914RS4 Tube Chassis 996 Suspension Audi 2.7TT Stage 3, ADDED RECAROS Options

[Andyrew]

ABS triggers a chime in the back of the cluster that I disconnected manually. Air bag light is on, but the check engine light doesnt come on as all the sensors not used have been coded out.

I'll be putting some resistors for the air bag light or simply remove the bulb. I plan on using the ABS stuff from the Audi so that light will stay in.

I wonder how hard it would be to use the 996 ABS system in my car. I have the entire system. Huuuuuuum. We need to talk.

The audi ABS system is incorperated into the stability control system
It uses the steering wheel angle, the abs wheel speed as well as 2ea yaw sensors.
What it does is it has a pump that constantly primes the ABS box and when it senses a situation that it needs to apply brakes to a wheel it will, on top of that it is connected to the ecu so it can shut off throttle or reduce it as needed. Its a fully self contained system that only requires those parts and runs off a separate ecu. Since you have a full spare car I would suggest ripping out the wiring harness in tact and stripping all the non essentials off. Thats what I am doing.. I started with the dash and engine harness and. I have the body harness stripped mostly down.

Good luck! This was a primary part of my build. I designed my build to incorperate this as I feel the 914 could benefit from both abs and stability control at this performance level.

[Curbandgutter]

Rudy - ABS is for wussies...REAL men lockem up at great speed; REAL drivers do it occasionally too. You do not need braking nannies... (IMG:style_emoticons/default/poke.gif)

T

ABS triggers a chime in the back of the cluster that I disconnected manually. Air bag light is on, but the check engine light doesnt come on as all the sensors not used have been coded out.

I'll be putting some resistors for the air bag light or simply remove the bulb. I plan on using the ABS stuff from the Audi so that light will stay in.

I wonder how hard it would be to use the 996 ABS system in my car. I have the entire system. Huuuuuuum. We need to talk.

(IMG:style_emoticons/default/stirthepot.gif) (IMG:style_emoticons/default/stirthepot.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif) Dang T.......lotta T in that post.

[Curbandgutter]

Jim I think I may just give the 996 ABS a look. Is this the system that I should be looking at? It is a 2 pin connector.

[Andyrew]

That 2 pin connector is the ABS pump for the stability control system. Basically it primes the ABS box to allow for the system to hit any of the brakes at any time. Its similar to the Audi pump in design.

The first pic is the ABS box. That takes a multi pin connector, similar to the Audi. (See below)
(IMG:http://www.914world.com/bbs2/uploads_offsite/msroadrace.com-172-1488222891.1.jpg)


Your going to have a 10x easier time if you use the Audi stuff as your donor chassis is already wired for it.

[jd74914]

Interesting-I haven't seen one like the second one before (note that I have almost no 996 knowledge). People call it the pre-pump? Not sure exactly what it does except that it's for PSM.

The one the 951 guys use is out of early Boxsters (and maybe 996s since it does have a 996 P/N) and looks like this:

[Cracker]

...and? (IMG:style_emoticons/default/confused24.gif) (IMG:style_emoticons/default/shades.gif)

T

(IMG:style_emoticons/default/stirthepot.gif) (IMG:style_emoticons/default/stirthepot.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif) Dang T.......lotta T in that post.

[jd74914]

That 2 pin connector is the ABS pump for the stability control system. Basically it primes the ABS box to allow for the system to hit any of the brakes at any time. Its similar to the Audi pump in design.

The first pic is the ABS box. That takes a multi pin connector, similar to the Audi. (See below)

Your going to have a 10x easier time if you use the Audi stuff as your donor chassis is already wired for it.

Andrew beat me!

The thing I worry about using an Audi unit vs. Boxster is that the two must have different vehicle dynamics "models" built into them. They both seem to use essentially the same hardware, but I'm sure Bosch has each programmed for the specific vehicle. I'm not sure about Audi weight distribution, but the fact that it is AWD means that there is definitely a different front axle response model which likely has some corrections for reduced lateral grip while applying power. It might work great though-the engineer in me is a little conservative. (IMG:style_emoticons/default/laugh.gif)

[Andyrew]

That 2 pin connector is the ABS pump for the stability control system. Basically it primes the ABS box to allow for the system to hit any of the brakes at any time. Its similar to the Audi pump in design.

The first pic is the ABS box. That takes a multi pin connector, similar to the Audi. (See below)

Your going to have a 10x easier time if you use the Audi stuff as your donor chassis is already wired for it.

Andrew beat me!

