adding Traction Control and ABS to my GTR
Discussion
I've been looking into adding TC & ABS to my GTR. With my Corvette computer the addition doesn't seem particularly difficult. I would need to add individual brake lines to each wheel and install sensors at each wheel and buy the EBTEM module like the one shown here but for a LS7. Can anyone think of problems I might have that I might not have considered?
Thanks,
Paul
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Thanks,
Paul
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Hey Steve,
Great question. It is my understanding that the EBTCM controls the following 5 functions:
Antilock Brake System (under braking if a wheel locks it reduce pressure to that caliper until wheel turns)
Traction Control (if one rear wheel rotates more than the other when the brakes are not being applied, reduces engine torque and possibly applies braking power to that wheel).
Dynamic Rear Proportioning (regulate rear brake pressure to balance braking effort between front and back).
Vehicle Stability Enhancement System (monitors steering wheel position and yaw and tries to correct for oversteer or understeer).
Rear Stability Control (monitors lateral acceleration and uses brake pressure to improve stability)
Because the VSES and RSC are programmed based on the Corvette they would probably be undesirable on the GTR. So I wasn't planning on using those systems.
But I think my GTR brake bar are currently set pretty well. When my brakes lock up (which isn't very often), the fronts lock first.
Does this make sense?
Thanks,
Paul
Great question. It is my understanding that the EBTCM controls the following 5 functions:
Antilock Brake System (under braking if a wheel locks it reduce pressure to that caliper until wheel turns)
Traction Control (if one rear wheel rotates more than the other when the brakes are not being applied, reduces engine torque and possibly applies braking power to that wheel).
Dynamic Rear Proportioning (regulate rear brake pressure to balance braking effort between front and back).
Vehicle Stability Enhancement System (monitors steering wheel position and yaw and tries to correct for oversteer or understeer).
Rear Stability Control (monitors lateral acceleration and uses brake pressure to improve stability)
Because the VSES and RSC are programmed based on the Corvette they would probably be undesirable on the GTR. So I wasn't planning on using those systems.
But I think my GTR brake bar are currently set pretty well. When my brakes lock up (which isn't very often), the fronts lock first.
Does this make sense?
Thanks,
Paul
Like your thinking, the corvette unit when turned off will not effect anything. It has 2 Larger inlet fitting (One front One Rear) then has 4 normal outlets, if it's turned off then it does nothing as I just had my 2001 Conv ABS ecu rebuilt and it was still ok to drive it was just normal manual brakes..... So you should be able to use the normal GTR Masters Cylinders
Problem is your going to have to give the ABS ECU it's normal signals it would receive from the BCM, and all the different Boxes hand shake when the cars started up to check alls OK. That I have no Idea on.... and I would suspect you may have to try and get nearly the same amount of pulses per rev for the sensors just so the software has a chance at being ok....
Next problem the software will be hard to reprogram if not impossible, and Trust me when it comes in in the lower gears it's apain. If I'm doing a hard start I turn it off, and a after market system can start to cut out cylinders slower, this just closes the Throttle on the FBW and to much in My Opinion for a Ultima......
But saying that it has saved my bacon twice so far, then again I do like drifting of the intersection only chance I get to do a nice sweeping bend on the way to work...
Problem is your going to have to give the ABS ECU it's normal signals it would receive from the BCM, and all the different Boxes hand shake when the cars started up to check alls OK. That I have no Idea on.... and I would suspect you may have to try and get nearly the same amount of pulses per rev for the sensors just so the software has a chance at being ok....
Next problem the software will be hard to reprogram if not impossible, and Trust me when it comes in in the lower gears it's apain. If I'm doing a hard start I turn it off, and a after market system can start to cut out cylinders slower, this just closes the Throttle on the FBW and to much in My Opinion for a Ultima......
But saying that it has saved my bacon twice so far, then again I do like drifting of the intersection only chance I get to do a nice sweeping bend on the way to work...
Trying to use Corvette (or any) ABS on your car could result in worse, not improved, braking.
ABSs are tailored for specific cars and make a lot of assumptions based on that original car. For example, consider a situation where you are braking hard. If the ABS sees that your tires are slowing down quicker than the corvette tires are capable of, (entirely possible in an Ultima), it will think that the tires must be starting to lock and will start backing off the brake pressure, causing you to take LONGER to stop than if you were using a purely mechanical system. In some situations this could conceivably cause you to hit what you are trying to avoid.
A modern ABS does far more than just preventing the tire from locking up; it tries to manage an exact percentage of slip based upon how fast the system thinks that your car is traveling. Its algorithms assume factors like; mass of the vehicle, front/rear mass distribution of the vehicle, mass of the wheels, caliper sizes, braking system pressures, and on and on. And virtually all of these will be different between a Corvette and an Ultima.
