My son and I just finished our first ever transmission rebuild on his 2001 Trooper, and while it went really well and we are quite confident that we did things correctly, we still have some slipping/shudder in 1st gear under load (hill or quick accel), so the band adjustment may not be quite right. I'll summarize as much as possible, but here's the backstory that will explain how we got here:
* He purchased the Trooper in the fall of 2019, and it drove well for a year as a daily driver locally.
* He'd purchased a Casita camper last summer (2500 lbs), and he towed it without any problems on one 200 mile trip last August.
* We went to FL panhandle together last Oct, and he towed the camper while my wife and I took our Class C RV.
* As we arrived at the site in FL he lost 1st gear drive. Next morning it could barely get moving, so we limped it to Miramar Beach and I towed his camper the rest of the trip.
* We drained and changed the fluid, and I researched and discovered the Winter Mode and band adjustment info, but we were only there for 1 night.
* Next day we found that Winter mode was sufficient to get us to Panama City Beach, where we were able to drop the pan, change the filter, and adjust the band. That didn't fix it perfectly, but being gentle with it he was able to get home to TN. (What a trip! But we still had fun in between!)
* After copious research we dove into a rebuild of the trans in March, and finished it up in early April. We took our time to do a thorough and careful job, and we were excited when it drove well after reassembly on a couple local test drives. We were pushing to get it done before a local camping trip, so he was able to tow his camper again... until it wouldn't! Again.
* It towed fine the 3 miles to the expressway, and when we came to stop at the first off ramp (almost exactly 20 miles from home), there was zero 1st gear. I had my strap so I towed him off the ramp and we assessed things and found that Winter mode still worked, so we limped it home and I ended up towing his camper for our trip.
* We have redone the band adjustment again, and we carefully counted rotations to see how much different it would be. It ended up adjusting over 2 full turns tighter the last time. But... it still slips/shudders a little on an uphill grade from a stop, or when punched from a stop. It's still not right.
We've seen disparity in the band adjustment instructions different places, so we've done them a little different each time. In FL I think we did 39 or 40 in-lb tight and 4-1/2 turns back. During the rebuild the manual and most advice we saw said it should be 5 turns back, so that's what we did (which was probably too loose after it warmed up). The last time, we only went 4 turns back. But it's still slipping. We need advice from someone who really knows these 4L30E's: How tight can we adjust this freaking band? Is it possible that we burned up the band in a 20 mile (mostly 4th gear) trip? What else could cause the slipping if the band is adjusted correctly? If we adjust it too tight, how will we know (short of burning it up)?
I know it'll be needed to know, so here's the details of our rebuild: Full rebuild kit with all new clutches, steels, band, gaskets, seals, bushings, etc. The works; Put in Superior K4L30E kit; Sonnax Thrust Washer Kit (54701-03K); Replaced the low band drum (old one was scored as the center of the band had lost it's friction material); Rebuilt torque converter; added an additional aux trans cooler in front of radiator and in series with factory cooler (flushed stock cooler!); new 1-2/3-4, 2-3 and TCC solenoids. New connector housings for both connectors. Cleaned and reconditioned the PRNDL switch. Due to cost and availability we did NOT replace the Bosch force motor or the band apply solenoid. Fluid fill was ACDelco 10-9240 Type III (H).
The last thing I did, after reading the suggestion somewhere here, was to disconnect the two electrical connectors and try it using only the mechanical manual shift. We only went up our fairly steep driveway and a hundred yards on the street, but it had no noticeable effect. Same slipping. We are ready to drop the pan again and tighten the band 1/4 to 1/2 turn and see if that fixes it, but if anyone has any better ideas or tests we can run, as Ross Perot would say: "I'm all ears!" (If you read all the way to this point, Thank-you!!)
* He purchased the Trooper in the fall of 2019, and it drove well for a year as a daily driver locally.
* He'd purchased a Casita camper last summer (2500 lbs), and he towed it without any problems on one 200 mile trip last August.
* We went to FL panhandle together last Oct, and he towed the camper while my wife and I took our Class C RV.
* As we arrived at the site in FL he lost 1st gear drive. Next morning it could barely get moving, so we limped it to Miramar Beach and I towed his camper the rest of the trip.
* We drained and changed the fluid, and I researched and discovered the Winter Mode and band adjustment info, but we were only there for 1 night.
* Next day we found that Winter mode was sufficient to get us to Panama City Beach, where we were able to drop the pan, change the filter, and adjust the band. That didn't fix it perfectly, but being gentle with it he was able to get home to TN. (What a trip! But we still had fun in between!)
* After copious research we dove into a rebuild of the trans in March, and finished it up in early April. We took our time to do a thorough and careful job, and we were excited when it drove well after reassembly on a couple local test drives. We were pushing to get it done before a local camping trip, so he was able to tow his camper again... until it wouldn't! Again.
* It towed fine the 3 miles to the expressway, and when we came to stop at the first off ramp (almost exactly 20 miles from home), there was zero 1st gear. I had my strap so I towed him off the ramp and we assessed things and found that Winter mode still worked, so we limped it home and I ended up towing his camper for our trip.
* We have redone the band adjustment again, and we carefully counted rotations to see how much different it would be. It ended up adjusting over 2 full turns tighter the last time. But... it still slips/shudders a little on an uphill grade from a stop, or when punched from a stop. It's still not right.
We've seen disparity in the band adjustment instructions different places, so we've done them a little different each time. In FL I think we did 39 or 40 in-lb tight and 4-1/2 turns back. During the rebuild the manual and most advice we saw said it should be 5 turns back, so that's what we did (which was probably too loose after it warmed up). The last time, we only went 4 turns back. But it's still slipping. We need advice from someone who really knows these 4L30E's: How tight can we adjust this freaking band? Is it possible that we burned up the band in a 20 mile (mostly 4th gear) trip? What else could cause the slipping if the band is adjusted correctly? If we adjust it too tight, how will we know (short of burning it up)?
I know it'll be needed to know, so here's the details of our rebuild: Full rebuild kit with all new clutches, steels, band, gaskets, seals, bushings, etc. The works; Put in Superior K4L30E kit; Sonnax Thrust Washer Kit (54701-03K); Replaced the low band drum (old one was scored as the center of the band had lost it's friction material); Rebuilt torque converter; added an additional aux trans cooler in front of radiator and in series with factory cooler (flushed stock cooler!); new 1-2/3-4, 2-3 and TCC solenoids. New connector housings for both connectors. Cleaned and reconditioned the PRNDL switch. Due to cost and availability we did NOT replace the Bosch force motor or the band apply solenoid. Fluid fill was ACDelco 10-9240 Type III (H).
The last thing I did, after reading the suggestion somewhere here, was to disconnect the two electrical connectors and try it using only the mechanical manual shift. We only went up our fairly steep driveway and a hundred yards on the street, but it had no noticeable effect. Same slipping. We are ready to drop the pan again and tighten the band 1/4 to 1/2 turn and see if that fixes it, but if anyone has any better ideas or tests we can run, as Ross Perot would say: "I'm all ears!" (If you read all the way to this point, Thank-you!!)