Brake bias control??

[PatienceMetalFab]

I have noticed that many of you guys run the Boss R abs unit-and swear by it, but what about brake bias control? I know in some motorsports abs units, you can interchange the bias valve, but not in the Ford unit. In almost all the road cars we have built, bias control is crucial to tuning the turn in and help with over/understeer issues. Anyone run a dual master cylinder bias box and the ABS? Seems you could do it easily as a front/rear split master cylinder with 2 output lines would basically be the same input to the hydraulic unit as a dual master cylinder box with 2 output lines (one on each cylinder)???

Just some food for thought...

 

[steveespo]

I don't know if you could do it like that. The ABS module and hydraulics block outputs to each wheel individually. If you starve the output from the MC I guess it might change fore/aft bias but you may get some wonky difference from side to side as the module tries to get its programmed proportions.


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[PatienceMetalFab]

I was trying to get details on the function of the abs unit from FRPP but we have never had a whole lot of luck getting useful technical information from those guys (or helpful diagnosis help, or really any help at all).

Traditionally, if an ABS unit does not have any sort of traction control function, it serves as nothing more than a fluid manifold allowing brake fluid/pressure to pass through as a normal, non ABS system would function. Only under the detection of wheel lock up should it interfere, engage or alter the fluid pressure in any way. All ABS manifolds have an internal fixed valve for the front to rear bias. On a traction control unit (especially in an awd car), the module may vary that bias. If this unit is truly a non TC unit, which I know it is, then it should allow any modified bias to pass through with the only change factor being the fixed bias valve in the unit.

.....all this of course, is only theory until tried.

 

[JAJ]

Ford's marketing material on the 2013/14 GT500 claimed that switching the car from "Comfort" to "Track" mode changed the front/rear brake bias. If that was actually true, then it had to be done in the ABS/AdvanceTrac box somehow.

 

[PatienceMetalFab]

Ford's marketing material on the 2013/14 GT500 claimed that switching the car from "Comfort" to "Track" mode changed the front/rear brake bias. If that was actually true, then it had to be done in the ABS/AdvanceTrac box somehow.

That's a good point but the gt500 was a street car with traction control (I believe). The Boss R ABS unit supposedly has no TC. It is strictly ABS, meaning only assistance for locked up brakes via pulsing or reduced pressure. Traction control systems play a much bigger role due to the need to stop wheel spin.

 

[steveespo]

Would be nice if we had a Ford Chassis engineer on the board to explain the ABS functions. @Shonuff82


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[Shonuff82]

The way the factory ABS works is by targeting a peak slip %. It does this individually for each corner by knowing the vehicle speed and individual wheel speeds.

Historically race tires make peak grip at a higher slip % so the Ford Racing targets this higher %.

There is also a electronic brake proportioning (EPB) algorithm that meters pressure to the rear. This is one of the knobs we use for trail brake sensitivity.

Unfortunately, there is really no way to adjust this as a customer.

If you are going to run race tires, the Ford racing controller is the way to go. It set and forget. This is the same part used by PWC, IMSA ect.




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[PatienceMetalFab]

The way the factory ABS works is by targeting a peak slip %. It does this individually for each corner by knowing the vehicle speed and individual wheel speeds.

Historically race tires make peak grip at a higher slip % so the Ford Racing targets this higher %.

There is also a electronic brake proportioning (EPB) algorithm that meters pressure to the rear. This is one of the knobs we use for trail brake sensitivity.

Unfortunately, there is really no way to adjust this as a customer.

If you are going to run race tires, the Ford racing controller is the way to go. It set and forget. This is the same part used by PWC, IMSA ect.

View attachment 1992


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This brings me back to my years as a dealer tech and getting descriptions of system functions from engineers when dealing with an odd problem.

So the EPB algorithm is fixed and not adjustable externally adjustable? You mention a knob to dial in trail braking-Is this only a function available during the R&D process? Is it a separate function of the module between stopping wheel slippage and changing the rear bias (one wheel vs both rear). I assume the algorithm is input based for change factors such as wet roads vs dry roads?

Is it safe to say that these race modules are putting as much rear bias as possible in to just shy of lock up? Traditionally when we set bias, well run the car with increasing rear bias until it locks up the rears. At that point we dial it back and start tuning from there. This is usually done through an adjustable bias bar on the pedal box.

 

[Shonuff82]

It is not externally adjustable and can not be tuned by a customer. It is a separate algo but works in conjunction with the individual wheel slip control. It looks at inputs like veh speed, yaw velocity/accel, brake pressure, decel rate, vertical acceleration, steering input ect and determines how much brake pressure the rears can take.

For instance... at very high vehicle speeds it will put less pressure to the rears to maintain stability but at lower vehicle speeds it can use more rear pressure to help the vehicle rotate.


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[PatienceMetalFab]

So it does much more than simply an ABS function to stop wheel slippage, which was what I was originally trying to figure out.

I like the idea behind it as you can have heavy braking before turn in (with more front bias) and once you bring the speed down, it adds bias to the rear for trail braking as you stated above.

Forgive me as this is the first car I have dealt with a motorsports ABS unit of any kind. Like I said before, we usually set the cars up with a bias bar brake system that allows on the fly adjustment to bias. For example, a slower track with a lot of turn in points will favor some extra rear bias as well as a little earlier engagement of the rear brakes for trail braking-keep the load off the front at turn in. This can get a bit hairy for the big fast tracks however. I have even seen some drivers adjust bias just before turn in....talk about multi tasking!