For a good discussion of what ABS is doing behind the scenes, go to
http://www.stoptech.com/tech_info/wp_abs_bigbrakek...
and scroll down to the section called
ABS Control In Super-Slow-Mo
Hope that helps.
ABSs are tailored for specific cars and make a lot of assumptions based on that original car. For example, consider a situation where you are braking hard. If the ABS sees that your tires are slowing down quicker than the corvette tires are capable of, (entirely possible in an Ultima), it will think that the tires must be starting to lock and will start backing off the brake pressure, causing you to take LONGER to stop than if you were using a purely mechanical system. In some situations this could conceivably cause you to hit what you are trying to avoid.
A modern ABS does far more than just preventing the tire from locking up; it tries to manage an exact percentage of slip based upon how fast the system thinks that your car is traveling. Its algorithms assume factors like; mass of the vehicle, front/rear mass distribution of the vehicle, mass of the wheels, caliper sizes, braking system pressures, and on and on. And virtually all of these will be different between a Corvette and an Ultima.
For a good discussion of what ABS is doing behind the scenes, go to
http://www.stoptech.com/tech_info/wp_abs_bigbrakek...
and scroll down to the section called
ABS Control In Super-Slow-Mo
Hope that helps.
NAPiston-
Thank you for your thoughts on this question. Your argument sounds very convincing. Wouldn't your logic also apply to the Factory Five GTM given its light weight? I know several guys that have installed the Corvette ABS and they seem to be pretty happy with it. Can you please share your background with us so that we can better understand the basis of your claim?
Thanks,
Paul
Thank you for your thoughts on this question. Your argument sounds very convincing. Wouldn't your logic also apply to the Factory Five GTM given its light weight? I know several guys that have installed the Corvette ABS and they seem to be pretty happy with it. Can you please share your background with us so that we can better understand the basis of your claim?
Thanks,
Paul
Braking performance should be similar, given that the weight is not dissimilar and the systems are configured to run on tyres of similar performance. Most high performance cars would be capable of generating similar performance in terms of G’s under brakes with a similar tire.
Also consider the fact that the corvette system will need to be configured to take into account the possibilities off a heavily loaded or striped out car, different gradients, head winds, tail winds. I think there would be a degree of freedom in this.
I have no experience with the corvette and its ABS, but I know the ABS on the car I drive doesn’t seem to kick up a fuss when you are towing a trailer, thereby indicating that it can cope with the differing loads to some extent (noted that I have just made the car heavier) this could be equated to putting more energy into the system, which we expect the Ultima to be able to achieve.
Also consider the fact that the corvette system will need to be configured to take into account the possibilities off a heavily loaded or striped out car, different gradients, head winds, tail winds. I think there would be a degree of freedom in this.
I have no experience with the corvette and its ABS, but I know the ABS on the car I drive doesn’t seem to kick up a fuss when you are towing a trailer, thereby indicating that it can cope with the differing loads to some extent (noted that I have just made the car heavier) this could be equated to putting more energy into the system, which we expect the Ultima to be able to achieve.
I freely admit that I don't have any direct experience with this, just giving feedback from what I have picked up about abs over the years that I have followed its development, as curious programmer.
As to the GTM; my logic should apply to that car as well, so I was curious to see what they said about it. Digging around on the gtm forums mostly what I could find as far as testing was one report from one guy who tested it by going fast downhill and then hitting the brakes, and reporting that it worked well with the abs. That is all of the testing results that I could find; all of the other stories on there seemed to use that case as their proof. Unfortunately, that would be about the most perfect situation to test it under, in a straight line, and going downhill, which is going to transfer weight forward and better match the corvette's front/rear weight distribution.
On the other hand there was this thread:
http://www.ffcobra.com/forums/archive/index.php/t-...
where a reader Bspeed chimed in, as "a vehicle dynamics/chassis controls development engineer for for GM" who worked "on the Delphi DBC7.2 system that is in the C5."
On the negative aspects of the GTM ABS conversion he said: "The weight distribution differences will have a significant impact on the calibration of the system, as will the overall weight, pitch, etc. Though all of that will be trival relative to the differences between the peak/slip mu differences between the OEM tire and the tire that goes on a builders GTM."
On the positive side he said: "The rear of the GTM will be stable because there is more normal force and the contact patch is bigger. So the DRP holds during a ABS event will be conservative, and not fully utilized. It will promote a safe understeer condition but not be 100% efficient."
This gets at what I was trying to say, that the car will be capable of better braking than the Corvette ABS system will allow, under good conditions. In those conditions the corvette abs system will cut in too early because it thinks that the corvette's maximum parameters have been exceeded. In a hard stopping situation on a dry road, you should find that you could stop quicker without the abs.
In wet conditions or conditions where the traction is not even at all four tires, even the corvette abs could quite possibly be better than mere humans with only one brake pedal could achieve, as the abs can modulate all four wheels independently. Once again, it would not be optimized to be able to achieve the best possible braking for the Ultima, but it still might be better than a single unaided human foot.
