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Re: Overdrives going backwards

To: "Scott Tilton" <sdtilton@yahoo.com>, <triumphs@autox.team.net>
Subject: Re: Overdrives going backwards
From: "Nelson Riedel" <nriedel@nextek.net>
Date: Wed, 1 Aug 2001 23:56:39 -0400
References: <20010802024921.81003.qmail@web13304.mail.yahoo.com>
> I had occasion to wonder today:
>
> I'm told that it is very very bad to put a car in reverse and back up with the
> overdrive (A type) engaged.
>
> So what I'm wondering is.. . . Let's say you have your car in second gear,
with
> overdrive engaged.
>
> Then (don't ask why) you leave the car in gear, depress the clutch and brake
> until you come to a stop.  (Car is still in gear, and OD is still engaged)
>
> Now pretend you are on a good sized hill, and you let off the brake. . .
> keeping the clutch depressed and the car rolls backwards while you are in
> second gear and the OD is still engaged.
>
> What happens?
> Does stuff tear up?
> Will the car not roll backwards very far cause the OD keeps it from going
> backwards?
>
> Tell me what you think.
>
> Scott Tilton

The car won't roll.  The system is locked.  A simple test I use on the bench to
check if  the OD is engaged is to try to turn the output shaft counterclockwise
(as viewed from the gearbox front) --- the reverse direction.  If in OD, it
can't be turned.   If you apply enough force, it will of course turn  ----
either the sliding clutch will slip or the unidirectional clutch will come
apart.  Setting on a hill is not enough force to cause damage.

The unidirectional clutch normally transfers all the torque for all forward
gears including jump starts in 1st.   The sliding member clutch transfers torque
when in OD --2nd 3rd & 4th, somewhat less torque then the 1st gear starts so my
guess is if it is forced, the sliding clutch will slip. Backing up with OD
engaged probably fells like the park brake is on real hard.

Nelson Riedel
Granville, OH
76 TR6 (repairing damage from fender bender)
68 TR250 (next project - new paint)
70 TR6 (all the parts in a pile ready to assemble)

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