Taz54904

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.

66_Jetstar

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

rocketraider

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.

Sugar Bear

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

oldcutlass

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

Taz54904

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.

oldcutlass

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

Taz54904

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

66_Jetstar

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

Taz54904

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

oldcutlass

Start with the vacuum modulator.

Taz54904

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.

joe_padavano

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

Sugar Bear

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.

Taz54904

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.

442man$

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.

Taz54904

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.

Taz54904

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

69CSHC

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 ...

Taz54904

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

Taz54904

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.

oldcutlass

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

Sugar Bear

Was vacuum to the modulator confirmed?

oldcutlass

Post 15

Sugar Bear

post 15
👍

Taz54904

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

matt69olds

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.

Taz54904

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.

Taz54904

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.