Just purchased a 2016 Lexus IS300 AWD. Trying to find information on the AWD system, how it works, how it compares to other systems, etc. Anyone have information or a link. Google search has revealed little.
AWD questions
- Thread starter MajorCavalry
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Your best bet would be to follow a good forum. You'll learn a lot more than just AWD.
It uses the Aisin A760H transmission. A7xxx series has been around since 2003 in models like FJ cruiser, with the 6 speed you have in service since 2006. It's a nice heavy transmission (range topping) suitable for trucks so it's under-utilized against that 3.5 V6 IMO. The AWD is essentially the same as an FJ or 4runner, with planetary-gear center differential, plus a wet-type multi-disc clutch control. The basic torque split is 30F/70R with 50/50 on command. There really doesn't seem to be much readily available technical discussion about the system logic but IIRC the diffs are open and the Vehicle Dynamics Integrated Management (VDIM) uses braking and engine torque management to achieve a "limited slip like performance". It's about standard for modern common AWD systems in that regard.
For giggles, here's what your tranny and transfer case look like, standard fare configuration for longitudinal 4WD/AWD.
check out my.is and clublexus.com and enjoy the ride.
For giggles, here's what your tranny and transfer case look like, standard fare configuration for longitudinal 4WD/AWD.
check out my.is and clublexus.com and enjoy the ride.
Thanks Peter,
I am a member of ClubLexus. You info was more than I was able to find. Thanks.
How sensitive is this system to tire size discrepancies? My car has a staggered tire set up so rotation is not possible. The front tires are known to wear more rapidly. Will this result in damage to the AWD? Will all four tires have to be replaced once there is a substantial difference in circumference?
I am a member of ClubLexus. You info was more than I was able to find. Thanks.
How sensitive is this system to tire size discrepancies? My car has a staggered tire set up so rotation is not possible. The front tires are known to wear more rapidly. Will this result in damage to the AWD? Will all four tires have to be replaced once there is a substantial difference in circumference?
Curious how it does compared to your previous SH AWD.
I have SH Awd and in hard conditions (mud/deep snow) would defeat the traction control. However on slippery stuff the SH Awd was a hoot on the 3 miles of gravel/packed snow with 1100' hill climb to our vacation home.
I have SH Awd and in hard conditions (mud/deep snow) would defeat the traction control. However on slippery stuff the SH Awd was a hoot on the 3 miles of gravel/packed snow with 1100' hill climb to our vacation home.
Originally Posted By: madRiver
Curious how it does compared to your previous SH AWD.
I have SH Awd and in hard conditions (mud/deep snow) would defeat the traction control. However on slippery stuff the SH Awd was a hoot on the 3 miles of gravel/packed snow with 1100' hill climb to our vacation home.
Haven't had the chance to experience the IS AWD in adverse conditions. The SH-AWD of the Acura was great. I never drove real aggressively but worked great in rough New England winters. Not happy the rear differential failed at 75k! Despite frequent fluid changes.
Curious how it does compared to your previous SH AWD.
I have SH Awd and in hard conditions (mud/deep snow) would defeat the traction control. However on slippery stuff the SH Awd was a hoot on the 3 miles of gravel/packed snow with 1100' hill climb to our vacation home.
Haven't had the chance to experience the IS AWD in adverse conditions. The SH-AWD of the Acura was great. I never drove real aggressively but worked great in rough New England winters. Not happy the rear differential failed at 75k! Despite frequent fluid changes.
The rear diff was the entire mechanism, guts and glory of the SH-AWD, and was likely limited in the amount of light abuse it could handle. It was not a differential, for one. It was more of a spool with an electro-magnetic clutch on each side to engage each half shaft. The clutches were variable, controlled by a drivetrain computer somewhere, which allowed the vehicle to bias traction to the left or right half shaft independently.
I recall in a service manual that bench testing the gearbox and clutches required a minimum holding power of 145 ft/lbs per axle to pass. In the world of multi-100hp engines pushing 4000 lb vehicles around, 145 ft/lbs, or 290 combined, is very, very little. It's enough to get a reasonably cautious driver through snow over roadways, but not enough to manhandle an suv through sporty on-road mild hoonage.
IIRC that unit was also hard on fluid, and needed 30k changes, or maybe it was 15 (the CRV's system, vastly different, IIRC was 15k, and I get them mixed up).
Still, for on-road use and dealing with snow, excellent systems.
-m
I recall in a service manual that bench testing the gearbox and clutches required a minimum holding power of 145 ft/lbs per axle to pass. In the world of multi-100hp engines pushing 4000 lb vehicles around, 145 ft/lbs, or 290 combined, is very, very little. It's enough to get a reasonably cautious driver through snow over roadways, but not enough to manhandle an suv through sporty on-road mild hoonage.
IIRC that unit was also hard on fluid, and needed 30k changes, or maybe it was 15 (the CRV's system, vastly different, IIRC was 15k, and I get them mixed up).
Still, for on-road use and dealing with snow, excellent systems.
-m
As for the OP, that's a lot of transmission to put behind that engine, overbuilt. Sounds like a pretty simple system - similar to what subaru did in the late 90's with the manual-trans AWD, which was intuitive, non-invasive, and reliable. (Don't get it confused with the auto trans, which was entirely different). If it was anything like that, it just works, and you won't really know it's there. I think for that trans, subaru said not to run tires more than 1/8" diameter difference F/R, I think. The risk is you'll wear down the clutches surrounding the center diff. They aren't critical until you actually lose traction, but having them in-tact retains a lot more capability, especially in snow/ice.
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