June 14, 2006 SRT Engineering Thread

[a-mechanic]

On the LX srt why no limited slip? Is it mainly because of "esp"?


The LX has an open diff, but the BLD (brake locking differential) functions as the limited slip quite effectively. BLD is an algorythm of the ABS/Traction control system. You'll notice that the LX SRT8 lays two strips of rubber at the drag strip. It also works great on split coefficient surfaces. With one drive wheel on ice and one on pavement, the system has enough torque capacity to spin the high traction wheel.

Quaife has a limited slip that we have run successfully at One Lap of America and Targa Newfoundland in a pair of cars last year and for the short term, It might be an avenue that you want to explore. Quaife is located in San Juan Capistrano California here in the States.

 

[JonB]

MS....

With the AZ Proving Grounds going away soon, where will D-C test HOT? Starting when?




Any plans to race more Jets? Does Herb have a new driving suit? His faded-orange VINTAGE suit wont pass tech any modern race venue ! I bet he could AUCTION that HISTORIC suit at VOI......Ill open at $10, (and WAY MORE if autographs are included)
Jon, stay tuned. I'm told they still fly jets in Arizona. And we're taking up a collection to buy Herb a new driving suit.

 

[2002_Viper_GTS_ACR]

you should however consider decelerating on your own.

Ok that was funny.

PS. Get to answering all the other questions, that are in the back log now, I am not so patiently waiting .. like a kid in a candy store !! thx again !!

 

[Cris]

When ABS is in default what is the front to rear brake bias? Can it be adjusted to provide reasonable brake performance?


The ABS system has no pressure bias via a prop valve or similar device. Full pressure goes to the rears and the EBD (electronic brake distribution) algorythms control the amount of rear brake. The system is tuned to give a <100ft stopping distance from 60 mph and maximizes the capability of the monster rear tires. The system is tuned for the production chassis setup.

So you are saying that when the ABS is in default mode rear brake lock-up is almost guaranteed? Same brake pressure, same brake caliper and rotor with much less weight on the rear.


If your ABS light is on and the system has faults, it would be wise to get the system fixed and not drive the car at the limit. Depending on what component (which wheel speed sensor, ABS pump, etc...) is at issue, EBD will function to maintain brake bias if it can. EBD operates at lower slip thresholds than ABS, and dumps pressure to the rears, so the hydraulic pump does not necessarily need to be functional for EBD to work. Most newer cars use EBD to maximize front brake pad life and stopping distance performance. The ABS light won't just be on, but will flash if you have lost EBD.

 

[madman]

Please address the frame defect issues described in this thread http://www4.forum.viperclub.org/sho...ts&Main=691914&Search=true#Post691914

How to fix the arm hook?

Is it possible when the cam bolt was loosened then retightened that the cam over-rode the stops and bent the clevis opening??

 

[418viper]

Quote
"On question 4 FYI the trunk release on the key fob will work with the ignition on if the car is stopped and the park brake is engaged"

The issue here is when the Key FOB is accidentally locked in the trunk, happens quite often from the posts I have seen.

That is why we equip each car with 2 key fobs and two keys...

 

[Jay Herbert]

Related to a previous question:

Can factory options that do not affect emissions such as a rear diff. cooler, shifter, etc. be added at CAAP assembly in additon to being available only as Mopar Options?

 

[SRT Engineers]

Coupes are running about 2/3 of production.

 

[SRT Engineers]

How much weight would be saved by changing from late gen 2 rims to the new five spoke SRT rims?

We don't have the weights handy, but they should be similar.

 

[GR8_ASP]

Any thought or work to make a high temp / track compatible ABS sensor?
In all of our track experience with the Viper we have never had a temperature related problem with the sensor - how are you using the car.

Normal track use. I have been told it is a common failure with comp coupes as well.

 

[a-mechanic]

Has anything been discovered as to why cat convertors are dying and then killing motors(overheating one side and seizing the rings) on the 04-05 models? I put it this way because it has been my experience cats don't die they are murdered, and if so what is the fix/problem?
thanks

I'm assured that no animals were harmed during testing of the Viper...

I'm sorry, catalytic convertors.
thanks again.

 

[Cris]

Anything to say to our invasive vette Z06 friends who come here to inform us that the Viper cannot beat the Z06 in ANY performance category? Not exactly a high pedestal to respond from.


Bring it on. On the track, multiple laps. Notice how stock Z06s do in One Lap of America compared to Vipers.

 

[Tom Sessions]

Is there a way to turn off the low tire alarm on the srt viper. We have quite a few owners that run track wheels with us at viper days and would like to turn this off.
Thanks

From SRT - No not easily...

