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loss of brakes after track event


spunout50

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Hi, I'm new to the Nasaforums so I probably should give a small introduction. I own a '86 Mustang GT convertible and live in Michigan. The car is slowly, but surely getting more prepared for road racing. I started attending open track events last year. I've retrofitted my car with cobra brakes all around and have done some suspension upgrades.

 

Last year I ran OEM brake pads. I knew they wouldn't be the best, but I didn't have the $$ for an upgrade. For this year I purchased some Cobalt friction road race pads. It was an amazing improvement at the track with these pads. The event went great and I drove home w/o any problems and parked the car. I went to take it for a spin on saturday and I had no brakes, the pedal went to the floor. I knew that I would need to bleed my brakes before another event, but I didn't expect this either. I flushed the fluid before the event and I use valvoline synthetic. It's got a relatively high dry boiling point for the price and avalability. I did bleed the brakes on sunday and everything seems to have returned to normal.

 

did I simply boil the brake fluid? If so, it appears I'll be moving to Motul or something similar. Is there something else it could be? There wasn't any fluid loss.

 

I tried performing some searches, but didn't pull up anything relevant.

 

Thanks,

Jeff

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It sure sounds like you boiled the fluid. I used a '99 Mustang GT in my first on-track event, with Carbotech Panther+ pads, on a track that's not easy on brakes (Carolina Motorsports Park, Kershaw, SC). I was concerned about boiling the fluid so I put Motul RBF 600 in it before the event and didn't have any trouble at all. At the same event, my brother boiled the factory stock fluid in his Focus ZX3, but not badly and only in one corner. The symptoms were the same, but not as serious.

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Another good fluid to consider is Ford's Heavy Duty Dot 3. I use that in my AI prepped 89 Mustang and have never had any boiling issues (or any brake issues for that matter... I'm running the complete Baer setup and Cobalt Fricton race pads.). Plus, given the chance you might need to add some, Dot 3 is readily available.

 

I was told that Ford developed this for their big cars (Lincolns, etc.) because a lot of the old people that were buying them had the tendency to ride their brakes and over-heating the brakes started becoming a problem. Check the boiling points on this fluid, you may be surprised. I know several racers who use it. Plus, even though I didn't really do any major price comparisons, I think it's pretty inexpensive. Anyway, just my .02 worth. Good luck.

 

Ed McGuire

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Thanks for the replies. I assumed it was the brake fluid, especially once I bled the brakes and everything was fine. I just didn't want to miss something. when I chose to use the Valvoline synthetic fluid, it showed a higher boiling point than the Ford heavy duty dot 3. What that means, I don't know. Maybe the reason I don't hear about too many people using Valvoline.

 

Hey Ed, do you run any brake cooling ducts?

 

I going to change to a different fluid, but I may have to think about some cooling. It was hot the day we ran, but I really didn't push the car the whole time. I'd rather build in a safety factor, rather than worry about it. Of course, it doesn't thrill me to spend the $$.

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Jeff,

 

Yes, I do have cooling ducts running to my front brakes. Sorry, forgot to mention that. They're not anything elaborate but hopefully they're doing some good.

 

As mentioned, I've pushed/used my brakes pretty hard at several tracks known to be hard on brakes (CMP being one of them...) with no problems. I'm not sure what HPDE level you're running but as you do more and more track events you learn to use your brakes more "strategically" which, hopefully, makes them last longer and work more efficiently. Just a thought...

 

Ed McGuire

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Ford HD is dirt cheap compared to anything else and has a 550* dry boiling point. Still running 11" front brakes on my Mustangs after 18 years (Baer kit finally coming), I haven't boiled the fluid since I was a novice with drum rear brakes (meaning none), and even then it was due to letting the inner pad get too thin. Fading pads is a different story, of course. The Valvoline has a better *wet* boiling point than the Ford fluid, not dry. I use the Valvoline in my street-only vehicles.

 

Another instructor has an '89 convertible street car with a full cage (heavy car) and the 2300K kit. Running PFZ front and stock rear pads he can quickly overheat the 17" tires from hard braking but hasn't seen a hint of pad fade, even on the stock front pads that came with the kit (though they wore out pretty fast). And even on that heavy car when he still had 11" fronts the Ford fluid never boiled. BTW, if the dust boots didn't melt on your front calipers then you're not even working those Cobra brakes yet.

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ATE Super Blue is an outstanding brake fluid. I've used it in my racecars for years. I always bleed my brakes after every event as a precaution, but there is never any air in the lines. ATE super blue is not DOT approved, but they also have a gold version that is identical and looks like any other DOT fluid.

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  • 3 weeks later...

Be sure to follow instructions in changing from syn to nonsyn and reverse. Some require COMPLETE flushing and cleaning of system before change of fluid.

 

I use the Ford stuff in my Camaro for HPDE with Carbotech pads with no problems.

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Synthetic brake fluid is NOT reccomended for track duty. It is paint friendly but NOT racer friendly. Ask the serious track guys, none use synthetic. Try Wilwood 550 or 600, ATE, Motul or if you got real deep pockets,Castrol SRF.

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I've switched to Motul. I think I found part of the source of my problem. I removed the MC and bench bled it. There was some trapped air. I did that just to see what was going on. I then flushed the system and switched to Motul. My brakes have much more response than they ever had. I can't wait to hit the track now

 

Thanks for the responses

 

Jeff

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