CVT transmission

  • Thread starter Thread starter shane
  • Start date Start date
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shane

Hi,
I have just purchased a Volvo 440 SE, with CVT transmission, which seems to
work ok, but the revs never go above about 2500 rpm, when I accelerate
hard, and when I'm driving at about 60 mph, and accelerate hard there is
very little change, and no equivalent to "kick down", is this normal for
CVT's?.
Also is the "L" position just for low speeds?.
 
Isn't that the whole point of a CVT? - To constantly keep the engine at
optimal RPMs
 
I have just purchased a Volvo 440 SE, with CVT transmission which seems to
work ok, but the revs never go above about 2500 rpm, when I accelerate
hard, and when I'm driving at about 60 mph, and accelerate hard there is
very little change, and no equivalent to "kick down", is this normal for
CVT's?.
Also is the "L" position just for low speeds?.
Click to expand...

How interesting! I didn't know that Volvo still used the CVT
transmission in the 4 series. From my recollection, the old
DAF/Volvo 66 didn't have a "L" position, but I would assume
that is for low speeds. However, what you describe - no rapid
response to acceleration, and no "kick down" is normal for
CVT's.

Do you know if the CVT used in the 440 SE is based on the same
principle as the CVT used in the DAF 66 and Volvo 3 series of
late '70s?

Thanks,
Beverly
 
Isn't that the whole point of a CVT? - To constantly keep the engine at
optimal RPMs
Click to expand...

Exactly right. However because of the way the DAF CVT works, which
was used in the DAF/Volvo 66 (don't know about the Volvo 440 SE), when
you accelerate, rpms transiently go high, until the CVT responds. This
seems to be true of CVTs in general based on this page ...
http://cvt.com.sapo.pt/control/control.htm
 
The Volvo 66 series used a different kind of CVT, it used rubber bands. The
where first used in the Dafodil beginning of the 60-ties. The newer version
used in the 440 and Fiat Uno (and other I suppose) work with a chain of
metal segments instead of rubber. The basics however are quite the same as
far as I know. The metal segements are carefully sellected together in the
factory to ensure the maximum amount of reliability. I once saw a
documentary some 12 years ago. It seems that is the best kind of automatic
transmission there is, but productions costs are slightly higher than a
conventional type. In the beginning CVT was only possible for cars with
rather small engines, dunno if that has changed.

In the beginning of the eighties we had backward races for cars with CVT,
the run as fast backwards as the do forewards!

BR

Martijn
 
shane said:
Hi,
I have just purchased a Volvo 440 SE, with CVT transmission, which seems to
work ok, but the revs never go above about 2500 rpm, when I accelerate
hard, and when I'm driving at about 60 mph, and accelerate hard there is
very little change, and no equivalent to "kick down", is this normal for
CVT's?.
Also is the "L" position just for low speeds?.
Click to expand...

No, when you accelerate even moderately hard the revs should rise up quite
high, under kickdown the CVT should allow the engine to rev to maximum
power- ~5200rpm and stay there whilst the car "catches up". Sounds like you
have a problem.

L is for slow speeds and for maintaining engine braking going downhill- it
holds a lower gear.

Tim..
 
No, when you accelerate even moderately hard the revs should rise up quite
high, under kickdown the CVT should allow the engine to rev to maximum
power- ~5200rpm and stay there whilst the car "catches up". Sounds like you
have a problem.

L is for slow speeds and for maintaining engine braking going downhill- it
holds a lower gear.

Tim..
Click to expand...
With the Daf "rubber belt" (they were like "industrial strength"
cambelts (Yeah, work of the Devil))CVT, it used to be possible to have
the car accelerate while the engine revs were falling. I wonder if that
still works on the 'new' CVTs?
 
Don't forget that DAF built a Formula 3 race car which was not allowed to
compete as it had an unfair disadvantage. The CVT allowed it to accelerate
faster than a Ferrari!!

Cheers, Peter.

:
:
: The Volvo 66 series used a different kind of CVT, it used rubber bands. The
: where first used in the Dafodil beginning of the 60-ties. The newer version
: used in the 440 and Fiat Uno (and other I suppose) work with a chain of
: metal segments instead of rubber. The basics however are quite the same as
: far as I know. The metal segements are carefully sellected together in the
: factory to ensure the maximum amount of reliability. I once saw a
: documentary some 12 years ago. It seems that is the best kind of automatic
: transmission there is, but productions costs are slightly higher than a
: conventional type. In the beginning CVT was only possible for cars with
: rather small engines, dunno if that has changed.
:
: In the beginning of the eighties we had backward races for cars with CVT,
: the run as fast backwards as the do forewards!
:
: BR
:
: Martijn
:
:
:
:
:
:
: : > On Sun, 18 Jul 2004 22:14:46 GMT,
: > shane ([email protected]) wrote:
: >
: > > I have just purchased a Volvo 440 SE, with CVT transmission which seems
: to
: > > work ok, but the revs never go above about 2500 rpm, when I accelerate
: > > hard, and when I'm driving at about 60 mph, and accelerate hard there is
: > > very little change, and no equivalent to "kick down", is this normal for
: > > CVT's?.
: > > Also is the "L" position just for low speeds?.
: >
: > How interesting! I didn't know that Volvo still used the CVT
: > transmission in the 4 series. From my recollection, the old
: > DAF/Volvo 66 didn't have a "L" position, but I would assume
: > that is for low speeds. However, what you describe - no rapid
: > response to acceleration, and no "kick down" is normal for
: > CVT's.
: >
: > Do you know if the CVT used in the 440 SE is based on the same
: > principle as the CVT used in the DAF 66 and Volvo 3 series of
: > late '70s?
: >
: > Thanks,
: > Beverly
: > --
: > Bev A. Kupf
: > "The lyfe so short, the craft so long to lerne" -- Chaucer
:
:
: ---
: Outgoing mail is certified Virus Free.
: Checked by AVG anti-virus system (http://www.grisoft.com).
: Version: 6.0.722 / Virus Database: 478 - Release Date: 18-7-2004
:
:
 
Yes, the new ones supposedly operate in a very similar fashion to the old
one, according to several publications I have read on them... Tho the ones
destined for North America apparantly have been reprogrammed to make them
feel more "normal", like an automatic (my thoughts on this are that if you
can't get used to the CVT, why not get the cheaper automatic? I've not
driven a car with a CVT yet, so I don't know how unusual it feels to drive).
 
Tim said:
No, when you accelerate even moderately hard the revs should rise up quite
high, under kickdown the CVT should allow the engine to rev to maximum
power- ~5200rpm and stay there whilst the car "catches up". Sounds like
you have a problem.

L is for slow speeds and for maintaining engine braking going downhill- it
holds a lower gear.

Tim..
Click to expand...
Does this apply to the CVT fitted to the 440, or earlier versions of CVT?
I believe the 440 CVT uses steel segments instead of rubber bands, as fitted
to earlier vehicles.
 
shane said:
Does this apply to the CVT fitted to the 440, or earlier versions of CVT?
I believe the 440 CVT uses steel segments instead of rubber bands, as fitted
to earlier vehicles.
Click to expand...

Yes it does use a steel belt, but that does not affect the way in which it
works. The engine should still reach max RPM during full acceloration.

Tim..
 
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