Hello, I have a bit of a project truck I just purchased. It is a 1988 Nissan with a '95 5.0L with little mods (port/polish stock heads with 600 cfm Holley and highrise intake). Truck runs excellent and just got the carb set up. The trans also has a Stage 2 shift kit. But under full throttle it wants to shift from 1st to 2nd at 4000 Rpm, 2nd to 3rd at 3500 Rpm and 4th at 3200 Rpm. I've tried adjusting the TV cable from one extreme to the other and all the places in between, with no better of a result.. Seems like the only way to really get any performance out of the trans is to manually shift from 1st to 2nd and so on. I dont want to goto a slap shift/manual shift kit..any suggestions of where to go from here?

 

does it have a modulator valve on it?????????

 

If I remember right, the AOD used to have pressure governor that was a light press on the back end of the mainshaft.. They liked to come loose and would make for poor shifts/timing.. Not sure if its your case, but something to check..

 

Ralphie...I believe those units use a cable to transmit engine rpm info to valve body.....not vacum modulator.

first check to make sure the TV cable is attached in the valve body inside the AOD...does the shift time change when you adjust it?? If so..then this isnt the problem...

use the following guidline for adjusting your TV...

(copied from http://www.becontrols.com/tech/tvlinkage.htm)
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NOTHING can ruin an AOD transmission as quickly as improper TV settings. If you are unclear or uncomfortable with the procedure do not attempt this adjustment yourself. This information is meant to supplement, not replace, information that can be found in Ford service manuals for adjusting the TV pressure. Always follow general shop safety rules (never go under a car supported by a jack alone, always chock the wheels, etc.) when perfoming automotive work.

Without a Gauge

If you don't have a gauge, or you are looking for a roughly correct place to start, you can remove the cable from the throttle body lever, and adjust it so that the cable is neither slack, nor under tension when the cable is reinstalled on the throttle body lever. This will get you fairly close. We do not reccomend this for a final setting. You should always use a gauge to verify your TV setting.

With a Gauge

You will need to install your gauge into the TV test port on the transmission. The port is eight inch pipe thread, and is located on the passenger side of the transmission. Toward the back of the transmission, above the pan rail you will find two 7/16" headed pipe plugs side by side. One plug is level with the outer edge of the pan rail, and the other plug is recessed. The recessed plug is the TV test port. Since this port is recessed, you may not see it if you are looking straight up from under the transmission, you will have to try to see over the pan rail.
Remove the TV test plug and install the fitting for your gauge. Attach the line from your gauge to the fitting in the test port. With the engine running the gauge should read 0 to 5 pounds at idle. If you happen to have the special tool for testing TV pressure (installs on the ball end of the cable to pull it a measured amount), the reading on the gauge should be approximately 30 psi with the tool installed. If you don't have the special tool you can tape the gauge to the outside of your windshield with the numbers facing in and have an assistant ride with you to watch the gauge. Normal acceleration from a stop should produce around 30 psi. You also want to make sure that as soon as you start to apply throttle, the gauge reading begins to rise. This is a good indication that there is no slack in the cable. If you would like you can also check the WOT pressure with the gauge mounted this way, it should read around 85 psi.
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if this TV setting is correct....

then this sounds like a transmission govenor problem....remember that the tranny uses BOTH the engine rpm info (TV cable)and the road speed (output shaft speed/govenor) to determine when to shift....

Your govenor pressure sounds like might be incorrect..

First check for damage.......govenor malfunction(shaft inside gov sticking?) or govenor bore wear (in case) or teflon ring damage(on outside govenor body) or govenor gear damage(on end of govenor).

gov shafts can stick...manipulate the weights on the gov..does the shaft move inside the govenor? if so.then move on..

Since the gov rings are teflon..then dont tend to wear out first they tend to make grooves in the govenor bore in the case...stick your finger into govenor bore in the case and feel for grooves worn into the case where the rings seal against the bore....

Is the govenor gear "apple cored"...or in other words worn out?

fix these issues if you find them.....

but if those check out ok....keep reading

The output shaft speed determines how fast the govenor spins....the govenor spins...the weights on the govenor adjust govenor pressure to valve body...telling tranny when to shift...

Since the rear end of your truck is a not a "typical" ford application....your output shaft speed might be spinning faster than the govenor needs to operate correctly. Thus..since the govenor is spinning faster as it should....there is too much centrifical force on the govenor weights....applying to much fluid pressure to valve body....causing it to shift early...

Try and compare rear end ratios if possible from your truck to whatever vehicle the AOD came from....you might need to change the govenor accordingly...

if you are strapped for cash....you can try reducing the govenor weights to see if you can get it to shift later.....the lighter the weights on the govenor..the same centrifical force doesnt act on the reduced weights as much...reducing govenor pressure.....and the later it will shift....this requires you to replace the weights on the govenor with aftermarket ones.

spend the money on aftermarket govenor....its the best way to go...

Grinding them down is a cheap way to do it without buying aftermarket stuff...but make sure you do it equally to both weights...or govenor will be off balance and wear the govenor bore prematurely..........

grind them and weigh them if you go that route....to make sure they are equal


just my two cents...good luck!

 

youre right my fault. oops