Welp, it all started 2 weeks ago when 3rd and 4th went out in my 98 with 4R70W. Did my research and called around to a few mechanics smarter than me and all said theyd recommend a rebuild. So me being the guy i am i decided id do the rebuild myself, and i did. Got the tranny back up in the truck today and what do you know, nothing changed. All the clutch packs where intact and no major damage. So the only thing i can think of is TC or something electrical, but i have no codes. Any insight will be appreciated.

 

If it were the TC, how would the TC know that the trans is in 3rd or 4th? How would it know to fix itself when the trans was in 1st or 2nd?

It could be a bad solenoid, a stuck valve, or a wiring problem to the solenoid. Are there any codes stored in the PCM?

 

No i dont have a code, im not really 100 percent on how a TC works. When i rebuild the trans i rebuild the valve body to. New seals and springs. it seems this is a common problem with many different sources of the problem.

 

Let me get a little more in depth about what the truck is doing to help paint a better picture.

Personally i think my TC is worn out. When i put my truck from P to R there is a delay. When i go from P to D there is a delay, and then it catches much like how it feels when you dump the clutch in a manual. When im first and i get on the gas there is very little power. My engine is operating at 100 percent. (Im much better with engines)

When i test drove the truck last night it went into 3rd twice, but would quickly fell out of 3rd, so i know the trans is trying to engage it but it seems like there isnt enough pressure in the TC to stay in 3rd. Like the clutch in the TC isnt wanting to catch? IDK

The shift from 1st to 2nd is extremely smooth, like a brand new truck.

I did the tranny rebuild 100 percent by the book, all measurements are within spec and everything is installed correctly. I took my time and spent 2 days doing it.

Anyway, i know i quite possibly could be wrong about the TC but hey im trying lol.

 

I see that you rebuilt the valve body and replaced the accumulator springs. I believe these are the principal mechanical components you rely on when shifting through the gears. Because you have issues going from Park to drive and reverse I would lean towards the transmission shift solenoids going out. I seem to remember there were solenoids specific to the shift, however I must defer to someone more knowledgeable to confirm this. I do think there is a test procedure for the shift solenoid. Hopefully someone will chime in and point you in the right direction.

 

Have you pulled any codes? Specifically PO570, PO755?

P0750* SSA SSA solenoid circuit failure SSA circuit failed to provide voltage drop across solenoid. Circuit open or shorted or PCM driver failure during on-board diagnostic. Improper gear selection depending on condition mode and manual lever position. See Solenoid On/Off chart.
P0755* SSB, wiring, PCM SSB solenoid circuit failure SSB circuit fails to provide voltage drop across solenoid. Circuit open or shorted or PCM driver failure during on-board diagnostic. Improper gear selection depending on condition mode and manual lever position. See Solenoid On/Off chart.


Read more: i rebuilt a 4r70w transmission replaced shift solenoids and - JustAnswer http://www.justanswer.com/ford/3a3so...#ixzz23jelU6HJ

 

The torque converter is not involved with shifting. You can eliminate that right now.

Since no shift solenoid is used shifting from park to drive or park to reverse, you can rule those out, too. The drive and reverse engagements have hydraulic pressure supplied by the manual valve, which is mechanically connected to the shift cable.

If either of those codes are present it could be causing the 2-3 shift problem. But not the reverse or drive engagement problem. That's usually bad seals or a weak pump.

 

Did you pull the pump apart and make sure the gear is not broke, and solenoids are not that expensive, replace the two shift solenoids and the torque converter lockup solenoid.

 

Ok I have no codes for this transmission so stop asking. Yes I did take the pump apart and replace the seals and yes the gears were in perfect condition. At this point I'm just about to start replacing one thing at a time till its fixed

 

I am not trying to beat it to death, but standard OBD2 code readers can't read Ford transmission codes. You need a higher end scanner. If you have scanned with one that's capable, please ignore this post.

 

I think that is all you are able to do.

 

how did you measure clearances in the pump?

 

I don't mean to sound rude, and in fact I come to this thread because need to learn about automatic transmissions myself. I see some pretty smart people in this thread and I would love to be able to pick their brains. I have a thread about a transmission problem I am having. What I am going to say is not to be mean, but to point out that I have made mistakes and I am a very smart electrical engineer. I say that when you have a transmission apart you may want to double check your work where tolerances come into play. It is just a suggestion. You say shifting from a stop is causing your problems and I think some smart guys here have attempted to rule out what it ain't.


One good thing that I am learning here is that I may delve into my own automatic transmission for the first time in my life to save myself lots of money. I believe I just have to replace a second gear shift solenoid and my world will be a happier place. I have been shifting manually into second gear for about 4 years.

 

With a depth gauge and a micrometer. Measure the depth of the pump pocket. Measure the thickness of the rotor. Subtract the thickness of the rotor from the depth of the pocket.