[Jacob1963]

So was out cruising last night in my 63 convert, my cruise o matic seems to shift through the three speeds very smoothly at low speeds. Once on the highway I fine I'm having to almost drive like a manual transmission. Letting up on the gas just slightly to get it to shift from 1st to 2nd and having to do the same to shift from 2nd to 3rd. Once in third gear I fine it very sensitive to the gas down shifting very easily with just the slightest acceleration. Any ideas of what could be the problem. I have read on here about adjusting vacuum modulator, do you think this would help?

 

[lagalaxie500]

Not being a GURU on the matter .,the same thing happened with our 63 . I changed the filter and fluid ,all is working fine and dandy.Best of luck.I did this back in 2010 right after I did the engine rebuild.

 

[puttster]

You might be able to test the modulator by unplugging&blocking the hose to it. If it shifts better with no vacuum, a changeout might be in order.

 

[Jacob1963]

Where do you guys purchase your transmission parts from? My local advance, oreilly etc.... Don't seem to have much of a selection for the cruise o matic.

 

[FEandGoingBroke]

Pioneer I think is a company that sells COM and C4 parts.

I'd also try a nice shot of new tranny fluid and a filter.

 

[galax-z]

check the vacuum to the modulator. loss of vacuum will cause delayed up shift. taking vac away will make the tranny want to be in passing gear all the time.

 

[Jacob1963]

That's what I'm thinking. Completely drain and replace filter. While I'm at it try to figure out where it is leaking from and I will just go ahead and change the modulator and check all lines going to it.