Thwunk! Temp drops...and so does my gas mileage.
#11
12-11-2008, 10:34 PM
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Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Thwunk! Temp drops...and so does my gas mileage.
It has been a bit of a surprise in how agressive the TC is! A few weeks ago we had a warm day with snow overnight. The residential streets were like skating rinks and I didn't have my winter tires on yet and I was barely moving from any stop.
It sounded like it was only trying to get going using only the electric and not the ICE.
It sounded like it was only trying to get going using only the electric and not the ICE.Do the same thing in a RWD or R/AWD and the TC system will INSTANTLY apply braking but will delay engine dethrottling for a few hundred milliseconds to allow the driver time to react, "feather" the throttle and use the traction remaining at the front to maintain directional control.
#12
12-12-2008, 10:22 AM
Re: Thwunk! Temp drops...and so does my gas mileage.
I will have to say I am generally very pleased with the TC system on this car. Coming into my 3rd winter still on the same OEM tires obviously traction is low without snow tires so I get a lot of chance to see TC in operation.
A car "without" TC will always be able to rip thru snow better than "with" if you know what you are doing, I'll admit. I learned to winter drive using an old Beetle on a frozen lake (way back, before global warming kept it from freezing) so I'm familiar with the funky stuff you can get away with in sheer ice or deep snow.
My first experience with TC, I had a Venture with the throttle limit/braking stuff that wwest mentions, I hated it. I routinely shut it off when in snow. In contrast, the TC on the TCH is much smoother and more civilized thanks to the electric motor drive. On sheer ice or snow when wheel slip happens the front wheel will go into repeated gentle on and off spins with enough persistance to make forward progress, just the sounds of the electric motor spinning up and down (as BOFH said) instead of the vibration of the braking system doing it's stuff like on the Venture.
I've found very little need to compensate for torque steer on really slippery roads. Some of my other FWD vehicles in the past I would routinely have to turn the wheels at almost 45 degree turns to keep the vehicle tracking straight. You really had to be careful about hitting a dry patch or suddenly the vehicle would launch to the side as soon as the wheels contacted the area of much higher traction. Totally not an issue with the TCH.
Going home for me there is a traffic light right before a long gradual uphill. During a snowstorm this means the area at the stop light gets very icy due to the wheel spins from vehicles starting and stopping. I always get worried if I get stuck having to stop here before the uphill, but even without snows it's always been able to pull me up the hill from stop, certainly at a leisurely pace with slow but always steady acceleration.
Often the traffic going up the hill will come to a stop mid-hill to allow for some guy in a RWD car to spend 5 minutes doing donuts desparating trying to climb the hill before finally giving up. Even in those conditions when the road has now been really iced over from all this spinning out, it's painfully slow at first but my TCH will still pull me up the hill.
I did have an interesting experience with the TC system in summer as well. I had to park on a grass hill at an event. It rained a lot that day and when time to leave it was not possible for me to backup so I was forced to go forward up the hill, it was very muddy. I noticed that as I applied pressure to the gas pedal nothing happened (I'd heard about similiar situations my others in deep snow). But as I applied more pressure I started to get very brief pulses of wheel spin, not enough to be useful. I ended up flooring the gas pedal and the TCH responded by becoming more and more aggressive with it's wheel spins as the pedal was pushed closer to the floor. It ended up inducing a quite noticeable rocking effect and eventually resulted in enough forward momentum to move up the hill.
A car "without" TC will always be able to rip thru snow better than "with" if you know what you are doing, I'll admit. I learned to winter drive using an old Beetle on a frozen lake (way back, before global warming kept it from freezing) so I'm familiar with the funky stuff you can get away with in sheer ice or deep snow.
My first experience with TC, I had a Venture with the throttle limit/braking stuff that wwest mentions, I hated it. I routinely shut it off when in snow. In contrast, the TC on the TCH is much smoother and more civilized thanks to the electric motor drive. On sheer ice or snow when wheel slip happens the front wheel will go into repeated gentle on and off spins with enough persistance to make forward progress, just the sounds of the electric motor spinning up and down (as BOFH said) instead of the vibration of the braking system doing it's stuff like on the Venture.
