Well, I think my Jetaway trans crapped out on my 67 Cutlass. I finally got a chance to put about 10 miles on it today. Things seemed to be okay at first and then I turned the corner, started accelerating and noticed the higher rpm and it wasn't shifting. She won't shift into high - whether manually or automatically. The trans fluid looks good but, I just changed it (and the filter) a few months ago, so I probably only have 50 miles on it.

 

The kick down switch could be stuck. Its a long shot but worth a check.

 

I had an ST300 variant in a 64 Tempest driver years ago that the kickdown switch would stick. Real PITA because it would invariably stick when setting the automatic choke on cold start. A light tap with a screwdriver would unstick it and you were good to go until the next cold start or forced downshift. Learned to spray WD40 in it weekly.

Also check the vacuum line to the modulator. Seen those rot and fall off too. Vacuum modulator itself could have failed.

 

Pull the governor, look for sticking weights and for a bad gear(s).

 

Make sure you have manifold vacuum at the modulator and look for any fluid leaks in the hose.

 

I should have added this in my original post, the trans was slipping in low all time, so I reset the low band adjustment to 4 turns, as described in the service manual - it was at 5.25 turns. That took care of most of the slipping. I have 25 miles on the car, after making that adjustment. Yesterday was my second time driving after making that adjustment. The trans did slip a little bit in low but not like before.

 

Also check the switch pitch operation of the switch on the throttle linkage at the firewall.

 

Is that procedure in the Service Manual? I'm still REALLY new to all this Jetaway stuff. Thx!

 

Just unplug it, that will disable high stall and the kickdown function. Take it for a rip and see if it behaves!

 

Thanks. I'll start there tonight and let you know how it goes.

 

Start with the vacuum modulator.

 

I'll check that out too. You mentioned earlier to check for fluid in the hose, are you talking about in the vacuum line that is connected to the modulator?

Just asking questions ahead of time so I can plan my "attack" when I get home tonight, well hopefully tonight.

 

^^^THIS! Without vacuum, the modulator assumes the engine is at wide open throttle and upshift will only occur at very high RPM.

 

Yes fluid in the tube or rubber hose that supplies vacuum to the modulator indicates a leaking diaphragm inside the modulator. There shouldn't be any fluid at all in the tube or hose.

 

UPDATE
The vacuum modulator does not leak, holds vacuum and the vacuum line is clear and works. The bad news is no one said "Watch out Russ, the 57 year old hold down bolt may be frozen." Now I have to get that SOB out.

 

I have a free trans if you need it south of chicago.Took out of a running 65 25 years ago. Taking up space in my garage.

 

I appreciate the offer...I'm not sure if I'm there yet. I need to check the Switch Pitch Control first and if that's not the problem then I have to determine what my next step is.

 

I've added that to my check list. Thx!

 

Sounds a lot like the dreaded transmission fluid grit wash out... Many a mechanic/gearhead have told me over the years not to replace the transmission fluid on well used ones... while some say its not a problem ...

 

Unfortunately, the trans was slipping when I bought the car with the old trans fluid and filter in it. My "detective work" continues. LOL

 

UPDATE:
I had the vacuum modulator sitting on the bench with trans fluid in it, for a few days, just to see if there was a slow leak going to the vacuum hose side but there wasn't.
I have the vacuum modulator back in.
I replaced the small section of vacuum hose between the hard line and the modulator, just to be on the safe side.
Trans fluid is at the proper level
Trans does not go into high.
Unplugged the power to the Switch Pitch and that made no difference, still no high gear.
I haven't gotten to the governor yet. That's next, but it might not happen until next weekend.

 

I would change the vacuum modulator, they are inexpensive and available through your local auto parts store.

 

Was vacuum to the modulator confirmed?

 

Post 15

 

post 15
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I have a vacuum module ordered. Hopefully I can get it swapped out and tested Wednesday after work.

 

When will that myth die?!?!

Any grit in a transmission is bad news, how long will an engine last with grit in the oil? Furthermore, what’s the purpose of the transmission filter?!?!?! Does the filter have the ability to filter only the “good” grit from the bad grit???

Assuming the transmission is working as expected and correctly, it will continue to work after a fluid and filter change.

 

Just out of curiosity, how long is the governor? I looked under the car tonight to see where the governor was located and thought "boy, I hope it's short otherwise it's either going to be a pain in the a$$ to get out or it's not coming out while the trans is in the car. "

I haven't replaced the vacuum modulator yet. Hopefully that will happen tomorrow after work.

 

Replaced the vacuum mod, that didn't fix it.
I am now trying to get the governor out of the trans. I'm trying to twist it like the Service Manual states but I'm not having luck.
Any suggestions, other than to replace the trans, would be greatly appreciated.

 

The car is back from the shop. The governor has been replaced and now the trans is working well. Looking forward to putting some miles on the car now!

 

Great news, drive it!

 

Good news Taz, enjoy it !

 

Thanks!
It took me 40 miles to drive 7 miles to work this AM, just a quick shake down cruise. It was great!

 

Thats the first time I've heard of a bad governor on an ST300, glad its fixed.

 

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Yup they're rated for 50 years of service, Taz got almost 7 bonus years .

It is amazing how long some of these parts last. I agree a governor failure is rare, plus his was stuck.

 

Ray's in Neenah?

 

No, it's at Automotive Specialist in Oshkosh (where I live). I have bookmarked Ray's though. Thanks, it's always nice to have another option in your hip pocket.

 

Well it's true, I "almost" got the bonus 7 years. LOL
Like I mentioned above, I put 40 miles on it yesterday morning and all was good. After work the wife and I took a cruise and 15 miles into the 25 mile trip, the trans stopped going into high again. And as luck would have it, it progressively got worse. Limped it home (meaning kept my speed under 45 - since it was in low only) and dropped it off at the shop again.

I am "this close" to saying F-it and swap out the trans for either a TH350, 200R4 or a 700R4. My wife was impressed by how calm I was on the way home - I told her that I'm hiding it well because I was not calm on the inside. LOL