Nathan Atkins

Ok, so let me be the first to say that I think burnouts are pretty stupid and that for most street tires they actually make you slower on drag racing which is something our cars already mostly suck at.

Taking all that as given, I had a buddy describing this line lock feature that ford has added to the mustang which basically allows you to hold the front brake while the rear brake is free so you an do monstrous burnouts without nuking your rear brakes.

Now it seems to me that if you have a car with abs, you could just induce a signal to the abs hydraulic module with a switch to actuate the solenoid to cut off brake pressure to the rear caliper. I guess you'd need a diode to keep from sending the signal back into the ecu, but it seems it would be pretty straightforward to do.

I'm not interested in starting a discussion about how burnouts are stupid/unnecessary or not, I'm just looking for anyone who is technically literate enough that they could comment on it being as simple as what I mentioned here or not. RIWWP I'm talking to you ;-)

RIWWP

iTrader: (2)

This is in General Automotive, so I don't know if you are referring to the RX-8 specifically or not.

In general though, it's going to be more complicated than that. I don't know for sure on any of this, but some thing to consider and questions to answer if you start digging into it:

• If there is any level of advanced ABS diagnostics, will any sort of ABS signal interruption simply cause the entire ABS to not work?
• Can you intentionally trigger the front ABS while preventing the rear from engaging? Without using pedal pressure.
• If you use pedal pressure, can you modify the junction block to bias 100% front brake force on demand?
• The ABS module works off of wheel speed sensors, would it be easier to simply fool the ABS block by sending it false wheel speed sensor signals?
• Attempting to use the Anti-Lock Brake System to lock the front wheels may difficult to accomplish by itself
• Would an easier option be to simply use electronic valving to prevent any brake force from reaching the rear brakes?
• ...and with anything dealing with modding the brake system, will a potential failure of the mod result in the complete loss of brake control?

Regarding the last point, an ABS failure in an RX-8 can be quite scary indeed, as 1 wheel can get all the braking force, nothing for the other 3.

Example:
Writeup in a thread: https://www.rx8club.com/series-i-whe...-fails-190041/

From the RX-8:

From the spun out car:


Given the acknowledged low value of the goal, I personally wouldn't be even attempting a mod like this, given the very high cost of a failure.

Nathan Atkins

Yeah I hadn't even thought about tripping an error code or bricking the whole abs module, it'd be something to try on a beater car that I don't care about just to satisfy my curiosity, but yeah I guess nothing is ever simple :-)

RIWWP

iTrader: (2)

Cars have advanced beyond points where simple electronics changes will actually work as intended. All the safe guards, fail safes, complicated coding and logic, etc... The only really effective solutions for anything like this involve building your own module with inserted coding logic.

Like if I WAS going to try this directly with the ABS system, I'd probably try hacking the ABS module directly, inserting the additional subroutines needed, adding the switch conditions needed to the logic, etc... Anything external is bound to cause problems, though obviously this is a significant undertaking, akin to building an ECU from the ground up.

A physical / mechanical solution, like brake bias valving, would be simplier to achieve. Something that just ignores the ABS system completely.

bse50

I'd just buy a car that suits my needs from the beginning. Motorsport ABS modules are very expensive (they cost more than an used rx8) for a reason.

RIWWP

iTrader: (2)

Entirely agree, I mentioned earlier that I wouldn't pursue any of it. That was simply noting the path I would take if I was trying to mod what I had (which I won't).