Author Topic: The CVT option - real drivers opinion  (Read 740 times)

culzean

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Re: The CVT option - real drivers opinion
« Reply #30 on: February 09, 2018, 10:43:07 AM »
This is from RoSPA.

When stationary in traffic, even for many minutes, it is not necessary to move the gear lever into neutral because the torque converter absorbs the engine’s propulsion force but does not transmit it all to the gearbox. No wear is taking place. Some people believe that more wear will take place if you engage neutral then re-engage a drive gear when it is possible to move off. This is not the case as the clutches that engage the gears are so well designed, built and accurately controlled that any wear that could take place is minimal. Most gearboxes will automatically select first gear when the vehicle becomes stationary. (Italics are mine)

http://www.kentrospa.org.uk/Automatic_Gearboxes_and_Their_Use

Yes. One reason why automatics tend to be better in snowy conditions.

Main reason Jazz is pretty good in snow is that it ain't got a lot of torque to initiate wheelspin, coupled with fairly narrow tyres - but CVT does help,  even my wifes previous (about 20 years ago)  Fiat CVT (Selecta) was pretty good on snow (when it was actually running LOL).   The Fiat had a 'magnetic powder clutch' - with powder between two plates and an energising coil that ramped up the current to stick the powder together till it became virtually a solid drive - it was so smooth and was probably the most trouble free part of the car. Only problem we had with the CVT was a £10 switch on the brake pedal which was there to stop drive engaging when brake pedal pressed,  but when switch failed it intermittently removed drive altogether - very embarrassing at junctions and Islands.

looks like Nissan used a similar setup

http://vaguevagaries.blogspot.co.uk/2010/02/replacing-electromagnetic-clutch.html

Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

Kenneve

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Re: The CVT option - real drivers opinion
« Reply #31 on: February 09, 2018, 10:58:55 AM »
When stationary in traffic, even for many minutes, it is not necessary to move the gear lever into neutral because the torque converter absorbs the engine’s propulsion force but does not transmit it all to the gearbox. No wear is taking place. Some people believe that more wear will take place if you engage neutral then re-engage a drive gear when it is possible to move off. This is not the case as the clutches that engage the gears are so well designed, built and accurately controlled that any wear that could take place is minimal. Most gearboxes will automatically select first gear when the vehicle becomes stationary.

Not entirely so. If I stay in drive when stationary, with the brake on and then release the brake, the car will creep  forward on a level road, even at tick-over engine speed, (circa 600 rpm). This means that the the engine, is not entirely disconnected from the transmission and is trying to do some unnecessary work.

madasafish

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Re: The CVT option - real drivers opinion
« Reply #32 on: February 09, 2018, 01:42:12 PM »
I think there is a bit of debate in various forums and there is a view that you should just keep the footbrake pressed at lights. If/when I go the CVT route, I'm going to be in neutral with handbrake on! That's what the IAM seems to recommend.

Some of us use handbrakes in traffic with car in D.. And the handbrake holds.Keeping footbrake on is unnecessary for the driver and unpleasant to those behind.In hot weather you may end up warping front disks is done frequently after hard breaking as the disk cools unevenly.

I take teh view of an automatic that you minimise driver work and thus make driving in heavy traffic/stop/start motoring that much easier...  - which is why I bought an auto and do as little as possible to the gearstick. Plus less movement means I am practising for lying still in a coffin... :P

Jocko

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Re: The CVT option - real drivers opinion
« Reply #33 on: February 09, 2018, 02:19:23 PM »
Brake discs don't warp. Material is transferred from the pad to the disc causing the thickness of the disc to vary in spots. This is a result of the pads being heated to temperatures well above their operating range. This could be caused by extreme hard braking and sitting for a long time, with the footbrake on, after coming to a halt but is not something you are normally likely to experience in a Jazz, in the UK. Unless you are using it for competition.

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