I've found very little need to compensate for torque steer on really slippery roads. Some of my other FWD vehicles in the past I would routinely have to turn the wheels at almost 45 degree turns to keep the vehicle tracking straight. You really had to be careful about hitting a dry patch or suddenly the vehicle would launch to the side as soon as the wheels contacted the area of much higher traction. Totally not an issue with the TCH.
Going home for me there is a traffic light right before a long gradual uphill. During a snowstorm this means the area at the stop light gets very icy due to the wheel spins from vehicles starting and stopping. I always get worried if I get stuck having to stop here before the uphill, but even without snows it's always been able to pull me up the hill from stop, certainly at a leisurely pace with slow but always steady acceleration.
Often the traffic going up the hill will come to a stop mid-hill to allow for some guy in a RWD car to spend 5 minutes doing donuts desparating trying to climb the hill before finally giving up. Even in those conditions when the road has now been really iced over from all this spinning out, it's painfully slow at first but my TCH will still pull me up the hill.
I did have an interesting experience with the TC system in summer as well. I had to park on a grass hill at an event. It rained a lot that day and when time to leave it was not possible for me to backup so I was forced to go forward up the hill, it was very muddy. I noticed that as I applied pressure to the gas pedal nothing happened (I'd heard about similiar situations my others in deep snow). But as I applied more pressure I started to get very brief pulses of wheel spin, not enough to be useful. I ended up flooring the gas pedal and the TCH responded by becoming more and more aggressive with it's wheel spins as the pedal was pushed closer to the floor. It ended up inducing a quite noticeable rocking effect and eventually resulted in enough forward momentum to move up the hill.
Last edited by Droid13; 12-12-2008 at 10:25 AM.
#13
12-12-2008, 09:37 PM
Re: Thwunk! Temp drops...and so does my gas mileage.
Don't feel bad, the weather here has turn really cold quickly and my mileage has really plummeted. I was doing a little shopping last night and it was -28C (-18F) without the wind chill, and I could not get much better then 10L/100km (24MPG) in town. I wasn't trying very hard to get good mileage, mind you since I wanted to keep warm. The temp is to drop even more this weekend and next week, so it will be a good test for the car, but speaking of tests, I noticed that in the last couple of weeks has it has been colder, and as I am driving in town, the engine doesn't get a chance to get too warm as I get into EV mode. I have insulated the front grille, but I noticed that the car will go into EV mode until the temp drops to about 60C (140F) and then the ICE will turn back on. If I keep ridding in town, and use EV, the engine never reaches what I consider normal temp around 80C(176F) to 90C(194F). It sit around 70C (158F) which I find fairly cold and I get concerned of deposits building up. Now I tried the ECO switch and noticed that not only the heater fan drops by about half, but that I can get into EV mode down to 50C (122F), an then the ICE turn back on. Wow, that is cold for an engine, so I dont get into EV mode much anymore. As a side note, most of my trips are short, about 20 minutes, which doesn't help. When I am on the highway, the engine reaches normal temperature and stays there. Also, as a side note, the temp gauge in the dash doesn't reflect a difference between the above mentioned temps, it always sits in the same position
I am not sure what WWEST is talking about when he mentions potential damage to the catalyst when using the block heater. If this was the case, almost all of the cars in our region would have this problem since everyone uses block heaters for about 4 months out of the year, and it is not the case, plus we are talking about decades of usage.
Cheers
I am not sure what WWEST is talking about when he mentions potential damage to the catalyst when using the block heater. If this was the case, almost all of the cars in our region would have this problem since everyone uses block heaters for about 4 months out of the year, and it is not the case, plus we are talking about decades of usage.
Cheers
#14
12-13-2008, 08:03 AM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Thwunk! Temp drops...and so does my gas mileage.
