As mentioned in my earlier post, I just replaced the transmission modulator on my 92 3.0 shorty.
After the replacement, I topped up the tranny fluid and went for a ride and discovered a severe flair up between 2nd and 3rd gears. I rechecked the fluid level and it was good.
Any ideas on what would cause this? This condition did not exist prior to the modulator replacement.

 

did the small pin found in front of the vacuum mod. rod go back in front of the new one...the vacuum modulator actuates the throttle control valve in the tranny which controls shift timing and firmness.

pull out the modulator and check for pin and alignment
correct Motorcraft part #TM74 vac. mod.
did the new one come with a body seal O ring?

is the vacuum hose plugged, leaking or collapsing? put in a new one...they become soft and fail from ATF/heat

or>


Diagnose By Symptom

Soft Or Slipping 2-3 Upshifts
http://autorepair.about.com/cs/troubleshooting/a/bl_45_at.htm
1. Main control assembly gaskets damaged or bolt out of torque.
2. Main control separator plate damaged.
3. Main control Electronic Pressure Control (EPC) solenoid stuck or damaged.
4. Center support assembly bolt not tightened.
5. Center support seal rings or grooves damaged.
6. Center support outside diameter or case bore center support damaged or leaking.
7. Direct clutch assembly friction elements burnt or missing.
8. Direct clutch check ball missing, not seated.
9. Direct clutch brake drum, intermediate band improperly adjusted or damaged.
10. Intermediate servo seal leaking.
11. Intermediate servo piston rod lever incorrect or damaged.
12. Intermediate servo case bore damaged.

 

Thanks for the reply... Is it normal for the modulator to be "spring loaded" when installing it? What I mean is that I had to push quite hard to get it in all the way then I had to hold it in while I tightened up the retainer bolt. If I didnt hold the part in, it would push it's self back out. Is that normal?

 

Hi Aerocook:

First question. There is a black pin about an inch long in the old modulator. It might have been left behind in the hole when you pull the old modulator out. That pin must go in the new modulator before you push it in.

Yes there will be a slight spring load, but nothing excessive. If the old pin is left in the hole, it might have been misaligned with the modulator.

 

I replaced a modulator and it was defective, 93 3.0. After another trip to the store for replacement, it made a big difference.

 

Usually, direct clutch frictions are bad.... Unfortunatly to replace them you have to dissasembly nearly all the tranny.... It is not difficult, but you have to do on a clean surface, and you need a new gasket kit.

 

To answer a few questions... Yes, I made sure the pin was installed in the new modulator. I have verified that the part number is correct (came with the O ring). Although I am not entirely ruling out the clutch pac / discs as the problem, I am having a hard time understanding how there could be absolutely no slippage in the transmission before I replaced the modulator then suddenly it appears quite severely, I think I would have felt a gradual deterioration, not so immidiate if this were the cause? I m going to take the modulator out again tonight and inspect. 96_4wdr, can you advise on "Proper allignment"? Looked to me like it only went in one way.

 

Iv2race. What were your symptoms when you installed that defective modulator?

 

Did not upshift correctly, slippage or hesitation between upshift. I bought an adjustable modulator and adjusted as the instructions said, but only a minor difference. Then the diaphram failed and was sucking trans fluid through the manifold.

 

1. new modulator may be defective
2. throttle valve may be sticking in case throttle valve hole....remove with snap ring pliers and check for debris/burrs
3. throttle valve actuator rod aka pin may be bent/worn/corroded
4. case mount hole for vac. mod. may be corroded or damaged from hammer pounding(soft alum.) and preventing new mod. from seating completely

my wife took my best tool from me, 16 lb sledge hammer.... The Terminator Persuader
the neighbors couldn't stand the 5AM vehicle killing sounds and cussing screams from the garage

 

Thanks 96_4wdr. The new modulator looks like it's seated properly. I had a look at it yesterday to confirm that it was in all the way. Is the throttle valve the item inside the hole that the modulator goes into?

 

Just wanted to provide you all with an update... On Saturday I went out and bought another modulator, but not an O.E. one this time. Installed it, went for a drive and had the same condition. I then disconected and plugged the vacuum line, same condition existed. I have concluded that the problem is internal and due to the milage (267000 kms) I decided that dont want to waste any more time on it, especially since I have a spare tranny in my garage with only 106000 kms. I have replaced trannys in many cars in my day and the Arerostars are one of the easiest I have done. In conclusion, I guess I will never know what the cause of the condition was. Thanks to you all for your valueable input and assistance.