Today I started to exchange all old vacuum hoses under the hood.

The one going to the transmission vacuum modulator is really hardened out, but I can't get that thing out.

Is it screwed or pushed in?

Didn't want to disassemble the whole bracket. 

Maybe it is a good idea to exchange the whole thing, but where can I find it? 

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Found it in the shop manual. 

I am still wondering what this is for...
And where to get replacement.

The vacuum modulator on the Th400 trans ( 64 Cadillac - some models- first year  ) controls the trans shifting 

If the trans does shift correctly just change the rubber hose from the trans to the carb and you should be fine if it shows age ( brittle ) 


No I have a 63 with the Jetaway. 

So no vacuum lines to that transmission? 

Correct if you have a Jetaway trans 


Do you know where I can get a new one or one to exchange?

The part in the picture that the vacuum line hooks up to is the Throttle Check Valve. It has nothing to do with the transmission. When you suddenly let off the gas, it slows down the movement of the throttle rod to carb to prevent the engine from stalling. It is referenced several times in your 1963 Shop Manual and adjustment procedures are in section 26.f page 10-33. If you apply vacuum with a vacuum pump it will start to retract the plunger until it is all the way in. Then it should hold vacuum.  If it leaks down it should be replaced. It has been my experience these are pretty rugged and hold up quite well compared to some of the other vacuum actuators. If your is leaking down I have them for $25 + s/h. Email me at

Got it. 
Problem is that I can't get it out *lol*
The hose on it is so hard I have to cut it, but can't get beneath.
I'll try some more.

There is a retainer clip that hold the diaphragm to bracket. Pull it out with a needle nose. Heat the hose up a bit on low setting with a heat gun. If it is that hard if you take pliers just squeeze the rubber at the nipple and it should break apart. Many ways to skin that cat.

Thanks. Will try that next weekend.

Managed to do that last weekend. 
No chance to pull it off, I had to disassemble the whole unit to do the hose.

So do I need to adjust something now on the bracket (not the throttle check valve)?



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