Don't feel bad, the weather here has turn really cold quickly and my mileage has really plummeted. I was doing a little shopping last night and it was -28C (-18F) without the wind chill, and I could not get much better then 10L/100km (24MPG) in town. I wasn't trying very hard to get good mileage, mind you since I wanted to keep warm. The temp is to drop even more this weekend and next week, so it will be a good test for the car, but speaking of tests, I noticed that in the last couple of weeks has it has been colder, and as I am driving in town, the engine doesn't get a chance to get too warm as I get into EV mode. I have insulated the front grille, but I noticed that the car will go into EV mode until the temp drops to about 60C (140F) and then the ICE will turn back on. If I keep ridding in town, and use EV, the engine never reaches what I consider normal temp around 80C(176F) to 90C(194F). It sit around 70C (158F) which I find fairly cold and I get concerned of deposits building up. Now I tried the ECO switch and noticed that not only the heater fan drops by about half, but that I can get into EV mode down to 50C (122F), an then the ICE turn back on. Wow, that is cold for an engine, so I don't get into EV mode much anymore. As a side note, most of my trips are short, about 20 minutes, which doesn't help. When I am on the highway, the engine reaches normal temperature and stays there. Also, as a side note, the temp gauge in the dash doesn't reflect a difference between the above mentioned temps, it always sits in the same position
I am not sure what WWEST is talking about when he mentions potential damage to the catalyst when using the block heater. If this was the case, almost all of the cars in our region would have this problem since everyone uses block heaters for about 4 months out of the year, and it is not the case, plus we are talking about decades of usage.
Cheers
I am not sure what WWEST is talking about when he mentions potential damage to the catalyst when using the block heater. If this was the case, almost all of the cars in our region would have this problem since everyone uses block heaters for about 4 months out of the year, and it is not the case, plus we are talking about decades of usage.
Cheers
I specifically left AK out since it gets so cold there a low wattage EBD/EOH was of little or no help. Back in those days in Fairbanks if you wanted to attend a movie, or dinner "out", in the evening you simply left the car idling for the duration.
Lots of things have changed over the succeeding years, engine Oil viscosity "range", lighter weight gear oil in the diff'l, etc.
But, obviously, there remain valid uses for EBH and EOH devices.
Let's assume, for the moment, that I am GOOD at my job an dthat job is to write the specifications for the overall HSD control firmware and I am reasonably cognizant of automotive technology.
So I would fully expect EBH/EOL devices to be used from time to time.
Since. clearly, the catalyst operation and "life" could be compromised otherwise I would need to have the ability within the firmware to compensate for same, the engine somehow being artificially HEATED.
At my disposal for doing this I have many "tools" "at hand". The most important probably being the OAT sensor and the engine coolant temperature sensor. "Fire" up the ICE the first thing in the early morning after a COLD night and....hmmm... the vehicle has been setting undriven for hours, the OAT indicates COLD, yet the engine coolant is WARM.
NOW....
I would know that the engine has been somehow preheated, so now I cannot use the rise in the engine coolant temperature to judge when/if the catalyst has risen to full operating temperature.
My alternative choice.....TIME...!!
Just simply use a longer period of time for running the ICE to be sure the catalyst has risen to operational temperature.
And...
Am I "bright" enough to foresee that since FE conscious HSD customers might be using an EBH/EOH device year 'round then the firmware compensation needs to be "active" even above, say, 35F.
And now keep in mind that ONLY Prius vehicles shipped to dealers north of the US border are equipped with an electric heaters as an aid to defrosting or defogging the windshield in cold climates.
I guess it doesn't get cold enough in Cut Bank MT, Ferndale WA, etc, just a few miles south of the Canadian border, to justify the additional cost. Oh, the otherwise stunningly luxurious Lexus LS4XX destined for the US market doesn't come equipped with a windshield heater as does the ones going into Canada.
"Almost all of the cars in our region..."
And how many of those have now reached a mileage level, 70,000-100,000 miles, wherein a catalyst failure might be "suspect"...?? And even so, where is the co-ordination of "data" such that the "collective" could take notice.
#15
12-13-2008, 08:04 AM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Thwunk! Temp drops...and so does my gas mileage.
