Re: Ultramatic Hard Shifting into Reverse

Posted by JeromeSolberg On 2017/5/19 21:37:12

Dear All (but especially Fred),

Sorry for all the questions.

I checked and I have about 10 degrees, maybe a little less, of rear end lash. I can see and feel play in the differential gears.

That might be it. Seems like a little more than it should be.

I had a leaky pinion seal and I had it refilled at a Speedy Oil Change because I couldn't get the fill nut off myself, it needed an air wrench. They told me it was only a little low.

The symptoms of the "clunky shift" are these:

1. When you first start the car and before the transmission is warmed up it shifts very gently from High to Low, from Low to Reverse, from Reverse back to Low, and from Low to High.

As the transmission warms up the shift from High to Low and back is still reasonably gentle, though perhaps the shift from High to Low is a little clunky. The shift from Low to Reverse and back is where you hear and feel a "clunk".

I checked and the band I adjusted was the rear-most one, e.g. for reverse. The rear-most one is on the passenger side, the forward (e.g. low-range) one is on the drivers side.

My thought is that band adjustment might make both of these shifts a little softer, but since they are soft and good when the transmission is cold, it would seem that it is not the band adjustment that is the primary thing. Also the fact that the shift from High to Low Range is reasonably soft.

But it seems perhaps it could more be a function of the differential gear lash?

When I got this thing running after around 10 years of sitting, I noticed the transmission was low. I put "Type F" in it. Ten years ago when my Dad and I were driving the Cavalier around (back when he was still alive) I had put Dextron II in it. So there is a mix of Type F and Dextron II in there (maybe even something else because it never was drained fully).

So it is a possibility that the symptoms are exacerbated by the fluid change/mix from Dextron to Type F?

What I am planning on doing is changing out the transmission fluid. I got a new gasket (and new transmission rear seal) from Kanters. The new gasket should also make the transmission reasonably fluid-tight, I hope.

From what I read the Type F should be "better" than the Dextron II, more compatible with the clutch material and probably a little bit more viscous than the Dextron II. So I probably should just put all Type F in it. But it makes one wonder...

Finally, does one think a competent rear-end shop could rebuild the differential on my Packard?

Thanks and Sincerely,

Jerome Solberg