S197 Losing brakes during autocross

[Bill Pemberton]

Good deal, and there are so many little things that could have caused the issue ( some really far fetched), but the main situation is brakes going out at an Autocross is just not an occurrence that should ever happen.

Keep us posted.

 

[blacksheep-1]

just for fun, have you checked rotor runout? maybe a huge case of knockback, but I still think it's something else, again, if a roadracer with identical brakes to yours doesn't have fade issues, you shouldn't.

 

[drj2k1]

Quick update: had some time over the weekend to disassemble the brakes, install new brake lines, and flushed/bled the system with Motul RBF. Pads/rotors were in good shape all around as expected, they've only been on the car for a couple months of minor street usage and 21 autocross runs.

When removing the rear brake lines, the old fluid was still fairly fresh but once the I got to the front lines it was an entirely different story... after only 21 autocross runs on this ATE Type 200 DOT 4



After the bleed, put everything back together and went to take a test drive only to find that the right rear caliper frozen. Took everything apart and the rear piston cannot be retracted at all. Caliper wasn't noticeably dragging prior to this brake service, but is now completely locked up. Ordered a caliper from the local Ford dealer today and another bottle of motul, hoping to have everything sorted by the next event on Sunday.

 

[302 Hi Pro]

I’d say you very well may have found your cause of failure. Good job & good luck at your next event.

Also, consider turning off all the Nannies even on your 1st run.

 

[xr7]

I second 302 Hi Pro's recommendation to turn off the nannies. One of the facilities I run at has some abrupt elevation changes in a couple of corners. Both are left hand turns, one in the bottom of a valley and the other is at the crest of a hill and both corners are reverse camber. The nanny does not like these corners and kicks in and waits for things to calm down for a split second, no throttle for you, until it figures out what's happening. These happen to be my two favorite corners its a real challenge. I always turn off (when I remember) the nanny when autocrossing and all is well.

 

[TMSBOSS]

IF you "Switch off the Nannies" it is possible for the system to switch them back on. The cure for this is an updated brake module. Likely not what you want to hear but a real possibility. I assume you rotated the piston in the rear caliper to reset the E-Brake.

 

[DaveW]

IF you "Switch off the Nannies" it is possible for the system to switch them back on. The cure for this is an updated brake module. Likely not what you want to hear but a real possibility. I assume you rotated the piston in the rear caliper to reset the E-Brake.

Yeah, this. I think you found most of the problem with the bad caliper, but I would recommend never, ever, ever taking an autocross run without both traction control and stability control disabled (long button press after starting). I would also recommend turning the car off and redoing the turn off process after each and every run, period.

The stability control tries to use the rear brakes to stabilize the car and it will smoke them in short order and put enough heat in the system to bring some problems to a head.

And even when disabled via the button, it will still turn itself back on if you do something violent enough. I got in the habit of even turning the car off between ProSolo course sides after the TC/ESC came back on by itself during a run.

The BOSS ABS module fixes this, but would not be legal in Stock or ST categories.

DaveW

 

[blacksheep-1]

Looks like you have a ton of moisture in the brakes, I'd bleed those several times until it was completely clear. This is why I like AP super 600, it's relatively cheap, and it works, so you don't mind over bleeding the system.

 

[Norm Peterson]

The BOSS ABS module fixes this, but would not be legal in Stock or ST categories.

It should still be class-legally possible by other means, under the logic that turning something off means you've turned it off for that entire key cycle. Otherwise, a car with no OE means of turning TC/ESC off would have an unreasonable competitive advantage over cars that did. The basic allowance should be that TC and ESC can be made to stay off until actively turned back on regardless of vehicle maneuvers.

13.9.G. On cars without the ability to turn off electronic stability control and/or traction control (ESC/TC) from the manufacturer, modifications to defeat the ESC/TC are permitted. These modification are limited to altering the inputs to the ESC/TC processor (e.g., removing fuses, unplugging yaw or steering angle sensors, altering signals) and may serve no other purpose. Any codes or error lights resulting from ESC/TC modifications are permitted.


Norm

 

[Bill Pemberton]

Interesting thought and considering how overly rigid SCCA is at times, that sure reads like there would be a case for some change. Fun thought, if nothing else, thanks Norm.

 

[Mad Hatter]

I found that my AED track tune has succesfully eleminated all the nannies with out going to a ABS module change. Would that get by the SCCA rules? That picture of the brake fluid soup is the worst i have seen!! Am sure your braking will improve!

 

[Norm Peterson]

I found that my AED track tune has succesfully eleminated all the nannies with out going to a ABS module change. Would that get by the SCCA rules?

Not legal in Street Category, but probably OK in Street Touring.

14.10.F The engine management system parameters and operation of internal combustion engines may be modified only via the methods listed below. Any OE OBD2 or newer communications port functionally must remain. The Check Engine Light (CEL) or Malfunction Indicator Light (MIL) may be disabled via software. Only sensors equipped from the manufacturer may be used for engine management.
1. For all model years, the following allowances apply:
a. The standard PCM/ECU may be re-programmed without restriction.

That picture of the brake fluid soup is the worst i have seen!! Am sure your braking will improve!

I'm not sure if it's the two piston sliding calipers or the OE brake hose, but I was getting dirty fluid in the front calipers every event with my '08. Not as bad as drj's fluid, though. Never got even a hint of fade, save for one instance of "green fade".

After installing the 14" SVT/Brembos and SS lines, I'm not getting any obvious color change (but I still bleed a couple of pumps worth per corner before each event).


Norm

 

[Bill Pemberton]

Norm is correct, fine for Street Touring, but not for the Street Classes. This used to be called the Stock Class and that sure seemed to make it easier to see that hardly anything could be done to your vehicle.

 

[drj2k1]

Yeah, this. I think you found most of the problem with the bad caliper, but I would recommend never, ever, ever taking an autocross run without both traction control and stability control disabled (long button press after starting). I would also recommend turning the car off and redoing the turn off process after each and every run, period.

The stability control tries to use the rear brakes to stabilize the car and it will smoke them in short order and put enough heat in the system to bring some problems to a head.

And even when disabled via the button, it will still turn itself back on if you do something violent enough. I got in the habit of even turning the car off between ProSolo course sides after the TC/ESC came back on by itself during a run.

The BOSS ABS module fixes this, but would not be legal in Stock or ST categories.

DaveW

Dave,

Will definitely try turning the car off between runs/resetting the TC & ESC at the next event. Maybe I'll switch it up and tire warm for my father so he can be more comfortable in the car without the nannies.

I've definitely been surprised to find how quickly we've found the limitations of some aspects of the car in street class (as Bill said I wish it was still called "stock" so it would be easier to convey the class restrictions to non-SCCA members). We'll finish the season out with the car in D Street (maybe even hit the Finger Lakes Champ Tour if NY continues to show improvement with COVID cases), then re-evaluate the car and classing situation for next season.

Thanks all for the input,
J