CVT tranny

[dft53]

I bought a new sx4 sedan and new to this kind of tranny and have a few of questions about it, hope anyone can help. 1. while in manual mode when i shift up to 6th gear sometimes it goes in, sometimes not. is there a problem with the tranny? 2. what are the speeds for up & downshifting? i don't see that in the manual for the cvt.3. does it hurt the tranny to go in & out of manual & auto? as i said i'm new to this type of tranny.

[Scudo]

Similarly with many modern automated transmissions with manual override. It won't shit into a higher gear if it deems the road speed is too low. Also it may not shit into a lower gear if it deems that the road speed is too high.

They may also shift without input if the road speed does get too low for the gear (shift down) or if you are approaching redline to prevent you from going into it.

With cvt leaving it in drive is the best bet (even if doing 1/4 mile runs on the drag strip) unless you want some engine braking.

[LMP]

AOK with all Scudo said.
You will also notice "out of the ordinary" (for an automatic) engine braking at low speed..until you are almost stopped and suddenly it lets the car go. THis is because now (at least relatively new for me..and I have seen it with other recent cars) the injectors are totally cut off on engine braking...until you are almost stopped and it does need some fuel to stay alive. While one would consider this a good move towards fuel economy, it is somewhat disturbing and in city driving, I will generally shift to neutral when i want to decelerate at a "normal" pace.

[LMP]

....and....you will notice that in manual mode 6th "gear", even if you floor the throttle, it will NOT deliver full torque...look at the fuel flow indicator....the fuel feed is computer limited in 6th to avoid transmission overstress. WIth a severe headwind, it will not even keep speed.
Flip in 5th and you have all the power available....so , as said, AUTO is the easiest way to go....alas...

[dft53]

Thank you all for the info. I think i'm finally getting used to it lol! I leave it in D and only use manual for downhills. Thanks again for the info!

[seh]

Thanks to LMP for the accurate post on slow speed engine braking. I experience that all the time and find it very upsetting. I'm thinking it's one of the reasons for the horrible fuel economy (16.2 l/100 km or 14.5 mile/us gallon)in 100% city driving, all short trips. This, on a new 2012 with 1500 km. on it!

Anyone else on this?

[digdug18]

You need to remember that a CVT doesn't have traditional gears. It infact is a series of geared bands, sorta like a timing belt, that are adjusted to create gear ratios.

Here's a link on youtube for you to see.

3D anitmaion of CVT Transmission - YouTube

3D anitmaion of CVT Transmission - YouTube

This engine is NOT for performance, increasing the performance of your engine will kill your transmission.

[LMP]

...naturally...and the "belt" is made of metallic cogs...so I take seriously what is reported in another thread about grooving the cones if you keep using the manually chosen positions..which could specially be and worsen the case using lower positions when towing....

[TheShadowFL]

The CVT system shown in the video, is almost exactly like what was used in the 1960 Harley Topper Motor Scooter.

In that case, centrifugal force on Fly-Ball Weights in the driven pulley caused it to squeeze the belt and cause it to ride higher in the pulley. The larger pulley was spring loaded so it could be spread apart and drop the belt to a lower position on the pulley, thus changing the gear ratio to "Road" gear.

Shifing was smooth and effortless from start to maximum speed. Take off was so positive I could even do Wheelies!

The first time I test drove a 2010 SX4 with the CVT, it felt a lot like my old Topper. It was nostalgic.

For those who have never seen a Topper, here it is:


That was a great ride for a 16 year old boy!

Cheers!

[TJinPgh]

I had a mini-bike back in the 70s that used that same basic torque converter setup.




Not really a new idea, though somewhat new to automobiles, I guess.