TF727 inspection and rebuild

[Wietse]

It is downshifting now so there is progress by adjustments, which means IMO there is nothing mechanically wrong or something.
It's just a pressure balancing act between the line pressure (increased by throttle pressure) and the governor.
Transgo knows the spring rates and associated pressures that should come with it, i send them an email with my pressure readings and will see what they reply.
I suspect my governor pressure does not work well with the combination.
My car had originally a 22" radiator, which means it came with a standard rear axle with a 3.23:1 ratio, now i am running a 4.10:1 ratio with a cone-type sure grip. (guess this was pulled from a donor car, incl. the 28" radiator)
My theory is that the governor i have installed is suited for the 3.23 ratio, now with the 4.10 ratio rear axle it provided too much pressure for the speed the car is going due to higher drive shaft rpm's.
And likely for that reason i need to force the throttle linkage to provide a higher pressure also earlier than normal to "counter-act" this behavior to get decent shift points.
This is why the "as-per-the-book" adjustment worked out really bad.

I am not sure about this, as far as i looked i did never find any different part numbers or whatever for different governor "guts" that suit different axle ratio's and nobody seems to know if there are any at all.

Before the overhaul the tranny also always required an extreme long rod setting to get it to shift decent, and even then i was always taking roundabouts in 3rd as it would not downshift until a full stop.
And now if i slow down it goes back to 2nd as well, so coming of a roundabout or tight corner it picks up much better in 2nd instead of being stuck in 3rd and drive like a dog.

 

[Wietse]

I've been in contact with Transgo now for a bit, the first thing they want to know is the line pressure.
Specifically with the tv valve at full forward and full backwards, there should be a 40 psi increase.
Lucky as I always am, mine actually loses 30 psi, it starts with 150 psi and drops to 120 psi at WOT position of the tv valve.
They suspect the PR valve is always boosting pressure up for unknown reason.
Guess i will have to drop the pan and pull the valve body to inspect it again, hopefully it is only the valve body that needs to come out.

 

[Wietse]

After sending some pictures they noticed my separator plate is not a stock one, so my valve body was modified also and with the TF-2 modification done there seems no way back to get it to work.
So now i will have to find a stock or already modified valve body to replace this bastard.
It's never easy is it....

 

[Wietse]

Since I can't continue on the transmission for now I removed the drive shaft again to replace the U-joints.
I ordered the Moog 248's, they are quite beefier than the old ones, also the grease fitting has been relocated to one of the roller bodies instead of in the cross.
From what i know this becomes a weak point once a hole is drilled for this.
Just wondering, what type grease nipple is required for this? Must be a needle or cone type?

Drive shaft is cleaned and currently coated in primer to dry for a top coat.
I found what i believe is the part number, as shown in the picture.
It was sprayed before in orange steel primer, i decided to stay with (hemi) orange color for some color adding underneath instead of black.

Anyone knows what the differences are between the stock type and Modified type valve body's A&A transmission sell?
I send them an email but had no reply yet.
Price is same, so instead of getting a stock one that i still need to upgrade with the TF-2 kit I might go their modified valve body route to save me the hassle.

 

[oldbee]

Looks like needle type.

 

[Wietse]

Looks like needle type.

But are there any different size/model of them?
I will order one but just never seen these before and have no clue what to order.

 

[dvw]

After sending some pictures they noticed my separator plate is not a stock one, so my valve body was modified also and with the TF-2 modification done there seems no way back to get it to work.
So now i will have to find a stock or already modified valve body to replace this bastard.
It's never easy is it....

Told you he was sharp.
Doug

 

[Wietse]

Well, after sending the part number of the other half of the valve body he came back and found i was quite lucky.
The one in the car is a '65-1/2 model which is a bit of both, pre '66 and 66-up.
He thinks we can get it to work, he had found by the separator plate part number the kit that was installed before, which is a B&M kit and he managed to re-engineer it to get it to work with the TF-2 kit installed as well.
I followed some instructions he send me and after testing the line pressure became normal and increasing as the throttle valve is functioned.
Before it was boosted all the time, causing a high line pressure all the time and no increase when the throttle valve is functioned.
So now with that good, the fine tuning had started to get the throttle pressure set right where it should be, which basically is no throttle pressure at idle, and as soon as the throttle is depressed slightly it should start to increase and finally find the max pressure to be at WOT.
I got no helper at the moment so it's going to be a little more time consuming as i will need to try to do all things at the same time but i think i can manage.
The man saves me $500 for ordering a new valve body.
Transgo deffinatly has some knowledgable and supportive tech team there, also considering they do old cars as well as a lot of modern ones and they know about 100's of different transmissions and what makes them tick.

More important is that my drive shaft now matches with my oil pan, with new U-joints.

 

[Wietse]

After a lot of screwing around i managed to find the starting point of the throttle pressure and where it it at it's highest and does not increase anymore, i set the linkage to suit the carb idle and WOT position and get 80 psi at idle and a final 122 psi at the WOT position. Throttle linkage on the transmission still has about 1/4" more stroke but the pressure does not increase over this part anymore.

It shifts too early and the 2-3 is very short after the 1-2 shift, there is no downshifting to 2nd also when slowing down to 10 mph or so.
Now what i feared already, the governor pressure seems responsible for issues, i measured the governor pressure at a range of speeds, it only starts at 15 mph where i am getting 18 psi.
As per the Transgo guy it should be equal to the road speed, but mine is about 10 psi too high at average.