The thing I worry about using an Audi unit vs. Boxster is that the two must have different vehicle dynamics "models" built into them. They both seem to use essentially the same hardware, but I'm sure Bosch has each programmed for the specific vehicle. I'm not sure about Audi weight distribution, but the fact that it is AWD means that there is definitely a different front axle response model which likely has some corrections for reduced lateral grip while applying power. It might work great though-the engineer in me is a little conservative. (IMG:style_emoticons/default/laugh.gif)

The way I see it, if race guys strip out the vehicle to weigh 1k lbs less than factory the ABS should perform the same. Stability control should perform the same.

I see the system responding to grip loss. Yes there are yaw sensors involved as well as steering angle but that will only tell the system where the car is trying to go and adjust throttle and brake in such a way to counter it.

The biggest thing that I wanted to make sure was correct for my vehicle was that I used the same size ABS teeth count for the rear as was OE for the system, so that if the system tries to read wheel speed and correct it wouldnt be dissimilar to anticipated wheel speed.

Same goes for the front of the vehicle. I run smaller overall tires in the front than the rear by a considerable margin. I would want the teeth count of the front ABS to match that ratio appropriately as the Audi runs the same size front to back.

So long as that is good, I imagine the system should be able to compensate for the weight/power balance differences.


Regarding AWD vs RWD and its limits for throttle imputs at the edge. An AWD based car has more mechanical grip on power ramp and therefore I would imagine that the base of the system would have a tendancy to oversteer on onset and then the system would bring it down when it noticed the rear wheel speed being significantly higher than the front.

[Curbandgutter]

That 2 pin connector is the ABS pump for the stability control system. Basically it primes the ABS box to allow for the system to hit any of the brakes at any time. Its similar to the Audi pump in design.

The first pic is the ABS box. That takes a multi pin connector, similar to the Audi. (See below)

Your going to have a 10x easier time if you use the Audi stuff as your donor chassis is already wired for it.

Andrew beat me!

The thing I worry about using an Audi unit vs. Boxster is that the two must have different vehicle dynamics "models" built into them. They both seem to use essentially the same hardware, but I'm sure Bosch has each programmed for the specific vehicle. I'm not sure about Audi weight distribution, but the fact that it is AWD means that there is definitely a different front axle response model which likely has some corrections for reduced lateral grip while applying power. It might work great though-the engineer in me is a little conservative. (IMG:style_emoticons/default/laugh.gif)

Jim, yes I was thinking about that as well. I'm not sure if they have a vehicle dynamic model built into the ecu or it's purely a comparison between wheel speeds?

Andrew, I have both systems so I'm not sure which way to go yet.

[Andyrew]

https://www.dropbox.com/sh/jux2hzn05strpsf/...1AWCaVbX_a?dl=0

Some required reading on Audi ESP (IMG:style_emoticons/default/smile.gif)


Also, some wiring info for you all if you wanted to know.

https://www.dropbox.com/sh/ot2v0w9h84a1ydl/...aaSqeQ5Fma?dl=0

[Curbandgutter]

https://www.dropbox.com/sh/jux2hzn05strpsf/...1AWCaVbX_a?dl=0

Some required reading on Audi ESP (IMG:style_emoticons/default/smile.gif)


Also, some wiring info for you all if you wanted to know.

https://www.dropbox.com/sh/ot2v0w9h84a1ydl/...aaSqeQ5Fma?dl=0

Wow Andrew......good stuff!! Decisions decisions. If I go with the Audi steering wheel, then it will have the turning angle unit built in, the g meter is under the seat, wow seems like it may be something to really look into. It seems that the vehicle dynamics is not built in but rather it's a real time sensor system that is continually monitoring an that will aid in the anti lock braking but will also will also brake a single wheel to help the car in over steer and under steer conditions. I'll have to really think this through.

[csdilligaf]

Man you guys and your wiz bang technology. I am anti-tech. I want minimal things that don't break down or have to spend a month to sort out. But that's just me, I'm still trying to conquer posting from my Iphone.

[Amenson]

https://www.dropbox.com/sh/jux2hzn05strpsf/...1AWCaVbX_a?dl=0

Some required reading on Audi ESP (IMG:style_emoticons/default/smile.gif)


Also, some wiring info for you all if you wanted to know.

https://www.dropbox.com/sh/ot2v0w9h84a1ydl/...aaSqeQ5Fma?dl=0

I work for Bosch and developed ESP for 12 years. I would strongly recommend that you not try to adapt ESP to your vehicle. Even if you were able to get a fault free system (which you won't) the control will be uncomfortable at best and likely dangerous. If you want to discuss in more detail, PM me your phone number and we can chat.

