Transmission likes to bog

[Big_Blue84]

Hello all forum members! My name is Anthony and I recently joined this forum 😀. I joined because I currently own a piece of history, and she needs some serious work. She sat for a good ten years in a couple of yards 😱. I bought her for the grand price of $600 dollars, and have since invested close to $1,800 in parts & labor costs in the very short amount of time that I've owned this car (3 months). She's in pretty good condition for her age, but the mechanics need some work. My transmission likes to bog out after I drive for a little while. It also depends on the temperature of the air as far as how soon it'll start bogging. Basically, I'll hit the highway, I'll be going anywhere between 55mph and 65mph, and the car will jump gears due to whatever reason (slight incline in the road, press the gas, or just because it wants to), and occasionally it'll grind and lurch. It's more frequent when I'm driving through town. And feels a lot worse. I can barely climb a hill sometimes (depending on degree of incline). The tranny gets stuck in 4th gear and I have to stomp on the gas a few times for it to go back to low. If I'm driving on a straightaway, It'll bog, jump to 4th, jump back to low, and then it'll even out. I'm honestly considering just buying another transmission instead of tinkering with this one. It's a 4-speed THM200-4R automatic. I'm having trouble locating one of these in good shape. So, I'm wondering what would be universal with this setup? It's all chevy product. So, essentially speaking, I could grab a transmission from a corvette, or a chevelle, or a monte carlo, or a camaro, even their 2wd pickups, and they would all work, right 😕? I don't want to junk this car. It's my pride and joy. I get compliments constantly, even with the body damage she has 😎. Fast responses are appreciated. Thanks in advance!

 

[HotZ28]

So, essentially speaking, I could grab a transmission from a corvette, or a chevelle, or a monte carlo, or a camaro, even their 2wd pickups, and they would all work, right ?

The THM200-4R was replaced by the THM700-R4 in 1985. Most of the cars you mentioned, would not work, unless the tail-shaft and all components were replaced. The tail-shaft is longer on the LeSabre and similar vehicles. You would have to measure the distance from the bell-housing to the end of the tail-shaft to be sure to get what you are looking for.

 

[Big_Blue84]

I figured that much. They all have different rear ends. Yolks and shaft would have to be swapped/balanced to match. All I'm really looking to do though is switch the transmission and the parts that need to be replaced. I'm trying to keep this car as original as possible. I know my u-joints are in rough shape. I hear them clank every time I go into reverse, or if I go back into drive, when I'm parking my car. Where would I find a transmission though? Ebay motors isn't offering much. Or maybe I'm not researching it correctly...? None of the local junkyards have this car anymore. And I'm not finding much in surrounding states either (NY, MA, RI.)