Anyone experienced the rear brake circuit lockout on the ABS? I managed to activate it in the wet at Spa (braking for the Bus Stop).
The explanation from Lotus (I have a letter) is that in extreme circumstances of weight transfer the system activates a solenoid valve which locks out the rear system leaving you with just front brakes.
The symptoms I experienced are the pedal going solid (caused I guess buy the reduced volume and short lines to the front) and reduced braking for a given force.
I’ve had that happen on mine at North Weald.
Heart in the mouth stuff, but fortuately only cones to hit.
Brief lift and then re apply and they were ok, but wasn’t something I care to have happening regularly.
There was another guy there that day with a VX220T who’d beeh having loads of problems with this, so he’s had a switch fitted on the dssh to disable to ABS for track use.
Not sure Rox, and really why I was asking the question. If anyone can think of a low speed test to get it to activate then please let me know.
To be fair it does only happen in extreme circumstances, I have only managed to activate it once at Spa in the wet where the braking zone for the bus stop is a corner. I guess it thought we were going to swap ends.
I don’t think it reset on that corner but was OK for the next.
Also, to clarify, you still have ABS (on the front wheels) it’s just the rear circuit that is disabled.
Not sure Rox, and really why I was asking the question. If anyone can think of a low speed test to get it to activate then please let me know.
To be fair it does only happen in extreme circumstances, I have only managed to activate it once at Spa in the wet where the braking zone for the bus stop is a corner. I guess it thought we were going to swap ends.
I don’t think it reset on that corner but was OK for the next.
Also, to clarify, you still have ABS (on the front wheels) it’s just the rear circuit that is disabled.
When it happened to me it seemed to reset when I came completely off the pedal. Its only happened once, and as you say in pretty extreme circumstances. I was going for a time through one of their autosolo courses on very cold AO48s, air temp was about -3 degrees C, although I don’t think there was any ice on the course.
Biggest scare for me was the way the pedal went completely hard and yet the braking force was much less than normal. Certainly knocked the confidence for a few runs.
Coming through the parabolica somewhere around the middle of fifth gear. Was trying to hang onto a 997 Gt3 which had pulled a good distance on me since the last second gear corner (as you would expect) Left my braking as late as i could, began braking only firmly at first to transfer the weight forward getting progressively harder and harder, felt the beginning of the abs kicking in and at the same time as i made a mental note to not press any harder the car felt like it had gone onto wet grass! I lost what felt like half my braking force (although it probably was not) and went straight onto the run off zone. At the next corner they felt normal, but i did not use them so hard again…
So i need to dissconnect the abs inorder to stop this?
I also need brakes which can take that kind of use lap after lap, you are taking off about 100mph everylap at this one corner as you brake from the fastest part of the circuit to the slowest. I have not found them yet.
Mine did this a few weeks ago as I was braking hard to come to a halt at a T junction, there was a crease in the tarmac about 15m short of the dotted line, the ABS went boing for a split second and then all braking went out of the window. I had to muller the pedal into the floor and I brought it to a halt with the front splitter about a foot over the line. Scary
I agree, i spoke to someone who said many cars do this in emergency braking to reduce the risk of a spin during panic braking whilst turning to avoid the accident.
I must say its not ideal on a track car. Had it happenened at the sachs kurve i would have gone straight into the gravel trap…which i would rather not do.
I’ve had this, under hard breaking just when the brakes are begining to do a good job they suddenly give up the ghost, the car feels like it’s gone onto water and there’s no feel? I just asumed it was the ABS, I might try Gav’s tip if he’s about at Oulton in a fortnight.
Is anyone clear as to the exact circumstances that active this mode? Is it dependant on very fast pedal activation or something. It sounds extremely dangerous at the track, I don’t like the thought of just understeering straight into another car
1st time I noticed it was sudden breaking for an unexpected T junction. I can provoke it with hard progressive breaking like the type of manouver you’d do when bedding the pads in, it’s not nice and I make adjustment for it on track. Until now I’d just thought it was the negative side of ABS.
I had it at the end of a long straight braking for a hairpin. I braked progressively later and later, expecting that at some point the abs would come in and i would run a little wide, at which point i would know i had reached the limit.
However what happened was as i felt the abs begin to work i felt a sudden reduction in retardation force and went straight up the escape road.
Imagine the following, lap after lap i brake at the correct place with a certain amount of force, which is, unbeknown to me just below the activation point of this mode. Then i am following someone and for whatever reason i brake a tiny bit harder or later, then instead of the abs saving me, it will send me sailing into the back of the guy i am following.
I would like to get to the bottom of this issue and see if there is a fix. At the moment it seems to be unplugging the abs.