hi all,
I have an 80 cutlass supreme with a stock turbo 350. It drives great but the shift points are really high. Idk what the rpms are as I dont have a tach but its wound up tight. I also have a really hard time getting the fluid levels right in the tranny as well. It jumps from the bottom of the fill line to 2 inches above with just 4 ounces. Ive changed the modulator and have pulled the pan and replaced the filter. Any help is appreciated.

 

Have you pulled the governor to make sure it not sticking and that it gear is not broken?

 

I haven't pulled the governor yet. It could be sticking i suppose. If I shift it manually then it'll work but it has some hesitation still.

 

Hi, welcome to the group!
Make sure you are getting good vacuum down to the transmission. Do a search on this forum for more details, like this one:
https://classicoldsmobile.com/forums...-cutlass-4534/
a wealth of great information here!
As for the fluid levels, are you checking with the engine running and at operating temperature? Take it for a quick drive to warm it up and cycle through the gears (including reverse), then park it and leave it running. At this point this is the best condition to check the fluid, should be right at the full mark.

hope this helps,
james

 

Some modulators have adjustment for shift firmness. All it takes is a small screw driver into nipple the vacuum line hooks to. Clockwise should firm them up. Dont go to far though can be damaging.

 

Are you referring to full throttle shift points or "normal" driving low RPM / low speed shift points?

 

Normal driving. Most of the time it won't shift at all unless its wound up. But then other times it works like its supposed to.

 

That sounds like it may be a vacuum modulator issue. Have you verified the vacuum hose connection from the modulator to the intake manifold, and verified there is a strong vacuum signal on the hose at idle?

 

I have checked the vacuum where the hose connects on the carb and its between 15 and 20. I havent checked it at the bottom where it goes into the modulator.

 

Check it at the bottom

 

Make sure the vacuum line is metal. I have seen many times over the years where people have used rubber hose the entire length. Add a few years of oil and grime, plus heat from the exhaust, and the vacuum hose can get sucked closed. No vacuum at the modulator=late or delayed shifts.

 

Its metal. I haven't checked it for pinholes yet though.

 

Ended up finding a small pinhole in the metal line. Can anyone confidently tell me which way turning the modulator does what and about what increments I should adjust it?

 

Clockwise raises & firms the shifts. Go about 1/4 turn at a time & test drive.

Keep in mind it only effects part throttle, WOT will still be the same.