[TR] TR Overdrive in reverse.

Randall TR3driver at ca.rr.com
Sat Apr 28 19:14:47 MDT 2012


> It would appear that the unit is coming out again, but 
> exactly what does
> driving an OD in reverse do that is so bad?

There is a one-way roller clutch (aka sprag clutch) in the tail housing that
prevents the output shaft from turning any slower than the input (to the
overdrive).  However, when you try to back up with the OD engaged, the OD
clutch and gears force the sprag clutch to turn backwards.  

I've only seen photos of the resulting damage, but it looked pretty bad.
The outer race of the sprag clutch had broken, taking the tail housing with
it.

However, unless it felt like you were backing over a curb, or you felt a big
lurch, most likely the OD didn't have enough pressure built to force the
clutch backwards.

Before you pull the gearbox & OD, I'd check that there isn't something else
going on.

-- Randall  


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