I've posted a few times about the strange issue I have with the trans on my 64 Fleetwood. When it gets warm and up to temp, I loose 3rd gear, but I never loose reverse. According to multiple sources, 3rd should be find as long as I have reverse. When the trans DOES shift, it does so with ease. I check and maintain the fluid level nearly daily as it does have a leak. But I have yet to find any answers in regards to this issue. 

I have a new pan seal and filter as a last Hail Mary to see if that is the issue, but I am not keeping my hopes up. The way I see it, if the filter doesn't solve my issues, I have two choices. 

1) I purchase a used trans from Jason and have it freighted to me here in Illinois. I order some new seals and have a trans shop swap them around for me. I'm not sure the exact cost for this option, but I am thinking it may save a little money vs. doing a rebuild. 

2) I just save for the rebuild. I am leaning towards this option as then I know the trans is worry free for the foreseeable future and I can drive and enjoy the car. However, I am getting quotes in the $2,500 range which is a little more than I want to spend in the next 6 mos to a year. IF I do go this route, I'm looking for someone who has recently had their 64 "TH400" rebuilt. I had two shops in my area tell me they won't touch a 64 because the internals are different than that of the later years. What overhaul kit did you purchase? How long did it take? Just factfinding at this point and would love your input!



Views: 133

Reply to This

Replies to This Discussion

As a follow up because I didn't want to make the post too long. I have replaced the vacuum modulator, serviced the governor and inspected that it was moving freely. Those were the two most common issues I have seen others have. Outside of replacing the filter-I am out of ideas and so is the trans shop that states they can rebuild a 64 THM400.  

It is true that 64 TH400 is not 100% identical to later years, but those differences are minor. Even here in Finland, far away from Caddy home, I can get 64 specific parts without problem. 
Unfortunately I am not able to tell the solution for the problem in you caddy.

Can you change from 2nd to 3rd gear manually?  ie. With warm engine drive fast (>50 mph)  with stick in 2nd gear and then move it to 3rd position. If it changes ok then valves and bands seem to work ok with warm engine. In that case I would search the problem from governor even you have changed that. 

From my research, everything internally seems to be OK. When it DOES shift to 3rd, it shifts very well. Reverse functions nice and strong when the engine is warm as well. Perhaps when I replace the filter and pan seal, Ill check all of those areas again as well. Certainly won't hurt anything!


I’m unaware of any vacuum shifter on the back of the carb. To my knowledge, there is a vacuum line there that goes to the modulator on the side of the trans. But no component other than the line. 

When I change the pan seal and filter, I’ll certainly check the gov again. Might replace the entire vacuum line as well. Logan

Per she shop manual on pg 10A-22, Fig 10A-16 look at H-I-K-N



  • Add Photos
  • View All


cornering lights

Started by Larry Rees in 1963/64 Cadillac Specific Discussion. Last reply by Jason Edge 3 hours ago. 6 Replies

Neither of my cornering lights are working. I started by focusing on drivers side. I removed the entire assembly and cleaned it up, replaced the wire to the socket, cleaned and lubricated the socket…Continue

Power Steering Hose Questions

Started by C. Van Tune in 1963/64 Cadillac Specific Discussion. Last reply by Russ Austin 6 hours ago. 1 Reply

My '64 Eldo's high-pressure P/S hose sprung a leak, so I want to change it (and the low-pressure hose.) My car is concours-level restored, so keeping as close to the stock fitment and appearance is…Continue

Pertronix 3 install and resistor wire

Started by Dave Fehrle in 1963/64 Cadillac Specific Discussion. Last reply by Dave Fehrle 20 hours ago. 17 Replies

A few questions on the resistor wire, what color is it in the pic? The yellow/blue or black? And connecting to the ACC on the fuse box seems easiest way to go with the new switched wire, but where…Continue

63 Exhaust Hanger Mystery

Started by Mike Travers in 1963/64 Cadillac Specific Discussion yesterday. 0 Replies

I'm in the process of installing a stainless steel single exhaust from Classic Exhaust on my '63 Coupe de Ville. I'm running into a mystery regarding my middle exhaust bracket. I have the bracket…Continue

Blog Posts

accumulator dryer

Posted by CHRIS CARLSON on December 6, 2023 at 10:54am 0 Comments

Who rebuilds original AC  accumulator dryers for 1964 Cadillac? I have been on Classic auto air in Tampa FL wait list for over a year ,  There is one on Old air products web site that looks very similar to the original # 21-4214A but states it fits 1962 Gm cars, The one recommended for a 1964 Cadillac is half the length 21-4215A    What  is everyone using ? I would prefer to be as original as possible. Thanks

'63 Eldorado trumpet horn + 2 standard horns restoration

Posted by Les Eastling on November 15, 2023 at 10:34am 1 Comment

My son, unbeknownst to me, had all three of the horns on our 1963 Eldorado completely restored. We had recently added the Eldorado trumpet horn to the two standard horns and the sound was not very good... we had heard good ones so we knew something was not right... but there was not much we could do to get better sound from the 3 horns. 

There is a restoration service called The Horn Works who my son…


Clock ‘64 DeVille

Posted by Matt Vander Hooven on July 23, 2023 at 7:36pm 2 Comments

Is there still a member in the Detroit area that refurbishes clocks?

Matt VH

Spark Plug Heat Range

Posted by Patrick Westphal on July 7, 2023 at 10:00am 1 Comment

I found a diagram that illustrates the main factor in determining a spark plug heat range that I was trying to describe to you during the chapter get together.

Here it is:


The main factor is the length of the ceramic insulator from the middle of the spark plug to the tip (where the spark happens)  

The insulator…



  • Add Videos
  • View All

© 2024   Created by Jason Edge.   Powered by

Badges  |  Report an Issue  |  Terms of Service