Why is it that the car will not go into 6th gear unless over 40...even when im traveling at around 35 for extended periods of time it stays in 5th...is that for mechanical reasons or is that just how lexus made it...?

 

Probably becuase at that low of a speed, the RPM's will drop too low if it were to go into 6th. If you've ever driven a manual and upshifted to too high of a gear, the whole car starts to shake and may stall.

 

5th and 6th are both overdrive gears. 6th is also temperature dependent. If the ATF isn't warm enough, it won't matter how fast you are going, it will not shift into 6th.

 

6th gear is too high for the speed traveling. It is designed this way so the engine does not knock.

 

Couldn't you just switch into sport-mode and make it switch to 6th if you really wanted to?

 

No, it doesn't let you go into a gear that will be harmful. No overrev or underspeed allowed.

 

No you can't... You can choose 6th gear, but the car will not shift into 6th if you're going too slow.

 

if you got a moutain bike.. imagine yourself on the highest gear going uphill.... this is what the car is going to feel... it's not good..

 

No, sport mode only adjusts the maximum permissible gear, it doesn't actually compel the tranny to upshift. It is no easier to coax the tranny into a higher gear in sport mode than it is with the selector in "D".

 

thank you all for the responses...but if i go over 40 it shift to 6th but when i happen to drop down in the upper 30s it stays there...

 

That is a hysteresis to prevent the tranny from switching in and out of a gear when sitting "right on the line".

 

Why in the world would you want to be in sixth gear at 35 mph
Please don't say that it is for gas mileage.

I use sport mode just for that reason. If I am in an area that I know I will only be doing 25-40 mph or so, I only open 3rd or maybe 4th gear so that I don't get into 5th or god forbid 6th gear at such a low speed. I think this tranny takes you to a high gear way to fast at slow speeds.

 

its not for gas mileage...i was just curious...im not exactly mechanically literate...

 

Considering your last post stating that you're not, "mechanically literate", I'll tell you that 6th gear (or 5th on a 5 speed transmission) is an "overdrive gear". This means that if your gear ratio was 1:1 then the engine would be at an rpm equal to the speed of your turning wheels. An overdrive gear is less than a 1:1 ratio so that your wheels are spinning faster than the engine rpm is which would put less strain on your engine and produce better gas mileage during long distance cruising. The power delivery, or transfer from the engine to the wheels, would not be so great because the gearing in 6th wouldn't allow for it. I hope this helps you understand the purpose of 6th gear in your car as well as why you probably would not want to be in 6th gear unless cruising on the highway.

 

thank you...makes sence now...and thank you to all the rest of you that responded to this thread...