Modulating Diaphragm Vacuum Hose
#1
Intermediate
Thread Starter
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The modulating pressure diaphragm on the auto box has a vacuum hose attached to it that goes from the modulator over the gearbox and connects to......where?
I pulled the gearbox out and forgot to detach the vacuum hose, and now that I've replaced the box, I can't for the life of me figure where the vacuum hose connects to.
Maybe someone can explain, or better yet, show a pic.
I pulled the gearbox out and forgot to detach the vacuum hose, and now that I've replaced the box, I can't for the life of me figure where the vacuum hose connects to.
Maybe someone can explain, or better yet, show a pic.
#2
Rennlist Member
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Depending on year, It goes to a hard line that travels forward on the Pass side of bottom of car and that goes to a small flex line (that is notorious for falling off or leaking vacume.) The flex line attaches to another hard line and that goes up into engine compartment and attaches to intake plenum.
#3
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The hard line is typically strapped down on the top of the torque tube, a soft line attaches to it on top of the front bell housing which goes to the rest of the vacuum supply lines under the air filter housing.
#4
Archive Gatekeeper
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As described, starts on the left side of transmission, flex hose crosses over to the right (US passenger side):
![](https://webfiles.uci.edu/redwards/public/Hebert%20Auto%20tranny%20showing%20vacuum%20modulator%20arrow%2011-23-11.jpg)
The flexible vac hose connects to a rigid pipe which lies within a hollow cavity in the foam insulation block on top of the transmission tunnel. The pipe runs along with the transmission shift cable:
![](https://webfiles.uci.edu/redwards/public/Hebert%20Auto%20tranny%20shift%20cable%20and%20vacuum%20modulator%20pipe.jpg)
The front end of the rigid pipe, on top of the bellhousing, connects to another length (dunno how long) of flexible vac line that connects to the 7-way vacuum connector at the top rear of the engine.
![](https://webfiles.uci.edu/redwards/public/Hebert%20Auto%20tranny%20showing%20vacuum%20modulator%20arrow%2011-23-11.jpg)
The flexible vac hose connects to a rigid pipe which lies within a hollow cavity in the foam insulation block on top of the transmission tunnel. The pipe runs along with the transmission shift cable:
![](https://webfiles.uci.edu/redwards/public/Hebert%20Auto%20tranny%20shift%20cable%20and%20vacuum%20modulator%20pipe.jpg)
The front end of the rigid pipe, on top of the bellhousing, connects to another length (dunno how long) of flexible vac line that connects to the 7-way vacuum connector at the top rear of the engine.
#5
Intermediate
Thread Starter
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Thank you, Gentlemen.
I traced the pipe from the inlet manifold, down the back of the engine onto the torque tube, as you guys described.
Seems like I'm going to have to drop the rear suspension and gearbox again to get my hands in above the torque tube to connect the flexible hose.![Mad](https://rennlist.com/forums/images/smilies/mad.gif)
So you learn.....
I traced the pipe from the inlet manifold, down the back of the engine onto the torque tube, as you guys described.
Seems like I'm going to have to drop the rear suspension and gearbox again to get my hands in above the torque tube to connect the flexible hose.
![Mad](https://rennlist.com/forums/images/smilies/mad.gif)
So you learn.....
#6
Rennlist Member
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You could just run another hard plastic line from front to back, I did this as a temp/permanent fix.
On the drivers side on my 88 there's a single brake line clamped to the floor going from front to rear, the clamps are for 2 lines, I was able to thread the plastic line through the empty side of the clamps making it nice and neat, keep it away from the exhaust of course.
Could save you some work and just wait till you go in there next time to fix it back to stock.
Just a thought.
On the drivers side on my 88 there's a single brake line clamped to the floor going from front to rear, the clamps are for 2 lines, I was able to thread the plastic line through the empty side of the clamps making it nice and neat, keep it away from the exhaust of course.
Could save you some work and just wait till you go in there next time to fix it back to stock.
Just a thought.