Trans Question

[ramsrt711]

Cross the 1/8 in 2nd and the 1/4 in 3rd. :burnout:
I tried the 390s and the 325s and they did hook great, but screwed shift points all up.
THe shift points are computer controlled and NOT based on the valve body itself but the transducer, OD lockup and Pressure solonoid based on preprogrammed shift points by TPS and MPH and RPM. Valve bodies and shift kits will only adjust firmness between gear shifts and hold the gear a lil longer under normal driving.

Maybe if I can extend 1st gear then it wont top out in second to quickly. That would only be a temp fix for the 8th.If I ever ran the 1/4 (none near by) It would not shift right 2nd to 3rd without letting off gas.Maybe I should go back to new factory solenoid. Before I went with conversion solenoid I was having the 1-2-1-2 problem.

 

[VENOMOUS1 RACING]

Ok but I don't care what you do to the valve body, the computer sees an incorrect speed due to the way shorter diameter of 390s and 325s. Put the Stock tires on and it'll shift gears correctly. The short tires or gear changes without corresponding changes to the PCM will yield improper WOT shifting. A hair taller tire than stock would make it shift at 56-5800 instead of 6.... And so on.

 

[JTS VENOM PERFORMANCE]

then install a stifer spring in the valve body and see if you do not over rev the engine and hit the rev limiter, done this too many times, I do know a few things from 40 years of turning wrenches, the pcm does control the tranny , but alot of things are taking into the shift points also, this is why I do not explain things any more, too many folks think they know too much

 

[VENOMOUS1 RACING]

then install a stifer spring in the valve body and see if you do not over rev the engine and hit the rev limiter, done this too many times, I do know a few things from 40 years of turning wrenches, the pcm does control the tranny , but alot of things are taking into the shift points also, this is why I do not explain things any more, too many folks think they know too much

Easy there big guy! I am simply stating from my many years turning wrenches as well. How many times would you be pulling the tranny pan and valve body
And swapping the Accumulator Springs to get it to shift at an exact rpm? Then if you wantto run street tires, well its not gonna shift right again ifyou set all thru this spring to the slicks. Manual valve body where you control the shift points. I interested in learning more about what you know about this tranny and how it knows when to shift under WOT conditions. These aren't the Turbo350/400s or 727 of yesteryear. Whole new breed. Hence my 6 gear swap!
I will be in control.
As far as these trannys, besides the ever going shift issues due to the elec. Parts in tranny,they were never built/designed to hold up to the internal rpms that a 6krpm motor puts out. The HP and Torque are fine. They were built for a diesel that spins 3500rpm!

 

[ramsrt711]

I put stock wheels and computer back on and it still does it so my guess it comes down to the conversion solenoid that caused it and I was just trying to see what else needed to be adjusted or changed to match the higher pressure from the solenoid. Thanks Guys I do see alot of useful info here.

 

[VENOMOUS1 RACING]

Just a thought, but are your stock wheels running the factory 305/40-22 tires. Any variance in tire size will not let the tranny shift at the right time under WOT. Front tire soze may affect this as well? Are you running 17s or anything up front? Anything other than stock?

You need to also verify your VSS( speed sensor) is reporting to the PCM correctly by using a GPS of some sort ( phone app, TOM-TOM, Garmin,etc) that will report your correct MPH and compare this to what the PCM is seeing! A few MPH off will do the same thing.

Personally at the track I experienced the 390s not letting me shift from 2nd to 3rd without barely letting outta the gas, then throwing the stockers on and shifting fine within about 20 min of each run. I later did the same thing on the smaller 325s and the same problem. Put the stockers back on and no issue. It's very obvious the difference in tire diameter.

