fwd fuse
02-28-2003, 05:14 AM
#1
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fwd fuse
Hi,
I just bougth a Subaru Legacy wagon 2000 with automatic transmission. I read in the owner book that you can put your car in FWD by adding only a fuse. What are the benefits and the problems to do that. I ask this question because sometime in summer I do more 600 miles in one week-end and I think that this could improve my gaz consumption, is it right.
Thanks
Kafou33
I just bougth a Subaru Legacy wagon 2000 with automatic transmission. I read in the owner book that you can put your car in FWD by adding only a fuse. What are the benefits and the problems to do that. I ask this question because sometime in summer I do more 600 miles in one week-end and I think that this could improve my gaz consumption, is it right.
Thanks
Kafou33
02-28-2003, 06:30 AM
#2
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yes, you can put a the fuse in and have fwd. i knew some people who came into the garage every summer to have us put it in. but i all reality, you won't really save much in gas. your car is driving the front wheels most of the time anyway. awd kicks in when you take corners, or take off from a stop, or accelerate fast. so i my opinion , unless yuo want to spin your tires when you take off, leave it in. and legacys with the fuse in, will spin the wheels when you take off hard. good for doing burnouts i guess...
-PJ
-PJ
03-01-2003, 12:52 AM
#3
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Your mileage won't improve much (if at all) by using the fuse to switch to FWD only.
There are two main reasons for lower mileage on AWD cars: weight and drivetrain loss.
By using the extra fuse you will even add weight.
And the drivetrain loss will not change much either as the rear wheels are still connected to the drivetrain and the whole system is still turning.
It will probably change the driving stability somewhat as the suspension (and the car at whole) is setup for AWD. And you may even decrease mileage dramatically due to wheel spin...
D.
There are two main reasons for lower mileage on AWD cars: weight and drivetrain loss.
By using the extra fuse you will even add weight.
And the drivetrain loss will not change much either as the rear wheels are still connected to the drivetrain and the whole system is still turning.It will probably change the driving stability somewhat as the suspension (and the car at whole) is setup for AWD. And you may even decrease mileage dramatically due to wheel spin...
D.
03-01-2003, 01:48 PM
#4
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Originally posted by Paisan
4EAT w/o VTD:
Have the FWD Fuse. It can be used for short distances when the temp tire is in place. I you run it like this on a semi-regular basis you will break your tranny. Power split is 80/20 under normal conditions and can go up to 60/40 during slippage, pre-00 4EAT used speed sensors to detect slippage only, post-00 speed, weight and computer pre-emptively splitting power was established. Uses clutch packs to vary torque. When in "1" the ATF line pressure is increased to max pump as well as the clutch fluid pressure, this will give it a faster reaction time according to the factory manuals. Pre-96 4EAT had an initial split of 90/10.
5MT:
No FWD fuse, cannot disable AWD via fuse or easy means. Center diffy is viscous and will vary power. 50/50 initial split with up to 80/20 and 20/80 under slipping conditions.
XT6 5MT:
Same as 5MT but has manually controlled locking center differential that will lock power in at 50/50 no matter what slippage occurs.
4EAT w/VTD:
No FWD Fuse. This has initial split of 45/55 torque and can vary it up to 80/20 and 20/80 during slippage. Uses planetary gears along with clutch packs to vary torque. Also uses speed sensors, weight sensors and computer pre-emptive torque distribution like the 4EAT.
4EAT w/VDC:
Same as VTD but adds: Yaw sensors and use of brakes to stop slippage of individual wheels.
4EAT w/VTD & Sportshifter:
Same as VTD but adds tiptronic like controls for changing gears.
What vehicles have what ATs?
Imprezas/Forester up to 01 had 4EAT w/o weight and Ecu sensors.
Legacy up to 99 had 4EAT w/o weght and ECU sensors.
02 WRX has 4EAT w/VTD
VDC has 4EAT w/VDC
03 Legacy GT has 4EAT w/VTD and Sportshifter
00->03 Legacy and Outbacks have 4EAT w/ weight and ECU sensors
88,89,91 XT6: 4EAT w/o weght and ECU sensors or 5MT w/Locking center diffy.
4EAT non VTD/VDC units have electronically controlled clutch packs (3)
4EAT VTD/VDC units have electronically controlled clutch packs (6) plus a planetary gearset.
Manual Button, and Power Light:
Vehicles with "power" mode light can engage "power" mode when you hit the accelerator quickly, even if you are in the "2" "3" or "D" positions, this will raise your shift points to redline.
Vehicles without the "power" light do the same thing, except there is no light to indicate this.
