has anyone changed the vacuum modulator ,on a 4T60E, steel line runs from throttle body down to the modulator, ant tips on removing the steel lines? Any tips on removing the modulator? Any tips on buying an original or after-market modulator!


Asked by May 18, 2014 at 06:18 PM about the 1994 Cadillac DeVille Base Sedan

Question type: Maintenance & Repair

just looking for any tips from someone who has replaced it

11 Answers


excuse my ant in the question - meant ANY

1 out of 1 people think this is helpful.

Well it has been too long and as I thought - nobody even knows what a vac modulator is or what is does, That will certainly mean that they don't know what a cable modulator is either. Youngsters")

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yes, i have. just make sure you clean the debris before removing the modulator. i keep the old one as a spare just incase i need a standby.. if the diafragm is not blown. it is good to replace the rubber hose too while u are at it. ..missed this post cozz too much work lately(premises tech).

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Best Answer

You answered just in time.I was ready to order an Adjustable Vac Modulator (after market) because that's the only one the parts guy said he could get. [when I first asked at the parts counter the guy just stared at me] He looked it up though and found an adjustable replacement. ....1/Will the after market be ok or should I try around to find an original?....2/While I've been waiting for an answer to my question I modified the vacuum line to decrease the amount of vacuum at low idle and it's working (tiny bit more positive engagement from dead stop but smoothes out at around the shift to second).....I'm almost wondering if I might leave it my way..>> any comment on just running with lower vacuum at idle?

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you might have to try that after market just in case. if possible, try to find something closer to original. ..i know that parts are harder to get for older cars. i had to depart with the 89 riviera because of that. hope u can get better shifts. your way might help but the diaphragm is wearing out.

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Thankyou very,very much. More than one post I read on other sites and one peice of advice I was charged for (my first and last stop at one of those sites >>> I got a refund though because I wouldn't give anything except a poor grade to the answers they were giving) had gone on to suggesting that running at a lower vac on modulator was going to cause too much PRESSURE IN THE TRANNY right at start... I couldn't see that as a concern ;because, the tranny pump causes hydralic pressure in the tranny and the vacuum modulator & governor only control the shift valve. The tranny is built for low vacuum on the modulator with rpm increase so that you can get a fast start . So tricking it into thinking I'm a lead foot but only applying gas normally is ONLY tricking it ...In other words;intstead of high vacuum at idle sucking at the diaphragm in the modulator for softer shift-- I have tricked it to thinking I am wanting to boot it (even thought engine RPM is low -I have modified the vac. AS IF the RPM were higher)... I couldn't see that being any worse than actually being a lead foot ; so I couldn't see the tranny being unable to handle it.... After all; the tranny wasn't only designed for granny to drive to church. Your comment puts my mind at ease re; tranny........and yes making a get-away kind of start isn't the smoothest but it is smooth at shift to second and to third and to OD ....thanks again ,you didn't tell me that a tranny isn't designed to handle a lead foot.

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I don't mind the positive feel of the shift but my wife wants it smooth- so I guess it's off to order a vacuum modulator {which one is up to what the part's guy can get}

1 out of 1 people think this is helpful.

i did not know the full technical side of it but i knew it was for shifting.. now i know the full function. yes, caddy trannys are built tougher than others.

1 out of 1 people think this is helpful.

it's always a good thing to hear something new or interesting about cars.Every make,model,year has it's own quirks.features,etc. My car has stuff that isn't mentioned in the owner's manual as to how to access... .OBD through the C.C.C. as an example. I couldn't bounce my problem's solution around with anyone face to face because everyone I tried to talk with knew nothing about trannys in general;never mind about mine specifically. Keep answering,learning and driving safe.

2 out of 2 people think this is helpful.

yes, the 89 riviera was on the cadillac E body line and, wow, it had the obd on too & the FIRST crt ever. that is how i know about it's servicing, all 190k miles of maintenance. GM does a great job engineering innovative products.

1 out of 1 people think this is helpful.

This is an old post but wanted to help the next person who stumbles onto it.The trany can take the higher pressure but not all the time.if you red line an engine it won't blow.but if you do it every time you run up a gear it is a matter of time till it blows.Same as boosting trans pressure to the valve body.It's hard on it over time.This trany is commonly bolted to the 240hp 3.8 supercharged grand prix gtp motor.It can handle a little abuse.If you are having trouble getting answers check for parts interchangeability.This trany was used by Cadillac and ALLOT of GM cars.A Pontiac chat room may have the answer for your Cadillac since it is the same part.Hope this helps someone.

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