need for detail
I believe it is an excellent addition to Winfred's review and puts into perspective the judgement call made by an expert as to what needs to be replaced versus what doesn't when rebuilding one of these transmissions.
George
Kirt Koeller's words:
I have to be honest in the fact I do not know what ZF does when it remanufactures a 4HP22 anymore. I have seen some 4HP22 with the ZF reman sticker and they were still installing the steel rings on the input shaft.
Here is what I do everyday:
Start with a core and do a visual inspection of the converter (gets replaced but might be a cause of a failure so you look at it) and the case itself. Now it gets completly torn down, valve body go to another table for later work. I now put on another table what I am going to replace on EVERY 4HP22 tranny. Starts with a paper and rubber kit (gaskets seals and o-rings) steel kit (which not only has steels but also the pressure plates) friction kit (steel and friction kits will differ between differant applications of the unit) and a solinoid kit (if electronic) and speed sensor. I get the case clean and dry and take a straight edge to check the case for warpage at the vavle body mating surface. Then I start with the pump, some need new pumps some don't judgement call here. All the rubber is replaced and a new bushing is installed most of the time another judgement call but most of the time it gets replaced (with a 4HP24 bushing it works better) Then I clean all the hard parts that are not clutch drums and use my judgement if I can reuse it or need new example is the planetary I usally reuse this as I never see them go bad unless they are in a Rover application. Look at all of the needle bearings sometimes they are fine and some need to be replaced. Then I move on to the clutch pack drums. This is where I take extra care making sure the drums themselves are in really good shape or I will get another one no real room for errors here. Replace all the frictions and steels and replace the pistons o-rings. Once all the drums are done you move on to the valve body at another bench. Same procedure here as with the tranny. Visual look, tear down, clean, inspect and reassemble put new solinoids on and a new speed sensor. Now you are ready to reassemble the whole unit. When done put reman converter in it and dyno it and send her to her new home. As you are aware there is a lot of grey area on what hard parts need to be replaced and that is where you seperate the men from the boys so-to-speak. I have been doing this for a while now and I have seen other peoples work from mom and pop places to the big reman places and seen good and bad from both. There is no real industry standard when it comes to what does make a reman unit vs. a rebuilt unit Too many grey areas to make a clear cut call on that. Remember that this is in no way a complete idea on what I do to every unit somethings are just to time consuming to go into and some are just my trade secrets I'd share them but you know I'd have to kill ya!(j/k) I know that what ever I do the tranny has to last for years to come so that is always in the back of my mind and I look at it as if it was my personal tranny. Kinda corny but thats how I feel. I will tell you this if a rebuild shop (or reman factory) tells you they replace everything with new they are lying through there teeth. I priced it on a 4hp22 with ALL new parts and it was a price that not many could afford (I belive it was 8 or 9K).