Also, in your tune ( if tuned) if your rev limit is set to 5900 and your shift setting is 5950-6050(example) then you will hit the rev limit before you can shift and have to let off TPS to get the shift to occur. The opposite is if a tuner adjust the rev limit but not the trans shift points, then you won't reach your engine rev limit before the shift. It will shift too early. Now this is from Ford and GM tuning and from talking with a few Dodge tuners, the DCM computers are very similar. Soooo..............if you are tuned, have your tuner bring your shift RPM for 2-3 shift down a few hundred RPM so you can make the shift. I believe the negative effect will be when you put the stocker tires back on, then at WOT it may shift way too early.
Just my .02
Scott

EDIT: John Hennessy engine controller????? Do you have access into the PCM and can you adjust parameters yourself?

 

[ramsrt711]

Yes I have stock 22" wheels in front and have raced that way. I wish I knew how to change shift points on the computer. I know what ya think of the JH controller and I bought it before I ever knew of this forum. It was actually an improvement considering it was the first upgrade I did. Now I know where to find the best vendors.

 

[ramsrt711]

Just a thought, but are your stock wheels running the factory 305/40-22 tires. Any variance in tire size will not let the tranny shift at the right time under WOT. Front tire soze may affect this as well? Are you running 17s or anything up front? Anything other than stock?

You need to also verify your VSS( speed sensor) is reporting to the PCM correctly by using a GPS of some sort ( phone app, TOM-TOM, Garmin,etc) that will report your correct MPH and compare this to what the PCM is seeing! A few MPH off will do the same thing.

Personally at the track I experienced the 390s not letting me shift from 2nd to 3rd without barely letting outta the gas, then throwing the stockers on and shifting fine within about 20 min of each run. I later did the same thing on the smaller 325s and the same problem. Put the stockers back on and no issue. It's very obvious the difference in tire diameter.

Also, in your tune ( if tuned) if your rev limit is set to 5900 and your shift setting is 5950-6050(example) then you will hit the rev limit before you can shift and have to let off TPS to get the shift to occur. The opposite is if a tuner adjust the rev limit but not the trans shift points, then you won't reach your engine rev limit before the shift. It will shift too early. Now this is from Ford and GM tuning and from talking with a few Dodge tuners, the DCM computers are very similar. Soooo..............if you are tuned, have your tuner bring your shift RPM for 2-3 shift down a few hundred RPM so you can make the shift. I believe the negative effect will be when you put the stocker tires back on, then at WOT it may shift way too early.
Just my .02
Scott

EDIT: John Hennessy engine controller????? Do you have access into the PCM and can you adjust parameters yourself?

Your experience at the track sounds exactly what Im talking about except when I put stock 22" wheels back on it still does it. I do not have a tune or never dynoed. I can't find anything in west texas. I know I need to get it tuned. Anybody know of a place?

 

[ramsrt711]

The more I think about it I never had problems shifting from 2nd to 3rd before the solenoid conversion. I also don't remember hearing anybody else that did the upgrade have any problems. It definitely feels like it has more power with it.

 

[JTS VENOM PERFORMANCE]

the upgrade lets more fluid flow, upping line pressure a small amount, some folks did have probs, that and the fact that more smaller particles can pass thru, now I suggest folks keep the oem solonoid, keep there bands tight an they dont have probs like yours now

 

[WOT]

Tires do not affect the wide open throttle shift rpm. That is completely controlled by the pcm based on engine rpm. However, the pcm actually has to learn the time it takes for the tranny to perform a shift so that it knows when to command the 1-2 and 2-3 upshifts. The PCM doesn't know what speed you are going. It only looks at drive shaft rpm and engine rpm. It doesn't care if you change the rear gear or tire size. It is still going to shift at a given driveshaft rpm at part throttle or a given engine rpm at full throttle. It doesn't even look at the front tires. The ABS controller does, but that is separate from the pcm and has nothing to due with the tranny.

The shorter tires make the engine rpm climb faster and the computer is mis-timing the shift. To prevent getting too close to the rev limiter and having it nose over, you can either raise your rev limit in the program, or have the WOT shift points lowered a couple hundred rpm or so in the program so that there is a bigger spread between the desired WOT shift rpm and the rev limiter. You could also use a dealer scan tool and put the pcm in tranny learn mode so that it will relearn the shift timing.

