You obviously have more experience with mopar transmissions than I do. Problem; I rebuilt my transmission, along the same lines as many on the web A 727 that sits behind a 400 big block in a 71 plymouth duster. I have NO passing or kickdown gear. I can hand shift and 1st through 3rd are there with no slippage. I adjusted the throttle with the kickdown lever so when carb is wide open trans lever is fully depressed back. NO passing gear or kickdown. Also trans shifts through gears really fast, shifts from first to third by 35 mph. I have pulled the tail shaft and checked and cleaned the govenor, also dropped the transmission pan and pulled the valve body taking it completely apart noting where the ball bearings go. Still the same... One question, this valve body is out of a RV transmission, would that matter? HELP!!!
No downshift, no matter the adjustment...
- Thread starter Lenny459
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Wietse
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The shifting points are a balancing act between throttle pressure (engine load) and the governor pressure (road speed).
To know exactly what you are doing you need to use a test gauge with microbore hose and hook it up on the individual test points on the transmission and record them to know what is going on and how to fix it.
I am busy with the exact same issues you are having, and without knowing actual pressures you are flying blind.
Not down shifting can be caused by governor pressure not returning to "0" when stopping the car or incorrect throttle pressure settings.
Governor pressure can be mapped easily with a test gauge connected and drive the car at 5mph speed intervals and record the pressure.
The pressure should be close to the road speed (mph) in PSI, so at 10 mph it should read about 10 psi, 20mph/20 psi, etc (and go to zero when coming to a stand still)
Regarding the valve body, was there anything done on this? Shift kit or something?
Did you check/set the adjustments of Pressure regulator as per book?
Having the throttle pressure at max at WOT is a little misunderstood, since both linkages (carb linkage & bell housing linkage) the initial starting point of throttle pressure can be altered.
Throttle pressure should start to increase as soon as you move the pedal, if the throttle pressure increase only starts to kick in at i.e. 15% it transmission will shift earlier than it should.
Again, a pressure gauge is a must to find and correct this.
You can try first to see if things improve by lengthen the bell housing linkage, and shorten the throttle linkage after to maintain that max Throttle pressure vs WOT position.
To know exactly what you are doing you need to use a test gauge with microbore hose and hook it up on the individual test points on the transmission and record them to know what is going on and how to fix it.
I am busy with the exact same issues you are having, and without knowing actual pressures you are flying blind.
Not down shifting can be caused by governor pressure not returning to "0" when stopping the car or incorrect throttle pressure settings.
Governor pressure can be mapped easily with a test gauge connected and drive the car at 5mph speed intervals and record the pressure.
The pressure should be close to the road speed (mph) in PSI, so at 10 mph it should read about 10 psi, 20mph/20 psi, etc (and go to zero when coming to a stand still)
Regarding the valve body, was there anything done on this? Shift kit or something?
Did you check/set the adjustments of Pressure regulator as per book?
Having the throttle pressure at max at WOT is a little misunderstood, since both linkages (carb linkage & bell housing linkage) the initial starting point of throttle pressure can be altered.
Throttle pressure should start to increase as soon as you move the pedal, if the throttle pressure increase only starts to kick in at i.e. 15% it transmission will shift earlier than it should.
Again, a pressure gauge is a must to find and correct this.
You can try first to see if things improve by lengthen the bell housing linkage, and shorten the throttle linkage after to maintain that max Throttle pressure vs WOT position.
mopar 3 B
Well-Known Member
Well that is just not enough information. What year of trans and what year of valve body? You have to watch it when mix matching parts.
With the clutch drums on the back of the pump before installation as well as after installation did you perform the air checks to ensure clutch packs engage with no leaks, as well as checking for proper function of L/R and kickdown servos? How many turns was the kickdown band adjuster backed out after proper tightening?
Demonic
Well-Known Member
I use big 4" face liquid filled gauges, 0-300 psig and 1/8" braided hose for pressure tests. Alternately, 1/4" AC gauge manifold hose is rated for higher pressures lately. Spend a little on good gauges.
Wietse
Well-Known Member
The below type hose is what I am using, a little over-rated at 400 Bar but the good part is the port adapters come with integrated check valve.
So you simply replace the 1/8" NPT plug with those and you only have to swap the hose over without removing/installing fittings and plugs.
When you are happy with everything just reinstall the plugs.
So you simply replace the 1/8" NPT plug with those and you only have to swap the hose over without removing/installing fittings and plugs.
When you are happy with everything just reinstall the plugs.
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If you have access to a stock, unmodified valve body, stick it in and see what happens. I have done this a few times with success. Make sure you have a spring pulling kick down lever ahead to full rest.
I just got one and cleaned it. It has 7 ball bearings including one on the other side of the divider plate and none in the bottom corner of the valve body where typically is a spring with a larger ball bearing on it. I was wondering if the valve body was different in some way. There is no shift kit that I know of in it. It's an easy fix if that is it. Also I have a few divider plates and noticed as I placed them on top of each other that there are some differences in some of the ports.
I did test the servo's with air and clutch packs and all was good. Bands were set at 72 IP with 2 turns counter clockwise. Funny I built one before with no problems other than trying to get the lokar cable adjusted just right.
Wietse
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This one is requested to be removed by several shift kits, in that case the divider plate is also not original and there should be no hole in the plate where this spring loaded ball sits.
Could be long search to find out if there is a mix of different valve body's combined with shift kit modifications.
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Sounds like this is starting to go sideways. There have definitely been different designs of valve bodies, separator plates, and lower channel plates over the years for different applications. Mix them up, and you are just asking for trouble.
Wietse
Well-Known Member
Same as me, a late '66 valve body in a '69 727 which had a B&M kit installed and I added the Transgo TF-2 kit without knowing all the aforementioned things.
Check upper and lower castings of valve body for part numbers and do a search of what year they are, find a clear picture of a stock separator plate for your cars year and compare it with what you have on hands.
If you get those 3 items to be correct (for any year) you got something to work with as you now know what you got.
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See post #9
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