Switch Pitch TH-400 (was something else)

Gwyn Reedy mgr at mgrcorp.com
Tue Jan 26 15:16:00 GMT 1999


Thanks for your response Max, and Shannen too.

Time to admit some ignorance. Haven't taken apart an automatic since I
rebuilt a powerglide back in the 70's.  Have driven Buicks with Dynaflow,
and a 66 Buick with 2 speed torque converter (my mom's car back then) and
various TH350s and TH400s and the 4l60E in my Impala.

Was under the impression that you can't put a locking torque converter on a
TH-350 or 400 because there is some kind of mechanical device (rod or
sleeve) that is in the trans and activates the locking of the clutches in
the converter. Seems like it would have to be that or else some kind of slip
rings to get electricity into the converter to lock an electrical clutch.

So what I'm asking is if the mechanism to switch the variable pitch torque
converter is similar enough to the mechanism of the locking torque converter
to be used for the latter. Not concerned about how the decision to switch
pitch or to lock comes about, but how does it get transmitted into the
converter.

Reason for the interest: I have a big block pickup with TH-400 and 3.08 rear
end. 4l80's are very expensive but is what I'd really like to have. If I
could get a locking converter to work on the truck I might spring for an aux
overdrive unit to mount behind the automatic and put in a 4.11 rear.

Do you have a reference to a site or book that explains the variable pitch
setup?

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
> Guenther,Max
> Sent: Monday, January 25, 1999 1:05 PM
> To: 'diy_efi at efi332.eng.ohio-state.edu'
> Subject: RE: Switch Pitch TH-400 (was something else)
>
>
> As for control I just used a cheap micro switch.  looked cheesy but
> works great!
>
> >----------
> >From: 	Shannen Durphey[SMTP:shannen at grolen.com]
> >Reply To: 	diy_efi at efi332.eng.ohio-state.edu
> >Sent: 	Monday, January 25, 1999 11:56 AM
> >To: 	diy_efi at efi332.eng.ohio-state.edu
> >Subject: 	Re: Switch Pitch TH-400 (was something else)
> >
> >Gwyn Reedy wrote:
> >>
> >> Coupla questions.
> >>
> >> Does any aftermarket vendor provide custom stall ratios on the variable
> >> pitch converters?
> >>
> >At one time Kenne Bell did.  Looks like rebuilt/strengthened factory
> >converters, two styles.  1800/2600 rpm, and 1600/2400 rpm stall
> >speeds.
> >Kenne Bell, 10743 Bell Court, Rancho Cucamonga, California 91730;
> >(909) 941-6646.
> >
> >> What mechanism is used to control the pitch switch? Could that
> be adapted
> >>to
> >> allow control of the clutch in a locking converter?
> >>
> >Old stuff, used in 65-67 Buick and Olds.  Mechanical switches close
> >circuit, switches to high stall at idle, and at 70%+ throttle
> >opening.  Electrically, it's opposite the TCC.  Original switches and
> >linkage are tough to locate, might as well use a manual switch.
> >
> >> 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: Sunday, January 24, 1999 10:50 PM
> >> > To: diy_efi at efi332.eng.ohio-state.edu
> >> > Subject: Re: DFI, Batch Fire, and other myths
> >> >
> >> >
> >> >
> >> > >
> >> > >Was just thinking yesterday that the switch pitch converter
> should be
> >> > >connected to tcc control , and detent solenoid should remain manual
> >> > >control.  BTW, 350 Buick HEI works, but must use drive gear from 455
> >> > >points dizzy.
> >> >
> >> > Ahh--dangerous thoughts, and hardware that gets
> forgotten--Anybody know
> >>of
> >> > any experience racing with switch pitch TH-400's????  Or
> whether such an
> >> > idea ever got tried with turbo motors??? :-) (Like switching
> the pitch to
> >> > let it rev up into the boost QUICKLY???)
> >> >
> >> > Regards, Greg
> >> > >
> >> > >Shannen
> >> >
> >> >
> >
> >
>




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