G'day folks. I'm new to the forum but have been reading posts for years.

I have a 58 olds that I restored more than 5 years ago. For a variety of reasons, it's been sitting in my shed until this year. I made an effort to work out all the kinks and start taking it to shows and Sunday drives. The only real remaining problem is an early 2-3 shift when the TV rod is adjusted per the book. If I shorten the TV rod the shift points move to slightly higher MPH then 2-3 shift is really harsh. Hoping some of you boys can give me your thoughts. Keep in mind I never got to drive this car before it was all rebuilt. I put in a Fastco full kit during the build.

Until last week I had the rod shorter. First to second occurred at about 8 mph under light acceleration. Very smooth. second to third occurred at 15 mph with light acceleration. This shift feels like the car was hit from behind. Third to fourth occurred at 40 +/- mph and very smooth. I reviewed the gm manual for possible causes, and it focused on TV rod length, accumulator valve or acc piston leaking or sticking. I pulled the pan and accumulator. Nothing found wrong at all. Clean and moving freely.

I put it all back together and test drove. No change. I then adjusted the tv rod per the book (longer). During the test drive it was smoother going between second and third, but it occurs so early the engine is lugging, Shift points are now as follows
first to second 6-7 mph / light acceleration / smooth / feel right
second to third 11-12 mph / light acceleration / pretty smooth / feels early as the engine is lugging
third to fourth 33-35 mph / light acceleration / smooth / feel right

It's been 40 years since I drove a car with a jetaway in it. I don't know what's right, but I don't think mine is behaving correctly. I've have adjusted the TV rod and either I get a harsh 2-3 shift or engine lugging because of low mph shift. My next step is to look into the governor so see if all is well. I welcome any solutions, comments or questions. Thanks all

 

The 58 jetaway was a slightly improved over the 57. Better coupling design. I rebuilt my two 57's using the Fatsco kits and they work great. I always add a can of trans X when installing new fluid. Not sure how much you are adjusting the TV rod, but you need to drive it and adjust one turn at a time. My 1-2 shift is hardly noticeable and 2-3 is shift more firm but not head jerking and then the 3-4 shift has that lazy feel to it. Just shifts as it should. I have to ask,,,,,,,,,,,,,,,,,,,,,,,,,,,,,do you adjust the clevist at the throttle linkage at the firewall? Or do you crawl under it and adjust it at the trans.? I seen on another forum where a guy recommend doing it at the transmission which does not make any sense at all. Why lay on your back, when all you have to do is open the hood and adjust it at the linkage. Try adjusting it in smaller increments and drive it. Good luck with it and have patience.

 

Thanks for the quick response zzcruzin. I use the clevis adjuster at the firewall. I don't see a need to go under the car either. Right now ( " long " ) the adjuster is such that when the throttle is closed, and the TV rod is pushed all the way back, the pin for the clevis just fits. I probably did 4 or 5 turns to the position I call short. Probably too much in one shot. I'll take your advice and do one turn at a time and see where it goes.

Question: Do the shift speeds I mention above seem low to you?

 

Those do seem a little low to me. I would shorten the rod one urn at a time and try it. I would think more like 8-10 on the first shift and 15-25 on the the second shift. One thing is, that everyone might have a little different way of accelerating and listening for shifts. My way might be a little different than yours. And when you put your foot in it a little more it might feel different. I think you have a good starting point with your adjustment. I think you just have to adjust and play with it to find the sweet spot.

P.S. I found this on the internet and just passing it on.

The 1957 Oldsmobile 88 has a 4-speed Hydramatic transmission. For best fuel economy, automatic transmissions should upshift when accelerating at the following speeds: 1–2 at 15 mph, 2–3 at 25 mph, 3–4 at 40 mph, and 4–5 at 45 mph.

 

I like the plan. I also appreciate the shift speed detail. I know it's not 100% because we all drive differently. I'll give it some attention during the next week. I'll report back my findings, Thanks

 

Car looks great! Where are you located?
You can try calling this guy Steve. He's an expert with these old transmissions and a really friendly guy.

 

I know Steve Peluso ^^^^^^ He rebuilt my '56 Jetaway about 10 years ago. As mentioned, he is THE expert on these old transmissions. He's in Mendon Massachusetts.

 

i sent you a private message.