Video - Track Braking Incident

[GR8_ASP]

Just finished uploading a video of an incident I experienced last week at the track. In essence I lost the ABS function unknowingly and my first indication was a sudden drift to the left when applying the brake at the braking point on the front straight (approx 125 mph). Took a second to recover the drift and then applied life/car saving maximum braking. I studied it under very slow motion and found the tires were spinning at a very slow rate - thus no flat spotted tires.

Note I have changed to 18 inch wheels all around with Sport Cups. I lost ABS many more times as the day progressed. To date I have not determined the cause. The fault code each time was RR speed sensor signal failure. Any ideas?

Video Link

 

[Early93Viper]

Re: Track Braking Incident

Glad to hear you didn't flat spot your tires. Sometimes I wish I had ABS as threshold braking seams to be my biggest hurdle on the track.

Hope you find out what the problem is.

 

[Kai SRT10]

Just finished uploading a video of an incident I experienced last week at the track. In essence I lost the ABS function unknowingly and my first indication was a sudden drift to the left when applying the brake at the braking point on the front straight (approx 125 mph). Took a second to recover the drift and then applied life/car saving maximum braking. I studied it under very slow motion and found the tires were spinning at a very slow rate - thus no flat spotted tires.

Note I have changed to 18 inch wheels all around with Sport Cups. I lost ABS many more times as the day progressed. To date I have not determined the cause. The fault code each time was RR speed sensor signal failure. Any ideas?

Video Link

I had this happen to me my first time out after I switched to the 18 inch wheels. Turns out there was a loose screw that holds the speed sensor that needed to be tightened and locktighted with heat resistant locktight. Haven't had any issues since.

 

[Steve 00RT/10]

Hey Ron,

Where's the credits for the video taker I know it's not a professional job, but she was doing a few cameras for us all.

Steve

 

[GR8_ASP]

She is on the credits for your copy

 

[Viper X]

Hasn't happened to me yet, but I have heard that the loose screw deal that Kai mentioned has happened to others.

These cars vibrate a bunch when tracked. It seems like I'm always tightening something.

Good luck,

Dan

 

[GR8_ASP]

I just saved a better version - higher speed but a bit bigger file. Dial-up beware.

New Video

 

[GR8_ASP]

I will check the screw tomorrow. I have a replacement sensor on order as well.

 

[nazology]

What do you run at gingerman if you dont mind me asking. Lap time?

 

[GR8_ASP]

With stock run flats about 1:33.

This year I never really got going. From PCV puking early and then the ABS issue I really never got a run at it. Once the ABS failure occurred I never trusted it as it failed 8 times that afternoon. None as exciting as the first as I was watching for the idiot light after that. But I gave it extra braking distance in case

We replaced the sensor this morning. The screw was tight so that was not it. Since it has not gone of on the street I may not know until another track event if it is okay. Early on it did seem to trip during a corner where I did some slight rear wheel spin (all right handers). For those that drive the SRT without a quaife you know that in a turn you spin the inside rear before the rear breaks loose. I believe that occurred before some of the incidents. Not sure if it did before all of them.

 

[Racer Robbie]

I was talking about the abs system in vipers with Luke at The Tire rack a month ago and he says the system is argaic in design. It only measures wheel spin every 1/4 turn. This should explain why you lost traction when braking as if it was not at the proper point in the tires rotation the abs becomes useless.

 

[GR8_ASP]

No, the ABS system turned itself off completely due to a fault. When off the front to rtear bias is terrible and causes the rears to lock first, thus resulting in the sudden direction change. When the ABS system is operational it is very good. It does give a bit of wandering due to the frequency response but excellent braking overall.

 

[Racer Robbie]

That makes a lot of sense. I was just telling you what Luke had told me though it sounded a little fishy at the time as he was trying to sell me tires with a different front to rear bias than stock. Glad you saved the car, it shows that you are a very good race car driver.

 

[Janni]

Luke has no business discussing a very technical and proprietary ABS system that can stop a 3400 pound car from 60-0 in less than 100 feet and calling it archaic. Jeez.

 

[ROCKET62]

Since no one else asked - what brake fluid you were using? Not sure if/how this would effect the ABS.

 

[GR8_ASP]

Not sure how brake fluid would impact it either as I had good brake feel through it all. I use a standard DOT 4, with a fluid flush 1 week before the track day.

