The good news is that the 996TT was awsome at the track. The bad news is that the C32's ESP malfunctioned on the front passenger side causing constant intervention even with ESP off.

We ran the Street of Willow CCW. I personally don't like this direction at all. I feel that although times are the same or a little quicker in this direction, the car is not as comfortable as running CW. Many of the turns become decreasing radius and require much slower entry speeds. However, the front and back straight through the esses are much quicker, hense the similar lap times.

The C32 failed from the start. We drove with ESP on the first few laps and noticed a consistant cutting of power everywhere and a loud clamping sound from the passenger brake pads. We turned ESP off and still had the same intervension to a lesser degree. The brakes were grabbing on the passenger side for almost the entire lap when ever the car was turning. I don't think it is a brake issue, but a ESP problem. Two conclusions: 1) that the differential of tire circumference was too great and the computer sensed constant wheel spin. The fronts are down to 2/32 shaved and the rears are brand new at 10/32 unshaved. That is only a .25" difference and shouldn't cause a problem but it could. 235 40 18 = 25.40". 265 35 18 = 25.30. That would mean that the worn fronts were at about 25.15" or a difference of .15" front to rear which should be within tollerance. 2) the wheel speed sensor is defective, damaged, unplugged, or something else that is causing it to send a signal to the computer to put on the brakes at that wheel. No other ideas at this time. Never had this problem a few weeks ago at the same track CW. What do you think?

The brake pad warning light came on towards the end of the session and we heard a loud noise at the front wheel area. We came into the pits to change the pads, thinking that the worn pads could have something to do with the problem. Passenger brake pads were smoking and these are Pagid Orange. We cooked the pads and used them beyond there operating temperature. After removing the pads, there was still about 1-2mm before sensor contact, so they were ready to be changed anyways. But why the warning? The sensor got too hot and melted? The brakes seemed to be fine. We bedded in the new pads with ten 60-5 stops back to back and then two stops from 80-5 and one stop from 100-5 and the brakes were feeling great so not a brake issue we think. Back on the track next session with ESP off, same thing and off pace by five seconds! Car not controllable and would not go where you wanted it to. Continued to drive the car to figure out the problem throughout the day but it persisted. Interestingly, the car in a straight line had flawless braking power. Speeds at the end of the straight were consistantly in the 110+ range down to about 30mph with no hint of fade at any time. The calipers changed color twice in one day finally settling on a dark shade of bronze. All I can say is that the stock brakes would have disintegrated with this much abuse. Kudos to Stoptech for an excellent BBK that withstood the demands of a world challenge car on this day. This ESP behavior cannot be duplicated on city streets, but only on a series of corner changes back to back which will be hard to duplicate on a public road until the next track day.

My frustration was calmed by the use of our 996TT for the day. Great car that ran consistant 1:33-1:34's all day long. After the first session the brake pedal was all the way to the floor with no pressure. Boiled the fluid I guess. After 30 minutes the brakes came back and we took it easier on them and they lasted the whole day without fad, although a slightly weaker feeling pedal since we were now under wet boiling point restrictions. This car had to be controlled to stay under 120mph at the end of the straight in order to make the first turn! A few drag races with the C32 proved that the turbo was faster but not by much, about 1.5-2 car lengths by the end of the straight. The 996 has a terrible case of understeer even with stability program turned off. A far better ride than the C32, but could use some help to be a serious track car. All in all, the suspension set up was great right out of the box for the street and light track duty, and very fun just the way it was. I would own this car in a heart beat. The camber settings are perfect and the P Asimetrico's were worn evenly across the tread. The tiptronic transmission is fantastic and shifts just like a manual, although I wish shifting could be done from the shift lever and not just the steering wheel which you cannot operate when turning beyond a quarter turn. The twin turbos spool up very nicely without feeling the boost of previous single turbo engines. I wish the C32 was working correctly to get a comparable time to the 996 in this CCW direction.

Any ideas as to the failure of ESP?

 

re your ESP problems: sounds like you are looking at the right places.

