View Full Version : Vacuum for transmission

12-22-2014, 10:02 AM
Hi All

Just bought my first V8 after 25 years with aircooled VW.
My car is a 1961 Thunderbird bought with a defective transmission.
When PO bought the car it couldn`t go in reverse, he opened it and replaced clutch plates and brake bands, but didn`t replace o-rings. He then put it togehter and the reverse was ok, but it can only shift from 2 to 3 when it`s very cold.
When I start in D1 it has a very bad noise, so I have bought another transmission.
Today I started the replacement of transmision and I then discovered that the transmission vacuum ain`t connected at the carburator, and I can`t figure out where to mount it.
As you can see in the picture the tube ends with a screw.
Has the carburator been replaced so I don`t have this vacuum output?


12-22-2014, 10:19 AM
The vacuum line to the transmission should be connected to the brake booster check valve. However you can connect it to any source of engine vacuum. The intake manifold is fine. The factory carburetors did not have any vacuum ports except for the vacuum advance to the distributor.


12-22-2014, 11:46 AM
Sorry, but don`t understand were to mount this tube.

12-22-2014, 12:20 PM
That tube is just somebody's poor attempt at blocking off the vacuum. That has nothing to do with the transmission line. You should have a rubber/metal/rubber line coming off the transmission modulator and going to the power brake check valve.


01-17-2016, 10:41 PM
Following up on an existing thread, I had removed the Brake Booster Check Valve and assembly (rubber/check valve/rubber/connector) and simply plugged the vacuum port while I cleaned up the parts.

However, I am not seeing where this vacuum line is supposed to plug in to. From this thread, it looks as if it goes to the transmission, but the lines are not that long. Can someone post a pic or drawing of where that is supposed to go? I cannot see anything in the '61 Shop Manual or Steve Christ's book, or anywhere else.

It looks like this line is actually short, as it reaches no lower than the right/passenger side exhaust manifold.

At the lower left of the second picture, there is a fixture there to plug into something, but where? :eek:

http://s23.postimg.org/jpqhw87bb/Brake_Booster_Vacuum_Line_Drawing_Fig_23_Close_U.j pg (http://postimg.org/image/jpqhw87bb/)

http://s9.postimg.org/o549ikf2j/Brake_Booster_Vacuum_Line_Drawing_with_Pointers.jp g (http://postimg.org/image/o549ikf2j/)

01-18-2016, 03:57 AM
When I route my vacuum line I start at the intake manifold, right where your picture shows the brass 'block' with the plugged hose. That block has a regular pipe thread.

I come out of the manifold with a 90 and continue a short distance to the back of the engine. Then I tee off. One side goes to the transmission and the other goes to the power brake booster. Just that simple. Your booster should have a check valve so the 'can' holds a vacuum after the engine stops. - Dave

01-18-2016, 10:55 AM
Hi Dave:

Thanks for the reply. So my quandary is this. I have a line that runs from the vacuum port (block) back to the brake booster. That's the line at the top of the diagram. The on the other side (toward front of the engine) of the same block, I have a hose where the check valve is attached, and at the end of that line, is a brass fixture that plugs in somewhere, and I assume that's the end that goes to the tranny. I think I am pointing to it in the second pic wondering "Where does this go?" Is that the end that goes into the Transmission? When I received the car, this line was just hanging off that block, but I assume it must of gone somewhere.

Right now, I simply removed that line and plugged that "front" side of the block. However, I am concerned that without that check valve in there, I may lack boost when the car is not running, as confirmed by your comment. So I assume it's important for me to fix.

If I cannot figure out where to plug in to the transmission, even it I re-route per your configuration, I don't know where to put in the transmission end. That's the female port I am looking for.



01-18-2016, 11:02 AM
Does your car have air conditioning. If so there should be a vacuum canister on the passenger side.

Here's the diagram for the transmission line. It's on the driver side not the passenger side.


01-18-2016, 11:32 AM
Hi John:

Thanks for the quick reply. I do not have A/C. So if you look at the figure I pulled from the '61 Shop Manual, I draw 3 arrows to the line in question. It seems to disappear on the passenger's side and leads down somewhere. That's that I am looking for. Where is that mystery port?

http://s7.postimg.org/d45brgvnb/Brake_Booster_Vacuum_Line_Drawing_Fig_23_Close_U.j pg (http://postimg.org/image/d45brgvnb/)

However your diagram gives me an idea. I will check the transmission section of the manual and the assembly diagram guide, and see if I can find it there. But if you know, inquiring minds want do know!

01-18-2016, 12:23 PM
Do you have vacuum or electric wipers. Some '61's had vacuum wipers.


01-18-2016, 12:37 PM
It looks like that goes into the firewall for your heater control. It's vacuum actuated.


01-18-2016, 01:53 PM
Hi John:

Hey, that looks like it. May I ask what is your resource? You seem to have a lot of these at your disposal. I own the '61 Shop Manual, the Assembly Guide (from Jim Osbourne) and Steve Christ's 390 Manual.

Electric wipers by the way.

You seem to have another set of resources, and I would love to get my hands on those too!

http://s22.postimg.org/60a40wqkd/61_heater.jpg (http://postimg.org/image/60a40wqkd/)

In the mean-time, I am running right down to my garage right now to find that coupling in the firewall!

01-18-2016, 01:56 PM
I have copies of the Ford Master Parts Catalogs from 1949-1972. I believe they are available on CD or via download.


01-18-2016, 03:00 PM
Hi John:

Ok, so you are correct in pointing me to the heater, not transmission. I did find a diagram in the Shop Manual, and then again in the Jim Osbourne Electrical Assembly Manual.

So it looks like this vacuum line goes into the heater assembly/configuration via the firewall. The Osbourne manual points me to a page & sheet I don't have. At this point, I see the configuration up to that point.

I don't want to obsess over something like this, as it looks like I would have to get behind the dash assembly to route this properly. I am not willing to do that right now. I capped the Intake Vacuum Port block on this side so there is not going to be any exposure to the brake booster line, and since this was just hanging off anyway, for who knows how long, and Betty is running fine and more importantly braking fine, I am going to let sleeping dogs lie on this for now.

Below are the diagrams I did find and they are helpful...to a point.....

http://s11.postimg.org/aw5pdoaj3/Comes_In_from_Firewall.jpg (http://postimg.org/image/aw5pdoaj3/) http://s11.postimg.org/bkejwm98v/Refer_to_Sheet_I_don_t_have.jpg (http://postimg.org/image/bkejwm98v/)

http://s2.postimg.org/lqajgxhjp/IMG_1750.jpg (http://postimg.org/image/lqajgxhjp/)

01-24-2016, 11:13 PM
I located the heating control line that takes the vacuum from the intake, routed it back through the firewall into the engine compartment, and connected the lines using the vacuum check valve. I went from a 1/4" line from the intake vacuum port tee to the check valve, then 3/16" from the check-valve to the brass reducer connector that took it from 3/16" to 1/8" line to the heater controller.

According to the manual, that should do it. Thanks for everyone's input and help on this. Each time I open the hood, I learn something new!

02-25-2016, 12:43 PM
Sorry to clog up a thread, but I wanted to update why this is important. Now that I have got this corrected, I can now actually regulate the heat coming from the blowers (both Defrost & Heat modes). Before I was only getting blazing hot air coming out, and now I can regulate it better.