1934 DR - Shutting down the free wheeling device has to be done properly...and that includes vacuum leak.

[Semmerling]

This winter I set about to completely rebuild the "600996-5 2-20" transmission in my '34 DR. This occurred after 2 1/2 years of tracking down every part inside that transmission. These transmissions, with their free wheeling feature are a tough to rebuild as right here is where Dodge sends out the door the last of the non synchromesh transmissions. Why would anybody not move to a synchromesh? Answer "They Wouldn't" with perhaps the "I don't buy the 1st year of a new contraption" being a strong reason not to...at first. Synchro was coming and it would make non-synched transmissions the "steam engines" of the "diesel electric" age.  Parts for the non-sychs would literally disappear of the shelves in the following 5 years as those that ground gears grabbed them up to make a go of the last hurrah.  This thread is about vacuum leak from the free wheeling (FW) actuator system that sits right in front of the driver's side of the firewall. It is this device that actuates the FW linkage that results in the ability of the centrifugal  clutch assembly, found in the final quadrant of the transmission to free wheel, to work.

 

So, what is this all about? Well, the FW system was not going to last very long. The issue was safety, specifically the technique, or lack of technique, that made sure that the driver never needed to "engine brake." In FW and on a Rocky Mountain road trip? Well, when you take your foot off of the accelerator, there is exactly ZERO engine braking and it take the great skill of readers yet to address this thread to get back in gear. Your period brakes will last about as long as it takes to read this paragraph and then....well then....you were really flying. Accidents happened, people were maimed or worse. Some States contemplated a mandatory ban on FW, requiring the device to be shut off permanently in order for the FW models to be registered. Many people (not including those who, to this very day, step forward to say "all any damn fool needs to do is throw the knob back to the forward position, double clutch with an especially high rev and throw it into 3rd regardless of noise to be heard" all while watching electric polls go by like picket fences and being unable to read "Curve Ahead...Slow Down...Bye Now...Electra Shave."  They are of course right, but in a very Darwinian way, they either attended enough funerals or are, as Ed would remind us, Captain Lance Murdock devotees. 

Many permanently shut the system down. And that is where any value to be found reading this thread begins.....

Inside these FW transmissions is a final device that has an integral (as in, its a factory proprietary ASSEMBLY) FW centrifugal clutch assembly. The bearing for this assembly is the frame cage the clutch! One replaces this unit as rebuilding it may be possible, but highly unlikely and the only person that I could find that said they had done it only gets 1/2 an hour a day to use a phone. That assembly has a slider ring that moves it in and out of operation be means of a internal side mounted linkage (passenger side) that goes through the transmission wall and connects to the two distinctive articulated arms that are actuated by the fore mentioned  diaphragm vacuum mechanism on the firewall. The means to set the FW system permanently off is to remove the the bar between those side mounted arms (on the tranny) and bind them forever static by bridging those arms. One does this so that the FW device in the tranny is in the forward position. Do that, and most did, and FW was ended. What I found in my tranny is that.....get ready for it.....the FW assembly was welded to the bearing. That made sure the assembly could not move to the activated position. It would have worked perfectly.....but.....the person that did the work (early welding) did not weld the unit in true center to the shaft. Yikes..... No leaving this behind.....no avoiding replacing the whole proprietary assembly.....no problem as I had found one. With that work done, I shut the system down by a static bridge between the two actuator arms. No FW. The new transmission was complete and had less miles on it the factory dealer delivered cars...as in zero driven miles. It runs magnificently. But....we are not done.....

If one is of the mind that you have a FW device and that you can properly shut it off and just enjoy a great ride, well, in my case the story has one more twist. The FW device uses vacuum of the intake manifold itself, as in, not off of the carb. The size of the vacuum tube itself is huge, so large that the standard 3/8 intake hole is bridged to a 3/4" female and then the FW vacuum line is set into it. So large that a wholly separate vacuum line has to be tapped at the rear of the carb for the windshield wipers. The point here is that when I determined that I would test to see if that shut-down vacuum line was truly dead....it wasn't. The intake was sucking small amount of air randomly (like an 8th term politician,)through the whole FW diaphragm device. And, when I took off the FW vacuum tube, backed out the 3/4" female, set in a new 3/8" to rubber hose barb piece, well....good things started to happen. First, my vacuum gauge jumped 12 units, requiring me to significantly re-adjust the fuel mix, re-adjust idle, etc. After the stunning 45 minute drive in a long while I pulled the plugs and they were spotless, something that they have not been and has bothered me for some time. 

Moral of the Story - If you are not going to use your FW device, close the vacuum port on the intake. 

Final notes - from the factory, the thin vacuum line for the windshield wipers is a tap at the lowest rear of the intake behind the carb. Know that that flared vacuum line end, held into the intake by a flare nut, has no internal face for the flare to butt into. Any air leak is going to be small....but as this whole read is about the importance of vacuum leaks of FW models. Find a small FAT O-ring and get it over the flare/nut and on the line. When you set the nut in, pull the line out if it moves at all, Slide the O-ring tight to the nut and tape the line behind the O-ring. 

