[SEL] OT R-10 Borg Warner overdrive.

[Elden DuRand]

Curt:

> > When the dash cable is pushed in, the 
> transmission free-wheels in all
> > three gears except reverse.  When the 
> transmission is put into reverse, a
> > pushrod from the reverse shift fork forces the 
> Overdrive to lock-out,
> > otherwise, the transmission would lock-up when 
> you tried to reverse and
> > could damage the sprag clutch or planetary gearset.
> 
> I'm not observing this. What I see is that the 
> one way clutch with the 12
> rollers aft of the planetary gears will not 
> transfer reverse rotation. In
> order to actually get reverse rotation of the 
> output shaft, the sun gear
> has to be locked to the ring gear. I'm not seeing 
> any lock up conditions
> you mention.
> 
Maybe I remember wrong.  I DO know, though, that if you have the O/D manually engaged (by bypassing the solenoid and making it stay engaged) and try to roll back, it will lock.

As a matter of fact, in my Perkins'd 50 Chevy, I used that little "undocumented feature" to hold the car on uphill grades  like at a traffic light on a hill.

What I would do would be to pull up to the stop with the O/D solenoid actuated then, after stopped just let the car roll back to -ease- it to the lockup condition.  Now, with a load on it, you can turn off the solenoid and the pawl will stay engaged until you begin to release the clutch, when it will drop back into low range to make it easy to take off on the grade.  I've done this thousands of times and have never had a problem but can almost guarantee expensive noises if you were rolling back with the dash cable pushed in and turned on the solenoid.

AND you are absolutely right about the free-wheeling being a bit dangerous below about 30 mph.  As a matter of fact, you can coast up to very high speeds with the dash cable pushed in and in gear because if, after the governor speed is reached and the solenoid pulls in, there has to be a momentary load on the O/D unit before it will be able to synchronize and engage.

It's always a good idea to lock out the O/D in mountains, etc.  Two reasons.......One is that with the lower ratios, engine braking will not be as strong and the second is that the free wheeling, even at lower speeds, can make for scary downhill driving.

Ain't this fun??!!

Happy New Year!

Take care - Elden
http://www.oldengine.org/members/durand