65 replies to this topic

[rob999]

or the real options are 1) press harder (while screaming) 2) fit ABS cut off switch 3) unplug sensors (same outcome as above) 4) upgrade to 4 channel ABS unit (which has newer code, which also has mixed reviews) 5) Brake earlier for bends 6) Buy a MX5 7) Drive like Rob999

[mbes2]

interesting read on the effect suspension has on brake distance, and how an active control antidive system performs

http://scialert.net/...11.28.41&org=11

Wow... now thats some details...



Looks ok to me

[Bargi]

earlier than mine was then

It's a strange one, some people get it others don't.
I didn't get it when the car was an NA, but then I'd only just started doing track days when I brought it, so wouldn't surprise me if I wasn't pushing it to the point for it to happen. Retset who owned previous to me said he did happen to him and he had it for about 3 years.
I SC'd it after a year, new disks and CL5+ all round and about 6 TD's under my belt I was probably more confident with spanking the car around?

Slindy you're a regular car bits guru, maybe you can make heads or tails of the patent info and to what it's measuring? (I tried but lost the will to live )

Edited by Bargi, 20 June 2012 - 12:03 PM.

[JG]

Here's the official Lotus explanation of this braking issue:

"The symptoms being described are a result of the Electronic Brake Distribution (EBD) system operating. This system is also referred to as Dynamic Rear Proportioning (DRP) and is, as the name implies an electronic system which, through the ABS control valve block restricts the line pressure to the rear brakes automatically to a pre-programmed algorithm. You can consider it as an electronically controlled proportioning valve which measures parameters like the rate of deceleration and rate of pedal application and uses this data to anticipate a rear wheel lock-up and then reduces the braking effort at the rear wheels as necessary. If the ABS system is left to do this, it can only react to a wheel as it starts to lock and therefore the car can already start to spin before the ABS can start to work. In extreme circumstances, if the driver brakes very suddenly the EBD system can lock off the pressure to the rear wheels completely; what pressure was at the rear brakes as the EBD system engaged remains there and the rear brakes are still working as a result, but further increases in pedal effort will not increase the braking at the rear of the car because the pressure to the rear brakes cannot increase. When this happens the brake pedal goes hard, as it is now pushing against the front callipers and a closed valve only, instead of against the front and rear callipers. The rear callipers are single piston and therefore quite flexible, so they are a major factor in making the brake pedal feel 'soft'. When the valve closes, the brake pedal pressure no longer flexes the rear callipers, hence the increase in pedal hardness. The front brakes are still working just as well as before the valve closed and will give more braking if the pedal effort is increased, while with the rear brakes working as hard as they can the braking is NOT affected. The problem is the driver feels like braking is reduced (even though it is not) because of the change in pedal feel. If the driver continues to push hard on the pedal, the car will continue to slow as fast as it possibly can in the circumstances. If he increases the pedal effort the front braking effort will increase and the rear effort will remain where it was. If he was to back off the pedal for a fraction of a second, the valve will reopen and the rear brakes will operate as normal again, with the pedal feel going back to normal.

Genius Ray, that is exactly what i experience on track.

[JG]

But unfortunately the solution creates the problem which techie mentions. if you disable any of the front sensors the car runs badly.

[techieboy]

It's only the nearside rear sensor that has that effect. ECU thinks you're trying to take the p!ss and bluff the odometer (and no speed reading) and after a while introduces a misfire.

[JG]

i thought the fronts did the sam? only off-side rear was immune (and which i use to kill ABS)

[techieboy]

Hmm, maybe it is then. Thought the front sensors had chuff all effect, other than for the purpose they're meant for. I did run a couple of times with one of the front sensors disconnected at the hub and don't recall any issues. Hardly an exhaustive test though.

[JG]

I could go and try, but the car is approx 1500 miles away so i'll just speculate instead. Yours is probaly 15.00 meters away from you

[techieboy]

About 2.5 metres, actually. But, testing it would mean driving it for some distance/time. That would clearly upset the status quo that the car and I have.

[JG]

it would probably enjoy a few miles prior to the national (in addition to the ones to get there )

[Bargi]

I've got my Front Left and Rear Right disabled, speedo and engine running fine.

[techieboy]

it would probably enjoy a few miles prior to the national (in addition to the ones to get there )

I drove it to Dave's and back. That must have been nearly 20 miles.

[m7mini]

So everyone needs 2 ABS cut off switches

Genius! Anyone know what cables the sensors are at the abs module as the normal cut off switch does not stop DRP?

[JohnTurbo]

i drove mine for well over a year with a front sensor disconnected and the abs definately did nothing in that time... i could happily lock all 4 wheels.

[OneYet]

I've got my Front Left and Rear Right disabled, speedo and engine running fine.

 

Time to dig up this thread again. 

 

Just to make me understand. 

If I unplugg the ABS-sensors like Bargi says here I will not have the Hard Pedal Feeling again. That is superb. 

I will however have the ABS-light shining in my face on the dash. That is annoying. 

There is no way to not have that?

 

How do you unplug the connections in reality? Simply unplug and let them hang there or tie them up in a tidy way or do you have any smart switches? 

[smiley]

 

There is no way to not have that?

 

 

 

Yes, fit an expensive 4 channel lotus abs computer, which will behave much better on track.

If you push the vx to an extreme, you may even go over this one, In that case the only thing left is an abs switch. (and that light)

[JG]

I no longer disable the ABS on track. 4 channel ABS is indeed the answer.

[JohnTurbo]

Jimmy's cluster hack also does the job...using the alternator warning signal to trick any ovet zealous mot testers. Used it to disable airbag light when removing belts for harnesses.

[OneYet]

I have the 4 channel thing.

It did get a lot better but I still got Ice-mode om track one time last year. And that is one time too many.

As I read Bargis write up it led me to believe that if I disconnected front left and rear right ABS-connectors I would still have the ABS but without the ice.

 

So my question is how to do it in a nice way.