Don't feel bad, the weather here has turn really cold quickly and my mileage has really plummeted. I was doing a little shopping last night and it was -28C (-18F) without the wind chill, and I could not get much better then 10L/100km (24MPG) in town. I wasn't trying very hard to get good mileage, mind you since I wanted to keep warm. The temp is to drop even more this weekend and next week, so it will be a good test for the car, but speaking of tests, I noticed that in the last couple of weeks has it has been colder, and as I am driving in town, the engine doesn't get a chance to get too warm as I get into EV mode. I have insulated the front grille, but I noticed that the car will go into EV mode until the temp drops to about 60C (140F) and then the ICE will turn back on. If I keep ridding in town, and use EV, the engine never reaches what I consider normal temp around 80C(176F) to 90C(194F). It sit around 70C (158F) which I find fairly cold and I get concerned of deposits building up. Now I tried the ECO switch and noticed that not only the heater fan drops by about half, but that I can get into EV mode down to 50C (122F), an then the ICE turn back on. Wow, that is cold for an engine, so I don't get into EV mode much anymore. As a side note, most of my trips are short, about 20 minutes, which doesn't help. When I am on the highway, the engine reaches normal temperature and stays there. Also, as a side note, the temp gauge in the dash doesn't reflect a difference between the above mentioned temps, it always sits in the same position
I am not sure what WWEST is talking about when he mentions potential damage to the catalyst when using the block heater. If this was the case, almost all of the cars in our region would have this problem since everyone uses block heaters for about 4 months out of the year, and it is not the case, plus we are talking about decades of usage.
Cheers
I am not sure what WWEST is talking about when he mentions potential damage to the catalyst when using the block heater. If this was the case, almost all of the cars in our region would have this problem since everyone uses block heaters for about 4 months out of the year, and it is not the case, plus we are talking about decades of usage.
Cheers
I specifically left AK out side it gets so cold there a low wattage EBD/EOH would be of no help. Back in those days if you wanted to attend a movie, or dinner "out", in the evening you simply left the car idling for the duration.
Lots of things have changed over the succeeding years, engine Oil viscosity "range", lighter wear gear oil in the duffel, etc.
But, obviously, there remain valid uses for EBH and EOH devices.
Let's assume, for the moment, that my job is to write the specifications for the overall HSD control firmware and I ma reasonable cognizant of automotive technology.
So I would fully expect EBH/EOL devices to be used from time to time.
Since. clearly, the catalyst operation and "life" could be compromised otherwise I would need to have the ability within the firmware to compensate for same, the engine somehow being artificially HEATED.
At my disposal for doing this I have many "tools" "at hand". The most important probably being the OAT sensor and the engine coolant temperate sensor. "Fire" up the ICE the first thing in the early morning after a COLD night and....hmmm... the the vehicle has been setting undriven for hours, the OAT indicates COLD, yet the engine coolant is WARM.
NOW....
I would know that the engine has been somehow preheated, so now I cannot use the rise in the engine coolant temperature to judge when/if the catalyst has risen to full operating temperature.
My alternative choice.....TIME...!!
Just simply use a longer period of time for running the ICE to be sure the catalyst.
Now...
Am I "bright" enough to foresee that since HSD customers might be using an EBH/EOH device year 'round then the firmware compensation needs to be "active" even above, say, 35F.
And now keep in mind that ONLY Prius vehicles shipped to dealers north of the US border are equipped with an electric heaters as an aid to defrosting or defogging the windshield in cold climates.
I guess it doesn't get cold enough in Cut Bank MT, Ferndale WA, etc, just a few miles south of the Canadian border, to justify the additional cost. Oh, the otherwise stunningly luxurious Lexus LS4XX destined for the US market doesn't come equipped with a windshield heater as does the ones going into Canada.
"Almost all of the cars in our region..."
And how many of those have now reached a mileage level, 70,000-100,000 miles, wherein a catalyst failure might be "suspect"...?? And even so, where is the co-ordination of "data" such that the "collective" could take notice.
#16
12-13-2008, 08:28 AM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Thwunk! Temp drops...and so does my gas mileage.
I will have to say I am generally very pleased with the TC system on this car. Coming into my 3rd winter still on the same OEM tires obviously traction is low without snow tires so I get a lot of chance to see TC in operation.
A car "without" TC will always be able to rip thru snow better than "with" if you know what you are doing, I'll admit. I learned to winter drive using an old Beetle on a frozen lake (way back, before global warming kept it from freezing) so I'm familiar with the funky stuff you can get away with in sheer ice or deep snow.
Nowadays an "old Beetle" might mean a front engine FWD vehicle, whereas for "my" generation "old Beetle" would be interpreted as being a rear engine RWD vehicle.
My first experience with TC, I had a Venture with the throttle limit/braking stuff that wwest mentions, I hated it. I routinely shut it off when in snow. In contrast, the TC on the TCH is much smoother and more civilized thanks to the electric motor drive.
