Overheated brakes?, Ever actually done this? Options

[lapuwali]

With all of the recent caliper discussions, I got to thinking: has anyone here actually suffered from stock rotors overheating? Street or track? Which calipers? Which MC?

I've personally only ever suffered from brake fade caused by overheating brakes twice, and neither time was in a 914. Once on a Alfa with inboard rear brakes and an overenthusiatic romp along a road with lots of downhill hairpins, the other time on a Mini with drums all round, also on a romp through a (different) set of downhill hairpins. The Alfa was heavy and suffered from bad cooling of those inboard brakes (which had vented rotors), and the Mini just used cheap iron drums (and I was deliberately trying to induce fade). Interestingly, another very similar Alfa that was much lighter (400lbs or so, from lighter body stampings and a four instead of a six) never suffered from fade despite solid rotors at both ends, on the same roads that would cook the brakes on the later, heavier car.

Much as I approve of the idea of good strong brakes, I wonder just how necessary big, heavy, expensive vented rotors really are on the car (at least with stock or near-stock power).

[Mueller]

QUOTE (lapuwali @ Feb 24 2005, 11:44 AM)

With all of the recent caliper discussions, I got to thinking: has anyone here actually suffered from stock rotors overheating? Street or track? Which calipers? Which MC? I've personally only ever suffered from brake fade caused by overheating brakes twice, and neither time was in a 914. Once on a Alfa with inboard rear brakes and an overenthusiatic romp along a road with lots of downhill hairpins, the other time on a Mini with drums all round, also on a romp through a (different) set of downhill hairpins. The Alfa was heavy and suffered from bad cooling of those inboard brakes (which had vented rotors), and the Mini just used cheap iron drums (and I was deliberately trying to induce fade). Interestingly, another very similar Alfa that was much lighter (400lbs or so, from lighter body stampings and a four instead of a six) never suffered from fade despite solid rotors at both ends, on the same roads that would cook the brakes on the later, heavier car. Much as I approve of the idea of good strong brakes, I wonder just how necessary big, heavy, expensive vented rotors really are on the car (at least with stock or near-stock power).

never on my 914.........

a few times with our S70 T5 Volvo, I've lost the brakes complelty from overheating...ran thru a stop sign once and the other time I missed the driveway going into the parking lot at work.......put in new fluid in and it solved the problem until I took the car to Thunderhill and beat on it for an afternoon...needed new fluid after that days event...


Butch and I put 300 miles on his 914 @ ThunderHill
Racetrack in one day....we switched drivers every 30 minutes or so.....we had the track to ourselves so no traffic and we ran the car hard...no signs of brake problems.........

[mudfoot76]

Yes, on my 914, during two different DE events at Putnam Park. Both days were very warm. I have 911M Calipers on the front w/solid rotors, stock rears, 19mm master cyl, DOT 4 fluid. The first time was during my first DE. I had heard about brake fade but never experienced until going into turn 7 rather fast, press the pedal and it goes to the floor. In my rookiness, I end up trying to make the turn anyways, and end up spinning....

The second time during a different DE, same track, was after putting new Hawk pads all the way around. I notice the fade before it gets too bad and I can allow things to cool some without getting into any trouble.

[SirAndy]

QUOTE (lapuwali @ Feb 24 2005, 10:44 AM)

I wonder just how necessary big, heavy, expensive vented rotors really are on the car (at least with stock or near-stock power)

the stock brakes (in good working order) are plenty for a stock car ...

having said that, the difference between my stock brakes and now '86 carrera calipers and vented rotors on all 4 corners is like night and day. the car now stops on a dime, anytime, anywhere.

i like it ...
(IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif) Andy

[VegasRacer]

I am hard on brakes with my driving style. I frequently had brake fade on my 4 cyl. race car when it still had the stock calipers. When I did the 5 lug conversion and put an entire Carrera front end on the car, the brake problems went away.

On a previous RX7 race car I also had brake fade problems late in a race. It was a spec class so I couldn't change the calipers. Just adding some dryer hose for cooling ducts solved the problem.

[airsix]

QUOTE (lapuwali @ Feb 24 2005, 10:44 AM)

With all of the recent caliper discussions, I got to thinking: has anyone here actually suffered from stock rotors overheating? Street or track? Which calipers? Which MC?

