67 deville hard shifting trans

[Peter Nieuwlandt]

a good friend of mine asked me about his 67 DeVille's trans wich has a hard time swifting gears.
My idea was to have a look at the modulator but does anyone have more info and experience with the Turbo hydramatic of thisvintage??My cars have all the old Hydramatic so maybe I'm missing something in diagnosing his transmission

Peter

[George 23923]

If all the shifts are faulty, the modulator is a good bet.
It can be tested without a lot of trouble.
Check the vaccuum line first. Make sure it has no breaks kinks or blockage.
The modulator on this year Cad is on the right front of the casing, and the line can be disconnected from here.
The vaccuum can be tested at the end of the line using a good vaccuum gauge the reading should be I think 17-20 inches of vaccuum at the end of the line. Check the shop manual for the correct reading.
A blip of the throttle should cause a sudden drop, then return to normal. this should occur fairly quickly.
If you can get a vaccuum hand pump, connect it to the port on the module, pump the required amount of vaccuum [ same as at the end of the line above] the modulator should hold vaccuum for at least 30-60 seconds. If not it's US.
If these tests are OK the trouble obviously lies elswhere.