Otherwise, awesome project! (IMG:style_emoticons/default/smilie_pokal.gif)

[Andyrew]

https://www.dropbox.com/sh/jux2hzn05strpsf/...1AWCaVbX_a?dl=0

Some required reading on Audi ESP (IMG:style_emoticons/default/smile.gif)


Also, some wiring info for you all if you wanted to know.

https://www.dropbox.com/sh/ot2v0w9h84a1ydl/...aaSqeQ5Fma?dl=0

I work for Bosch and developed ESP for 12 years. I would strongly recommend that you not try to adapt ESP to your vehicle. Even if you were able to get a fault free system (which you won't) the control will be uncomfortable at best and likely dangerous. If you want to discuss in more detail, PM me your phone number and we can chat.

Otherwise, awesome project! (IMG:style_emoticons/default/smilie_pokal.gif)

So does that mean you can help us develop slip angles and modify the bosh HEX codes? (IMG:style_emoticons/default/evilgrin.gif) (IMG:style_emoticons/default/idea.gif)

[Amenson]

https://www.dropbox.com/sh/jux2hzn05strpsf/...1AWCaVbX_a?dl=0

Some required reading on Audi ESP (IMG:style_emoticons/default/smile.gif)


Also, some wiring info for you all if you wanted to know.

https://www.dropbox.com/sh/ot2v0w9h84a1ydl/...aaSqeQ5Fma?dl=0

I work for Bosch and developed ESP for 12 years. I would strongly recommend that you not try to adapt ESP to your vehicle. Even if you were able to get a fault free system (which you won't) the control will be uncomfortable at best and likely dangerous. If you want to discuss in more detail, PM me your phone number and we can chat.

Otherwise, awesome project! (IMG:style_emoticons/default/smilie_pokal.gif)

So does that mean you can help us develop slip angles and modify the bosh HEX codes? (IMG:style_emoticons/default/evilgrin.gif) (IMG:style_emoticons/default/idea.gif)

It is a bit more complicated than you are thinking.

How about this, if you come anywhere close to describing how to accurately determine the speed of the body (in order to calculate wheel slip) while driving uphill with the wheels spinning, I will give you some offline hints on how to get ABS to work on your project.

Edit: The vehicle is AWD with open differentials.

Have fun,
Scott

[Curbandgutter]

https://www.dropbox.com/sh/jux2hzn05strpsf/...1AWCaVbX_a?dl=0

Some required reading on Audi ESP (IMG:style_emoticons/default/smile.gif)


Also, some wiring info for you all if you wanted to know.

https://www.dropbox.com/sh/ot2v0w9h84a1ydl/...aaSqeQ5Fma?dl=0

I work for Bosch and developed ESP for 12 years. I would strongly recommend that you not try to adapt ESP to your vehicle. Even if you were able to get a fault free system (which you won't) the control will be uncomfortable at best and likely dangerous. If you want to discuss in more detail, PM me your phone number and we can chat.

Otherwise, awesome project! (IMG:style_emoticons/default/smilie_pokal.gif)

Wow thank you got your input Amenson. Looks like I may be back to 996 3 channel abs at most. Or just screw it and go without abs. That was my original direction anyway. Thanks again.

[Andyrew]

https://www.dropbox.com/sh/jux2hzn05strpsf/...1AWCaVbX_a?dl=0

Some required reading on Audi ESP (IMG:style_emoticons/default/smile.gif)


Also, some wiring info for you all if you wanted to know.

https://www.dropbox.com/sh/ot2v0w9h84a1ydl/...aaSqeQ5Fma?dl=0

I work for Bosch and developed ESP for 12 years. I would strongly recommend that you not try to adapt ESP to your vehicle. Even if you were able to get a fault free system (which you won't) the control will be uncomfortable at best and likely dangerous. If you want to discuss in more detail, PM me your phone number and we can chat.

Otherwise, awesome project! (IMG:style_emoticons/default/smilie_pokal.gif)

So does that mean you can help us develop slip angles and modify the bosh HEX codes? (IMG:style_emoticons/default/evilgrin.gif) (IMG:style_emoticons/default/idea.gif)

It is a bit more complicated than you are thinking.

How about this, if you come anywhere close to describing how to accurately determine the speed of the body (in order to calculate wheel slip) while driving uphill with the wheels spinning, I will give you some offline hints on how to get ABS to work on your project.

Edit: The vehicle is AWD with open differentials.