Yes, the relatively light weight of the HSD electric motor's permanent magnet rotor's vs the pistons, crankshaft counterweights, etc, would allow much smoother TC modulation of the "drive" torque.
On sheer ice or snow when wheel slip happens the front wheel will go into repeated gentle on and off spins with enough persistance to make forward progress, just the sounds of the electric motor spinning up and down (as BOFH said) instead of the vibration of the braking system doing it's stuff like on the Venture.
Hmmm...
Smoother enough that the front brakes need not be used for TC torque modulation....I hadn't thought of that possibility.
Anyone know that to be true...??
I've found very little need to compensate for torque steer on really slippery roads. Some of my other FWD vehicles in the past I would routinely have to turn the wheels at almost 45 degree turns to keep the vehicle tracking straight. You really had to be careful about hitting a dry patch or suddenly the vehicle would launch to the side as soon as the wheels contacted the area of much higher traction. Totally not an issue with the TCH.
"This" is NOT torque stear, but "plowing" or understear, the front wheels not having enough traction to move, "force" the vehicle's weight/momentum into a turn. Your TCH undoubtedly has VSC, the ability to use differential braking or "unbraking" (along with dethrottling) in order to bring the "moment" of the vehicle into "line" with the stearing direction.
Going home for me there is a traffic light right before a long gradual uphill. During a snowstorm this means the area at the stop light gets very icy due to the wheel spins from vehicles starting and stopping. I always get worried if I get stuck having to stop here before the uphill, but even without snows it's always been able to pull me up the hill from stop, certainly at a leisurely pace with slow but always steady acceleration.
Often the traffic going up the hill will come to a stop mid-hill to allow for some guy in a RWD car to spend 5 minutes doing donuts desparating trying to climb the hill before finally giving up. Even in those conditions when the road has now been really iced over from all this spinning out, it's painfully slow at first but my TCH will still pull me up the hill.
I did have an interesting experience with the TC system in summer as well. I had to park on a grass hill at an event. It rained a lot that day and when time to leave it was not possible for me to backup so I was forced to go forward up the hill, it was very muddy. I noticed that as I applied pressure to the gas pedal nothing happened (I'd heard about similiar situations my others in deep snow). But as I applied more pressure I started to get very brief pulses of wheel spin, not enough to be useful. I ended up flooring the gas pedal and the TCH responded by becoming more and more aggressive with it's wheel spins as the pedal was pushed closer to the floor. It ended up inducing a quite noticeable rocking effect and eventually resulted in enough forward momentum to move up the hill.
A car "without" TC will always be able to rip thru snow better than "with" if you know what you are doing, I'll admit. I learned to winter drive using an old Beetle on a frozen lake (way back, before global warming kept it from freezing) so I'm familiar with the funky stuff you can get away with in sheer ice or deep snow.
Nowadays an "old Beetle" might mean a front engine FWD vehicle, whereas for "my" generation "old Beetle" would be interpreted as being a rear engine RWD vehicle.
My first experience with TC, I had a Venture with the throttle limit/braking stuff that wwest mentions, I hated it. I routinely shut it off when in snow. In contrast, the TC on the TCH is much smoother and more civilized thanks to the electric motor drive.
Yes, the relatively light weight of the HSD electric motor's permanent magnet rotor's vs the pistons, crankshaft counterweights, etc, would allow much smoother TC modulation of the "drive" torque.
On sheer ice or snow when wheel slip happens the front wheel will go into repeated gentle on and off spins with enough persistance to make forward progress, just the sounds of the electric motor spinning up and down (as BOFH said) instead of the vibration of the braking system doing it's stuff like on the Venture.
Hmmm...
Smoother enough that the front brakes need not be used for TC torque modulation....I hadn't thought of that possibility.
Anyone know that to be true...??
I've found very little need to compensate for torque steer on really slippery roads. Some of my other FWD vehicles in the past I would routinely have to turn the wheels at almost 45 degree turns to keep the vehicle tracking straight. You really had to be careful about hitting a dry patch or suddenly the vehicle would launch to the side as soon as the wheels contacted the area of much higher traction. Totally not an issue with the TCH.