I've experienced brake fade with stock 914 brakes on both street and track. These were completely stock brakes with good pads, fresh fluid, and freshly bled.
On the track I was running an autocross with a 1.4 mile course with multiple 70mph sections. There were three sections of accelerating to about 70 followed by braking to about 5-10mph one right after another literally back to back. At the end of the third-in-a-row braking section there was very noticable fade.
On the street I was trying to chase down a 911RS (turned out to be a clone). Braking from about 110mph for a 20mph left turn the brakes went away at about 35mph. To this day my seat cussion is still gripped tightly between my buttox.
Both occassions were on very hot days (close to 100 F) and driving on very sticky tires. Right before the brakes went while chasing that 911 I remember feeling smug at my braking prowess because the fronts were starting to chirp and smoke, but were not locked - it was the perfect threshhold braking, and then suddenly there were no brakes, I had both feet on the pedal and I was flying into a corner 40% faster than I had intended. I kept it out of the ditch and went on to install 19mm MC, Tilton bias valve, and vented 911 A's on all four corners. I've tried repeated at-the-limit braking from 120mph* to see if they will fade and they don't.

-Ben M.

*post-turbo

[seanery]

I did on the track, but I was on god-who-knows-how-old brake fluid. I figure with some good fresh fluid no problems. (IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif)

[redshift]

Ok, in my 23 years I have lost brakes maybe... 7 or 8 times, at least twice coming south out of Asheville on 40.

This piece of shit I have now lost the brakes once, but I REPLACED MOST OF THE BRAKING SYSTEM TO THE TUNE OF AROUND $1800 AND NOW THEY WORK BETTER THAN WHEN OTTO SCREWED ME.


M

[davep]

Stock brakes on my 73 1.7 at Watkins Glen. Came off the track and went down into town. It feels like a 1000 foot drop, but may be about half of that. Almost continuous braking going down, and you DON'T want to have your brakes go out. Next year with an "S" front end there was never any problem.

[Demick]

I've had serious brake fade from driving down the back side of Mt. Hamilton Drive coming down from Mt. Hamilton Observatory. That's the only time. Never autocrossing, and never at the track.

Demick

[ArtechnikA]

saw the evidence once (cracked rotors) in my '72 1,7

the ex had been driving it.

"the car's really down on power and the back brakes smell bad."

"...did we forget to release the parking brake again ? " (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif)

[Eric_Shea]

QUOTE

the car now stops on a dime, anytime, anywhere

Andy... I hate to be the one to tell you this but (everyone is talking behind your back) nobody cares about your brakes. They are however, extremely concerned about my "browser issue". Right gang!?! (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

(come on... play along, help a browser challenged brotha out here)

On subject. Never in a stock car with stock brakes. I agree with Andy (you'll get your "Sir" title back when you beat the shit out of a few ISP guys and get my browsers working again), stock brakes are plenty and then some for a stock car.

[Eric_Shea]

James,

Did you get the goods today?

[Mueller]

one thing to consider is that some people have been installing larger tires and rims that more than likely weigh more than the stock setup...a heavier assembly will have more energy and be harder to slow down and can lead the braking system to work harder.........

[Eric_Shea]

Sure... but what about my browser? (IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif)

[lapuwali]

QUOTE (Eric_Shea @ Feb 24 2005, 12:18 PM)

James, Did you get the goods today?

Ooh, ooh. Did they ship? I'll find out when I get home...

Now I just have to get some new e-brake cables and I'll have 100% working brakes again...

[redshift]

I am also worried with Eric's browser problems.

Eric, PM me if there is anything I can do.


M

[BigD9146gt]

I've boiled mine on several occasions. The worst was the same as Sammy stated, Streets of Willow short track events. At the motel later that night (9pm-11pm (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) ), i had my 914 up on jack stands to remove the back brake sheilds and bleed everything again. I had fresh super blue in there, and still over heated them. My best time was a 1:30.1, 2L webers rivieras and 195 60R15 bridgestone with a 300 rating compound.

In a lot of cases, if the fluid boils, one can blame it on inexperiance and too much braking. But keep in mind that the front hubs and rotors are one cast peice, and steel retains heat way more than aluminum... which is one reason why the 911 hubs are aluminum. Plus being a solid rotor is a killer, the last 911 to have a solid rotor on the front was the '68, and everything up to '68 in the rear with the exeption of the 911T and 912 in '69 had solid rears. After that, vented took over.

[lapuwali]

So, it appears that "yes, it can be a problem on the track" is true; and "no, it's not really a problem on the street" is also true, which is more or less what I expected.

I find it interesting that Sammy managed to overheat even vented rotors, though. Style plays a role, here, as does the nature of the track (The Streets are pretty short, and that's a pretty heavy punishment). I've not been to Thunderhill since they opened the whole back half of the track (I did a track day there on the front half after they'd been open for a few weeks), so I can't comment on how hard that track would be on brakes. Perhaps Mike and his friend are easy on brakes. Perhaps the track is. Hard to say.

[TimT]

Ive cooked the brakes on my 914 a few time also. Currently the rotors are vented/drilled/slotted, pads are hawk blue, fluid is Ate blue. Hauling the car down from 140 or so repeatedly did it.

Ive since cured this by ducting more air to the brakes.

I fall into the "its a problem on the track" since I only drive this car on the track (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)