Exige v6 cup abs too intrusive

[Maxi_z]

Hi

The standard abs on some 2zz lotus models and on the exige v6 cup and cup r is know to be sometimes too intrusive on agressive track use and especially with grippy semi slick tyres or slicks.

The abs will react as older abs systems by releasing the brakes too much and making the pedal go up again and will not brake a lot except if you release it and push it back.

On other Lotus forums they call that the ice effect and I also read that on older model part of the problem was that there was a kind of valve that goes to the back wheels and would close if locking is detected at the rear but don t know if the exige v6 still have that valve system.

I easely felt that problem on the exige v6 cup r on track a few times with trofeo r tyres but on te newer exige 380 cup also with good semi slick tyres I really never felt the abs was a problem.

I know a bosch motorsport abs can be fitted and works perfectly but as on the oem 380 cup there is not any special abs problem I was looking to see if there could be some other cheaper and easier solution.

Is the standard abs system the same on the older exige v6 and on the newer 380 or is it different?

Could it be the same unit but programmed differently and in that case could the software be updated?

If different unit could it probably be replaced with the newer one?

Also could the abs be disconnected but the servo brake booster used?

 

 

[Bibs]

The ABS has been tuned to work with the OEM tyres. Semi-slicks or slicks will give it a real headache which you're seeing here. 

@nimes has the Bosch ABS system fitted to his monster 3-Eleven to alleviate this issue, it can be used with whichever tyres you wish as I believe it's fully customisable for levels of traction.

[Maxi_z]

I know about the abs motorsport system as also Jack fitted it to his cup r and might install it but what I was wondering is that if I compare the old exige cup system with the 380 cup oem system both driven on the same track with similar tyres

the 380 cup oem abs works perfectly and I was wondering what are the differences as if I could just buy the oem parts for the 380 cup abs it would probably be ok and cheaper.

 

[Arun_D]

Maxi,  depending on which circuit / corner i'm braking into, I experience this in my original V6 Cup, both on ZZR and Cup2 tyres. Not sure I'd want to or can switch to the Bosch motorsport system as per Jack et al, but I will keep an eye on this thread with interest, especially if there is an update to the 380 cars that improved this.

[Maxi_z]

On the bell and colvill spare parts website I could only find one abs module number for the exige v6 but maybe someone familiar with lotus parts or with some dealer could ask if there is a way to upgrade the abs software or if the 380 uses a different module etc

 

[Jack]

Maxi, I don't believe that the Lotus standard Bosch ABS system that is found on the 380 vs older V6's is different.  As Bibs commented above, the stock system has been programmed to work with the  Lotus recommended R-comp tires of a given OD and with the stock variable traction control and DPM.  Once you deviate from that tire OD and significantly increase grip, the stock programmed ABS will be compromised.  Comparing two different cars will only reveal results if they are both driven by the same driver on the same track with tires are of the same condition (grip wise) and when ambient temps, as well as track conditions are identical.  What I'm trying to say is that numerous variables are at play when on track, which will affect braking and translate into a particular ABS system's effectiveness.  I guarantee that a 380 car/driver will encounter "ice-mode" or feel the ABS is be too intrusive under certain conditions....an individual's braking style is also a key variable in this equation.

Even with my Motorsport ABS, I will select different levels/programs depending upon environmental conditions as well as tire degradation -- that's the beauty of having this magic rotary knob.  Also, with Motorsport ABS, you still activate ABS but the car will "STOP" -- in other words the brakes work and you can rely on them to slow you down and you won't be caught out with the "ice-mode" phenomenon.  The next mod is go to a  dual master/pedal box and ditch the vacuum booster, in order to increase the granularity/modulation of the braking system   That combined with Motorsport ABS is the ideal setup.  The vacuum booster is too much like an "on/off" switch....no real race car has power brakes. 

Also, as I mentioned to you before, if you want to experiment driving on track with no ABS, disconnect the RF wheel speed sensor.  Your brake booster will not be affected.  If you had variable traction control or DPM (as on a street V6), it would become inoperative but you don't have it on the R....that's why you see the "skidding wheels" icon on the stock instrument cluster with the CupR.

