00bigred

Good day all!!!

Here is a break down of my break down... I got this as a deal knowing it had transmission issues... I have rebuilt a few 4R70W's up to 450HP specs so not much of this is new to me... There is one thing that I have not been able to figure out......... WHY does the OD servo retaining ring break?! I've searched on here for hours and have found countless repairs on the ring, but none (that I read) included WHY the ring breaks... From what I know, it looks as if the return spring is too much for the servo when it releases... When I rebuild this, I will probably put a softer return spring in there... So, on with the good stuff!!! Oh, I have the "B" code meaning 4R75W mated to the 5.4L 3V...

The Truck...


When I dropped the pan, I found the fluid very dark and nasty (technical term!)... There was a good amount of metallic debris on the magnet (I cleaned it prior to getting the picture - sorry)... I found part of the OD ring in the drain pan after I removed the Valve Body (VB)... No pieces were found in the VB... I pulled the VB completely apart and everything looked normal... Cleaned and reassembled... The rest is what I found after pulling the trans out and apart... I didn't take pictures as I disassembled the trans cause I wanted to find out what failed internally....... This is what I found....

The ring and OD servo...


The trans assembled without the case and minus the intermediate clutches and pump...


Off comes the reverse drum and Mechanical Diode (MD)...


This is where the OD band goes... Make note of the MD retaining ring... Not sure if this was an oversight during assy or as a result of the issues with the trans... I'm thinking the latter... I pulled the forward drum off for picture purposes...


Here are the marks the rev drum made... The drum is pushed in farther than it would normal sit due to the absence of the forward drum...


Next to come off is the forward drum...


This gear engages the forward clutches to the planetary assy... Both bearings are good...


Next out is the stub shaft... This has been updated over the years and is of the stronger design...


End of part one due to limit of 10 images per message...

00bigred

Part Two...

Next out is the sunshell... You can see both sets of gears are a total mess... The bearing between them is still good... Make a note of the "rub" marks around the sunshell... That is from the debris on the turbine sensor... This sensor picks up the lands and grooves on the forward drum, but does that through the sunshell... If you have the dual sensor case, you have a NON-MAGNETIC sunshell... In other words, a magnet won't stick to the sunshell... Interesting thing I just found out...


This is where this band goes... I'm not sure if you can see the grove it made, but there is a fair sized lip on the drum... There is also metal debris in the friction material of the band... The one way clutch here is good...


Next out is the planetary gear assy... This is a total mess... However, despite all the damage, the gears didn't fail totally... There was very little debris within the gears, so I'm thinking most, if not all the destruction at this point was over... The bearing inside the assy was still good... If this bearing did fail, you would need to replace the entire assy as you can't get that bearing out...


Next out is the direct drum... This is where I found the failed item... The bearing between the direct drum and output shaft assy failed... The only reasons I can think of why this failed is lack of fluid to that area ...OR... it couldn't handle the speed it was turning for extended periods of time...




Damaged area where the bearing was...


This drum must be made of much stronger material than the planetary assy and associated gears... This one chipped tooth is pretty much the only damage I found...


Planetary gear damage...


Sunshell gear damage...


Well, that is about it... I didn't take any clutch packs apart yet... I may find some worn clutches, but initial inspection revealed most were still good...

Have a good one all!!!

Cheers!!

00bigred

Good day again all!!

More history: The truck didn't work all that well when I got it, so I didn't have a good baseline as to what it was doing before... I have been trying to figure this out all weekend and I am just unable to find the reason I'm still having issues...

I got everything replaced and all put back together... I first thought the issue was the 1-2 shift solenoid... But logically that isn't the issue... So, I will put the symptoms out there and see what happens...

Shift into R... No issues
Shift into N... No issues
Shift into D... Slow to take off and "Trans failure" message appears a few seconds later with "O/D" light flashing.
(Reset computer so NO trans fault message) Shift into 2... Slow to take off but no message (this should be normal; taking off from stand still in 2nd gear).
(Reset computer so NO trans fault message) Shift into 1... Initial normal condition, but a second later truck quickly slows to a stop and it's like I have engaged the E-brake... Slight tap on the gas and it "seems like" it wants to move...

If I have the trans failure message, OD hunts to 3rd and back if I take my foot off the gas...

If I start off in 2 and get the truck moving, I can shift into D and all is fine!! No trans failure message... OD works fine with no hunting to 3rd and back...

I made no modifications to the transmission when I put it back together, other than replacing the broken stock parts... New Mercon V... I purchased 15 qts, but only used 11.5...

My thoughts is the FWD Clutch pack is slipping with high torque, but holding otherwise...

Your thoughts!?

Thanks all!!!

Cheers!!

00bigred

Good day all!!

I don't mean to keep bugging everyone about this, but is there a 4R70W expert out there that will let me take up some of his or her time? I can rebuild these all day long, but this issue has me stumped!! The only problem with my trans is first gear (in D or in M1)... Once I get moving, even just a little, even first gear in D works fine... M1 just doesn't work at all... I tried to get it to move in M1 and I think I was slipping one of the bands forcing it to move... I only tried that for maybe a foot as I didn't want to chew up anything...

Thanks for your time!!

Cheers!!