5R55E shutter in D (1st) after warm up

[MPVQAE]

99 Ford Explorer XLT 4.0 SOHC
After a lot of reading, I rebuilt my very first 5R55E. (Steels, clutches, torque converter, oil pump, OD and Intermediate servos, rebuilt valve body with trans-go shift kit, bands, O-rings, gaskets, etc.) I also know that we hate long descriptive posts. But, I don't know any other way to describe this crazy problem.
Starting up cold, place in R, back out, place in D, pullout is strong and shifts great, although the shift from 3rd to 4th seems a little short to me (I think it could hold 3rd a little longer.) But, that's not the main reason for the post. During the first 15 minutes or so, you can stop along your journey, place in Park, or Reverse, or N, and then return to Drive, pull out strong again, shifts great, no problems. Problem is, after about 15-20 minutes of driving, if you stop, remove the shifter from Drive, move to P, R or N, then return to Drive... it shutters (like it is not fully re-engaging 1st gear). Trying a few different shift scenarios, I have found the following sequence will prevent the shutter. As mentioned, after it warms up and you remove the shifter from Drive, shift to P, R, or N, then return to Drive, it will absolutely NOT shutter if you drop the shifter down below D to 2nd, or 1st (either one), then back to Drive. You can then pull out and she is perfect! As long as you stay in Drive, all is well. It's only after it warms up will it struggle with re-engaging 1st gear after being removed from Drive. But just touching 2nd or 1st on the shifter, then moving the shifter to Drive...all is well. I am wondering if there is an issue associated with the low/reverse servo. I did change the O-rings during the rebuild. Reverse seems OK and does not fell like it's slipping, although it feels a bit harsh to me going into Reverse. Could I possibly have a slight leak in the VB gasket from when I installed it? Maybe only leaks enough when the fluid is hot and thinner? I just know that being able to touch the shifter to 2nd or 1st before moving to Drive, seemingly making things work, has me a bit confused. I do have fairly high confidence in the TC and Pump. There is no shutter in either manual 1st or 2nd. I don't have a pressure gauge, but suspect that may be the next stop on this 5R55E rebuild journey, unless someone reads this and goes, "Yes, I've seen this before and know what's causing it". Or, I may just print a new user's manual for my old Explorer. Sorry for the long post.

 

[transman304]

Classic symptoms of a failing OD sprag. Most times you will loose reverse also. Sounds as if yours is still able to work in reverse but after warm up the expansion of sprag and race will loose the clearance that is required to make it function. Did you replace the sprag in overhaul? Will transmission obtain all gears once moving?

 

[MPVQAE]

I appreciate the response. I did not install a new sprag. But, I did replace my sprag and front planetary gear assembly, with inner sprag clutch race, with another unit which looked good, although I did not check clearances. Mine appeared a bit worn and 1 of the 3 planetary gears was tight. The replacement seemed to catch in one direction and release for spin in the opposite direction. The contact surface on the race looked good, with no marks and etc and the sprag and planetary were mates. The swap also included the needle bearing, sun gear, and coast clutch adapter. Maybe I should have replaced it all with new ones, but the parts I installed seemed good. The transmission has all the gears and shifts good, although the shift from 3rd to 4th seems a little quick to me and Reverse seems a little too harsh. I think it should hold 3rd a little longer and Reverse should be a little softer, but I may just be paranoid. But, all gears work. Even when it’s hot after driving for a long time, it won’t slip or shutter in stop and go traffic, until you take it out of Drive and then attempt to return to Drive. But as mentioned, just shift down past Drive, return to Drive, hit the gas and all is good and shifting great. You can full throttle from a start with no slip. We pulled a jet ski with it this weekend with no trouble. If you follow the new shifting rules, she works great. It really has me baffled. Of course being my first transmission build attempt, this would be my luck.

 

[MPVQAE]

I appreciate the response. I did not install a new sprag. But, I did replace my sprag and front planetary gear assembly, with inner sprag clutch race, with another unit which looked good, although I did not check clearances. Mine appeared a bit worn and 1 of the 3 planetary gears was tight. The replacement seemed to catch in one direction and release for spin in the opposite direction. The contact surface on the race looked good, with no marks and etc and the sprag and planetary were mates. The swap also included the needle bearing, sun gear, and coast clutch adapter. Maybe I should have replaced it all with new ones, but the parts I installed seemed good. The transmission has all the gears and shifts good, although the shift from 3rd to 4th seems a little quick to me and Reverse seems a little too harsh. I think it should hold 3rd a little longer and Reverse should be a little softer, but I may just be paranoid. But, all gears work. Even when it’s hot after driving for a long time, it won’t slip or shutter in stop and go traffic, until you take it out of Drive and then attempt to return to Drive. But as mentioned, just shift down past Drive, return to Drive, hit the gas and all is good and shifting great. You can full throttle from a start with no slip. We pulled a jet ski with it this weekend with no trouble. If you follow the new shifting rules, she works great. It really has me baffled. Of course being my first transmission build attempt, this would be my luck.

Just an update...as described above, I elected to just drive it “as is” and use the vehicle. Two weeks ago, (about 15 months of service) it lost all gears, except 1st. I spent a little more money and ordered a correctly rebuilt valve body. After the install, ALL issues, including the above described problem (having to shift down to 2nd, then move to Drive after the transmission was warm) has been resolved. At this point, this transmission seems to be top notch perfect! I wanted to share this news because you will find a lot of valve body rebuild sources when repairing, or rebuilding, your 5R55E. I will not promote a source in this post. But, I will share some good advice which applies to a lot of things in life. When searching for a rebuilt valve body, remember....when you are expecting to get an updated valve body with all the known shift upgrades and improvements, “You will never get more than you pay for!” In the long run, it’s best to buy from proven quality sources. Hope everyone had a great Thanksgiving!