 

[Jack]

On 25/04/2019 at 06:22, Arun_D said:

Maxi,  depending on which circuit / corner i'm braking into, I experience this in my original V6 Cup, both on ZZR and Cup2 tyres. Not sure I'd want to or can switch to the Bosch motorsport system as per Jack et al, but I will keep an eye on this thread with interest, especially if there is an update to the 380 cars that improved this.

Arun, exactly right ^^^^.  I have retained the stock abs system on my 2-Eleven and I experience what has been described as "ice-mode".  With the S2 variant ABS (which I understand to be an ancient Kelsey-Hayes abs system), ice-mode is what you get (sometimes) when you go to the brakes and the brake pedal gets hard as a rock but the car doesn't slow down. You will then need to lift off the brakes and back on quickly to reset the system and regain braking -- quite scary if unexpected.  But as you mentioned, it will always happen at the same braking point for certain corners on a given track and one can work around the issue since it is expected.  The abs issue I experienced with the stock Bosch abs was somewhat different than with my 2-11..... same overall effect (i.e., loss of braking) but a completely different pedal feel -- it did require a quick lift and re-application to sort out, but it really prevented you from using the brakes to help turn the car, if you know what I mean.

BTW, you could switch to the Bosch motorsport abs system -- everything will work on your car (i.e., VTC and DPM), but it is a quite an expensive modification.  The unit alone is close to 10K $US before installation costs.

 

[Bibs]

I remember speaking to Nick Adams about this on the 2Eleven and it's not ice-mode at all. I'll see if I can find the post that explains exactly what the brakes are doing when it feels like this. 

https://www.thelotusforums.com/forums/topic/27531-brake-issues/?do=findComment&comment=265190

[Jack]

How about this explanation from a Lotus engineer ..... Opps, just read your link..... I still call it "ice mode". 

"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.

In the case of releasing and re-engaging the pedal the car should not be able to slow any faster than it was with the system engaged unless either 1: the driver triggered the system in the first place by stamping on the pedal too fast or 2: the system triggered because a rear wheel was unloaded when the brakes were applied and would have locked up but is now fully loaded once again and able to sustain a greater braking torque. If the rate of deceleration does improve when the pedal is reapplied then it is telling the driver that he is over braking either in terms of the ultimate ability of the brakes (cause 1 above) or the track condition (cause 2 above) and needs to adjust his driving style to suit. If the system were not fitted or disabled and he continued to drive that way he would be in danger of spinning when applying the brakes. 

The suggestion that the system is running out of vacuum is just plain wrong. The system carries an internal reservoir of vacuum sufficient for three full brake applications. As with every servo system ever fitted to a car there is a one way valve which prevents the vacuum being lost when the car is on boost. The only way this reserve can be depleted is if the driver is maintaining boost while applying full brakes, i.e.: left foot braking very badly. In this instance I would argue that depleting the vacuum is probably a good thing as it should provide him with a warning that he is doing something awful to the car and it may reduce the speed of impact when he finally hits something as the brakes fade to nothing!! In normal use the throttle is closed when the brakes are applied, there is therefore no boost and the vacuum is automatically replenished as it is used."

 

[k20Rob]

Since moving from my s1 I am finding the v6 brakes too over assisted for my liking, especially now I have pf08 pads and the bigger brake kit all round, I am finding them harder to modulate.

Im working on my braking technique, but is there any sort of plug and play cost effective solution for a bit less assistance? Im not looking to pull the car apart or anything, but could a smaller booster be swapped in at all?

 

 

[Maxi_z]

On 30/04/2019 at 17:34, Jack said:

Maxi, I don't believe that the Lotus standard Bosch ABS system that is found on the 380 vs older V6's is different.  As Bibs commented above, the stock system has been programmed to work with the  Lotus recommended R-comp tires of a given OD and with the stock variable traction control and DPM.  Once you deviate from that tire OD and significantly increase grip, the stock programmed ABS will be compromised.  Comparing two different cars will only reveal results if they are both driven by the same driver on the same track with tires are of the same condition (grip wise) and when ambient temps, as well as track conditions are identical.  What I'm trying to say is that numerous variables are at play when on track, which will affect braking and translate into a particular ABS system's effectiveness.  I guarantee that a 380 car/driver will encounter "ice-mode" or feel the ABS is be too intrusive under certain conditions....an individual's braking style is also a key variable in this equation.