I have my shift points at 5700 rpm and my rev limiter at 6000 rpm. That way, on cold days when I floor it going down hill, I don't hit the rev limiter before it does the 2-3 shift.

Oh, and by the way, the valve body is completely mechanical for shifts 1, 2, and 3. But the govenor is electronic. The way the tranny commands it to shift is to spike the governor pressure. That makes the mechanical valve body shift. It doesn't have individual electronic shift controls in the valve body. It just tricks the valve body by raising the governor pressure long enough for it to upshift and then holding the governor pressure to a certain level so that it doesn't down shift again or upshift 2 gears in a row. But the computer doesn't reallly know what gear the tranny is in. It learns by looking at the rpm change when it shifts. But, if it screws up, it doesn't correct and try to shift again. It just keeps going until the valve body reacts to the next event. That's why we have the 1-2-1-2 shuttle shift: the pcm doesn't know (and doesn't care) that the tranny is doing it.

The TV cable adds detent pressure that acts against the govenor pressure. The combination of these two pressures is what determines when the valve body will shift. The computer usually just lets the valve body figure out when it wants to do the part throttle shifts. That's why adjusting the TV cable will change part throttle shifts. If the engine starts to climb to too high of an rpm during part throttle, it will then spike the governor pressure, but that's only after it revs up pretty high. Normally, it waits for the valve body to make the decision mechanically. If you press the throttle far enough so that the the throttle position sensor (TPS) registers more than 2.84 volts, it signals the computer that you are in WOT mode and it holds the goveror pressure low so that the TV cable's detent pressure wins and the tranny doesn't shift. It waits until the rpm gets close to the WOT shift point and then spikes the governor pressure a learned number of seconds before that point so that it shifts at the correct WOT rpm. It only has one setting that is used for both the 1-2, and 2-3 shifts. So you cant have your 1-2 shift at 5200 rpm and your 2-3 at 6000 rpm. It tries to shift them both at the same rpm, but sometimes it is off a little.

 

[ramsrt711]

Tires do not affect the wide open throttle shift rpm. That is completely controlled by the pcm based on engine rpm. However, the pcm actually has to learn the time it takes for the tranny to perform a shift so that it knows when to command the 1-2 and 2-3 upshifts. The PCM doesn't know what speed you are going. It only looks at drive shaft rpm and engine rpm. It doesn't care if you change the rear gear or tire size. It is still going to shift at a given driveshaft rpm at part throttle or a given engine rpm at full throttle. It doesn't even look at the front tires. The ABS controller does, but that is separate from the pcm and has nothing to due with the tranny.

The shorter tires make the engine rpm climb faster and the computer is mis-timing the shift. To prevent getting too close to the rev limiter and having it nose over, you can either raise your rev limit in the program, or have the WOT shift points lowered a couple hundred rpm or so in the program so that there is a bigger spread between the desired WOT shift rpm and the rev limiter. You could also use a dealer scan tool and put the pcm in tranny learn mode so that it will relearn the shift timing.

I have my shift points at 5700 rpm and my rev limiter at 6000 rpm. That way, on cold days when I floor it going down hill, I don't hit the rev limiter before it does the 2-3 shift.

Oh, and by the way, the valve body is completely mechanical for shifts 1, 2, and 3. But the govenor is electronic. The way the tranny commands it to shift is to spike the governor pressure. That makes the mechanical valve body shift. It doesn't have individual electronic shift controls in the valve body. It just tricks the valve body by raising the governor pressure long enough for it to upshift and then holding the governor pressure to a certain level so that it doesn't down shift again or upshift 2 gears in a row. But the computer doesn't reallly know what gear the tranny is in. It learns by looking at the rpm change when it shifts. But, if it screws up, it doesn't correct and try to shift again. It just keeps going until the valve body reacts to the next event. That's why we have the 1-2-1-2 shuttle shift: the pcm doesn't know (and doesn't care) that the tranny is doing it.

