FennyMike

Currently selling my 07' is250 and looking for an is350 3is, found out that the AWD has the 6-speed transmission that I am used to but the RWD has an 8 speed dual clutch transmission. Want to know how this performs, is there a big difference? Is it worse than the 6 speed? I would appreciate all the commentary and knowledge you guys have. Thankyou.

EDIT: Also heard that even in manual mode the car autoshifts right before redline, is this true? Is there a way to disable that?

05RollaXRS

I have driven both the 8 speed auto version in the RX350 F-Sport AWD (Same as the one in the IS350 F-Sport RWD) and I own an AWD IS350 F-Sport. Having extensively driven both, the 8 speed is much better than the 6 speed auto. The engine needs to be kept near its powerband as it is a bit of a peaky engine and the 8 speed does a better job at that. It is not a dual clutch, but still it feels very snappy for an auto even in the IS350 F-Sport RWD. No slushbox feel in manual mode. The 8 speed auto rev matching is also better than the 6 speed auto rev matching. It is still very different from the 8 speed AISIN in my RCF where the torque converter completely is locked out in manual mode and also software tuning is a lot more aggressive/faster and the gearing is different. Still the 8 speed in the RWD IS350 (or RX350 F-Sport AWD) is geared more optimally to work with the powerband, From my experience, the 6 speed auto is geared too long. In a 1/4 mile acceleration, interestingly their test numbers seem to be nearly identical of around 13.9 - 14.0 seconds, though.

Regarding the auto upshift, I found a solution to that in my 6 speed auto. If you disable traction control completely (hold the button down for 3 seconds), it will allow you to bounce off the rev limiter.

arentz07

I have owned both an AWD and RWD IS, and I agree with this summation. The 8-speed, simply put, feels more modern than the 6-speed. While it's not as snappy and smooth as a ZF, it's a lot better than anything you'll find in the average mainstream car out there, including FWD Toyota models with their 8-speeds. It'll let you bang off the rev limiter if traction is fully off, which is fun, and if you're either in Sport mode at high RPM or Manual mode, it'll give you a little kick between shifts. The only real issue I've noticed is that it tends to stumble for a couple of minutes in cold weather on a cold start. You may experience some rev flare and less-smooth shifts on your first start of the day, but it should resolve itself after a few minutes of driving.

FennyMike

Thank you for both of you, I appreciate it tons believe me. I gladly don't have to worry about cold weather as I am in Miami. Don't mean to bother and maybe it is obvious, but is the feel in power difference between an is250 and a 350 that major? 250 has been the only car I have ever owned so I don't have much to compare it to.

05RollaXRS

Yeah. there is a major difference between 250 and 350. I have driven both and the 250 feels really underpowered, in my opinion. The IS350 with 311 HP (2017+) and 306 HP fore before that, is a lot more fun and more than sufficient power for the streets.

E46CT

The 8 speed in the IS350 is a traditional torque converter transmission, no dual clutch. It's smooth. however shifts are a bit slow and mushy. It's not super responsive. it's an old old transmission with dates back to the older LS.

arentz07

The fact that it was designed for an LS is a good thing in comparison to a lot of other transmissions available. For one thing, you know it'll be over-equipped for the amount of power the 350 produces. Another is that it does a pretty good job keeping the revs down when you are driving chill. It also responds in a progressive way to throttle inputs and is super smooth on take-off unlike some dual-clutch transmissions.

Yeah, it's "old" but not broken!

jtrue28

My only complaint with the 8sp is when you kick it over to manual, it's in 6 or 7th gear and you have to downshift multiple times if you're using the engine to slow down. Whereas in the 6sp, it automatically goes over to 4, which will immediately slow you down, and easier to go to 3 or 2 (if needed). My experience is the 8sp in the 2020 RX350 and the 6sp in my 2022 IS350 AWD.

arentz07

In my experience it'll only go down to 6 if you are going too slow for 7 or 8. Same with the 6-speed. There's a minimum speed you must be traveling in a given gear.

If I go into manual mode at lower speeds, it'll go down to 5 or 4.

You could also just shift into Sport S/S+ first, then manual... might remove a couple of the extra paddle pulls.

TGPCanada

Massive difference. I had a 250 before my 350 and it is night and day. Now, I'm moving from the 350 to the 500. Keep climbing the HP ladder (and the $$$ ladder) and moving down the MPG ladder. LOL.

FennyMike

That's the goal my man. Congrats the on the new car and the hard work.

05RollaXRS

8 speed in the IS/RC is a very good transmission and shifts really well in manual mode. The one in the IS350/RC350 is not the LS transmission. It is actually a different one called AA81F. The one from the old LS was improved and strengthened to give higher torque capacity, more clutches per gear and torque converter lock-up for the ISF for mechanical engagement. It was called the AA80E. The shift speed in the ISF was 1/10th of a second (or 100 ms as opposed 350 ms for the IS/RC) back in 2008. At the time, 2008 GTR dual clutch used to shift at 150 ms. The AA80E transmission was updated mostly on the software side for better drive logic. It was modified for the RCF in 2014 with improved new software giving faster shifts, G-AI shift control, transmission coolers were added