95' 12 valve street/strip build

I'm a double posting fool this morning !!

Here's the case all cleaned up. Nothing a little brakleen and a pressure washer can't handle

Here's the view from inside the case

So my Trans was shifting consistently at 2900/3000 at wot. The truck accelerates much faster if I hold the shifts at 3500 rpms manually but that is not a very consistent way to drive this truck as the column is old . I've been tempted to go with a full manual valve body, and a custom slap shifter/ center console setup but my wife drives this truck a few times a month and I don't want her having to deal with a manual vb.

Once I get to the valvebody portion of this rebuild I'll cover some things there for raising shift points. Since 1-2 and 2-3 shift are already at the same rpm and I have the hydraulic governor apart I'm going to be playing with the centrifugal weight/valve that's responsible for raising line pressure and causing the valve body up shift to the next gear once it sees x amount of pressure. I have some spare gov parts off an older 727 torqueflite and a spare diesel 47rh governor. By lightening the weight / valve assembly it's going to cause later 1-2 and 2-3 shift points.

The diesel version of these trans typically see 3 psi per mph up until 3rd gear and the pressure peaks. Some gasser Trans see 1 psi per mph. There's no exact amount of weight for me to remove from the weight/valve assembly To achieve the exact rpm per gear shift increase. The governor is located in the very back of the overdrive housing and is a pia to get to when the Trans is in the truck. So I started weighing different gov weights. I'm I kin some up tomorrow from a tranny shop . The diesel weights are brass and the heaviest, v8 gasser is the lightest - aluminum, and 47rh gov weights that are from a v10 truck would be ideal.

But I think I'll err on the slightly to heavy side and keep the shifts from being up near 4k rpm or more. If I need some more rpm after the gov mods I'll try a stiffer spring on my throttle valve on the valve body. The stiffer the spring the later the up shift- but you can only go far with the TV settings.

Here is the steel gov weight from the early 70s Chrysler Newport 727 trans. It had a 400 big block and I assume the shift points were not very high for a v8 car but they were probably to high for my application.

Here is the inner weights . They ride on a spring inside of the larger weight and use a snap ring to keep them assembled.

My friend has a nice setup at his shop - AC machine works LLC.

Here is a plate mod that isn't covered in the Transgo kit. I upgraded my work tcc timing valve and these mods came with the valve instructions. Trim the plate and enlarge he hole. This adds lockup pressure

Almost done with the vb. brakleen and compressed air make these things shine.

Here is a little trick I should have included in the beginning- the bolts that hold the overdrive to the main case thread into 2 special holes on the pump. You use a slide hammer to pop the pump out. You can also pry on the between the low/reverse drum and the sun shell. I prefer the slide hammer with vise grips welded on.

Here is the sonnax super servo being installed. It works well with the 4.2 apply lever, hd strut and anchor. I'm running 2 internal springs instead of one. That helps prevent bind up on the 2-3 shift. "Shift overlap".

It's a mother to get it in the case. One trick I do is pack the snap ring retainer groove with assembly grease. I've had the cast ring hang up in the groove and cause me a lot of grief. Then I use these big cowboy clamps and snap it it with one quick movement.

I forgot to take pics during the overdrive rebuild. It has a tcs billet output shaft, the rest of the rebuild is by the book except for the over drive brake clutches. They supply friction that transmits power through the overdrive planetary gears. Mine were toast so I upped the count this time around.

I purchased a 48re stepped backing plate to replace my stock piece. It's thinner and allows me to use an extra friction and steel. I increased the count from 5 clutches and steels to 6 clutches and steels.

Here is a pic of the finished Trans. Next will be the turbo install.

Truck is alive !!!!! This turbo added 6-700 rpm of power band. It winds out to 3500 now , where it use to nose over at 2700.

The altered 1-2 governor plug in the Transgo TFOD HD2 shift kit was causing major issues also. It does say in the instructions " not for diesel or rv" this is the best one I've built out of 7 units. Devon was cool gave me a couple tips when I was picking his brain.

I backed the truck off to mid 40s for boost and it doesn't seem much slower. I am on stock head bolts still with 19 timing , 5x.016s and delivery valves along with that 64mm I'm asking for a headgasket to pop. I'm going to try some 130$ "mighty diesel head bolts " the dealer is running 30* timing and 70 psi on his puller. Should be good for my 500 hp truck- combo is good for 600+ but my timing is that high


You should try building a trans. I've only done the 07' and older styles but they are fairly simple