I think I said it earlier in the thread, but shorter gears are just going to make you slower. If your looking to get the most out of your power, swap back to the stock diff or find one with a longer drive. Do you know of any fitting diffs with a longer final drive?

 

Finished the install this morning and went out for a quick test drive. Initial impression is a huge thumbs up. My car is stock except for the IS350 diff. Accelerating on the highway, if you let off at 80 mph, your head snaps forward. The car pulls like a freight train all the way up too. Stock tires definitely need to go and get replaced with something wider.

Now, to figure out what I want to do for an exhaust...

 

I dunno of any longer gear sets but I found a used 2010 isf rear end with LSD for 950 used that I will be scooping up... To me that LSD is so important for the track and 60 ft times on the strip it will be a much greater improvement than changing gearing. Plus I hate being limited to 130 mph it's not even funny

 

I got that from the video lol. You sounded like a kid at a carnival who's balloon just popped haha.

 

Where and are there more? Please pm me! I have been searching car-part.com for a while and nothing comes up..

 

Interesting.

 

After a few weeks of driving the car with the diff (in automatic) I gave It a try in snow mode last night. The car seems to drive totally normal, the car is no longer jerky, it shifts up and down properly. Anybody else give it a try yet?

 

I've not tried snow mode, but after driving around a couple of days in automatic mode, it seems pretty normal. It does shift a lot lower and it will get into 8th gear around 30-35 mph.

 

This was fun but i miss top end.. if anyone is thinking about it im selling mine in classifieds. 350 shipped

 

I agree with slay. It only helps in the first gear - after that, the stock ratios are close ratio and it won't help at all. If somebody has time, they should plot a mph vs. torque at the wheel chart and the 350 diff will initially ramp up quicker but then will have little sawteeth shaped graph while the stock one will ramp up just a touch slower but will have a little larger sawtooth graph. In theory, the 350 will be a touch more powerful but because of the extra shfits, any gain will be negligible after the first gear - that's if you can even put down the power in first gear. I have no intention of changing my diff.

 

Here you go:


I finally got my older gen LS diff with the 3.277 final drive. I need to pull it apart and see if the guts can be transplanted into a newer style diff since I think 3.277 would be the way to go. Improvement almost all the way across the board.

 

Thanks for posting - like I was saying, the biggest benefit is the first gear and after that, it's back and forth depending on what speed you're actually at. At the local track, most of my time is spent from 50-110 mph (2-4 gear) and with the IS350 diff, I'd be shifting from gears 3-4-5-6 (an extra gear) and with no real torque to the ground benefit. Also, besides the drag strip, first gear is already pretty short and barely able to maintain traction anyways. Typical acceleration is about .75 G in first gear which is about the maximum my tires can handle. Based on that graph, the IS350 can pull about 1.0 G in first gear - but that's assuming the tires can hook up!

 

The car certainly feels more responsive driving around and the shifts are noticeably firmer.

I think it's a wash performance wise as you said, but as far as driving fun goes, I like the 4.09. It puts a big smile on my face when I drive the car. I don't drive on the highway a lot, so my fuel economy isn't really much different, but that might be a dissuading factor for some.

i'll try to get some data on the 3.266 over the winter. It looks like you only lose torque in a few places, but net about a 10% improvement in almost 3/4 of the places.

 

So, my wife is complaining about how aggressive the car is so I have no choice but to change it out again. I'm sick of hearing her wine like a baby. I love the feel of it, but I dont like the way my head pounds after the wife is done complaining. I will be pulling it within the next few weeks, I live in the GTA, for sale for $350. I just picked up a stock 2010 Diff with LSD. if somone wants it I will be more inclined to swap it out faster. Let me know.