I noticed that the RWD model IS 350s have a 4.08 final drive gear ratio, but my AWD model has a 4.10 gear ratio. Would swapping my 4.10 for the 4.08 make a noticeable difference in acceleration? And would it even be possible to swap them? The car is most definitely quick as it sits rn, but it’s definitely not as quick to 0-60 as the RWD models and am curious to why that is!

 

If you want acceleration, that's going the wrong direction. After that, the difference in ratio would cause binding between the two ends. You would gain nothing.

 

The IS350 AWD and RWD share the same ratios in the transmission and the final drive of 4.08 vs. 4.10 is effectively the same. Basically, the cars have the same gearing.

Jeff

 

FWIW, was only trying to apply the concept, not state it won't work. There are applications where the front diff ratio is lower than the rear as it travels further in the corners and on ice for example, this keeps the front at the front as the rear is less likely to pass it if it's being pulled vs pushing like a RWD car.

My F250 and F350 both had a 0.1:1 higher ratio in the rear. 4.09:1 /4.10:1 and 4.10:1 / 4.11:1... These also had locking hubs and an not differentiating transfer case. It was in or out. No proportioning front to rear. So on dry pavement it was easy to bind things up especially if trying to get it out of 4 low or 4 high.

 

Sorry for resurrecting an old thread but my question is related. Can anyone confirm if the rear diff on a AWD and RWD is350 are the same? Is it a direct swap? I don't mind if there's a difference in final gear ratio, I just want to know if it'll bolt up with no issue. More specifically, Im looking to swap an is350 diff onto my 2011 ISF. I know some ppl have done that but I need to know if it's only compatible with is350 RWD or AWD as well. Thx