The wheel speed sensor is is a likely culprit. Mine failed after a car wash and threw a code, the TelAid guy said should self-heal and it did. Obviously mine was a wet connection in the wheel area. The sensor connectons are not the greatest design. You would think that would persist though.

The ESP program must be using math based on the OEM tires, which are not the same size f/r, so keep your differences from OEM in mind.

I'll add that you probably changed your brake fluid, maybe you had some air or contamination on one side.

One would think the car with just a driver would prefer CCW vs CW. But you drive with a passenger? Do you think you could have been lifting the passenger side tire in the CCW?

 

Stock tires are 24.97 front, 24.71 rear, or about .25" greater in the front. The Toyo's are 25.40 front, 25.30 rear, or .10" greater in front. With the worn front, I am 25.15 front, 25.30 rear, or .15" great in the rear. So stock to current front difference is .18", and stock to current rear difference is .59". The total difference is .41". Toyo to Stock differences at full tread is only .16". Typically in a plus one size upgrade, you don't want to exceed .50" in rolling circumference. Are MB's ESP/ABS computers that sensitive?

Although more than a second slower, we have been driving with a passenger in the car to evaluate the modifications made and take subjective notes during each session as both a driver and passenger. At SOWS, going CCW, most of the problems occurred turning left whick loaded the passenger side front tire, so I believe wheel lift is not a problem.

When cleaning the wheel's interior surfaces with a long brush, great car is taken not to hit the pad sensors which are in plain site on the BBK. I am unaware as to the location of the wheel speed sensor and may be hitting it during cleaning or adjusting the RS suspension valve settings. I will take a look this week.

 

The more thay I think about this I feel it is the rolling diameter difference, ie the ESP is that sensitive. My reasoning:

1) we all know ESP seems very intrusive, and it really cannot be totally disconnected.
2) when you load the passenger side tire you are decreasing the rolling radius even more, aggrivating the rolling differential.
3) Tire shaving/differential is one of the few variables you changed.
4) a sensor connection failure should act differently, ie cause a hard code, act up on the city streets etc.

Good luck

 

steve,

I have had the same exact ESP problem when I run my victoracers shaved with esp. I did not have this problem with my Toyo Street tires on the same track. I actually thought that it was normal because ESP programming was not able to cope with the slide characteristics of the tire but now I realize that it may be because it was shaved. However if it is the tread depth that is the problem then that would stand to reason that if we reduced the height of the tires this same problem would happen. Has anybody tried this? I was planning to on my next set but instead just reduced the width instead to play it safe.

I have had my ESP module replaced once before in my car and I always thought that I had an overly sensitive module but it appears that maybe all of them are that sensitive.

Were you running R comps? Is this the first time doing so with this car in a shaved configuration?

I did not have that brake problem you are describing though. But depending on the design of the brake sensor the excessive heat can melt the sensor and thereby thinking that the brakes are worn. This actually happened on my Axxis pad because the heat melted the link on the sensor. I had over 50% left. I actually couldn't pull it out without taking out the brake pad. Thankfully I used up my pad the same day so I had to change it anyways and now I just use a heat resistant tie wrap and tie the sensor to the brake line. The air flowing through that area ensures that the sensor won't melt.

Also have you had a problem with the inside pad wear out faster than the outer pad? That happened to me on my brakes and it caused me to actually score my rotor accidentally because I only inspected the outside one and thought I was ok.

Prasith

 

Doesn't dyno mode disable ESP completely? I know when I've tried it the dash lights up red with a warning saying ESP is disabled.

 

If it is a diameter difference between the front and rear you would think that the ESP would be braking the front wheel not the rear, since the fronts are smaller in diameter.