"This" is NOT torque stear, but "plowing" or understear, the front wheels not having enough traction to move, "force" the vehicle's weight/momentum into a turn. Your TCH undoubtedly has VSC, the ability to use differential braking or "unbraking" (along with dethrottling) in order to bring the "moment" of the vehicle into "line" with the stearing direction.
Going home for me there is a traffic light right before a long gradual uphill. During a snowstorm this means the area at the stop light gets very icy due to the wheel spins from vehicles starting and stopping. I always get worried if I get stuck having to stop here before the uphill, but even without snows it's always been able to pull me up the hill from stop, certainly at a leisurely pace with slow but always steady acceleration.
Often the traffic going up the hill will come to a stop mid-hill to allow for some guy in a RWD car to spend 5 minutes doing donuts desparating trying to climb the hill before finally giving up. Even in those conditions when the road has now been really iced over from all this spinning out, it's painfully slow at first but my TCH will still pull me up the hill.
I did have an interesting experience with the TC system in summer as well. I had to park on a grass hill at an event. It rained a lot that day and when time to leave it was not possible for me to backup so I was forced to go forward up the hill, it was very muddy. I noticed that as I applied pressure to the gas pedal nothing happened (I'd heard about similiar situations my others in deep snow). But as I applied more pressure I started to get very brief pulses of wheel spin, not enough to be useful. I ended up flooring the gas pedal and the TCH responded by becoming more and more aggressive with it's wheel spins as the pedal was pushed closer to the floor. It ended up inducing a quite noticeable rocking effect and eventually resulted in enough forward momentum to move up the hill.
Apparently TC implementation in an HSD is a bit if a different animal.
Torque stear....
Is the result of different "windup", twisting, of the different length left and right front drive halfshafts under high torque conditions, most of the effects of this will be felt in an accelerating TIGHT turn.
Last edited by wwest; 12-13-2008 at 08:35 AM.
#17
12-13-2008, 04:04 PM
Re: Thwunk! Temp drops...and so does my gas mileage.
LadyLou's original point about mileage dropping seems to come up every winter. It can be frustrating to see mileage drop from near 40mpg to the low 30's -- or even lower. But you will feel a lot better if you compare what happens with the TCH with what owners of regular cars see. Eveyone's mileage takes a big hit. Cars that might average 27 - 28 mpg in the summer are down in the teens for the winter.
So why are TCH owners so conscious of the drop? Because TCH owners actually are paying attention! We're so used to cruising past gas station after gas station, and get downright giddy about seeing "Tank Average 40.0 mpg" on the display, that we get all depressed when mileage goes down to the level that still would delight owners of conventional cars!
Bill
So why are TCH owners so conscious of the drop? Because TCH owners actually are paying attention! We're so used to cruising past gas station after gas station, and get downright giddy about seeing "Tank Average 40.0 mpg" on the display, that we get all depressed when mileage goes down to the level that still would delight owners of conventional cars!
Bill
#18
12-13-2008, 08:29 PM
Re: Thwunk! Temp drops...and so does my gas mileage.
This last is a bit interesting, in a standard FWD vehicle TC would have been using engine dethrottling along with the brakes to control, abate, wheelspin/slip arising from too much, the driver attempting to use too much, engine drive torque for roadbed surface traction conditions. Within a few seconds of continuous TC activity as you describe the ABS pumpmotor would have been shut down to prevent its failure due to overheating.
Apparently TC implementation in an HSD is a bit if a different animal.
Torque stear....
Is the result of different "windup", twisting, of the different length left and right front drive halfshafts under high torque conditions, most of the effects of this will be felt in an accelerating TIGHT turn.
Apparently TC implementation in an HSD is a bit if a different animal.
Torque stear....
Is the result of different "windup", twisting, of the different length left and right front drive halfshafts under high torque conditions, most of the effects of this will be felt in an accelerating TIGHT turn.
Older FWD vehicles had the half-shafts different lengths (some recent GM full-size like the Impala still do), which makes high torque output tougher to tame. Even with that design limitations, good design and materials selection will limit the torque steer to tolerable levels.
Also, the ABS-based traction control limits the operation not for the sake of the ABS pump but for the sake of overheating the pads and rotors; braking against slippage will generate considerable heat into the rotor. This is a design limitation in all brake-based traction control systems; an easy work-around is to 'super-size' the brake rotors and pads to handle the heavier duty cycle.
