Over-Active ABS on Track

[Minimaxman]

Hi All,

Had my first outing in my newly acquired Ph2 172 (non-cup) at Brands on Monday and had a great day in the car but now have a list of things to tinker with.

The most notable issue was over-active ABS when trail braking in to a corner. In a straight line through a bumpy braking zone, pretty much no matter how much pedal force was applied I couldn't get the ABS to activate. However as soon as you turned in and carried the brake towards the apex, even with very moderate to light brake pressure (as you roll off the brake towards the apex) the ABS would kick in, you'd lose front braking force, weight would come off the front of the car and you'd sail past the corner if you weren't expecting it,

My initial thoughts are that as the inside rear wheel is off the ground on the way in to the corner, any light braking force is going to be able to stop this wheel from spinning at which point the ABS assumes you've locked up and kicks in.

I've read loads of threads on here about what's required to remove the ABS and install a bias valve but with the speedo stopping working I'm not too keen. Couldn't find any info on anyone installing a bias valve whilst retaining the ABS?

The car is running standard calipers, Brembo HC disks all round, DS3000s up front and PBS pads at the rear. Car weighs 950kg without driver, running BC DS coilovers, and AR1s. Road legal car used predominately for track days.

Would be interested to hear other people's thoughts. Thanks!

 

[JB21]

Could be something daft like a dodgy steering angle sensor giving false readings to the ABS ECU. Could also be something a little as a intermittent ABS sensor or maybe a worn/corroded/broken ABS ring.. I had never ending ABS issues with my old 182. In the end I pulled the ABS fuse and ran it without but with that it reverted to 50/50 bias which was great fun.

 

[Minimaxman]

Just to update this for anyone who may be interested; I found a very simple solution to disabling the ABS. As many people have posted before, it seems like simply pulling the ABS fuse would give you 50:50 brake bias which would be interesting to say the least, so I didn’t fancy that. Instead I disconnected the left rear ABS sensor by simply unplugging the connector underneath the car near the left rear wheel. This completely disables the ABS but as far as I could tell after a full day on track at Blyton it retains the normal brake bias, or if anything it knocks it forwards slightly.


Without the intrusive ABS every time you trail braked it completely transformed the driving experience for the better. This is how I’ll be running the car on track from now on.

 

[bloke]

Front is a bit easier to unplug or wire a switch in the circuit and just turn it off that way.