So I guess in conclusion, the community needs a guinea pig for this. Test it in a few different circumstances with it on and off. Hard braking in the wet and dry around a curve and in a straight line. How does it compare with ABS on and ABS off?
As to the GTM; my logic should apply to that car as well, so I was curious to see what they said about it. Digging around on the gtm forums mostly what I could find as far as testing was one report from one guy who tested it by going fast downhill and then hitting the brakes, and reporting that it worked well with the abs. That is all of the testing results that I could find; all of the other stories on there seemed to use that case as their proof. Unfortunately, that would be about the most perfect situation to test it under, in a straight line, and going downhill, which is going to transfer weight forward and better match the corvette's front/rear weight distribution.
On the other hand there was this thread:
http://www.ffcobra.com/forums/archive/index.php/t-...
where a reader Bspeed chimed in, as "a vehicle dynamics/chassis controls development engineer for for GM" who worked "on the Delphi DBC7.2 system that is in the C5."
On the negative aspects of the GTM ABS conversion he said: "The weight distribution differences will have a significant impact on the calibration of the system, as will the overall weight, pitch, etc. Though all of that will be trival relative to the differences between the peak/slip mu differences between the OEM tire and the tire that goes on a builders GTM."
On the positive side he said: "The rear of the GTM will be stable because there is more normal force and the contact patch is bigger. So the DRP holds during a ABS event will be conservative, and not fully utilized. It will promote a safe understeer condition but not be 100% efficient."
This gets at what I was trying to say, that the car will be capable of better braking than the Corvette ABS system will allow, under good conditions. In those conditions the corvette abs system will cut in too early because it thinks that the corvette's maximum parameters have been exceeded. In a hard stopping situation on a dry road, you should find that you could stop quicker without the abs.
In wet conditions or conditions where the traction is not even at all four tires, even the corvette abs could quite possibly be better than mere humans with only one brake pedal could achieve, as the abs can modulate all four wheels independently. Once again, it would not be optimized to be able to achieve the best possible braking for the Ultima, but it still might be better than a single unaided human foot.
So I guess in conclusion, the community needs a guinea pig for this. Test it in a few different circumstances with it on and off. Hard braking in the wet and dry around a curve and in a straight line. How does it compare with ABS on and ABS off?
Paul,
Had you not thought about using something like a RaceLogic aftermarket unit?
They are eminently configurable, provide launch control, as well as full throttle gearchange and traction control which is adjustable in the cockpit. Unfortunately no ABS though!
I have an LS7 and GM ECU as well as one of these units, so I am hoping this does the jobby. The only question is if it all works together with the GM ECU!
cheers
keith
Had you not thought about using something like a RaceLogic aftermarket unit?
They are eminently configurable, provide launch control, as well as full throttle gearchange and traction control which is adjustable in the cockpit. Unfortunately no ABS though!
I have an LS7 and GM ECU as well as one of these units, so I am hoping this does the jobby. The only question is if it all works together with the GM ECU!
cheers
keith
Edited by V8 Vum on Monday 6th October 15:43
The megasquirt guys are looking at driving the std bosch abs system via the GPIO add-on - but unlikely to be any time soon.
http://www.msgpio.com/forums/viewtopic.php?f=7&...
http://www.msgpio.com/forums/viewtopic.php?f=7&...
....aaaargh...what did I just say?
Keith,
I've seriously considered the Race Logic option. It looks like a great one, but I was frustrated by the high cost given the dollars unfavorable exchange rate currently. So I was looking for viable options and thought of the option that many Factory Five guys are choosing for their GTM's. I really like the RL product, but thought that if I could get ABS too, that would be a slam dunk decision for me. But now I'm really confused and need to investigate further.
Thanks,
Paul
I've seriously considered the Race Logic option. It looks like a great one, but I was frustrated by the high cost given the dollars unfavorable exchange rate currently. So I was looking for viable options and thought of the option that many Factory Five guys are choosing for their GTM's. I really like the RL product, but thought that if I could get ABS too, that would be a slam dunk decision for me. But now I'm really confused and need to investigate further.
Thanks,
Paul
San Diego GTR said:
NAPiston-
Thank you for your thoughts on this question. Your argument sounds very convincing. Wouldn't your logic also apply to the Factory Five GTM given its light weight? I know several guys that have installed the Corvette ABS and they seem to be pretty happy with it. Can you please share your background with us so that we can better understand the basis of your claim?
Thanks,
Paul
Just because they're happy with it doesn't mean it's working better or properly. Thank you for your thoughts on this question. Your argument sounds very convincing. Wouldn't your logic also apply to the Factory Five GTM given its light weight? I know several guys that have installed the Corvette ABS and they seem to be pretty happy with it. Can you please share your background with us so that we can better understand the basis of your claim?
Thanks,
Paul
I hate electronic driving aids.
Jeff S
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