Fordomatic change in shift timing

B

bfdinardo

Member
Good afternoon all,
I've recently got my 1956 Victoria back on the road after a motor rebuild this past winter. I followed the procedure in the book to reset the carb and throttle linkages to the FOM. On the first handful of drives, (a total of probably 100 miles over the course of 5 trips) the ****** shifted a bit earlier in the RPM range than before the rebuild but was nice and smooth and I figured that was more correct than before so was happy. I checked fluid level at the same time of adjusting the linkages and all was good. Yesterday I took it for a drive (10 miles or so) and the ****** didn't shift until significantly higher in the RPM range and was significantly more harsh of a shift. Upon getting home, I checked fluid level again and was unchanged still in the middle of Max and Min lines.

I'm not very well versed in Transmissions so am looking for input on what controls the shift point and what could have changed in the mechanism to change the shift point. Thank you in advance for your advice!

Brian
 
The throttle valve rod controls the shift pressure for all of the old Borg Warner design transmissions. Your shop manual for that year model should have the instructions. They used special tools to set them up initially so it's helpful if you know an old timer to the transmission overhaul game to help with that. The tools were just gauges to get the angles of the bell crank and lever set up for the throttle valve initial setting. A person can use a pressure gauge also. They all have a place to connect up the gauge but the vehicle has to be run on stands to do it. Small adjustments without a gauge can be made by trial and error but it will take a test run after each small adjustment and you have to remember what you did each time in case you need to undo it. The governor controls the shift points and the throttle valve controls the quality of the shift through pressure applied.

You will want a shift that is a happy medium between a dragging *** slow shift and a full on bang shift. The governor is just a flyweight and spring on a pressure valve. They seldom have problems unless there is an internal leak with a loose tube or a bad seal somewhere.
 
So, what made me suspicious is that you mentioned engine rebuild, but then you said you re-adjusted linkages by "the book". What book?
The only place I know that gives a full and detailed description of the passing gear adjustment in the Ford-O-Matic shop manual and you should get the book for your specific year of car because in some cases, linkage components differ from year to year. You will probably be okay with a '55 or '56 Ford-O-Matic shop manual.
 
Best bet on the FOMs & COMs is to pull it with torque converter in place when doing engine work and don't adjust anything unless it has a problem after reinstallation. The initial settings can require more adjustments to get them back where they want to be. You end up adjusting it to specs and then readjusting it back to where it was before adjustments. If the unit is getting older, a person should expect problems from rubber deterioration and overall wear. Sometimes problems can be adjusted out but it depends on the problem.
 
I performed the adjustments post engine rebuild per the steps in the FOM book as shown below. the shifting for the first 100 miles after these adjustments was great, very smooth. I'm just trying to figure out what could cause the shifting point and action (much higher RPM's before upshifting and smooth to harsh) to change suddenly.
 

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The linkage setup/adj is only to get that portion somewhat into specs. You have to determine correct linkage adj and TV pressure with a fluid pressure gauge. Only then can there be correct trans operation (if no defects).

Think of it as an early AOD. It will burn.

How long since band adjustments and service?

CLOSE is only applicable to horse shoes, hand grenades, and/or Thermo-Nucleur warfare.
 
KULTULZ said:
The linkage setup/adj is only to get that portion somewhat into specs. You have to determine correct linkage adj and TV pressure with a fluid pressure gauge. Only then can there be correct trans operation (if no defects).

Think of it as an early AOD. It will burn.

How long since band adjustments and service?

CLOSE is only applicable to horse shoes, hand grenades, and/or Thermo-Nucleur warfare.
Click to expand...

I've had the car about 2 years and have not had any band adjustments or service done to it to this point.

Where would I go about hooking up a fluid pressure gauge? Is there a port I could hook up to somewhere?

Good point about getting close with the "by the book" procedure. I felt I did get really close by the feeling of the way it drove but can't figure out why it suddenly changed seemingly overnight.
 
I've had the car about 2 years and have not had any band adjustments or service done to it to this point.

Where would I go about hooking up a fluid pressure gauge? Is there a port I could hook up to somewhere?
Click to expand...
The PRESSURE CHECK (and ADJ) is not covered in the 1956 FM SHOP MANUAL? If not, I will see if I can find it. The TRANS has to have correct fluid pressure to operate correctly.

Think of band adj as adjusting brakes before self-adjusters. Same principle. As the friction materials wear, they need to be brought back into spec. The fluid is a lubricant, coolant and cleanser (dispersants/detergents). As the old clutch material collects in the filter, it may affect pressure/volume.

Once you have the PRESSURE/ADJUSTMENT satisfactory, any malfunction(s) is easier to diagnose.
 
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Internal fluid leakage due to deteriorated o-ring seals will drop the pressure. The symptoms might give a person an idea of where its leaks if that's the trouble. Bands have to engage properly and clutches have to have enough pressure against them for everything to work as it should. Worn ring seals on the back end or loose tubes can have the same affect. Nothing mechanical lasts forever without maintenance or overhaul.

There should be a port plugged on the left side of the transmission near the TV & shift levers but I could be wrong. All my books are for the older FOMs of the flathead era. A person needs the specific transmission book to see the illustrations or photos. The original manuals have good photos but reprints sometimes loose the photo quality depending on how they were copied.
 
bfdinardo, all is not lost. I'm going through this right now on my 57. You adjusted it correctly if you followed those instructions that you posted the photo of.
Based on what you have said; 1) you need to put a piece of tape on the cowl, and keep track of your adjustments there, so you can go back to the previous step at any time. 2) Pull the cotter pin and the attaching pin on the rod that goes down to the transmission. This is the TV (throttle valve) rod. your shirting late, and a little too "snappy" so you want to shorten the rod. I'd say start off turning it shorter 1 turn. 3) take it for a drive, noting shift speeds with similar amount of thorottle depression. One other piece of advice, don't overengineer the problem. It was fine, and now it's not. Try the simple stuff first. What your transmission is thinking now is that you have the accelerator pedal down farther than you do. Therfore you want to shorten the rod. Think of it as a throttle position sensor on a newer car. Same thing, only instead of it being a sensor it's a linkage. LAST BUT NOT LEAST, reply back here with you findings after you have it narrowed down. It's only fair, and it's the only way we all can learn to help each other. Gene (Cols., OH)
 
All, thanks for everyone's input. I finally got a few minutes to investigate using you input. I took the air cleaner off and went to confirm linkage adjustment near the carb and something sprung back into place. I took it for a quick spin and all seems back to normal. I simply sprayed all joints with WD-40 and made sure bends in the springs etc. had more clearance. All is well! Thanks.
 
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