A727 Torqueflite Shift Points?

[EngineerDoug]

I built a 727 to go behind my 493 stroker and have questions about the resulting shift points. Here's a quick rundown:

1974 Torqueflite entirely rebuilt (my first time) using top quality parts from a very reputable transmission builder. Built to easily handle the ~550 hp of the stroker.
Includes new street/strip valvebody.
Using a Bouchillon kickdown cable setup with their supplied 6 pack throttle bracket.
Kickdown cable adjusted so that WOT at the carburetor leaves 0.100" slack before trans throttle lever is full back position.
Converter custom built by Dynamic Converters, about 3000 rpm stall.
Engine is a mild 493 using a mopar 528 solid lifter cam.

OK so I have a hundred miles on this combination and am puzzled by the shift points. If I drive it around town = easy, the 1-2 shift happens at maybe 10mph. Very quick & crisp, but almost too soon. Accelerating up to say 45 mph, however, and it does not want to shift into 3rd. I can hold the speed steady with no throttle movement and it will often remain in 2nd. Let off the throttle a bit and it will shift. This shift is also quick & crisp. This whole engine & trans combo is new, so I have yet to really romp on it.

I have adjusted the throttle pressure lever both ways (less slack @ WOT, and more slack @ WOT). If I dial in less slack, it won't shift into 3rd. More slack and the 2-3 shift will happen around 40 mph, but it goes into 2nd not long after the car starts moving.

Obviously the combo is far from stock, so I am left wondering if this is to be expected? I have contacted my transmission builder, and he offered to build a new valvebody for me - which I appreciate - but I am reluctant to conclude that the valvebody is at fault. Could I have done anything wrong when I rebuilt the trans? Could the governor be the issue? I would rather not start pulling the trans apart only to find that these shift points are "the nature of the beast".

Your thoughts? Thanks.

 

[Lefty71]

Most of this is left to the valve body/reprogramming kit manufacturer.... I say most, because the governor comes into play as well, but is usually not provided by the shift kit maker. Unless you have instructions to do otherwise, I would start with factory kickdown instructions for the specific trans.....then maybe change the governor springs to match your desired shift RPM....

Maybe someone else with more "seat of the pants" input that has dealt with your exact situation will chime in.

 

[Photon440]

These are the expected upshift points from the 1970 FSM:

 

[66Satellite47]

Why do you .100 left on the throttle lever? The '74 727 will likely have a slow shift point. With a auto shift valve body, the governor will still control the shift pattern. Set the cable to get full lever tight at full throttle.

 

[66Satellite47]

Another simple answer is to switch to a manual valve body. Then you will know what gear you are in when you want it. You have a modified motor, why try to fight with a stock style trans. I find the manual shift 727 is very simple on the street, especially with a big ich motor. You can start from a stop in 2nd with no problem. Just say'n.

 

[EngineerDoug]

I left some "slack" on the throttle pressure adjustment because if I take up all the slack, it will not shift out of 2nd unless I completely release the gas pedal. That's really the issue; I am wondering if the governor is mismatched to the rest of the build? I do know that the throttle pressure lever and the governor work against each other to determine shift points. Maybe the governor is binding slightly?

I have given some thought to a manual valve body - how do you like it on the street?

 

[66Satellite47]

Not sure what you have going on there. The throttle pressure lever and governor work together in an auto shift trans. You have something not set up correctly.
My manual valve body is just fine on the street. 500 inch Satellite. Can easily start in 2. But I am an old school drag racer used to manually shifting a 727.

 

[forphorty]

Another simple answer is to switch to a manual valve body. Then you will know what gear you are in when you want it. You have a modified motor, why try to fight with a stock style trans. I find the manual shift 727 is very simple on the street, especially with a big ich motor. You can start from a stop in 2nd with no problem. Just say'n.

Yep. I got my first RMVB over 30 years ago. Every car since has gotten one . Daily driver street cars with occasional strip.

 

[Lefty71]

Governors are very sensitive....I doubt yours is actually sticking....more likely a mismatch because of your build deviating only in part from factory spec. I have read that A&A transmision in Indiana will work with you to select the proper governor springs and will help you out if they pick wrong for you.... I suspect John Cope at CRT would likely do similar.... I'd try giving one of them a shout and see what they suggest.

 

[Dave6T4]

One thing I used to do on high performance 727 rebuilds, was I replicated the governor weight/spring set up used for Street Hemi. The automotive factory that I worked in had an in-house tool room, and one of the machinists would lighten the standard heavy weights to my spec. The increased line pressure from modified valve body will only do so much. You really need modified governor set up to get the rest of the way. A&A Transmissions near Indianapolis sells these. They also sell a kit to replace weak 1-2 and 2-3 shift springs in the valve body. At WOT the 727 should upshift from 1-2 and 2-3 at roughly the same rpm. If it does not, you have a soft spring in the valve body.They have a very good catalogue of parts and services they sell. I have used a lot of their stuff over the years with no complaint.
In my experience, I have not liked the cable kick down setups. A lot of goofy shifting problems I have experienced with customer cars have been traced to poor calibration of these. The 727 has a definite " sweet spot " of line pressure versus governor pressure.