The TV cable adds detent pressure that acts against the govenor pressure. The combination of these two pressures is what determines when the valve body will shift. The computer usually just lets the valve body figure out when it wants to do the part throttle shifts. That's why adjusting the TV cable will change part throttle shifts. If the engine starts to climb to too high of an rpm during part throttle, it will then spike the governor pressure, but that's only after it revs up pretty high. Normally, it waits for the valve body to make the decision mechanically. If you press the throttle far enough so that the the throttle position sensor (TPS) registers more than 2.84 volts, it signals the computer that you are in WOT mode and it holds the goveror pressure low so that the TV cable's detent pressure wins and the tranny doesn't shift. It waits until the rpm gets close to the WOT shift point and then spikes the governor pressure a learned number of seconds before that point so that it shifts at the correct WOT rpm. It only has one setting that is used for both the 1-2, and 2-3 shifts. So you cant have your 1-2 shift at 5200 rpm and your 2-3 at 6000 rpm. It tries to shift them both at the same rpm, but sometimes it is off a little.

If you dont mind me asking, What tranny upgrades have you done. Was it a complete rebuild.

 

[WOT]

If you dont mind me asking, What tranny upgrades have you done. Was it a complete rebuild.

Dealer did a rebuild and then I upgraded the valve body myself to one from HTS with different springs in the detent valve, increased line pressure, and drilled out passages for faster shifting. I also did an upgraded 2nd gear accumulator (billet vs. the stock plastic), 2nd gear piston return spring (stiffer), and blocked out the 2nd gear piston damper with a thicker washer. I also installed a drain plug in the pan (best mod yet, lol).

 

[ramsrt711]

Dealer did a rebuild and then I upgraded the valve body to one from HTS with different springs in the detent valve, increased line pressure, and drilled out passages for faster shifting. I also did an upgraded 2nd gear accumulator (billet vs. the stock plastic), 2nd gear piston return spring (stiffer), and blocked out the 2nd gear piston damper with a thicker washer. I also installed a drain plug in the pan (best mod yet, lol).

Have you ever drag raced your truck. What was the cost of the upgraded parts.

 

[WOT]

Have you ever drag raced your truck. What was the cost of the upgraded parts.

I haven't drag raced my truck at a track yet, but I have done many 'unofficial' runs against my various buddies.

The rebuild was done under warranty, and the parts from HTS were around $500-$600. I put them in myself. They can be done without removing the tranny. If you have the tranny out, you can do more upgrades. I wish the dealer would have let me give them the parts I wanted to put in, but that wasn't an option.

So, if my tranny blows, I'll rebuild it with all heavy duty parts. But really, they are pretty stout pieces if they are built right, even with mostly stock parts. If you are going to make over 700hp, you probably will want more upgrades than what I have done.

 

[ramsrt711]

Ok when I added the GM solenoid I had a trans shop do it. All along I was blaming the solenoid. They changed trans filter and fluid and adjusted my bands. I had a feeling that the bands were not adjusted right and did not want to give in to the idea that trans was going bad. I have never adjusted bands before but thought would be hard. It was very easy and trans shifts right again with stock ECU. World of difference. You would think a trans shop can adjust bands. It shifted around 5500. I put JH ECU back in and shifting flawless around 5700. I cant wait for the track to open back up. My best was 8.6 with shifting problems. I think I can beat that now.

 

[ramsrt711]

I can not stress the importance of getting the bands adjusted right. I will not leave it up to a shop anymore. I will be adjusting them myself so I will not have to second guess If they are done right.

 

[JTS VENOM PERFORMANCE]

I can not stress the importance of getting the bands adjusted right. I will not leave it up to a shop anymore. I will be adjusting them myself so I will not have to second guess If they are done right.

thats best, I have found most shops do not know how to adjsut them properly, its not that hard to do , plus most will actually learn more on there trucks

 

[bigredv10]

Congrats! Glad you got this figured out finally. I'm guessing 8.2 next time :burnout:

 

[JTS VENOM PERFORMANCE]

Congrats! Glad you got this figured out finally. I'm guessing 8.2 next time :burnout:

HUSH YOUR MOUTH!!!!!!!! he best be doing 7.9's:aetsch::aetsch: