Brake Fluid for Racing

[ecoangel]

What is the best for Fulvia racing? DOT 4 currently in the car seems to get rather hot. The CSCC racers tend to use AP551 (not silicone based) which also works on road cars. See: http://www.apracing.com/car/brakefluid/index.htm

Thanks

[Tim Heath]

Whats wrong with silicone - it doesnt absorb water therefore much less likely to boil and fade????

Tim

[Huib]

Brake fluid is hygroscopic for good reason. Water molecules are dispersed and cannot freeze. In silicone fluid the watermolecules form drops which can freeze.

Slicone fluid absorbs air and becomes compressable. As a result the pedal becomes soft.

[P. de R. Leclercq]

Yes Silicone fluid is reputed to give an inferior pedal - hardly what one wants racing.

I recommend Castrol SRF: it was the best tweak for the Evos on track days (owners always complained about pedal problems) - and I well recall my old SII Fulvia having an extremely long pedal after a track day - so I imagine racing would be more demanding.

The beauty of SRF is that it is not one of these fluids that must be put in the system five minutes before the race and then drained afterwards. It is good for about a year so they tell me.

Paul

[Ed Levin]

Castrol's product data sheet lists an 18-month max. service life for SRF

[P. de R. Leclercq]

Well even better, but it is always wise to be conservative with brake fluid.

Paul

[Tim Heath]

I've run fulvias with silicone for 5 years without changing and pedal is not soft at all, includinging mild rounds at Goodwood, Prescott, and a bit of gentle rallying. I like a firm pedal and certainly one with feel and not a lot of travel so am suprised by these comments. Maybe I am not trying hard enough as the racing fluids do have a higher boiling point. Fulvias are well served in the braking department if properly maintained so should not be over heated as a rule. If you dont have stainless brake cylinders ordinary brake fluid does not inhibit rust unlike silicone which is good for long term low use classics. All to his/her own I guess.

[1600hf]

Good news, ecoangel: You are going fast then! Go for the suggested fluid from Paul, but watch out with the next effect: Fulvia Girling brakes are extremely good if you ask me (better for instance than the fiat stuff i have to live with on my 131 abarths right now). But if you start using them hard, make sure you do your cool down lap always: I have wrapped 5 sets of rather expensive front discs on the Fulvia's.

[P. de R. Leclercq]

Yes, cooling down is important.

A SII front caliper weighs (with pads) 4.9kg. That's a lot of cast iron which takes time to lose its heat.

Years ago I found that after a track day (ALWAYS with new fluid) the drive to the pub afterwards was done with the pedal half-way to the floor.

However after a pint or three it was fully recovered (like me).

Paul

[ecoangel]

Thanks for all the comments.

Looks like SRF if affordable or AP551 for me.

The issue I was having was the fluid not returning from the front calipers to resevoir - so trapped fluid got hot, expanded and pushed pistons on so as to lock front wheels.

I have now shortened the rod going from the brake pedal to master cylinder and hope this does the trick!