Updated, another question... Draining oil out of a 1971 3-on-the-tree transmission

[904Bronco]

I don't see a drain plug, there is a fill plug. (It has been a long day)

Did I miss something, somewhere?

How does one drain the fluid out of it? It is being removed for a 5-spd conversion.
And I will freely admit I haven't done much work with the factory 3-spds.

Thanks in advance, Doug.

 

[jamesroney]

I don't see a drain plug, there is a fill plug. (It has been a long day)

Did I miss something, somewhere?

How does one drain the fluid out of it? It is being removed for a 5-spd conversion.
And I will freely admit I haven't done much work with the factory 3-spds.

Thanks in advance, Doug.

The Lower extension housing bolt goes thru, and will let it drain. It’s 7/16 threaded, so it’s slow but it works.

 

[Broncobowsher]

Correct. The bottom bolt that holds the transfer case adapter to the back of the transmission is the drain.

Now if the 9" were only that easy...

 

[904Bronco]

Thanks Gents...

 

[73azbronco]

before you start open top, to be sure you can fill. and gives relief of air pressure for drain.

 

[904Bronco]

So I should be dropping the transmission tomorrow... The drain bolt removable worked great!
I noticed this connector on the transmission, it is not for the backup lights.
I followed it up to the engine compartment, the single wire joins another wire (red) both wrapped in tape. The other wire is not connected to anything, just hanging loose at the back of the intake. Both wires terminate near the distributor, they are not connected to anything, both have bakelite connectors for a flat spade connector.
Me thinks it might be smog related?
What do the experts say?

 

[Broncobowsher]

That is a top gear switch that plays with some strange emissions stuff from the day.
Short answer, don't worry about it.

 

[Oldtimer]

Transmission Regulated Spark

Ambient sensor switch is mounted on driver A pillar door post.

AI Overview

Ford's Transmission Regulated Spark (TRS) system is a vintage emission control setup designed to reduce hydrocarbon and carbon monoxide output by disabling distributor vacuum advance in lower transmission gears.

How the TRS System Works

• Lower Gear Restriction: In lower gears (such as 1st and 2nd), a transmission-mounted switch grounds a circuit to a solenoid-operated vacuum control valve, blocking vacuum from reaching the distributor's vacuum advance unit.
• High Gear Activation: When the transmission shifts into high gear (or reverse, depending on the setup), the pressure or linkage switch opens, allowing normal vacuum advance to resume.
• Temperature Override: An ambient air temperature switch (or coolant/pillar sensor) overrides the system in cold weather to prevent engine stalling or poor driveability before the engine warms up.

Key Components

• TRS Switch: Screws into the transmission case (such as near the C6 servo) or mounts to the linkage to sense gear selection.
• Solenoid Vacuum Control Valve: Opens and closes vacuum lines running between the carburetor and the distributor.
• Ambient Air / Temperature Switch: Deactivates the emission delay when outside temperatures are cold.

 

[904Bronco]

Thank you for the info Gents...

Yes, I did note that there is an ambient temp sensor on the drivers door frame, As well as remembering seeing a vacuum control solenoid back in the day attached to a valve cover bolt. Being that everything has been disconnected, I didn't think there would be any issues, but just thought I would ask for my own knowledge.

Loved the "Vintage emission control" statement...

 

[DirtDonk]

With all of those clues Doug, are you sure it’s a 71?
The general feeling is that those were a 73 only part. However, it did seem to run back into late 72 models.
Having both the transmission switch and the actual sensor in the door frame, instead of the dimples, kind of points in that direction.
Did you check the VIN and the build month on the certification label?

 

[904Bronco]

With all of those clues Doug, are you sure it’s a 71?
The general feeling is that those were a 73 only part. However, it did seem to run back into late 72 models.
Having both the transmission switch and the actual sensor in the door frame, instead of the dimples, kind of points in that direction.
Did you check the VIN and the build month on the certification label?

Manufacture date of 10/71, emissions sticker on the valve cover says Ca emissions...

 

[DirtDonk]

Interesting. An Oct build "would normally" be for the next model year. But as we've found with Broncos, not always!
Does it have just the dimples in the door frame, or is the ambient sensor bolted to it?
If so, then that puts the ambient switch applications much earlier than I had thought for a long time. Pretty sure not all '72's had them, but then that was probably the difference between CA and FED spec rigs.

I love coming across all these little anomalies in Bronco production. Or maybe it's not an anomoly after all. Maybe all '72's from CA got them? Tim's did not, and neither did our buddy Mark's '72. I don't "know" that they were both CA spec, but very likely they were.
So yours is still a unique one in my experience.

Paul

 

[okie4570]

Manufacture date of 10/71, emissions sticker on the valve cover says Ca emissions...

That build date would be a 72' model.

 

[EPB72]

Interesting. An Oct build "would normally" be for the next model year. But as we've found with Broncos, not always!
Does it have just the dimples in the door frame, or is the ambient sensor bolted to it?
If so, then that puts the ambient switch applications much earlier than I had thought for a long time. Pretty sure not all '72's had them, but then that was probably the difference between CA and FED spec rigs.

I love coming across all these little anomalies in Bronco production. Or maybe it's not an anomoly after all. Maybe all '72's from CA got them? Tim's did not, and neither did our buddy Mark's '72. I don't "know" that they were both CA spec, but very likely they were.
So yours is still a unique one in my experience.

Paul

My 72 . built 10/71 california emisions , 4900gvrw , was equiped TRS had both the switch and temp sensor and the wire was there but cut off ,, the rest of it was long gone so prior to me buying it in 1989 someone was passing it during emissions testing.. .. I do recollect that the emissions books back then had TRS as a Numberd footnote ..would have to see if I can find an old book for the actual details .. may have one at work ...

 

[DirtDonk]

Thanks for chiming in EPB. Maybe I'm remembering it bassakwards, and it's really the '72's that had the system, and the '73's had the residuals in the sheet metal.
Or maybe it was for both years? I'd make up something about it being a light-duty truck thing, but yours is the heavier duty 4900 model. So that goes out the window too.
It's doubtful that all three of the '72's my friends bought in '74, and '75 were all from out of state, but it's still possible. No matter how implausible that is.
I don't think the Marti reports list any of this stuff, do they?

Paul

 

[904Bronco]

Does it have just the dimples in the door frame, or is the ambient sensor bolted to it?


Paul

The sensor is there Paul...

 

[DirtDonk]

Thanks. Pretty sure Tim's '72 had just the dimples.
Now we've gotta' ask him the next time we talk, just to be sure.

Paul