 

[kickinasp]

Ummmm, being I have worked on the Conti-Teves ABS brake system that is the same model as the Viper (for Jeep)MK20e, I will suggest you dont know what the hell your talking about. There are 41 tooth tone wheels are the four corners of the vehicle that control wheel lock down to 3 MPH. That is NOT ever 1/4 turn but rather approximately every 9 degrees. The loop time on the software is 10 msec, and the control aligorithm operates every 20msec. While the Viper does not have ESP, this is the state of the art ABS system. Ron and myself have talked and at the time its one of two things. When the system detects a fault, it shuts down ABS and lights the lamp on the dash. It also records a fault. Read the fault and it will tell you what the issue is. Its either a intermittent speed sensor at one of the wheels, and that could be due to being loose or temperature effects. Its a hall-effect sensor so excess temperatures can effect it. You are running the same size tires now, versus 18 & 19, so the system calibration is off. It is calibrated to see 807 Revs per mile on the front and 757 on the rear. Having the same size tires can effect this calibration. So the system could be shutting down (I doubt it) for the reason of this mis-match. I have a call into Conti...but if it were shutting down due to the mis-match I am pretty sure the fault code set would be Incorrect Tone Wheel Failure, which is the one called out for the "tire size that does not meet specifications". Obviously it takes a period of time for the module to detect this situation versus you spinning the hell out of the rear tires versus the front.

 

[GR8_ASP]

Thanks Jim. The fault was an intermittent speed sensor signal as we discussed. Saturday we checked and could find nothing wrong with the mounting. The sensor was replaced as a inexpensive precaution. I have not had the fault since I left the track. If it ever dries out here I will take some aggressive corners with inside tire spin to see if I can recreate it. Gingerman has more right turns and I believe I had significant tire slip before several of the occurrences, including the dramatic one. In turn 11 I definitely experience slip as I tend to ride over the inside apron, which is tapered.

Note I also had a DRB on when driving around and the speed signal is consistent, albeit inaccurate based on the tire diameter difference. I sure hope it is not a calibration type issue. Not sure if you were able to determine if the comp coupes had a different cal as they come with 18" all around.

 

[Chuck 98 RT/10]

I'm not sayin' a word.

 

[SylvanSRT]

come on chuck what do you want to say i'm quite curious

 

[SCLSSRT10]

It is not a calibration issue. I have been running 18's front and rear for three years and never had any problem. I have however had problems with the sensor wireing which was detected and then shut down the ABS. Beleive me it is a litte scary when you lock up the wheels in turn 17 at Sebring. We replaced (thanks to Russ @ Archer Racing) the right rear sensor and the problem disapppeared. Moral of the story is keep an extra front and rear sensor in the trailer you WILL need them some day.

 

[GR8_ASP]

Steve I think that is the conclusion we are coming to. I did replace the right rear sensor last week.

Kickinasp (see above) verified the cal can handle the difference in tire sizes and not cause a system fault.

And I know about scary. Mine was turn 1 at Gingerman. I have been informed to use stock rear pads in place of Brakeman 3's, while using the Brakemans up front, to minimize the front to rear bias issue in case this occurs again. That is my plan for the next time.

 

[Racer Robbie]

Hi Kickinasp. I do not understand why you say I do not know what I am talking about. I said from the beginning that what I posted were Luke's at The Tire Rack's comments during a conversation we had on the phone and not my opinion. So saying "I will suggest you dont know what the hell your talking about" is not fair to me.

 

[Casey 111]

Glad to hear you and the viper are both safe! BTW those wheels look amazing on it.

And for anyone watching the video...if your to impatiant to watch the hole thing, the incident is at about 3:00 min.

 

[Vic]

With 41 teeth on the "tone wheel", it would be highly improbable that the processor only detects every 1/4 of wheel rotation.

Some people sound so assinine when they try to talk technical. (Luke the Tire Rack genius)

 

[GR8_ASP]

I really do not want to get into a technical argument here as I know just about nothing of the ABS system (other than the apparent weakness of the ABS sensors to temperature).

However, inputs such as the tone wheel sensors are only one factor with the output frequency. That is the output may be limited by processing, valve actuation speed, or other factors. In most situations the input frequency is not the limiting factor.

Also remember that the reference to Luke was second hand. The only person here with first hand knowledge is Atro, and he may have misinterpreted or misconstrued things.

 

[Racer Robbie]

"Also remember that the reference to Luke was second hand. The only person here with first hand knowledge is Atro, and he may have misinterpreted or misconstrued things."

Call Luke and ask him about the srt vipers abs system if anyone here has any doubts.

 

[GR8_ASP]

I will. But I seriously doubt that he will say he has experienced the braking first hand. I have.

 

[Racer Robbie]

I am sure you are quite correct that he has not experenced that scary ride first hand. I would not want to at my old age.