TH425 Trans

[bc...@juno.com]

I believe the switch pitch versions of the TH425 transmission are
still prized for the GMC, along with the 3.21:1 final drive from
66/67. So I am passing along this note I received. Bruce Roe


Received this message from a gentleman in Ferrisburgh, Vermont:
Hello, I have three Toronados melting into the yard out here in VT.
I am a salvage yard and I am going to crush them soon. There are
still some good parts on them if anyone wants anything. Scrap metal
value takes them all.

From his description they appear to be all 66s. If you have any interest,
please contact him directly:
Morris Palmer, 802-425-2...@palmersgarage.com

[James Hupy]

If you think that you only "MIGHT SOMEDAY" need some Toro parts, better jump on these. Never find them cheaper! They are not making them or spare parts for them.
Jim Hupy
Salem, Oregon

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[Dick Paterson]

I Might suggest ---: if you get the trans/fd ----be sure to get the {output} drive shaft with it. ..... Spline is unique .

[Jon Roche]

Would be nice if someone could save these.

Especially like dick said. We have a few 3.21’s now I know of here locally. But they do not have the passenger side shaft, so they are really useless without the shaft.



> On Jun 16, 2024, at 8:56 PM, Dick Paterson <di...@paterson-gmc.com> wrote:
>
>  I Might suggest ---: if you get the trans/fd ----be sure to get the {output} drive shaft with it. ..... Spline is unique .

> To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/001e01dac059%249949e4b0%24cbddae10%24%40paterson-gmc.com.

[Larry Weidner]

Oh please…anyone in the area get to that yard, and if they are a 66 or 67 toro, get the transmissions with FD’s and don’t forget the right hand short shaft with bracket. That shaft is fits the 3.21 only. Don’t let them go to scrap.

Bruce, pretty please... post this information to the GMC Motorhome Forum.
Larry :-)

[gbec...@graestone.org]

I had a switch pitch with a 3.21. Nice setup, but we are in hilly country and after 3rd gear clutch problems 3 times, I put a guage on it. Each one made about 4K miles.  

Driving 65mph, let off the gas, pressure went 55lbs. (Edge of low.) The failures were always going down hill. I would hear a change at say  65, look at the tach and it was at idle. Of course, that burnt things. Then on flat land it would slip out of third gear into a 2nd gear ratio. However if I let off the gas, the engine would go to idle. Freewheeling sorta like the old overdrives.

After new internals, new torque converter, and a new case, I abandoned the Switch Pitch. My current transmission presseure never goes below 82 psi when idling or deacclerating.  

Manny uses switch pitch in his diesels, but they have no vacuum “breaking” so there is no pressure on the transmission when the pressure drops. Don’t know what is happening internally, but the SP transmissions were not designed to slow down a 11K vehicle.

On Jun 16, 2024, at 5:46 PM, bc...@juno.com wrote:

I believe the switch pitch versions of the TH425 transmission are 
still prized for the GMC, along with the 3.21:1 final drive from 
66/67.  So I am passing along this note I received.  Bruce Roe

---------

Best Wishes,

George
gbec...@graestone.org