6R75 Replacement

And Ford makes it hard to change oil plus says not to even do it...………..

So today I was thinking over, anyone with experience care to hypothesize what fails in general on 6R converters? Reason I ask is originally I figured the lockup clutch material was worn out....but the fluid was bright red and there was nothing in the pan. Does the piston that engages the lockup clutch on the converter sometimes fail or seize and not engage the clutch to the housing? I guess it’s possible the fluid was pre changed when I bought the truck too but you’d think you’d still get dirty fluid over miles.

I still have the old converter, do you folks think I should open her up to check out what failed since we are all sitting at home bored during this time lol? Might be an interesting saga to see what happened since we know this is a relatively documented occurrence on the 6R75 and even documented on earlier 6R80s in the F-150s.

I’ll also add I did the last hour doing some serious digging, that original converter that came out of my 6R75 is part#7902 but with the first 4 digits of the part number differing from my new one. A search in my Ford dealers parts database for old one comes up with ‘Obselete’. When I plug in my VIN searching the Torque Converter for my truck it comes up as #7902 again in the database which checks out as that’s the new one I installed and the pictures available match the new converter. The starkly different part numbers peaked my curiosity even though physically they were similar. It seems the original converter was made obselete and replaced some time ago. I can find these older #7902 units rebuilt but they were mainly found in the 6R60 behind the 4.6L.....a search for a 2011 Expedition also yields the same #7902 in the database but at different MSRP.

Therefore my hypothesis is the original converter in the 6R sometimes proved to be too problematic when put behind the larger 5.4L, so Ford came out with the 6R80 and superseded the converter compatibility for the 6R75 to the new style converter by keeping it the same physical dimensions and flex plate pattern as the 6R75....solving the issues for both the 6R75’s coming in for work and for future 6R80 products. Maybe.

Those things are usually a mystery and I'm just glad they update things to make them better. It's usually best to just go with the latest part #.

I find this stuff so cool lol

JExpedition07 said:

I find this stuff so cool lol

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Years ago you could just unbolt them to open, and we used to rebuild them. Now some have clutches in there but none did before.

I wonder if 5 star tuning addresses the factory shift and lockup strategy. I’ve scanned a lot of complaints about this on the F-150 forums. I borrowed my dads 2016 F-250 with the 6R100 when I was doing the work to the Expedition and noticed the F-250’s initial lockup of the converter in the morning is very soft (program holds lockup until engine warms a bit). This means they are allowing the clutch to slip some as part of the program so the driver doesn’t detect the lockup without looking at the tach. It essentially is to make a more “seamless” shift.

Now that my 6R75 is all fixed up I have taken notice that the factory program is the same as the F-Series on the Expedition! That initial lockup when cold is pretty soft and you have to be looking at the tach or have fine tuned feel to notice.

No doubt this softer lockup programming must produce some wear on the lockup clutch friction rings over miles on these 6R transmissions. Perhaps though there is some purpose behind it that I overlook as well. The questing is did Ford do it for comfort or utility? I’m betting comfort but I’m going to leave it alone.

JExpedition07 said:

I wonder if 5 star tuning addresses the factory shift and lockup strategy. I’ve scanned a lot of complaints about this on the F-150 forums. I borrowed my dads 2016 F-250 with the 6R100 when I was doing the work to the Expedition and noticed the F-250’s initial lockup of the converter in the morning is very soft (program holds lockup until engine reaches operating temp). This means they are allowing the clutch to slip some as part of the program so the driver doesn’t detect the lockup without looking at the tach. It essentially is to make a more “seamless” shift.

Now that my 6R75 is all fixed up I have taken notice that the factory program is the same as the F-Series on the Expedition! That initial lockup when the engine makes temp is pretty soft and you have to be looking at the tach or have fine tuned feel to notice.

No doubt this softer lockup programming must produce some wear on the lockup clutch friction rings over miles on these 6R transmissions. Perhaps though there is some purpose behind it that I overlook as well. The questing is did Ford do it for comfort or utility? I’m betting comfort but I’m going to leave it alone.

Click to expand...

Probably comfort, transmissions get softer shifting as time goes on. The 4 speed hydramatic of yesteryear raised the car every time it shifted due to the trailing arms connected to the rear end. Probably one reason the cvt trans got popular. (Like in my snowmobile).

Just thought I’d update: 6R75 Transmission has been flawless for the last two months since the reman converter install and fluid/filter change. If you lose lockup you don’t have to be in for a whole rebuild....mine did not have any burned fluid or metal inside. It seems that the piston inside the converter that locked the clutch seized.

JExpedition07 said:

Just thought I’d update: 6R75 Transmission has been flawless for the last two months since the reman converter install and fluid/filter change. If you lose lockup you don’t have to be in for a whole rebuild....mine did not have any burned fluid or metal inside. It seems that the piston inside the converter that locked the clutch seized.

Click to expand...

Some welcome good news after the rough spell of luck you had.