Have fun,
Scott

Well, this is a theoretical problem right?
ABS sensors on the wheel determine individual wheel speed. Open differentials on an AWD vehicle will have a mechanical torque based slip on the front to rear ratio, Left to right differentials will be open allowing for the wheel with the least amount of grip to spin, So if the right rear has the least amount of grip it will spin, however if the center differential has a 40/60 F/R split it will still send 40% of the power to the front allowing the vehicle to accelerate forward.

To determine body speed the wheel with the lowest wheel speed would be the most accurate in relation to road speed. Calculate the rotations of the wheel to the overall tire diameter can determine overall body speed.

Or did I misinterpret the question?

[tygaboy]

Adding absolutely nothing helpful to this current set of posts, I have to say:

I am in awe of you guys who "get" all this new-fangled technologlogicalnessism.

Makes what I'm trying to do feel like working with Tinker Toys. OK, maybe an Erector Set.

Really, it's impressive what you're up to. Keep up the great work! (IMG:style_emoticons/default/pray.gif)

[jd74914]

It is a bit more complicated than you are thinking.

How about this, if you come anywhere close to describing how to accurately determine the speed of the body (in order to calculate wheel slip) while driving uphill with the wheels spinning, I will give you some offline hints on how to get ABS to work on your project.

Edit: The vehicle is AWD with open differentials.

Well, this is a theoretical problem right?
ABS sensors on the wheel determine individual wheel speed. Open differentials on an AWD vehicle will have a mechanical torque based slip on the front to rear ratio, Left to right differentials will be open allowing for the wheel with the least amount of grip to spin, So if the right rear has the least amount of grip it will spin, however if the center differential has a 40/60 F/R split it will still send 40% of the power to the front allowing the vehicle to accelerate forward.

To determine body speed the wheel with the lowest wheel speed would be the most accurate in relation to road speed. Calculate the rotations of the wheel to the overall tire diameter can determine overall body speed.

Or did I misinterpret the question?

All wheels are spinning so none correctly give vehicle speed. The one spinning slowest may be most accurate, but you don't know if it's correct enough. From my understanding in ABS terms it likely is, ESC its unlikely.

Thinking about it really quickly it would seem that you have to back it out from the measured acceleration, some simplified tire/vehicle dynamics models, and engine outputs. Perhaps it really a iterative shooting procedure since it must happen real-time? Need to give this some more thought on my end...definitely not a trivial calculation. ESC is crazy complicated.

Sorry for the hijack Rudy. (IMG:style_emoticons/default/smile.gif)

[Amenson]

It is a bit more complicated than you are thinking.

How about this, if you come anywhere close to describing how to accurately determine the speed of the body (in order to calculate wheel slip) while driving uphill with the wheels spinning, I will give you some offline hints on how to get ABS to work on your project.

Edit: The vehicle is AWD with open differentials.

Well, this is a theoretical problem right?
ABS sensors on the wheel determine individual wheel speed. Open differentials on an AWD vehicle will have a mechanical torque based slip on the front to rear ratio, Left to right differentials will be open allowing for the wheel with the least amount of grip to spin, So if the right rear has the least amount of grip it will spin, however if the center differential has a 40/60 F/R split it will still send 40% of the power to the front allowing the vehicle to accelerate forward.

To determine body speed the wheel with the lowest wheel speed would be the most accurate in relation to road speed. Calculate the rotations of the wheel to the overall tire diameter can determine overall body speed.

Or did I misinterpret the question?

All wheels are spinning so none correctly give vehicle speed. The one spinning slowest may be most accurate, but you don't know if it's correct enough. From my understanding in ABS terms it likely is, ESC its unlikely.

Thinking about it really quickly it would seem that you have to back it out from the measured acceleration, some simplified tire/vehicle dynamics models, and engine outputs. Perhaps it really a iterative shooting procedure since it must happen real-time? Need to give this some more thought on my end...definitely not a trivial calculation. ESC is crazy complicated.

Sorry for the hijack Rudy. (IMG:style_emoticons/default/smile.gif)

This is not a theoretical problem. In a slip based controller accurate knowledge of the body speed is critical and a good portion of the ECU capacity is used figuring it out. Andrew did well by getting to the slowest wheel as the best indicator of body speed and jd74914 identified the issue that best probably is not good enough for ESP.

Add this to the complexity of all of the other sensors and factors that obscure the reality of what the vehicle is doing or what the driver is requesting and hopefully you will come to the conclusion that it is not a system that can be swapped between vehicles. Years of effort go into adapting the system to each production vehicle.

Once it is adapted, things like programmable drift angles are fun engineering exercises!

Cheers,
Scott