subaru AWD info wanted
12-04-2003 | 04:56 PM
#1
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subaru AWD info wanted
i was just woundering how the the AWD worked on my subby i heard some where that the newer subbys are like 70% of the power to the back and 30% to front or some ratio around that and changes % as traction is lost or gained.
I was woundering if that is correct first and if older modles 1998 impreza L spesificaly was like that
I was woundering if that is correct first and if older modles 1998 impreza L spesificaly was like that
12-04-2003 | 07:23 PM
#2
I believe that most Subaru's have a 90/10 front/rear split (although I've also heard 80/20) under nominal conditions. Power is shifted around when needed.
EDIT: Looks like I'm wrong, slightly. Its only the Auto's that have this powersplit. The manuals have a 50/50 split.
EDIT: Looks like I'm wrong, slightly. Its only the Auto's that have this powersplit. The manuals have a 50/50 split.
Last edited by Nick Koan; 12-05-2003 at 05:23 PM.
12-04-2003 | 08:00 PM
#4
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the 4EAT (auto Tranny) has a 90/10 spit is what I read somewhere. and the Manual has a 50/50 split. the STi can manually be changed to 35/65 I believe and its goes from 50/50 to 35/65 in auto mode. I may be incorrect the exact #'s but the Auto and the Manual has different splits.
12-05-2003 | 12:59 AM
#6
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From: Roseville, CA
Car Info: 1995 Subaru Impreza 1.8 L
Originally posted by wrxwagon2b
the 4EAT (auto Tranny) has a 90/10 spit is what I read somewhere. and the Manual has a 50/50 split. the STi can manually be changed to 35/65 I believe and its goes from 50/50 to 35/65 in auto mode.
the 4EAT (auto Tranny) has a 90/10 spit is what I read somewhere. and the Manual has a 50/50 split. the STi can manually be changed to 35/65 I believe and its goes from 50/50 to 35/65 in auto mode.
12-05-2003 | 09:30 AM
#9
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Originally posted by hashiriya
OK then, whatever the actual dist. is, how bad is the understeer, really? See, I don't have my car yet, it hasn't been delivered. Can the under be corrected with just suspension mods, and it so, how extensive need they be?
OK then, whatever the actual dist. is, how bad is the understeer, really? See, I don't have my car yet, it hasn't been delivered. Can the under be corrected with just suspension mods, and it so, how extensive need they be?
12-05-2003 | 04:19 PM
#10
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Forester S; According to Subaru of Americas' technical dept and Subaru Australla my Forester with AT has a default power torque split of 60 front/40 rear untill a difference in wheel torque is detected. Power is then proportionally tranfered to the rear. The default (no torque difference) is determined by the transfer gear set behind the transsmission but, before the continously variable clutch pack. This is shown clearly in the Subaru shop manual. The manual transmission used a locked center differental instead of a variable clutch pack. The center differentals default ratio is 50/50 untill a difference in front to back wheel speed is detected. A silicon friction clutch will heat up when wheel speed difference is present and power is then shifed to the rear of the car. Subaru claims that the transfer gear set is reversed in the Impresa RS to give a default ratio of 40 front/60 rear to give a more sporting feel in spirited driving. Hope this sheds some light on the irronious 80/20 or 90/10 or some other misquoted split being passed around. Eddie
12-05-2003 | 05:43 PM
#11
Well, the 90/10 split is only erroneous because the powersplit on the 4EAT moves around.
Basically there are two extremes that the "continuiously-variable transfer clutch" can have, full lock and full release. Under full lock, the car has a perfect 50/50 split. Under full release, there is only a little bit of fluid friction between the two plates of the transfer clutch, this accounts for the oft quoted 90/10 split.
Subaru has some other AWD systems too, and they are all different.
The automatic WRX's come equipped with a Variable Torque Distribuition (VTD) AWD system which is nominally a 45/55 powersplit. I'm guessing this is similar to the transmission in the Forrester S?
The 5 speed manual (as stated above) is has a 50/50 nominal powersplit.
I have no clue about the 6 speed manual, or the Outback's VDC, but I'm sure they have slightly different properties then what has been mentioned here.
Basically there are two extremes that the "continuiously-variable transfer clutch" can have, full lock and full release. Under full lock, the car has a perfect 50/50 split. Under full release, there is only a little bit of fluid friction between the two plates of the transfer clutch, this accounts for the oft quoted 90/10 split.
Subaru has some other AWD systems too, and they are all different.
The automatic WRX's come equipped with a Variable Torque Distribuition (VTD) AWD system which is nominally a 45/55 powersplit. I'm guessing this is similar to the transmission in the Forrester S?
The 5 speed manual (as stated above) is has a 50/50 nominal powersplit.
I have no clue about the 6 speed manual, or the Outback's VDC, but I'm sure they have slightly different properties then what has been mentioned here.
12-05-2003 | 06:14 PM
#12
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Putting on a stiffer rear sway bar should correct the understeer
If I get the sway bar and reinforce the fronts bottom half would I relieve most of the understeer?
12-06-2003 | 08:22 AM
#14
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The power torque split produced by the "continiously variable clutch pack" of the (standard) AT is not either on or off but is "continiously variable". I have seen no data describing what the extreams are, but Subarus' techical department is quite explecit stating it is variable.