Last edited by Frodo; 12-13-2008 at 08:32 PM.
#19
12-13-2008, 09:02 PM
Re: Thwunk! Temp drops...and so does my gas mileage.
Well, I feel better having heard from all of you. The weather warmed up to the high 30's today and I did get better gas mileage. I really miss seeing the "Excellent"!!
#20
12-13-2008, 10:55 PM
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Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Thwunk! Temp drops...and so does my gas mileage.
Sorry - wrong for all of the Camry line. The diff is offset,
Offset, yes.
So the total DRIVELINE on the long side will endure more "twist" than will the short side. I have heard this argument before, but tell me, please, why do you think that "long side" diff'l output, extension shaft plus the halfshaft, isn't subject to more "twist" than the short side halfshaft alone. The sum of the twist angle will AWAYS be greater for the long side drive line.
but the drive shafts outboard of the inner CV joints are equal length. This is provided by a diff-mounted center shaft. You could argue around relative stiffness of the right vs. left side, but the big issue is one of angles, which the Camry design addresses. The Camry, even in the V6 version, has the torque steer reasonably well controlled.
And you're sure, certain sure, there isn't some minor level of engine dethrottling, engine torque control, in order to limit torque to the roadbed in he lower gear ratios, especially in a tight accelerating turn. And with DBW between you and the throttle, how would you know if it were limiting the engine. That was what Cadillac did, quite a few years ago (before they abandoned FWD totally due to the unsafe nature of same) when it was discovered that their high torque Northstar engine coupled with FWD could to easily, too readily, cause loss of directional control.
Older FWD vehicles had the half-shafts different lengths (some recent GM full-size like the Impala still do), which makes high torque output tougher to tame. Even with that design limitations, good design and materials selection will limit the torque steer to tolerable levels.
Also, the ABS-based traction control limits the operation not for the sake of the ABS pump but for the sake of overheating the pads and rotors;
No, to prevent brake component over heating, and on FWD as a safety measure, it dethrottles the engine, quickly. The complete shutdown of ancillary ABS pumpmotor functions is to preserve its use for the PRIMARY functionality and to prevent overheating and subsequent failure
braking against slippage will generate considerable heat into the rotor. This is a design limitation in all brake-based traction control systems; an easy work-around is to 'super-size' the brake rotors and pads to handle the heavier duty cycle.
Offset, yes.
So the total DRIVELINE on the long side will endure more "twist" than will the short side. I have heard this argument before, but tell me, please, why do you think that "long side" diff'l output, extension shaft plus the halfshaft, isn't subject to more "twist" than the short side halfshaft alone. The sum of the twist angle will AWAYS be greater for the long side drive line.
but the drive shafts outboard of the inner CV joints are equal length. This is provided by a diff-mounted center shaft. You could argue around relative stiffness of the right vs. left side, but the big issue is one of angles, which the Camry design addresses. The Camry, even in the V6 version, has the torque steer reasonably well controlled.
And you're sure, certain sure, there isn't some minor level of engine dethrottling, engine torque control, in order to limit torque to the roadbed in he lower gear ratios, especially in a tight accelerating turn. And with DBW between you and the throttle, how would you know if it were limiting the engine. That was what Cadillac did, quite a few years ago (before they abandoned FWD totally due to the unsafe nature of same) when it was discovered that their high torque Northstar engine coupled with FWD could to easily, too readily, cause loss of directional control.
Older FWD vehicles had the half-shafts different lengths (some recent GM full-size like the Impala still do), which makes high torque output tougher to tame. Even with that design limitations, good design and materials selection will limit the torque steer to tolerable levels.
Also, the ABS-based traction control limits the operation not for the sake of the ABS pump but for the sake of overheating the pads and rotors;
No, to prevent brake component over heating, and on FWD as a safety measure, it dethrottles the engine, quickly. The complete shutdown of ancillary ABS pumpmotor functions is to preserve its use for the PRIMARY functionality and to prevent overheating and subsequent failure
braking against slippage will generate considerable heat into the rotor. This is a design limitation in all brake-based traction control systems; an easy work-around is to 'super-size' the brake rotors and pads to handle the heavier duty cycle.
