Splain please about the lockup converter in your 68? I didn't know you
could put a lockup converter with a torqueflite? How does it compare
performance and mileage wise to the non lockup car? I'd think it would act
as a slight overdrive.
----- Original Message -----
From: <dardal@xxxxxxxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Thursday, December 12, 2002 4:48 PM
Subject: IML: converters/ fluid couplings
> Quoting "John G. Napoli" <john@xxxxxxxxx>:
>
>
> > Correct, there is no lockup clutch. However, the nature of a fluid
> > coupling
> > (as opposed to a torque converter) permits it to effectively lock up
> > once it
> > reaches a certain rpm. At that point, the entire fluid mass is
> > rotating
> > around and 'locking' the driven disk to the driver. Fluid couplings
> > have
> > straight vanes, and just a driver and driven member. Torque converters
> > have
> > curved vanes and three elements. This is an oversimplification that
> > perhaps
> > someone can expound upon, but the fluid coupling does act as if it is
> > locked
> > up.
> >
>
> John. Even the fluid coupling will have some slippage. Usually, fluid
> couplings have a bit less slippage than torque converters (especially at
low
> rpm) as you said, but in order to transmit the torque through the fluid,
some
> slippage is necessary. Zero slippage, zero torque (unless there is a
lockup
> clutch). The higher the rpm, the less the slippage required for a given
> torque. The 3rd element of the torque converter that you are discussing
is
> responsible for the multiplication. There is a sprag clutch between this
3rd
> element and the engine side of the converter, and when the speed is low
and
> slippage high, the clutch engages, and this element (don't remember its
name)
> redirects the fluid flow at a sharper angle against the impeller blades of
the
> transmission side of the converter (I think that's called "turbine") and
thus
> you get the multiplication. Of course, there is a price to pay, and that
is
> the higher slippage. At higher speeds, this spag clutch will disengage,
and
> the converter will act as a normal fluid coupling. A low stall converter
will
> still have almost negligible slippage (of the order of 1-2%) at high
speeds
> (say over 3000), even at high load. However, due to the multiplication
> feature, it will have to rev faster to get to this low level of slippage.
So,
> effectively, it generates more heat than the older fluid coupling.
>
> D^2 w/ a lockup converter in his 68 LeBaron and a non-lockup converter in
his
> 68 Sedan.
>
>
>
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