 

[steveespo]

That's why you come to TMO for real Mustang track tech. Thanks Chris.


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[Drlee50]

That's why you come to TMO for real Mustang track tech. Thanks Chris.


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So is the boss unit required for running 305 square slicks then ? I go thru a full set of front carbotech 20s in a day. I've gone thru 4 sets in 3 weekends. I've owned the car 6 weeks. I have brake cooling and I put brand new calipers on before road America last week. Ate a set of pads in 3 sessions . 600+ degree temps. I am a competent driver and am not hard on my brakes at all. In gonna get rid if the car if this is how the consumables are. The rears are carbotech 10s and are still near new and haven't worn in the 3 weekends on track. I did switch the 13.8 rear rotors . wtf should I do ?? This is with t.c. off . I have run it in sport mode and regular tc off and the t.c. kicks in still too much. I've had issues where it goes into limp mode due to cylinder misfire and since I was already in the session I had to change tc settings thinking it had something to do with it. Anyway, with tc on, brakes are automatically kicking in and boiling my fluid it gets so hot.

Long story short, what's the secret to cool brakes on this damn car ???

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[TMSBOSS]

Road America is hard on brakes. Three heavy braking zones followed by long straights each lap are hard on brakes. I have run through a set of Pagid pads in a weekend, two day event, total of 12 runs. At Blackhawk I can run 7-8 days on a set.

Have you swapped out the stock ABS controller yet?

 

[Drlee50]

Road America is hard on brakes. Three heavy braking zones followed by long straights each lap are hard on brakes. I have run through a set of Pagid pads in a weekend, two day event, total of 12 runs. At Blackhawk I can run 7-8 days on a set.

Have you swapped out the stock ABS controller yet?

I went thru a full set of new pads in 2 days at gingerman. As well. Twice on 2 different weekends. 1:42-144 lap times at gman and 2:40 at RA.
I don't have the 302r and module. Gonna search for it right now and buy that damn thing . its gotta be eating my pads. My 1200 hp twin turbo viper didn't eat pads like this and I would hit 180 to 185 on the front straight and 155 into turn 5 and after the kink in to Canada corner. I could get a full weekend out of a set of pads easy. This mustang is ridiculous. I'd expect the cooling time would be better at RA. My temp gun was over 600 degrees on the rotors each session at RA and at Gman. Nuts!

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[TMSBOSS]

When I switched to the 302R controller rear wear increased to the point to changed rear compounds. The back feels a bit lighter on braking, likely from being closer to max. In fact the first time out with the 302r controlled I went through a set of rear pads, not fronts. This should help with bias.

 

[Drlee50]

When I switched to the 302R controller rear wear increased to the point to changed rear compounds. The back feels a bit lighter on braking, likely from being closer to max. In fact the first time out with the 302r controlled I went through a set of rear pads, not fronts. This should help with bias.

That's good to know! I definitely need the rears to do some work!

Do I need the module with hydraulics? Or just the regular one ? I don't know what that means and none of the venders actually tell you the difference.

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[TMSBOSS]

This is what I installed.

https://www.kohrmotorsports.com/product/boss-302sr-updated-abs-module-wo-bracket/

 

[Drlee50]

This is what I installed.

https://www.kohrmotorsports.com/product/boss-302sr-updated-abs-module-wo-bracket/

That's what I will go with then. Thanks !!!

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[ls110]

I hear your pain on pads and rotors. So painful for me this year I made the change from Brembo 302S front calipers and GT500 rear calipers to Wilwoods AEROs to lower the consumable cost.

Still burning through them just as fast although my cost is almost half. This year has been especially hard on brakes for me averaging only 6.2 hours per set of rotors, 2016 was 12.6 hrs, and 4.5 hours per set of pads. This is my largest consumable expense with tires following closely behind.

 

[Swiss Boss]

I went thru a full set of new pads in 2 days at gingerman. As well. Twice on 2 different weekends. 1:42-144 lap times at gman and 2:40 at RA.
I don't have the 302r and module. Gonna search for it right now and buy that damn thing . its gotta be eating my pads. My 1200 hp twin turbo viper didn't eat pads like this and I would hit 180 to 185 on the front straight and 155 into turn 5 and after the kink in to Canada corner. I could get a full weekend out of a set of pads easy. This mustang is ridiculous. I'd expect the cooling time would be better at RA. My temp gun was over 600 degrees on the rotors each session at RA and at Gman. Nuts!

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Sorry to say this but it looks like you reach the limit of the stock Brembo. Your next solution is to upgrade to race setup. Just make sure you get a caliper than can get a 1" thick pad.

I had the same problem last year. My front pads (Pagid RST-2) woulds only last 6-7H on a easy for brake track. I did kill one set in 4H at Indianapolis Motor Speedway. And my brake pedal was gone after 2-3 laps and I have 4" brake ducts.
I installed the AP Racing with the race ABS kit last winter and it's one of the best mod I've done so far. I can get 10-15H on the pads and absolutely no fade, even at IMS for the full 20min.
https://www.essexparts.com/essex-de...brake-kit-front-cp9668372mm-mustang-s197-0613