Smooth strategy)

[Gwyn Reedy]

In 1956 the Hydra-matic got the second fluid coupling. Oldsmobile called it
'Jet-a-way' Hydramatic. It was internal to the transmission and replaced the
bands for the 2-3 shift. Instead of clamping (or releasing)the band, they
just filled or emptied the small coupling.

I remember it well, although I might have the 2-3 shift thing wrong.
Something else tells me that the coupling got 'used' twice during a complete
shift sequence. Purpose was to add smoothness to the shifts. TV ads touted
the engineering skill required to fill or empty the coupling in just one
second.

Was a high school kid at the time and devoured car magazines. The 56 Olds
had a one second slower 0-60 time than the 55, yet had about 25 more
horsepower. Thus we figured the extra fluid coupling was costing between 1
to 2 seconds. There were kids in my class whose families had both 55 and 56
models, so it got discussed a lot.

Gwyn Reedy
Brandon, Florida
mailto:mgr at mgrcorp.com

> -----Original Message-----
> From: owner-diy_efi at efi332.eng.ohio-state.edu
> [mailto:owner-diy_efi at efi332.eng.ohio-state.edu]On Behalf Of Greg
> Hermann
> Sent: Tuesday, February 02, 1999 12:02 AM
> To: diy_efi at efi332.eng.ohio-state.edu
> Subject: Re: Smooth strategy)
>
>
> >On Mon, 1 Feb 1999 19:57:53 -0500 "Gwyn Reedy" <mgr at mgrcorp.com> writes:
> >>Take a WWII tank or a 40's Chrysler product with 'fluid drive' and you
> >have
> >>a fluid coupling with a standard transmission.
> >>
> >>Gwyn Reedy
> >>Brandon, Florida
> >>mailto:mgr at mgrcorp.com
>
> Early four speed Hydra Matics (up to '56) (Also the boxes which got B&M
> hydro started, and which were made famous by folks like Big John Mazmanian
> & his Hemi-Willys coupe in the old A-Gas  NHRA class) used a two element
> fluid coupling, which only carried about 45% of the torque in the top two
> gears. The post '56 four speed H-M units had a second, smaller fluid
> coupling as well as the main one. Forget exactly what it did.
>
> Greg
> >
> >Mercedes also uses it in their Unimog 4X4 and 6X6 trucks.
> >
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