CVT gearboxes

Submitted: Saturday, May 24, 2008 at 22:13
ThreadID: 57965 Views:5297 Replies:5 FollowUps:7
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Hi comrades,
Considering buying a CVT trans. Final drive ratio is given as 6.120 vs
4.235 for a manual. Is it a fact that any non manual trans will always be reving faster at any given road speed in 6th gear.
Nissan X trail dealer tried to tell me that the CVT delivers better fuel consumption than manual because of ..........
Mitsubishi lancer with CVT shows 8.2l/100 vs 7.7l for manual on windscreen sticker.Quite a different story.
Whats the real story? Anyone able to give feed back on CVT use?
Thanks
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Reply By: ben_gv3 - Saturday, May 24, 2008 at 23:13

Saturday, May 24, 2008 at 23:13
The CVT is not the issue with increased fuel consumption. All autos I know of use more fuel, CVT or not, compared to manuals. This is due to the torque converter which is a essentially a fluid coupling and hence there are losses (10-15% I believe).

Still, I would choose the auto over the manual anyday of the week as it is much easier to drive around town, on sand etc. The only time a manual would be better is going down steep terrain where engine braking capability is reduced.

CVT is the next generation of autos as it gives theoretically an infinate amount of ratios, but realistically has defined ratios, since it's hard to market infinate gear ratios as oppossed to 6, in your case.

A CVT is basically 2 cone shaped gears (facing opposite directions) lnked by a belt. Move the belt either way and you get different
ratios.
AnswerID: 305689

Follow Up By: wigger - Saturday, May 24, 2008 at 23:25

Saturday, May 24, 2008 at 23:25
Thks ben....
My understanding is that CVT dispenses with the use of a torque converter, which is the 'slippage' component that accounts for the increased consumption in a 'normal' auto (as opposed to a manual). This is the argument that the dealers put forward in support of BETTER fuel consumption. When you drive one of the CVT vehicles quietly, it is very apparent that the revs keep dropping back to a low fig, less than you would get even in a manual. i.e. you seem to be running along on absolute min revs if there is no significant load on the engine.
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Reply By: ben_gv3 - Saturday, May 24, 2008 at 23:49

Saturday, May 24, 2008 at 23:49
Nissan CVT

The link gives an interesting read.

Didn't know they are now torque converterless.
AnswerID: 305693

Follow Up By: wigger - Sunday, May 25, 2008 at 11:12

Sunday, May 25, 2008 at 11:12
Ths ben,
Good site. Will have to investigate further but i think that cvt by its very nature doesn't need a torque converter.
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Reply By: Ray - Sunday, May 25, 2008 at 08:39

Sunday, May 25, 2008 at 08:39
Didn't D.A.F. have a similar system years ago?
AnswerID: 305702

Follow Up By: wigger - Sunday, May 25, 2008 at 11:22

Sunday, May 25, 2008 at 11:22
Yes Ray , 1958 DAF sold a small car with CVT and you might remember that blond haired showoff who used to be on tv about 15 years ago, Albie Mangels who drove around Africa in one. Claimed he sold it to the DAF museum for megabucks. Reckoned he shagged every bird he ever met but it wouldn't have been in the DAF.
On Scrapheap Challenge the other night the teams had to build a tractor unit to pull chariots and one of them used a DAF engine and trans because it meant that they didn't have to worry about cables to effect gear changes. You could actually see the pulley arrangement
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Reply By: Peter 2 - Sunday, May 25, 2008 at 17:36

Sunday, May 25, 2008 at 17:36
How is the wear factor on the Nissan setup, given that it appears to be all metal to metal in fluid (probably ATF).
I realise it is a new thing but are there any ideas on life expectancy of the CVT trans?
Peter
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AnswerID: 305777

Follow Up By: wigger - Sunday, May 25, 2008 at 19:38

Sunday, May 25, 2008 at 19:38
Peter,
It's not all that new. Honda used it in the early Civic, and still uses it. All Mitsubishi cars us it as their "auto" box. The problem has been in developing it to cope with increasing power levels.

New X trail is available with CVT but their site hasn't got any reportbacks on it yet. Nissan have also fitted it to the Maxima and there aren't any complaints on motorsm .com which is where all the horror stories can be found.
A couple of years ago I was in a workshop at Rushcutters Bay and they were working on a Micra (about 8 yrs old) with CVT and the guy said that it was going to be expensive to do the trans. but unfortunately i didn't get any more details.
I am going for a CVT because the manual X Trail is now fitted with a dual mass flywheel and if one of these goes, as have Patrols, then you are up for more money than the cost of taking the 'auto' option cost when buying the vehicle.
If longevity is roughly equal and repair costs are comparable, then why wouldn't you go for CVT because it's lighter, has fewer moving components, and gives better fuel economy than a traditional auto box using a torque converter.
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Reply By: Member - Phil G (SA) - Thursday, May 29, 2008 at 22:25

Thursday, May 29, 2008 at 22:25
Fuel figures are:
9.5 l/100k for manual T31 Xtrail
9.3 l/100k for CVT T31 Xtrail and
9.8 l/100k for 4 speed auto T30 Xtrail.

The CVT is a plus. But we didn't like the rest of the vehicle, so our last Xtrail purchase was a runout T30 model with the old 4 speed auto. They say the CVT is simpler, and hence reliable.
AnswerID: 306635

Follow Up By: wigger - Saturday, May 31, 2008 at 07:55

Saturday, May 31, 2008 at 07:55
Hullo Phil,
Yes these are the figs I got from them but the curious thing is that while Nissan are saying that the cvt is using .2l less, Mitsubishi are saying that the 2l Lancer engine uses .5l more. Are they operating differently?
Why didn't you like the T31, because by all accounts they have improved it by shifting the instrument binnaccle and getting rid of the understeer. I looked at one previously in 2001 and it might have been the tyres fitted but it was a chronic understeerer. We have to climb the winding steep road out of Murwilllumbah to Kyogle and on a narrow road, you can't afford to run wide.
Suppose you are aware that ther is an X trail owners forum.
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Follow Up By: Member - Phil G (SA) - Monday, Jun 02, 2008 at 09:15

Monday, Jun 02, 2008 at 09:15
I would have definitely preferred the CVT and the traction aids in the T31. The extra airbags don't make much difference to safety - still only 4stars. But I didn't like the changes in the body. It was a fair bit longer, so would have been a tight squeeze into our garage. That extra length was not well used - no extra seating space, and it had more overhang. And we really like the centre dash and layout in the T30. And of course saved a fair bit of $$ by doing a deal on a runout demo with a heap of extras.
We potter around in ours, so handling doesn't matter - we have to drive a long way to find a hill in Adelaide, but we use ours in 4wd all the time, so I don't spin the wheels and annoy my wife :-))
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Follow Up By: wigger - Tuesday, Jun 03, 2008 at 18:50

Tuesday, Jun 03, 2008 at 18:50
Phil,
We human beings are very idiosyncratic creatures and this is why manufacturers can take advantage of the fact that dishing up an alternative will always attract more buyers.
I was having a bit of a mental problem buying one with the centre binnacle because it took me back to the time when I had to drive round in a Morris 1000 and I have never hated anything as much as that thing. Even the lo light that I had before it was less humiliating.
You're right, the runout price was great. Usually I'm trhe tightarse
but my partner said the equivalent of " I'm a bling girl and I want a bling car" . It was being paid for out of her car allowance so I just smiled and said YES.
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