Brake fluid question

[donyas]

2024 Integra A-spec w/tech, cvt. I did a track night at Sebring. It was my first, so I was not running hard to become better acquainted with the car and track. The second 20 min. session (out of 3) and my brake warning light came on(with a spongy brake pedal feel). It reset before the third session and reset before my ride home.
Shortly after the track night I had an oil change at the dealer and had a brake fluid flush with a change from dot3 to dot4 fluid done at the same time. Another track night experience a month later saw the same results with the brake light and subsequent reset. Drove home with no problems.

My question is has anyone used dot5.1 brake fluid in their integra and do you think with the higher boiling point it would stop the brake light (and spongy pedal that goes with it) from occurring?

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[slowcountry]

2024 Integra A-spec w/tech, cvt. I did a track night at Sebring. It was my first, so I was not running hard to become better acquainted with the car and track. The second 20 min. session (out of 3) and my brake warning light came on(with a spongy brake pedal feel). It reset before the third session and reset before my ride home.
My question is has anyone used dot5.1 brake fluid in their integra and do you think with the higher boiling point it would stop the brake light (and spongy pedal that goes with it) from occurring?

Interesting... I havent had that issue yet in the CVT, but I haven't tracked the car yet either. Curious - do you have oem rotors & pads? Also, did you track it in S drive mode or regular D?

I have new calipers, pads, and slotted & drilled rotors that i need to install. The calipers came with Stainless Steel brake lines to replace OEM, and I'll be using Motul 660.

 

[Gregg]

A higher boiling point is definitely what you are looking for and going to DOT 5.1 is not a necessary step. There are many DOT 4 fluids that are more than suitable for track day use, such as Motul RBF 600 and 660 (RBF 700 is likely overkill for what you're doing) or ATE Gold 200.

It's going to be very important to keep a keen eye on brake pad life as well. The OEM pads really are not meant for the track. In addition, the car's stability control uses the rear brakes heavily for attitude control. As someone who is on-track for the first time that's a good safety net to have, but as you continue to progress, you'll want to learned the "pedal dance" to fully deactivate traction & stability control. It will serve you well and assist in not (unknowingly) using the brakes.

And when the time comes to go with a more aggressive pad that is also more resistant to fade, I sugges that you call my friends at G-LOC brakes. They can set you up with the best compounds for your current skill level.

 

[Spart]

Whatever DOT 4 they put in at the dealership is not necessarily representative of all DOT 4, and DOT 5.1 is not necessarily better than all DOT 4 fluids. In general, fluids meant for racing will be DOT 4, not DOT 5.1.

DOT 5.1 fluids are about more than just boiling point. The DOT 5.1 spec also covers longevity and viscosity, and fluids meant for racing typically are meant to be flushed more often and will not meet the DOT 5.1 spec even if they easily exceed the DOT 5.1 wet and dry boiling point numbers.

That being said, if you're going to track your car regularly I'd highly advise switching to an actual racing brake fluid of some kind and Castrol SRF has been my go-to for years. At first you may get sticker shock from this ($70ish per liter) but realize that your brakes are keeping you from flying off track and it's really cheap insurance to go with the best fluid available. Also, the wet boiling point of SRF is as good as the dry boiling point of Motul DOT 5.1, even though SRF is listed as a DOT 4.

Get your own power bleeder and DIY. The minimum change interval on SRF is 18 months, and if you track the car a bunch you'll want to do it more often. Relying on the dealer to do this may cause you issues, because they may not be as thorough.

Consider a pad change as well, because once the fluid is able to handle higher temps the next thing to give up will be the OEM pads.

 

[ashmostro]

Agree with the above. SRF and proper track pads will solve this.

 

[Spart]

There are many DOT 4 fluids that are more than suitable for track day use, such as Motul RBF 600 and 660 (RBF 700 is likely overkill for what you're doing) or ATE Gold 200.

These are good fluids as well.

Castrol SRF's trick is it's unusually high wet boiling point. While you may want to change a fluid like RBF 600 or 660 every 2-3 track days, you can stretch SRF much longer.

That factors into your consumable expenses as well as your time investment.

I accidentally went two years without flushing SRF once in my GT350 and it did not hamper me on track at all.

 

[ashmostro]

Exactly. While some harp on other brands' higher dry boiling point, I feel that only matters for race cars that get all their fluids swapped out after each weekend. For a street car, there's nothing more effective than SRF due to its wet bp. You just don't need to worry about it as a variable.

 

[donyas]

Thanks to all for the great feedback! I'm still on the factory original pads and rotors. I tracked it in S mode on the CVT and of course in the Sport setting for the rest. I'm out of the free dealer maintenance and although I do some DIY, I'm going to look for a good Indie shop. Going forward I will be doing more track days because they're so much fun but the car is still my DD. I'll probably address the fluid, pads and rotors in that order, but within reason for my limited track use.

Thanks once again for the feedback, I really appreciate all the considered recommendations!

 

[Victorofhavoc]

The "brake system" light is going to come on regardless of the fluid. There's a dtc code that gets thrown underneath and when you scan the car with an appropriate tool it will read "brake pad temperature too high"... Can confirm, it gets quite hot on track. I throw that light every single time on track, even with carbotech xp10/12 pads, titanium shims, and Rbf600 fluid. With this setup I never boil fluid, the pedal is always solid, and there is no effect on braking with the light on.


Now... Why acura has a brake pad temp sensor but not an oil temp sensor or coolant level sensor are questions to scratch your head over.

 

[Frenzal]

Also important to brake hard for a short time vs brake soft for a long time. If you did the second, you'll heat the brakes way more.

 

[donyas]

The "brake system" light is going to come on regardless of the fluid. There's a dtc code that gets thrown underneath and when you scan the car with an appropriate tool it will read "brake pad temperature too high"... Can confirm, it gets quite hot on track. I throw that light every single time on track, even with carbotech xp10/12 pads, titanium shims, and Rbf600 fluid. With this setup I never boil fluid, the pedal is always solid, and there is no effect on braking with the light on.


Now... Why acura has a brake pad temp sensor but not an oil temp sensor or coolant level sensor are questions to scratch your head over.

The light coming on doesn't concern me as much as knowing and understanding what is going on to cause it. Your explanation tells me if I address the fluid, pads and rotors properly, I will be OK and not really have to be concerned with the light

 

[creaturemachine]

You're one of a very few a-spec owners who might actually benefit from a big brake kit.

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