't really had any issues with leaks since, just the usual "sweating".
Also, as a precaution, put a wristband on the cap, or wrap a towel around the reservoir to prevent any drips onto the paint.

 

[Tucson 302]

If you are running DOT 3 fluid it will boil and leak on track switch to DOT 4

 

[93cobra]

Thanks for the help. Any concern with cloth in the engine compartment? It gets hot under there!

 

[ArizonaBOSS]

Thanks for the help. Any concern with cloth in the engine compartment? It gets hot under there!

Wristband or piece of elastic from a sock will be just fine snugged up on the cap. Other option is a shop towel and a zip tie lol

 

[06mach1]

shop towel and a zip tie works for me too

 

[JScheier]

shop towel and a zip tie works for me too

Ditto

 

[Grant 302]

shop towel and a zip tie works for me too

Me too. Just as a precaution.

Switch to DOT4 if you haven't already. Ditto on brake cooling ducts.

 

[93cobra]

What level do you keep the fluid at in relation to the full line?

 

[JScheier]

I run 1/2 way between Min and Max on the reservoir.

As an FYI (and you probably already know this)... make sure to thoroughly flush / clean any area where brake fluid contacts your paint. I've now got a bald spot on my frame rail from Ford's overfilled reservoir from the factory.

 

[93cobra]

I brought paper towels and simple green with me as I was afraid it was going to occur!

 

[steveespo]

This is a normal track issue. I use window cleaner after each session to clean. I had a Brembo wrist band on there but it got soaked and I didn't put it back on. Gonna get another. Not much to do about it.
Steve

 

[blacksheep-1]

We use AP 600, it's cheap, it works and we don't have a big problem with the expansion thing in the master cylinder. We also use some pretty massive cooling ducts and try not to let the brakes heat soak, if we know we are going to be parked awhile (like during a red flag) we'll move the car up a couple of feet every minute or so.

 

[VTBoss302]

As mentioned, this is a very common track issue

Lowering the level of fluid helps, but does not eliminate the problem

 

[VTBoss302]

We use AP 600, it's cheap, it works and we don't have a big problem with the expansion thing in the master cylinder. We also use some pretty massive cooling ducts and try not to let the brakes heat soak, if we know we are going to be parked awhile (like during a red flag) we'll move the car up a couple of feet every minute or so.

The race cars use a different brake booster with a larger fluid reservoir which probably helps

EDIT - link to FRPP brake booster

http://fordracingparts.com/parts/part_details.asp?PartKeyField=8112

 

[GB899]

Dot 4 brake fluid helps a lot... I still use a sweat sock and zip tie just in case..

 

[blacksheep-1]

The race cars use a different brake booster with a larger fluid reservoir which probably helps

EDIT - link to FRPP brake booster

http://fordracingparts.com/parts/part_details.asp?PartKeyField=8112

That may be true I only see the racing aspect of it, same with clutches, we prefer a single disc which accommodates our trans but not what most of you are running.