 

Now thats a vacuum line for a '34...
Small black line is the wiper line....

 

 

 

 

 

 

 

[vintage6t]

Interesting read regarding the FW feature and operation of the trans. Thanks for sharing the technical history.

 

Moving forward in time, I believe that the overdrive transmissions also free-wheeled with OD engaged. Easier to disengage though so maybe not as dangerous.

 

The FW transmission may of become obsolete but the engineers didn't give up on vacuum operated devices. My 41 Plymouth convertible had two of those vacuum ports comming off the manifold.

 

One for operation of the power top. Vaccuum canisters on each side and a two port valve in the dash make the top go up and down. They operate like modern hydraulic top cylinders.

 

The second is for power assisted shifting of the 3 manual three speed transmission. There's a dual sided vacuum canister hooked to the normal transmission linkage. As you start to move the shift lever a valve will open vacuum to one side or the other to help push/pull the shift linkage in the direction your moving the shift lever. Makes for easy shifting.

 

Of course the wipers a vacuum operated as well.

 

Point is there is a complex vacuum operated system(s) running through out the car. Unlike the OP, I want to keep these systems operational. Same as the OP,  a leak anywhere in the system will have a negative effect on engine performance. So agree have to be diligent about vacuum leaks to get top performance out of the car.

 

 

[Semmerling]

6T, I agree with you in all regard. 7 years later a great deal had changed and you are enjoying some major advancements. The overdrive orbitals are far superior to the original FW assembly. You can get into OD and out of OD just as you point out. The only point that I was trying to make was once one makes the decision to shut a function down one is most apt not to recognize the deterioration that very same system goes through over, in my case, 88 years. Finding the FW tranny internals was supposed to be close to impossible, in the process of finding it I never came across any of the service pieces for the larger diaphragm system. It was pretty much a one way ticket.  The friends I know with '34s do not even use the "600996-5 2-20" transmission and have all opted for a tranny with OD. Can't say as I blame them, no sync is a two extra steps to the right and a toe tap before the pirouette. 

 

 

[Bob Riding]

Thanks for the in-depth look at free wheeling. I'm sure that others will benefit from your process and description.

Just one question- where does The Freewheeling Tony Smith  fit in? 

[TodFitch]

Unless they radically changed how it was implemented between 1933 and 1934, I think the description of how the controls work is wrong.

• The cable from the control knob on the dash goes to a  lever on the side of the transmission.
• That lever operates a dog clutch to lock or unlock the freewheeling assembly.
• Another cable on the lever on the side of the transmission goes forward to a spool valve on the vacuum clutch assembly.
• Also connecting to the vacuum clutch control spool valve is a linkage from the accelerator pedal.

The control knob on the dash has three positions:

• All the way out: Everything locked out.
• Middle position: Freewheeling only.
• All the way in: Freewheeling and automatic clutch enabled.

Aside from being scary as h*ll to use, the spool valve on the side of the automatic clutch had no air filter and the road dust quickly wore them out to the point of no repair. I agree that disabling the whole system will involve blocking the vacuum to the spool valve.

 

The easy way to permanently lock out the freewheeling is to loosen the clamp screw on the cable coming from the dash. Then move the dash knob all the way in, move the freewheeling lockout lever on the transmission to the locked out position, and finally tightening the clamp on the control lever.

[Semmerling]

12 hours ago, TodFitch said:

Unless they radically changed how it was implemented between 1933 and 1934, I think the description of how the controls work is wrong.

• The cable from the control knob on the dash goes to a  lever on the side of the transmission.
• That lever operates a dog clutch to lock or unlock the freewheeling assembly.
• Another cable on the lever on the side of the transmission goes forward to a spool valve on the vacuum clutch assembly.
• Also connecting to the vacuum clutch control spool valve is a linkage from the accelerator pedal.

The control knob on the dash has three positions:

• All the way out: Everything locked out.
• Middle position: Freewheeling only.
• All the way in: Freewheeling and automatic clutch enabled.

Aside from being scary as h*ll to use, the spool valve on the side of the automatic clutch had no air filter and the road dust quickly wore them out to the point of no repair. I agree that disabling the whole system will involve blocking the vacuum to the spool valve.

 

The easy way to permanently lock out the freewheeling is to loosen the clamp screw on the cable coming from the dash. Then move the dash knob all the way in, move the freewheeling lockout lever on the transmission to the locked out position, and finally tightening the clamp on the control lever.

 

I like your solution even better. The system that is in my '34 was purposefully shut out a long long time ago. Here is a pic of the weld job on the that unified bearing and centrifugal FW assembly. The point of separation for the shaft is under all of this.