15 mph: 18 psi (start presssure)
20 mph: 27 psi
30 mph: 39 psi
40 mph: 51 psi
50 mph: 63 psi
60 mph: 77 psi
65 mph: 84 psi

From what i understand i need to lighten the governor weights and different spring maybe, hard to move on from here without knowing what to do with this governor.
Likely this governor is factory tuned for the 3.23 gears the car came with originally.
Hopefully the guys at Transgo have any idea what is the best try, not looking forward of pulling the tail housing several times to alter the governor.
But in the end, it's better than needing to remove the complete tranny again.

 

[Wietse]

Anyone have some recommendations on a plier for the retaining ring of the tail housing bearing?
I found a few pliers but I am not sure what the required spread is to fully open the retainer.

 

[Fran Blacker]

Snap ring pliers with pins on the end bent at 90* and open outward when you squeeze . Not mine. The pliers bottom left.WORKPRO 4-Piece Snap Ring Pliers Set - Heavy Duty 7-Inch Internal/External Circl | eBay

 

[Wietse]

Thx Fran,

I wonder what the required spread is and what is needed for the tail housing snap ring.
This opening size is most of the time not mentioned with these pliers.
I found one that has 1.25" opening, would that be enough?

 

[Wietse]

Anyone any idea what is the bolt size of the 2 lower (big ones) bolts that secure transmission and engine together?
I am away from from home so i can not check but I want to order some new bolt to use when I get home.
The threads are half stripped in the transmission aluminum bell housing so I want to use a longer bolt to get the full thread and secure it with an additional nut on the other side.
I guess the thread is 7/16" or 1/2"?

Edit:
I think the below plier should do the job for the bearing retaining ring.
Performance Tool W88001 Performance Tool Lock Ring Pliers | Summit Racing

 

[69ChargerR/TSE]

The large 2 are 7/16-14 X 2.0 HX .75 CONI SEMS PHOS.

The other 4 are 3/8-16 X 1 1/4 HX .75 CONI SEMS PHOS.

Chrysler Individual Fastener Kits

Here you will find the best, most finely detailed Chrysler individual fastener kits for classic Mopar cars available anywhere!

www.amkproducts.com

 

[Wietse]

The large 2 are 7/16-14 X 2.0 HX .75 CONI SEMS PHOS.

The other 4 are 3/8-16 X 1 1/4 HX .75 CONI SEMS PHOS.

Thanks for the information.
Good website too what you are referring to, all details are there. That will be saved under favorites

 

[Wietse]

It has been a while on this, but with the great help of the Transgo tech department i got a lot of issues sorted out.
Since the car was originally supplied with a 3.23 gear and now has a 4.10 gear the governor was out of specs, after shortening the original spring to provide the correct spring pre-load at the installed height the governor pressure is as good as equal in psi as the road speed in mph.
Only thing there is it does not give any pressure up till 20mph for some reason. (need to verify this once more)
Also the throttle linkage was not even close to being correct, the throttle lever cam weld was broken, causing slack.
Welded it back and set the throttle pressure adjuster screw as per specifications with a 5/8" spacer as per book, after set the linkage up to be in the right starting point and fully functioned at WOT.
Now i am getting 95-135 PSI over the throttle linkage range which is perfect.
Test drive was a real pleasure, with the trans now set correct and the new torque converter it goes like a rocket.
Drives like a different car now, flooring it and it kicks down...flash stalls to 4000 rpm. (TC is a Hughes Performance 3000)

Only little issue remaining is that the 2-3 shift is a bit harsh at light throttle, with moderate or hard throttle it is short and firm though.
If i am not mistaken, going to 3rd gear only the front clutch engages.
Since i used the red eagle frictions and kolene steels (5 thin frictions) i wonder if this is causing the harsh shift?

It is a real need to have a pressure gauge that can be connected to the test points.
And as mentioned, thanks to Transgo tech his great help and patience I could clear up these problems.

 

[Dave6T4]

As for harsh 2-3 shift at light throttle, did you block the accumulator valve ? I have found this makes the shift harsh. I usually just remove the accumulator spring, and let the valve float. Still too harsh? Try finding a lighter spring to replace stock spring.

 

[Wietse]

As for harsh 2-3 shift at light throttle, did you block the accumulator valve ? I have found this makes the shift harsh. I usually just remove the accumulator spring, and let the valve float. Still too harsh? Try finding a lighter spring to replace stock spring.

I put it back as it came out, still using the original spring that sits between the accumulator and valve body.
The Transgo instructions say to put it back together as it came out, spring could be on top, below or none at all.
Stupid enough i do not have a single picture of the accumulator, i believe it only had that 1 spring right?
Think there was nothing else to it then the accumulator spool that had 2 rings to be replaced.

 

[Dave6T4]

I put it back as it came out, still using the original spring that sits between the accumulator and valve body.
The Transgo instructions say to put it back together as it came out, spring could be on top, below or none at all.
Stupid enough i do not have a single picture of the accumulator, i believe it only had that 1 spring right?
Think there was nothing else to it then the accumulator spool that had 2 rings to be replaced.

Just the one spring. Sometimes truck transmissions did not have the spring.

 

[Wietse]

Transgo tech told me to decrease the hole size of the orifice "C" in the separator plate to remove the 2-3 harshness.
If I am not mistaken I think i measured something like .160 - .180" hole on this orifice so making it a little smaller should smoothen the shift out a bit.
As per their instruction it should be between .140 - .187" for street/strip.