Transmission vacuum line/test fitting
08-08-2013, 12:52 AM
#1
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Transmission vacuum line/test fitting
Friends,
I have an '87 S4, automatic.
Where does the vacuum line attached to the transmission? Does this line lead from the booster? Shifting into gear is kind of rough/slam.
I want to make a pressure tool to measure the pressure of my transmission in order to adjust it property. Where do I get the banjo fitting from an ALDA unit? Anyone know of a suitable equivalent?
Please see attached document so you'll know what I'm going on about.
Thanks, Josh
I have an '87 S4, automatic.
Where does the vacuum line attached to the transmission? Does this line lead from the booster? Shifting into gear is kind of rough/slam.
I want to make a pressure tool to measure the pressure of my transmission in order to adjust it property. Where do I get the banjo fitting from an ALDA unit? Anyone know of a suitable equivalent?
Please see attached document so you'll know what I'm going on about.
Thanks, Josh
Last edited by Bonton; 08-08-2013 at 01:27 AM. Reason: Forgot to include model/year/trans
08-08-2013, 01:48 AM
#4
Nordschleife Master
Josh,
That's a good year.
The vacuum line to the transmission originates at the 'T' off the manifold. It goes down over the bellhouse and makes a union with a metal hardline along its course above the torque tube. Just before the torque converter it makes a union to a rubber line, goes over the transmission from R to L and terminates at its attachment at the green pressure modulator.
If you have hard shifting I would do this:
Make sure you have the appropriate ATF level - this is a must.
Measure you have vacuum at the 'T' and make sure it is adequate for vacuum function to all attachments - should be no less than 18mm Hg and this is the low end - should ideally be 20 - 24.
If this is good at the 'T' now measure pressure at the end of the line before the modulator to test integrity of the line. Remember out of the factory there are two joining points.
If this is good, then test modulator to see if it holds vacuum. It should at 20 - 24 ideally.
Use a MityVac for this.
To measure transmission pressures there is no dealing with banjo bolts. There are three test ports. Two on the R, and one on the L. The pressures to be measured are the operating pressure, the governor pressure, and the modulating pressure. Only the operating pressure can be measured when the car is up. This is the working pressure of the transmission, and the highest pressure. The two other pressures are measured when the car is in motion under specific parameters. The test ports are closed with M8 bolts if memory serves me.
I'll give you some links that are very thorough. These 722 transmission links are pdf's and can be saved. I'll also give you a link to a nice pressure measuring set up. I would start with evaluating the vacuum to the modulator, the integrity of the line, and the status of the modulator first. Horses before zebras as we say.
Craig
http://www.w124performance.com/docs/...722_repair.pdf
http://www.w124performance.com/docs/...2_Mitchell.pdf
That's a good year.
The vacuum line to the transmission originates at the 'T' off the manifold. It goes down over the bellhouse and makes a union with a metal hardline along its course above the torque tube. Just before the torque converter it makes a union to a rubber line, goes over the transmission from R to L and terminates at its attachment at the green pressure modulator.
If you have hard shifting I would do this:
Make sure you have the appropriate ATF level - this is a must.
Measure you have vacuum at the 'T' and make sure it is adequate for vacuum function to all attachments - should be no less than 18mm Hg and this is the low end - should ideally be 20 - 24.
If this is good at the 'T' now measure pressure at the end of the line before the modulator to test integrity of the line. Remember out of the factory there are two joining points.
If this is good, then test modulator to see if it holds vacuum. It should at 20 - 24 ideally.
Use a MityVac for this.
To measure transmission pressures there is no dealing with banjo bolts. There are three test ports. Two on the R, and one on the L. The pressures to be measured are the operating pressure, the governor pressure, and the modulating pressure. Only the operating pressure can be measured when the car is up. This is the working pressure of the transmission, and the highest pressure. The two other pressures are measured when the car is in motion under specific parameters. The test ports are closed with M8 bolts if memory serves me.
I'll give you some links that are very thorough. These 722 transmission links are pdf's and can be saved. I'll also give you a link to a nice pressure measuring set up. I would start with evaluating the vacuum to the modulator, the integrity of the line, and the status of the modulator first. Horses before zebras as we say.
Craig
http://www.w124performance.com/docs/...722_repair.pdf
http://www.w124performance.com/docs/...2_Mitchell.pdf
Last edited by MainePorsche; 08-08-2013 at 02:03 AM.
08-08-2013, 02:20 AM
#6
Nordschleife Master
If you don't have the Workshop Manuals, here's a link.
http://www.2010.cannell.co.uk/manual...s_porsche.html
http://www.2010.cannell.co.uk/manual...s_porsche.html
