PSA: Boss 302S ABS has a hazardous failure mode

[treynor]

The good news is: other than the chin splitter and some minor plastic bits, my car is undamaged.

The bad news: I had a catastrophic loss of brake function in my '13 Boss 302S today at Laguna Seca entering the Corkscrew. The brakes had been working normally until that point, and braking moderately at my usual spot (the white line on the left shortly before the crest) had worked unremarkably on the previous two laps. The third lap, I pressed the brake and... almost nothing. The pedal was firm, but the car wasn't slowing appreciably. I came over the crest and pressed the brake harder as the car settled, and still ... nothing. My speed was still very high at this point, and I made a split-second decision and turned right into the escape road / gravel trap. The car came off the track and went 3/4 of the way through the gravel trap before coming to a stop (!). It all happened quickly, but it is sobering in retrospect.

Back in the pits, we verified that there was nothing mechanically wrong with the brakes. I contacted my Ford racing connection, and was informed that in some cases with that car's ABS system, if an ABS wheel sensor fails or the wires to the ABS sensor short, the ABS system will go into 'ICE mode' and you lose almost all braking ability. Not good.

So, not sure what to do yet, other than start by using a diagnostic tool to verify the cause of brake failure was indeed a bad ABS sensor. We'll fix the brake issue, but... this incident was unnerving. I'm curious if anyone else has run into this problem with their Mustang (or other vehicle) and if so, what you did to address it?

 

[VoodooBoss]

Wow that’s scary. You’ve got to be doing 100+ before hitting that braking zone. Glad you’re ok and there wasn’t much damage to your car. I have no knowledge of this but maybe @steveespo or @Black Boss might.

 

[gripdriver]

Has anyone ditched the ABS on these cars?

 

[steveespo]

I would really have to hear this information from more than one Ford Performance person. Perhaps a Ford Engineer. The race ABS supposedly eliminates ice mode but that is only hearsay from various race team guys who don’t always disclose the whole story to maintain competitive edge. Just seems odd Ford would have a fail safe mode that limits braking power. It is much safer to have wheels lock than reducing brake power to almost nil. @Shonuff82


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[Black Boss]

+1.

There were several versions of the 302S module. The later ones were more sophisticated, but lit up the dash on street cars .

 

[treynor]

I would really have to hear this information from more than one Ford Performance person. Perhaps a Ford Engineer. The race ABS supposedly eliminates ice mode but that is only hearsay from various race team guys who don’t always disclose the whole story to maintain competitive edge. Just seems odd Ford would have a fail safe mode that limits braking power. It is much safer to have wheels lock than reducing brake power to almost nil. @Shonuff82

And how. Surprise lockup, I can deal with. No brakes -- that's a problem. If there's an updated ABS module which eliminates this possibility, that would be hugely helpful.

 

[the5]

And how. Surprise lockup, I can deal with. No brakes -- that's a problem. If there's an updated ABS module which eliminates this possibility, that would be hugely helpful.

In my 302R I removed the problem completely by Upgrading to a Bosch ABS Race unit. Cost for the unit is about 6k plus install but it also gives you 12 position adjustable race abs.

 

[treynor]

In my 302R I removed the problem completely by Upgrading to a Bosch ABS Race unit. Cost for the unit is about 6k plus install but it also gives you 12 position adjustable race abs.

I have probably the same unit on my 488 GT3, and it's magic. It is one of the routes I'm considering going with the Boss. If you liked the outcome of the swap and/or if you would be willing to share some details about how you did it (settings, any issues, etc.) I'd be grateful for the info.

 

[the5]

I have probably the same unit on my 488 GT3, and it's magic. It is one of the routes I'm considering going with the Boss. If you liked the outcome of the swap and/or if you would be willing to share some details about how you did it (settings, any issues, etc.) I'd be grateful for the info.

The Swap was preformed by Racers Edge when they ran in IMSA. I purchased the car from them after it was de-homologated. The ABS has been flawless, there is a huge difference in a street system adapted for the track vs a track system made for racing. The unit itself is only about $5k, the extra cost comes from the harness that you have. You can either go with the "stock" harness which is just the regular one-size-fits-all or a custom race harness with mil Spec connectors, But expect cost for just the harness to be $6k. I am in the process of getting a new M4 system for my other car and will be using just the basic harness. I will snap a couple pictures when I put it in but that wont be for a month or two.

 

[treynor]

The Swap was preformed by Racers Edge when they ran in IMSA. I purchased the car from them after it was de-homologated. The ABS has been flawless, there is a huge difference in a street system adapted for the track vs a track system made for racing. The unit itself is only about $5k, the extra cost comes from the harness that you have. You can either go with the "stock" harness which is just the regular one-size-fits-all or a custom race harness with mil Spec connectors, But expect cost for just the harness to be $6k. I am in the process of getting a new M4 system for my other car and will be using just the basic harness. I will snap a couple pictures when I put it in but that wont be for a month or two.

I've already experienced the difference you're describing - that slightly greasy, handles trail-braking-like-a-Boss function of a great racing ABS is a joy to experience. I hadn't figured on making the switch in my 302S - it's already typically amongst the fastest cars on track when I go to a HDPE day - but now that I'm thinking it's a safety issue, that's a different matter entirely.

Pictures and other details would be most appreciated. I think I'm talking myself into this upgrade as I write this

 

[the5]

I've already experienced the difference you're describing - that slightly greasy, handles trail-braking-like-a-Boss function of a great racing ABS is a joy to experience. I hadn't figured on making the switch in my 302S - it's already typically amongst the fastest cars on track when I go to a HDPE day - but now that I'm thinking it's a safety issue, that's a different matter entirely.

Pictures and other details would be most appreciated. I think I'm talking myself into this upgrade as I write this

Ill be sure to snap some, I will be talking to Bosch this Week at PRI as they have now introduced an M5 ABS system. I will report back on the differences.

 

[ArizonaBOSS]

My guess on M5 is "More modes, more money"

 

[the5]

My guess on M5 is "More modes, more money"

From what I have seen its the opposite. At least for the cheaper ClubSport option

 

[ArizonaBOSS]

From what I have seen its the opposite. At least for the cheaper ClubSport option

INTERESTING...let us know what you learn...Although I probably need a 22-gallon fuel cell before I need a true motorsport ABS...or something.

 

[treynor]

Ill be sure to snap some, I will be talking to Bosch this Week at PRI as they have now introduced an M5 ABS system. I will report back on the differences.

An update: I ordered a Motorsport M4 system for my Boss. My wife insisted [emoji16]

 

[the5]

An update: I ordered a Motorsport M4 system for my Boss. My wife insisted [emoji16]

Youll love it! If you want I can Send you my configuration file. Ford did the R&D on it when they ran the car in IMSA.

INTERESTING...let us know what you learn...Although I probably need a 22-gallon fuel cell before I need a true motorsport ABS...or something.

Also not sure where Racing ABS falls into ST rule sets. But Im not sure why you are jumping to a fuel cell if your cell is holding up fine. OEM cell is lower CG and I have to say lighter than a properly installed cell.

 

[treynor]

Youll love it! If you want I can Send you my configuration file. Ford did the R&D on it when they ran the car in IMSA.

Hey, that would be awesome!