Fordomatic late shifting ('57 thunderbird)
 

Update 12/17/20 — issue in this case turned out to be the throttle valve installed wrong in the valve body. Dominic Hide nailed it in post #23. His picture shows one that was stuck. Mine ended up being installed incorrectly by the rebuilder. Once this was corrected, the transmission shifted correctly.

********************

Howdy everyone. Apologies in advance for the long post. Any help you have to offer is greatly appreciated! Done a lot of reading on here and elsewhere and can't seem to find a solution.

Looking for some advice/direction on how to solve late shifting and very harsh downshifting issues on a medium-case Fordomatic in my '57 bird.

Background:

Transmission was rebuilt by a local trans shop that specialized in older stuff. We pulled engine out to keep costs down and took trans in for a bench job. Everything went back together fine. Shift points are very late (30+mph regardless of throttle pressure) from 2nd to 3rd. It also downshifts back to 2nd at around the same speed (harsh).

All linkage adjustments were checked and reset several times per the shop manual to try and remedy. No change in shift points — it doesn't matter how far the rod is shortened or lengthened. Car went back twice to the shop and they basically threw in the towel and said that's how it works. Car went to two other shops where the valve body was dropped and they discovered a sticky throttle valve. This also made no difference to the shift points. Reset linkage again and no matter where the adjustment, car shifts same (late). In fact, it shifts the same with the kick-down rod completely disconnected. Something else is going on here.

The transmission goes into gear very quick and crisp from park to reverse, drive & low and shifts nice and firm — just late. From reading the Fordomatic manual, I was leaning toward the governor being a possible issue. I pulled it out and it appears to be in good shape. Piston is not sticking and no contamination visible. Appears to have been installed correctly. (Was hoping it wasn't and would be the cure to the problem.)

video of governor:
https://youtu.be/yBX84igvJ2M

We have a couple of other cars with this same transmission and have no problems adjusting the shift points with the kick-down rod. In fact, they're fairly sensitive to small adjustments. They all can be made to shift around 22 mph per the shop manual as well.

Should I be looking at something else? Fluid is still very nice and red and fresh smelling. Running Type F. Only a 150-ish miles put on since the overhaul. I really hate to have to pull this thing back out again. Hoping it's fixable in the car!

Thanks in advance!
Kent

Re: Fordomatic late shifting ('57 thunderbird)
 

Hello Kent,

I have a 1957 Skyliner with the Fordomatic transmission. Last spring I pulled the transmission to install a "front seal kit" (front trans. pump seals, large converter o'ring). When I reinstalled the transmission, I noticed that started to shift later than before and I fiddled with the transmission throttle valve linkage which really didn't help much. On my transmission, the late shift seemed to correct itself once the transmission had warmed up and then continued to shift well as long as the transmission was at operating temperature. I thought about pulling the pan to look at the throttle valve but decided instead to add Sea Foam Trans Tune Additive (16 oz). Now I know there are lots of opinions on additives, but I'm telling you that on the very first drive with the additive, the transmission began shifting (both up and down) quite nicely and went back to what I would consider normal. It now shifts up (2nd to 3rd) at around 20-25 MPH with light throttle which is exactly what I was looking for. The additive does not contain seal conditioners (which I really didn't want) and specifically indicates it can clean and free up sticky valves. I got my Sea Foam at O'Reilly's but it is available at most any automotive store or Amazon.

Good Luck,
Dave

Re: Fordomatic late shifting ('57 thunderbird)
 

for whatever it's worth...
When I asked the shop that rebuilt my Fordomatic what fluid to use they said, "Mercon".
Other folks here have said the fluid used makes a difference in the smoothness of the shifting.
.

Re: Fordomatic late shifting ('57 thunderbird)
 

Dave -
Thanks for the info. Mine does seem to shift sooner once it's warmed up but never before 30 mph. When it's cold, it's closer to 40 mph which is almost twice the speed the shop manual says (22 mph).

What fluid are you running?

Thanks,
Kent

Re: Fordomatic late shifting ('57 thunderbird)
 

I have heard that as well. We went with Type F on the advice from the rebuilder. I'm sure it's contributing to the firm shifts. I'm not sure it would cause it to shift so late though.

Run Type F in 2 other fordomatics and they work just fine. Not sure what to think other than the shop didn't do the job right... ugh.

Re: Fordomatic late shifting ('57 thunderbird)
 

I agree with dmsfrr. Type F is not a recommended replacement for type A (the original type fluid). I have also heard other folks complain about hard, abrupt shifting when using type F in Fordomatics. Dexron/Mercon fluid is the recommended fluid to use in Fordomatics.

Re: Fordomatic late shifting ('57 thunderbird)
 

If there is no difference in the position of the passing gear link with regard to shift/mph, I would immediately suspect that the shifting fork inside the transmission is not connected at all.
I recommend NOT continuing to run in this condition until that situation is explored, or possible damage could result.

Re: Fordomatic late shifting ('57 thunderbird)
 

Listen to the man. The pre-1961 FM is controlled by throttle valve pressure and the correct pressure is determined with a pressure gauge. Setting the linkage gets it in the ball park for vehicle assembly/service but it was adjusted by gauge before it went out the door. Same procedure for service.

