SlimJim transmission reliability

[furrycritter]

How reliable is the SlimJim(RotoHydramatic) from early 60s Oldsmobiles and Pontiacs?

[rocketraider]

This is as simple as I can put it. When one is working right, it's right, and when it's not working right, look out.

They are very sensitive to fluid level and throttle valve rod adjustment. They are also difficult to find someone qualified to service them. Parts availability is good; several companies have the rebuild kits. Torus covers are prone to cracking, creating an internal fluid leak which will affect operation.

Most have a rough 1-2 shift, but it's no worse than a later GM 700-R4 or 4L80E in a truck.

They tend to confuse younger service techs when taking the car in for service. I've had more than one ask me how to make the car back up?

Other than these quirks, SlimJims are no worse to live with than other earlier automatics. Lack of people who know anything about them is the biggest drawback to owning one. Most of those guys are long retired or dead. Case in point: a trans shop here. The founder of the business could rebuild Hydra-Matics, SlimJims and Dynaflows in his sleep. He died in 1997, and his 35 year old son, while a competent trans man in his own right, knows nothing about these transmissions. He says he understands how they work, but has never tackled one himself and sends them to a guy 40 miles away who cut his teeth on them on the 60s. I wish he would do one himself, so I'd know there's someone still young enough to be around for a while that can work on it.

[furrycritter]

Thanks for the information.