Longer Gears

[Poodles]

Originally Posted by slicktop

Lower RPM doesn't always equal better fuel economy. Your powerband also plays into fuel economy.

If the lower RPM band requires more load on the engine (more throttle = more fuel) to maintain speed, you will lose fuel economy. If your RPM band is slightly higher than that, but reduces that engine load requirement, your fuel economy increases.

Sure higher RPM will have more combustion, however, notice how at lower RPM you have to really floor it compared to the higher RPM (powerband).

If you're going for economy only, keep your FD in there. I'm 100% positive that the engineers designed it properly in that way. I mean, I had mid-30 MPG on a 1500 mile road trip in mine. That's calculated by fuel receipts, not the gauge.

For example, I get worse MPG by the dash when I'm cruising at the speed that puts me in the torque dip. Above or below it the MPG goes up considerably.

[Cal3000]

Originally Posted by Dipstik-sportech

You rang!!! I've done the 3.73 diff swap. For forced induction it's almost a must do. Makes highway pulls a much less frantic experience lol, less shifting and more speed per gear.

I've been thinking of doing this for a long time. Do you have any vids of highway pulls with this diff?

[wparsons]

Originally Posted by dwx

Is there anything special about the non LSD vs the LSD one if you are going to install an aftermarket LSD? I plan on using an OS Giken LSD.

The whole benefit to the IS300 part is that it's a direct swap without having to pull the ring/pinion and diff apart. If you're already swapping in a new LSD you could just look for a new ring/pinion instead of an entire rear end as well.

[Lawnik]

Anyone know the Lexus PN for the M85 3.73 ring and pinion?

[kodyo]

Originally Posted by Lawnik

Anyone know the Lexus PN for the M85 3.73 ring and pinion?

Your best bet is to go to a parts website for the 2002 is300 and use their parts diagram.

[Lawnik]

I did end up finding the PN for both. Here they are for the community;

The M85 Lexus 3.727 Ring and Pinion PN 41201-80050 replaced by PN 41201-80781

The M98 Lexus 3.909 Ring and Pinion PN 41201-80052

[continuecrushing]

What speed per gears are you guys getting after the swap? Even just ballpark ish if you don't know exact