The best you can do is disconnect the TPM module (Schraeder Box) but that means you need to pull apart the instrument panel. Even at that the low tire symbol will still stay on steady.

You could put the ignition switch feed to the module on a toggle for a "Track Mode". And just turn back on once you are on the programmed street rims.

 

[Cris]

Can you reply with a color or bold or italics so we can quickly see what is the response? [color:red] something like this [/color]

[color:red] [/color] Test. Test. HTML does not appear to be working. Sorry


We are working on th

 

[SRT Engineers]

Related to a previous question:

Can factory options that do not affect emissions such as a rear diff. cooler, shifter, etc. be added at CAAP assembly in additon to being available only as Mopar Options?

We are continuously evaluating opportinites to bring new features into CAAP but we have to balance this with a thing called build complexity which affects quality adversely.

 

[SRT Engineers]

Hello?

 

[2002_Viper_GTS_ACR]

1. What is the difference between an srt-10 differential and a comp coupe differtial

2. Early diffs were more prone to breaking, what did you guys do to beef them up, and what year did that happen, and was anything done differently for the 06 model year?

3. Did the 2006 srt-10 Coupes get stiffer shocks or springs vs the srt-10 convertibles?

4. What are the weights of the 4 different types of srt-10 wheels

5. Any suspension changes for the 2006 srt-10 coupe over the srt-10 convertible, like sway bars, or any other type of suspension related change, or alignment difference?

6. How much more rigid is the 2006 srt-10 coupe over the srt-10 convertible?

7. What additional changes did the 2006 srt-10 coupe get, other then a hard top and subsiquent rear deck changes, anything in the interior, in the motor, in the driveline, etc?

8. 04 (i believe) at least 05 srt-10 and later vipers have knock sensors, are they actually being used, what is their purpose? Will they back out timing if knock is present?

9. from 03 to 06 srt-10/srt-10 coupes do the computers have any timing changes or fuel curve changes?

10. How much hp or tq can a srt-10 stock tranny, diffential, 1/2 shafts and clutch take before being at risk for breakage?

11. I dont suppose you guys have a clue on total production numbers for srt-10 coupes yet, ball park?


SRT Response:

Question 1: The Comp Coupe LSD Diff is a fairly expensive Ricardo race part very similar to what went to Lemans. The production unit uses clutch packs with an intergral pump which help to clamp the discs.

Question 2: We continually upgrade components as the engine power increases.
Metalurgy of selected components has been upgrade over the last few years.

Questions 3: and 5: Coupe and Convertible are the same.

Question 4: They are all about the same except for the Sidewinders (previously answered)

Question 6: Coupe is 30% stiffer torsionally

Question 7: Roof, sportbar, headliner, quarter panels, rear fascia, taillights, liftgate (duh), CHMSL, side glass, and some more details.

Question 8: Knock sensors pull out spark and then add a small amout of fuel under high temperature conditions.

Question 9: Fueling was adapted from year to year to meet increasing emissions testing complexities while maintaining engine output.

Question 10: Now you have to define what year the stock parts are from. If you believe a certain John from TEXAS, the driveline is bullit proof up to 800 HP although we would not agree. We apply the necessary upgrades when we raise up the power but cannot test with all the mods that our customers cleverly add on.

Question 11: Coupes are running about 2/3rds of this years production...

Jon

So I appeciate answers to SOME of my questions, what about the rest? Or are questions your not able to answer, just ignored?

Thx.

Jon

 

[Jay Herbert]

We are continuously evaluating opportinites to bring new features into CAAP but we have to balance this with a thing called build complexity which affects quality adversely.

As a Manufacturing Engineering Manager... have to laugh. We build in the 4 digit # of SKU's.... keep telling Materials/Scheduling/marketing that the changeovers are not good for line uptime.... you must have a more supportive scheduling group than me

Line uptime is not as big an issue with us as quality is. Remember, Vipers are hand build by craftspeople at CAAP so the mass production philosophy is foreign to us.

 

[Jay Herbert]

We are continuously evaluating opportinites to bring new features into CAAP but we have to balance this with a thing called build complexity which affects quality adversely.

As a Manufacturing Engineering Manager... have to laugh. We build in the 4 digit # of SKU's.... keep telling Materials/Scheduling/marketing that the changeovers are not good for line uptime.... you must have a more supportive scheduling group than me

Line uptime is not as big an issue with us as quality is. Remember, Vipers are hand build by craftspeople at CAAP so the mass production philosophy is foreign to us.

OK, ya got me.... line uptime AND quality. We designed to new line to do changeovers inside of one cycle.... and quality is designed in (DFM)... if it is not a good part.... it won't fit!