 

It was the front wheel that was the one acting up. I am still running the Toyo T1-S's except this time I kept the shaved fronts on from last track session. They started at 5/32's and ended up between 2/32-3/32, so that is where I started the other day. Since the rears were bald from drifting I only replaced the rear and decided not to shave them because tire wear is very good on the rear. There is no feathering and even wear across the tread. The rear camber is on average between the two sides about 1.5 degrees negative. In fact the insides wear a little faster than the outsides. So this is what was changed from before. Maybe it is the problem. But I am also getting a periodic noise from the front hub like a diesel sound ticking sometimes, then it goes away. At the track we heard a loud band and then the pad sensor light came on. On the BBK, there is always some noise with the two piece rotors and the slotted design. It also takes a few corners to push the pistons back into their caliper housing after braking, but this noise was different. My pad sensor was melted within the pad and required a screw driver and a hammer to remove it!

The problem was more pronounced with ESP off as you could feel and hear the pads clamping off and on. With ESP on, the intervention was more consistant and therefore you could not feel the engagement as much. Either way it was significantly more than last time out. The problem with new front tires at full tread depth is that they will chunk. Last time out, I had 5/32 fronts with 1-2/32 rears, so the rears were spinning a little faster than the fronts but this did not seem to affect ESP's functioning.

 

Hey Vadim, any ideas? I stopped by on Saturday to see you at Willow Springs, but you were not there and Brad was on the track. Thanks Simon for speaking with me. We though about pulling out all the fuses for ESP but there are about 4 or 5 that would affect other functions of the car. Maybe we are just driving the car too hard for such a tight course. The Porsche didn't mind it though!

It was fun to observe your track day participants. The collection of Radical's on hand was impressive and they were very competent on the track. It was fun watching the 911's turning 1:20's! and the two Evosport BMW's were very competitive amoungst the competition. You guys always put on a great track day.

Like brake pads, gloves must have sufficient material to prevent heat transfer which I proved when changing pads with old gloves that were not up to the task and acutally burnt a hole in a few fingers. Here is a pic of the brakes after the first session. Later that day, the calipers were considerably darker.

 

Here are some of my observations. On my C43 when I had 245/40/17 fronts and 255/40/17 rears on I did not have this problem on my favorite back roads and the Cruise Control functioned great. Since changing to Victoracers, 255/40/17 front and 275/40/17 rear my Cruise control does not work and the ESP stability control kicks and applies the brake to the left front on right turns and the right front on left turns. The ESP think the car is going into oversteer and is appling the proper braking action to correct.

A short term fix has been to back off the rebound damping of my Penske shocks in the rear to allow the rear tires to stay in better contact with the ground and this has greatly reduced the ESP stability control intrustion. If the rear shocks on your C32 are adjustable for rebound damping I would try softing the damping rate in the rear and see if this reduces the problem.

Jeff

 

Jeff,

I think this is exactly the same issue you had with your C43. I felt the same thing happening as I drove SMG's car. As you roll into corners, the car would begin to "drift" just a tad and the car would brake the outside front wheel in an effort to correct for oversteer. The streets of willow has more right hand turns and this explains why the ESP system cooked the right front brake. As the car tries to correct for the non-existent skid.

I actually had this same idea for the car felt a tad "lose" and I thought the shocks could be set to soft up front or to hard out back, thereby causing the car to be tail happy. When all checked out ok, I personally felt it had to be tire size causing the issue here. All else worked fine at the track the last time and the tires were the only item to be changed since then. So I think new fronts should solve the issue but SMG still doubts my thoughts.

Maybe ill have to have 2 tires delivered to his door for testing before he believes me.

Thanks for the input. I’m always glad to hear from fellow MB track day users.

This should help solve the issue. Time to get a set of Sport Cups for the C32. Have you ever used these tires on your C43?

 

Interesting commentary that makes sense. But... why does the car continue to exhibit this unwanted behavior when ESP is off and you should be allowed to get some attitude in the corners? It did not happen running CW. Are speeds did seem to be faster entering the corners CCW and this could have been the problem since the track CCW is decreasing radius, we needed more steering imput than CW and this may have triggered ESP even though it was off. The car did not want to break loose in the tight corners when applying throttle like it did going CW. Still makes no sense to me. Two track days previous, we were running a brand new front passenger tire, and a half worn driver's front tire with no problems CW. I will change the front just to eliminate the variable, but I still think there is some problem. What was the loud "pop" noise that we heard at the track when the warning light came on. What is the strange noise I hear occationally on the street? Is the hub bearing shot?