 

[Mark Barnes]

I have a brand new rebuilt 727 with the exact same 2-3 shift issues. 1-2 shifts as expected,
2-3 shifts late and only when Iet off the accelerator. Also using a cable setup for kickdown. Waiting to hear the fix for this one!!

 

[EngineerDoug]

Mark,

Can I ask you about what was done to your valvebody? Is it stock, or fitted with a shift kit?

I did call A&A and they did not think the governor is the issue. Looking at the factory shift points from the manual cited above, these translate to the following RPM:

440 engine
1-2 upshift, full throttle @ 3280 - 5290 RPM
2-3 upshift, full throttle @ 3980 - 5120 RPM

At this point, before I tear into the trans, I think I will measure some pressures using the external test ports. I am probably overthinking this, but I really like to understand as much as possible before jumping into replacing parts.

To be fair, I have yet to really lean on this thing to see how it shifts with more throttle. New motor, built by me, with all the best stuff....never been past 1/4 throttle. That might be coloring my assessment of the transmission. Thanks for your thoughts on this.

 

[Dave6T4]

The way that factory kick down linkage is engineered, whatever distance the linkage hole on the carb moves through its arc from closed throttle to wide open must be matched at the linkage hole on the transmission kick down lever. Messing with this 1:1 ratio makes the shifts do weird things. As an example, if the carb hole moves through 1.5" in its range, the kick down lever hole must move through that same 1.5". Achieving this ratio with aftermarket linkage or cable may entail using longer or shorter lever, or drilling new attachment hole in lever or carb linkage. It will be a process of experimentation.

 

[Lefty71]

It will be a process of experimentation.

IIRC, the possibility exists that the kickdown lever at the trans end (came with the trans) may not match the original application... this should be considered as well when trying to set the kickdown to factory spec. Sounds like he is heading in the right direction.

 

[Mark Barnes]

Mark,

Can I ask you about what was done to your valvebody? Is it stock, or fitted with a shift kit?

I did call A&A and they did not think the governor is the issue. Looking at the factory shift points from the manual cited above, these translate to the following RPM:

440 engine
1-2 upshift, full throttle @ 3280 - 5290 RPM
2-3 upshift, full throttle @ 3980 - 5120 RPM

At this point, before I tear into the trans, I think I will measure some pressures using the external test ports. I am probably overthinking this, but I really like to understand as much as possible before jumping into replacing parts.

To be fair, I have yet to really lean on this thing to see how it shifts with more throttle. New motor, built by me, with all the best stuff....never been past 1/4 throttle. That might be coloring my assessment of the transmission. Thanks for your thoughts on this.

My valve body has a Transgo TF2 shift kit installed, with the appropriate holes drilled. Second one I've done, and first time I've had any issues. I set up the cables in a number of different configurations, and still shifting late into 3rd, and only when I let off the accellerator. I'd be happy to hear of any possible fixes anyone may have.

 

[micmoe]

Had the same problem after installing a cable for the kick down. Attempted several adjustments but couldn't get it to shift into 3rd. Got a local shop to help, they found it needed a return spring on the kickdown lever. Spring was installed and problem solved. You may want to try this fix.

 

[Mark Barnes]

Had the same problem after installing a cable for the kick down. Attempted several adjustments but couldn't get it to shift into 3rd. Got a local shop to help, they found it needed a return spring on the kickdown lever. Spring was installed and problem solved. You may want to try this fix.

Thanks, gonna try it. I'll let you know.

 

[dvw]

The cable should work the same as the linkage. If the carb attachment distance from the throttle shaft and the kick down lever are the same lengths as factory. There are 2 different kickdown lever lengths depending on the factory carb type. There are many different valve body calibrations and governor weights. Now add in an aftermarket shift kit. You can see why the shift timing gets skewed. The bottom line is this is how it works. When governor pressure overcomes throttle valve pressure (kick down) the shift valve moves. Changing any of these parameters will affect the shift.
Doug

 

[Geoff 2]

I never liked the Ch kick down/up shift with levers & rods. Engine modifications, different carbs, distance from throttle shaft to link pin, etc changes the distance that the linkage moves...& hence the upshift points. Might have to drill some holes in the lever & experiment with ratio changes to get the desired shift point.

 

[Mark Barnes]

Had the same problem after installing a cable for the kick down. Attempted several adjustments but couldn't get it to shift into 3rd. Got a local shop to help, they found it needed a return spring on the kickdown lever. Spring was installed and problem solved. You may want to try this fix.

Here's the update- finally got around to adding a return spring to the kickdown lever. Didn't realize that that there was about 1-1/2" of travel to the front of the trans that doesn't get taken up without a spring.
Fired it up and drove it, and surprise! It shifted at the expected rpm's smoothly, no issues. Thanks for the tip!
That said, I'm no transmission guy, so I hope it doesn't cause any other issues, but for now, it seems to be OK. If I'm in danger of burning up my trans by doing this, someone let me know! Thanks!