The early FM will burn as will an AOD w/o the correct pressure setting. It is also difficult to adjust by linkage alone now as everything (linkages) will be worn.

TYPE F is for a firmer shift and is safe to use.

TYPE A(s) has long since been replaced by a continuing series of DEXRON. Normal driving calls for current DEXRON.

Re: Fordomatic late shifting ('57 thunderbird)
 

Kent,

I am using Type F transmission fluid in my 1957 Skyliner with 312 and Fordomatic. Prior to owning this car, I had a 1957 Fairlane 500 with 292 and Fordomatic. I had that car for 17 years and ran Type F fluid in that car for all of those years with absolutely no problems. I know there are lots of opinions on type of transmission fluid, but I feel quite comfortable with the type F fluid and I like the more firm shifting that comes from this fluid.

Dave

Re: Fordomatic late shifting ('57 thunderbird)
 

As mentioned earlier, the throttle valve may not be properly indexed with the internal linkage. Have you had a pressure gauge on it? Use the port behind the throttle lever and compare pressure readings with the specs. in the manual. If the throttle valve is properly connected, check for wear in the governor valve bore. If the valve is too loose, fluid may be leaking past the valve, causing low governor pressure, thus causing late shifts.

Re: Fordomatic late shifting ('57 thunderbird)
 

Thanks for the tips on the throttle valve! One of the shops said they fixed a 'sticky' throttle valve in there, but no change was observed. I have no way of knowing exactly what they did.

I pulled the valve out of the governor and made a new video. The piston has a very slight amount of side to side play. Could this be a possible issue with pressure loss? Moves nice and smooth without any roughness. Here's the video:

https://youtu.be/u06DsbFrAh8

I need to get a pressure gauge and test. Do y'all happen to know the thread of the mentioned port above the throttle lever? Looking at something like this:

https://www.amazon.com/JIFETOR-Press...NsaWNrPXRydWU=

I'd like to get some pressure readings before I drop the pan again.

Appreciate all the help!

Re: Fordomatic late shifting ('57 thunderbird)
 

Drag racers use Type F because it reduces slippage, resulting in firmer shifts, but slippage creates heat, which will kill an automatic transmission, and it wastes horsepower, all of which are concerns when trying to get down the track as quickly as possible. For all other applications, I would change the fluid and clean/replace the filter more frequently when using Type F.

Re: Fordomatic late shifting ('57 thunderbird)
 

The pressure port is 1/8" pipe thread.

Re: Fordomatic late shifting ('57 thunderbird)
 

Thank you, sir!

Re: Fordomatic late shifting ('57 thunderbird)
 

If a person does the pressure test and it seems to be in the range but on the low side then it may have an internal leak. The transfer tubes can leak, the piston rings can leak, and the servo pistons can leak. The governor is back there with the tubes & piston rings. If shifts are positive but late then I would gravitate toward that area around the governor. Leaky servos will not give very positive shifting and especially with the old metal clutch packs.

I don't think this problem would have much to do with the type of ATF.

Re: Fordomatic late shifting ('57 thunderbird)
 

I think I might be onto something here. After watching a ton of tear-down/rebuild videos and looking at diagrams, I think the governor was installed backwards at the time of rebuild.

Here's a link to the video I made. Apologies on the quality. Working under a '57 bird without a lift is no picnic. I pulled the top part of the governor off previously to check the piston operation.

https://youtu.be/xWXLqUnh5Sw

If anyone can confirm that the governor is indeed on backwards, that would really help! Also if anyone has ever pulled a fordomatic tail shaft on a 55-57 thunderbird in the car — that would be good to know if it's even possible.

Thanks for all the help!
Kent

Re: Fordomatic late shifting ('57 thunderbird)
 

Just looked at your video. The spring is something added by a rebuilder to either compensate for worn governor or as a performance modification to do exactly what you are describing, late shifting. Reinstall it without the spring and your trans will shift normally. If the governor is worn the most noticeable consequence will be the trans will remain in high gear at a stop light and not change down until you start to pull away and fluid pressure is increased. Under this condition a helper spring can be used, but no where near as long as the one you have. A single tapered coil is plenty, and when compressed the wire should not lay on top of itself. (The spring under the float on a Holley 4000 carb is a good source from which to cut a coil)


ps the governor is installed in the correct position.

Re: Fordomatic late shifting ('57 thunderbird)
 

Attachment 444857

Some reshaping of spring may be necessary.

Re: Fordomatic late shifting ('57 thunderbird)
 

Dominic —

Thanks for clarifying this for me. I have bought a NOS governor and will use that extension on my existing gov body when it comes in.

Glad to know pulling the tail shaft is not necessary!

Thanks again,
Kent

Re: Fordomatic late shifting ('57 thunderbird)
 

A little tip that you may find useful when it comes time to reinstall. If you replace the stock slot head screws with equivalent size socket cap head screws, a flat head allen wrench (not ball end) will hold the whole assembly, making it a one handed operation.

Attachment 445201