Minor 727 Torqueflight Issues

I was doing some work on my other 1970 Challenger R/T, replacing the transmission filter and pan gasket plus fixing a bad connector for the reverse light. These things are normally something that could be done in an afternoon but when you’re working on a car that’s 45 years old and has had some engine and tranny swaps, the job may not be straightforward.

  1. Wire color code may not match replacement part.
  2. Transmission filter size varies between mid 60’s and 70’s

These are the kinds of issues that can occur when the car no longer has the original equipment and when previous owners or mechanics don’t care about maintaining vintage consistency. Problem may occur with the lack of correct matching parts availability, for example, a wiring harness or transmission.

I have not run into these specific problem before so without taking anything for granted, I was able to trial connect the 3 wires leading to the new electrical connector, but I am not willing to replace the filter without someone else confirming the interchangeability of the filter.

So  here are some notes and photos about my work in progress.


That’s enough clearance to access the tranny pan and reverse-neutral-safety switch which has a broken connector. The tranny pan leaks, so the gasket and filter will be replaced.


I hate it when people work under a car without jack stands. I was run over by a car many years ago, so I am gleefully paranoid about having another, much heavier car fall on me. Here’s a point to place a stand under the lower control arm.


Stand number two: under the frame near the tranny crossmember.


My reverse lights don’t work, so a place to check is the connector or the safety switch located on the left side of the tranny slightly above the pan. The wires were broken at the connector.


Peeling back a few inches of black electrical tape that was very greasy, I exposed the three wires. After taking a cloth to clean off the residue, I checked the wires to see if they were brittle. They felt okay and so I cut back a couple of inches before stripping the ends to connect to the new lead wires extending from the new connector.


The color coding on the new connector didn’t match what was on the car, but there was enough correspondence that I could guess the first time the right connection. The new connector comes with a black, purple and brown wire with yellow stripe. The existing wires are brown, black and what looks like black with a white stripe. I temporarily connected the brown wires together, the black wires together and the purple and black striped wire together. THe reverse light works and the engine can turn over in neutral.


YES! It’s a great feeling to fix anything with the car. There’s got to be some weird genetic switch that gets triggered when an you get something to work that was broke.


The new filter, which is designed for the 1970 B-727 Torqueflight is bigger than the old filter which I suspect is from a 1967 type 727.  The car originally was equipped with a 4 speed and some previous owner converted it to an automatic., apparently an older than 1970 version. The filter mounting holes are the same.

By the way, to remove a transmission pan that is not equipped with a drain plug, you need to loosen the screws and while retaining loosened screws on the “uphill” side, carefully pry apart the pan from the tranny on the downhill side and let the fluid drain into a larger vessel (like a large oil drain pan). I used a broad tip flat tipped  screwdriver to pry the pan enough to break the seal. Make sure you do not chip the sealing surface, avoid bending the pan, or possibly damaging anything internal with you prying instrument. Make sure the retaining screws are adequately loosened to allow the pan to tip at an angle without bending any metal.

Once the pan is off, expect a little more fluid to drain when you remove the filter.


The top side (tranny valve body side) of the new filter has one hole.


The top of the old filter, has two holes. One is in the same location as the new/larger filter. There is enough differences, that I, who do not have experience or knowledge in this area, am unwilling to ASSUME, that sticking the new filter is going to work. THe last thing I need is to seal this tranny back up with a filter that doesn’t work. Your expert or knowledgeable feedback is welcome.


Here’s the dirty pan with the old gasket. Sealant was used on the bottom, but not on the top (facing the transmission). I’ve read several recommendations that no sealer should be used to avoid sealer from getting loose into the tranny fluid.


A wide bladed instrument like this old trowel worked well to scrape the old gasket and silicone like sealer of the pan. Avoid gouging the sealing surfaces.

Do you know for sure?

If you know if the larger filter is safely interchangeable with an older type, please comment.

About my keys…

I DID have a hard time looking for my keys which was a drag because I could not check the reverse light function without them, but I finally found them in one of those places that I thought safe and I would not forget…

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The Dodge Kid in his youth about 1976. I think I wore this hat everyday through my Freshman year in high school. Photo by Nick Yee

The Dodge Kid in his youth about 1976.

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2 thoughts on “Minor 727 Torqueflight Issues

  1. Challen,

    First, the normal disclaimer of “proceed at your own risk, as I offer no guarantee and am providing information that I believe, but do not guarantee, to be correct”…

    Yes, they do interchange. The larger filter was introduced in 1973 as a running change to address a potential slow shifting issue, caused by fluid starvation from the smaller,, more easily plugged, filters. As such, the larger filter is actually preferred but not mandatory.


    • Hi Bob,
      Thanks for taking the NESTEA PLUNGE and posting a response. Since I’m not in too much of a hurry, I’ll see if I can get a consensus. The thing that bugs me is the two hole versus one hole, plus it looks like the bigger one will ride up against valve body screw heads. Maybe no big deal and that’s the way it’s supposed to be, but we’ll see. – Challen

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