IS350 AWD powertrain detail
09-10-22, 12:41 PM
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IS350 AWD powertrain detail
I have an IS, a '17 350 AWD. Is there a description available for the powertrain elements and how the "power" flows to the wheels? Thanks if you can provide a link or a clarification.
I just got under my car for a few minutes the other day, and this is my guess as to how it works. First time I've seen this system up close. I'm just kind of thinking out loud here. Bear with me.
I'm assuming it was originally designed as a RWD car and then Lexus adapted it to be AWD. The engine and transmission is obviously oriented in a longitudinal direction like a typical RWD car. It seems that there's a transfer case at the back of the transmission so the power can go to the rear wheels as "normal" via the driveshaft and a rear differential, but also to this beefy other "shaft" which goes back towards the front of the car. I don't know the proper name for this other secondary shaft; maybe it's called a propeller but that doesn't seem right. Anyway, this second shaft goes from the transfer case to what looks like a (front) differential and then power goes from there via the front axle shafts to the front wheels. Let me know if this is correct, or not?
I have a couple obvious questions. Do each of the two differentials have a ring and pinion gear like a traditional diff? I guess if they do, they would have to have the exact same ratios. (?) Do the two diffs - front and rear - have traditional spider gears and axle gears? Are either or both of the two differentials Limited slip (LSD)? Is it the transfer case that divides the available "power" (torque) which is normally 70 - 30? How does it do this?
Any info you can provide is appreciated. Most articles I see on these topics just gloss over the details and don't get into the nitty gritty.
Jim C.
I just got under my car for a few minutes the other day, and this is my guess as to how it works. First time I've seen this system up close. I'm just kind of thinking out loud here. Bear with me.
I'm assuming it was originally designed as a RWD car and then Lexus adapted it to be AWD. The engine and transmission is obviously oriented in a longitudinal direction like a typical RWD car. It seems that there's a transfer case at the back of the transmission so the power can go to the rear wheels as "normal" via the driveshaft and a rear differential, but also to this beefy other "shaft" which goes back towards the front of the car. I don't know the proper name for this other secondary shaft; maybe it's called a propeller but that doesn't seem right. Anyway, this second shaft goes from the transfer case to what looks like a (front) differential and then power goes from there via the front axle shafts to the front wheels. Let me know if this is correct, or not?
I have a couple obvious questions. Do each of the two differentials have a ring and pinion gear like a traditional diff? I guess if they do, they would have to have the exact same ratios. (?) Do the two diffs - front and rear - have traditional spider gears and axle gears? Are either or both of the two differentials Limited slip (LSD)? Is it the transfer case that divides the available "power" (torque) which is normally 70 - 30? How does it do this?
Any info you can provide is appreciated. Most articles I see on these topics just gloss over the details and don't get into the nitty gritty.
Jim C.
07-21-24, 05:43 PM
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It's a bit late if a reply but better than never.
It's actually a fairly old system, found first in late 90s Toyota Crowns I believe. That said the newer models have moved to a torsen center diff. But it being old means it's fairly reliable and can usually sustain higher load on the secondaryy drive wheels longer than those clutch based systems found on most newer cars, especially those that are Transverse
https://toyota-club.net/files/faq/11..._ifour_eng.htm
It's actually a fairly old system, found first in late 90s Toyota Crowns I believe. That said the newer models have moved to a torsen center diff. But it being old means it's fairly reliable and can usually sustain higher load on the secondaryy drive wheels longer than those clutch based systems found on most newer cars, especially those that are Transverse
https://toyota-club.net/files/faq/11..._ifour_eng.htm
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