Cost to track a C32 has just gone up!!

 

SMG,

This is one of the many problems we will face in trying to track a car such as this with no way to turn off stability control in total. There may not even be anything wrong with your car. It is totally possible that turning left in a CCW direction at SOW just brings out the worst in the C32's ESP/ASR/BAS/ABS controls.

So I guess you try to see if tire diameter differences front to rear fix the issue by changing sizes. If that does not fix it then you might disable ABS and check your brake balance to see if maybe the right front locks up sooner than the others.

Otherwise you could be looking to get this fixed at the dealer. Although with no codes being thrown they will more than likely be of little assistance. With Steering Angle Sensor, Accelerator Pedal Position, Yaw Rate Sensor, Lateral Acceleration Sensor, Brake Pressure Sensor, Wheel Speed Sensor all contributing to the ESP calculation this could be a nightmare to figure out. Then again it may be software and could never be fixed.

 

what is the "real" difference in the hardware/software of the c32/c55 Formula-1 Medical cars? I'm sure that they are "different" than ours. Also, since the new c55 supposedly has a "less-intrusive" ESP program why can't we flash this and at least start with that as a new reference point?

 

actually I just realized that you mentioned this happens when turning left.

That is exactly when it happens to me as well. It happens only with my shaved tires and not with street tires. The ESP kicks in when I try to power out of turn 12 in NHIS - the one that leads to the main straight. It is a left hander and not an especially tight one but it comes right after a chicane so the car is a little unbalanced but when I try to hit the apex and power out ESP goes crazy - no loud sound from the brakes but that may be because I have the stock kit.

This drives me crazy because it cuts power for the straight which is the only straight on this course.

Steve take a look at this track map and let me know if it is a similar configuration.

Look at turn 11 and Turn 12. I get some ESP in turn 10 too but not as bad as in turn 12.

It may just be our system and the braking sound could be the use of ESP with your BBK and slotted rotors.

 

 

noel,

how are you? I came to the school in May but you weren't there. I wasn't able to make the school last week because something came up at work at the last minute on Sunday night before school. I sent Alvin an email on that night but it was really too late to let anybody else go in my stead I guess.

Will you be in the fall school?

We should meet up sometime.

Prasith

 

Prasith, are you running with ESP in the OFF mode? and this is still happening?

 

Steve,

Yes esp is off via the button on the dash.

And when this happens I get some feedback on the steering wheel as ESP usually does. It happens only on that turn.

I didn't turn it off via the dyno mode which doesn't seem to work for me still.

Prasith

 

Shut all your commputer's down and you will go very fast like the M3!

 

It is my understanding that you cannot completely shut it down unless you remove it! You can disconnect the ABS connectors and pull some fuses but the other systems are always standing by in the wings. Very frustrating.

 

I told this to carvin also but there is a ESP sensor on the trunk. It's under the carpet . It's a gyro sensor that detects yaw and pitch. I can check WIS again and comfirm this. If you pull the plug, you should get a message that states "ESP NOT AVAILAVBLE, VISIT WORKSHOP"

 

Noel,

How can we shut all the computers down? Do you mean the dyno mode? Then we lose ABS too which I wouldn't necessarily want at this stage. I am not anywhere near as good a driver as you are.

Sunman,

With the sensor does this mean that esp will no longer cut power? What about ASR? What other functions will we have? I assume that this will not do anything to ABS. That would be ideal but then I assume our car will act like a car with no LSD which is what it basically is except for all that computer mumbo jumbo.

Prasith

 

YOu can try it. It won't hurt. The sensor is a rotational force sensor used for ESP. THe main ESP computer is in the engine compartment drivers side attached to the ESP Hydraulic Unit. (the one with all the metal pipes coming out. YOu can disconnect that and you have completely disabled ESP.

 

Just checked WIS, ESP and ABS are combined in that one unit. Better leave that connected then