Hi Jack

Thanks for your feedback as usual

Of course I don t know all the details on how the Lotus abs system work but I have to say that I felt the ice effect problem on the cup r on track with p zero trofe r tyres on the standard size

I don t know if the abs will also be triggled by the actual deceleration or loss of speed by some gmeter etc or only by the abs sensors on the wheels (of course a cup r with aero less weight and faster downshifting will loose speed on track when brakinge more than a street car) but I did drive both cars on my local track in the same conditions and with the same type of driving (but not the same day) so same driver same track and same driving style and also I was as agressive with both cars even if of course the cup r was a few seconds faster

I never had on the 380 cup that abs ice effect not even at mugello circuit when the circuit was still with some wet parts

But I m not saying that I know for sure that the programming is different as there might be other reasons just that on the 380 I never felt that while that I was told that the cup r could do that and I felt it at the first track session with it

Probably going for the bosch motorsport is the better solution but still I would like to know if there are differences or not with the later cars

 

 

 

[Maxi_z]

After using the exige 380 cup with the komotec 430 kit at the track I have to contraddict what I previously wrote

With the car going faster than before there is sometimes some ice effect from the abs but still it feels less exagerated than with the v6 cup r and it seems that with the 380 cup even if there is that effect you can still just keep pushing the brake pedal and it will come back to normal

Is that just because with the cup r you are faster or is there some sowtare upgrade on the 380 cup I don t know

 

[geartox]

On 30/04/2019 at 17:34, Jack said:

Even with my Motorsport ABS, I will select different levels/programs depending upon environmental conditions as well as tire degradation -- that's the beauty of having this magic rotary knob.

do you have links/docs about this ABS system in order to install it on Exige V6 ?

[Jack]

Sorry Nicolas for the late reply..... but I do not have any links/docs relating to the install of the Bosch Motorsport ABS system, as my local race shop did the work.

I do have a couple pics....

[<Rainer>]

Hi Jack,

are you sure that your ESP is still working? Would you mind sharing the contact details of your race shop?

Best Regards,

Rainer

[Jack]

8 hours ago, said:

Hi Jack,

are you sure that your ESP is still working? Would you mind sharing the contact details of your race shop?

Best Regards,

Rainer

Rainer, I have a V6CupR w/sequential and LSD-- no DPM from the factory, but I do have variable traction control which now works properly with my slicks since I've added the Bosch Motorsport ABS.

Given my change of tires from the R-comps  (which came standard on the CupR  and have  different ODs than the Yokohama slicks), the standard ABS system could not handle the extra grip, intervened excessively; and, perhaps more importantly, the way the ABS intervened was frightening.....like your brakes were virtually ineffective.  You would have to lift off and go back on quickly to reset the system.  The only way to drive around this abs deficiency would be to brake easy at first and slowly increase brake pressure.... not the ideal braking technique for track use.

Since going with the motorsport abs, the next step will be ditching the brake booster and going with a "pedal-box" to provide more granularity/resolution when applying the brakes.  The brake booster is virtually the equivalent of an "ON-OFF" switch, making precise brake pressure modulation quite difficult.

Not sure my race shop would be of much help as they are located in the US.

[<Rainer>]

Hi Jack, thanks for the speed reply. I'm just a hobby driver and probably not even a good one. I'm driving on tracks with Trofeos and also with a sequential with LSD. My major concern with the stock ABS is not so much the ice mode, which I only experience after jumps when accidentally braking while not all wheels have ground contact. Probably my braking technique is not yet ambitious enough to force the ice mode under normal conditions. The - in my eyes - limited corner braking capabilities are my major concern and I was hoping the Motorsport ABS could improve on that significantly. Do you know if your garage had to replace all the sensors (wheel speed, gyro, etc) or was it possible to use some of the existing periphery like loom and/or sensors?

Your plan with the brake booster sounds very interesting and I'm looking forward to hear more about it once you have it and If you don't mind.

Cheers, Rainer