The Ford Barn - View Single Post - Fordomatic late shifting ('57 thunderbird)

oldave57 · 10-15-2020, 02:12 PM

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

10-15-2020, 02:12 PM	#2
oldave57 Member Join Date: Jun 2014 Location: Burlington, IA Posts: 46	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