If you have the "manual" button on your car, then you hit the manual button and place the car in "2" or "3" and the car will be held in that gear regardless of where the 4EAT thinks it should be.
Vehicles w/o the "manual" button, you can start out in 2nd gear by placing the shifter in the "2" slot, this will start you in 2nd gear and bounce you off the rev limiter.
I recently took my '92 SVX to Limreock Park for a track day. I tried several different combinations of gear slections. Finally settled on "2" which kept me in 2nd gear most of the track, when I hit the straightaway, it hit redline and upshifted to 3rd.
Hope this helps.
4EAT w/o VTD:
Have the FWD Fuse. It can be used for short distances when the temp tire is in place. I you run it like this on a semi-regular basis you will break your tranny. Power split is 80/20 under normal conditions and can go up to 60/40 during slippage, pre-00 4EAT used speed sensors to detect slippage only, post-00 speed, weight and computer pre-emptively splitting power was established. Uses clutch packs to vary torque. When in "1" the ATF line pressure is increased to max pump as well as the clutch fluid pressure, this will give it a faster reaction time according to the factory manuals. Pre-96 4EAT had an initial split of 90/10.
5MT:
No FWD fuse, cannot disable AWD via fuse or easy means. Center diffy is viscous and will vary power. 50/50 initial split with up to 80/20 and 20/80 under slipping conditions.
XT6 5MT:
Same as 5MT but has manually controlled locking center differential that will lock power in at 50/50 no matter what slippage occurs.
4EAT w/VTD:
No FWD Fuse. This has initial split of 45/55 torque and can vary it up to 80/20 and 20/80 during slippage. Uses planetary gears along with clutch packs to vary torque. Also uses speed sensors, weight sensors and computer pre-emptive torque distribution like the 4EAT.
4EAT w/VDC:
Same as VTD but adds: Yaw sensors and use of brakes to stop slippage of individual wheels.
4EAT w/VTD & Sportshifter:
Same as VTD but adds tiptronic like controls for changing gears.
What vehicles have what ATs?
Imprezas/Forester up to 01 had 4EAT w/o weight and Ecu sensors.
Legacy up to 99 had 4EAT w/o weght and ECU sensors.
02 WRX has 4EAT w/VTD
VDC has 4EAT w/VDC
03 Legacy GT has 4EAT w/VTD and Sportshifter
00->03 Legacy and Outbacks have 4EAT w/ weight and ECU sensors
88,89,91 XT6: 4EAT w/o weght and ECU sensors or 5MT w/Locking center diffy.
4EAT non VTD/VDC units have electronically controlled clutch packs (3)
4EAT VTD/VDC units have electronically controlled clutch packs (6) plus a planetary gearset.
Manual Button, and Power Light:
Vehicles with "power" mode light can engage "power" mode when you hit the accelerator quickly, even if you are in the "2" "3" or "D" positions, this will raise your shift points to redline.
Vehicles without the "power" light do the same thing, except there is no light to indicate this.
If you have the "manual" button on your car, then you hit the manual button and place the car in "2" or "3" and the car will be held in that gear regardless of where the 4EAT thinks it should be.
Vehicles w/o the "manual" button, you can start out in 2nd gear by placing the shifter in the "2" slot, this will start you in 2nd gear and bounce you off the rev limiter.
I recently took my '92 SVX to Limreock Park for a track day. I tried several different combinations of gear slections. Finally settled on "2" which kept me in 2nd gear most of the track, when I hit the straightaway, it hit redline and upshifted to 3rd.
Hope this helps.
//Mark
03-06-2003, 12:52 PM
#5
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Thanks for your answer,
These are good information for me. So I wil let my car in AWD any time except if I use my spare tire or my car car have to be towed.
You said that the Legacy with automatic transmission is 80-20 F/R most of the time and can go up to 60-40 F/R. Does it mean that the front wheels will always have 60% and more of the power even if the front wheels are on the ice. That not sound to me as good as with the manual transmission. If it is like that, that seem to be not to much better than the Honda CRV. I'm I right? Of course I talk about the automatic transmission.
Thanks
Kafou33
These are good information for me. So I wil let my car in AWD any time except if I use my spare tire or my car car have to be towed.
You said that the Legacy with automatic transmission is 80-20 F/R most of the time and can go up to 60-40 F/R. Does it mean that the front wheels will always have 60% and more of the power even if the front wheels are on the ice. That not sound to me as good as with the manual transmission. If it is like that, that seem to be not to much better than the Honda CRV. I'm I right? Of course I talk about the automatic transmission.
Thanks
Kafou33
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