New governor for a TH 425

Got a new Allison AT540 governor to see if it would adapt to an TH425 transmission. It does! The Allison governor has no speedo gear but the gear from a TH425 fits on it. The Allison governor has no can as it fits inside the transmission in it's original configuration but it will fit inside a TH425 can. It does fit, shift and the speedo works. The Allison governors were available in several different rpm ranges to go with whatever engine was driving it. This particular governor is for 3000-3400 rpm and is a code 462. Sonnax makes them new.http://www.makcotransmissionparts.com/Allison-AT540.html

Part number on the Allison governor

Speedo gear swapped from the broken TH425 governor on to the Allison.  I think the weights and springs could be swapped and then it would act like a TH425 governor.

TH 425 governor loose yoke

Here is a couple TH 425 governors that have the yoke coming loose.

 Yoke brazed back in place. I submerge most of the shaft in water so none of the fits get hot and change dimension.

 Some of the new gears are different and need shimmed. Got caught on this last time. Got die button shims on order which should work. Need to get these done and back to Jim K.

Another quirk, this governor has an additional spring between the bottom of the spool and gear. First time seen this.

Sight seeing flight over the flood

Missouri river way out of it's banks

 Approach to KOMA. Airport would be under water if there was no dike. Many wells were put in and kept pumping to keep the water table down and save Epply Airfield

Sue had me painting

 

Walmart boondockers from Georgia and South Dakota. Big van was present day before too.

Road testing transmission governors and machining new cans for them.

Governor weights

Drilled a 1/4 hole in the primary weights and could not tell any difference in how the gov acted.
Swapped in this lighter weight and there was a slight difference. Mostly the 2-3 shift was later.
Parts swapping
A few parts. Spring color seems to be somewhat random, same color different spring. Some springs are wound left hand and some right hand. These are random turbo hyramatic governor springs and weights from the junkyard except the tagged spring. The tagged spring was behind the vacuum modulator spool, took that out in 2007. Removing it gave more range on the vac modulator.

TH 425 Governor cans part 5

3 1/2 schedule 80 pipe to make seal retainers out of. Pretty close to what is needed I.D and O.D. This stuff doesn't machine as good as some other, gummy like.
Chuck it up short.
Boring to fit over the can top.
Parting, out kinda far so bull nose center to stiffen it up.
Going slow here, no support.
Ring and can top
How it fits on, hold an O ring seal and has a lip to get a screwdriver in to pop it apart.
Together with a slot for prying it back open. Need to tack weld the retainer on. Ripe for weight and spring changes...tune it like you want.
Bail holds it together and in the hole.
can parts.
how the originals fit.


parts ring out.

TH 425 Governor cans part 2

Old school calipers
Parting, Used a power hacksaw to complete the cut
Dial in and center drill after a cut
Last two top to top
cutting cans apart

TH 425 Governor cans part 3

Patients. These are Turbohydramatic 425 transmission governors.
Last two just a stub left
all that is left over
Blanks and a sample
Zero check

TH 425 Governor cans part 4

Oil it!
Boring
Carnage
Ready to machine the top
Some done. These are the new bottom part of the cans and will seal with an o ring to the original tops. The original was crimped together and not serviceable.

Dan And Teri

My friends Dan and Teri were having transmission shifting problems with their GMC. I went to their home and we worked at it until it was found that swapping governors cured it. Took the non working governor back home and I think fixed it. Photos here
http://www.gmcmhphotos.com/photos/showgallery.php?cat=5470
Swapped the fixed governor in my GMC and it seems to be OK now.