Diagnose My 4R100
#1
04-27-2003, 10:23 AM
Join Date: Nov 2002
Location: Plano, Texas
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Diagnose My 4R100
Yesterday my 4R100 began having issues when shifting from 1 -> 2 and back again.
When accelerating, the transmission will not shift from first to second unless I completely release the gas pedal. And, when it does, it does so with a clunk.
Also, when in second, and at speeds of up to 60 MPH, it will downshift into first with only moderate gas pedal travel.
I was beginning to suspect a Throttle Position Sensor or something like that but then I used the gear selector and put the transmission into 2nd and got a very weird response. It acts like it is in first as far as the RPM to vehicle speed, but once you gain a little speed, the engine will race around like it's in neutral until it rises to meet the vehicle speed and then it will engage. And when it does engage the RPM's suggest that it is in first. If I manually put it in first, it acts normal and engages throughout.
Additional info:
I purchased the vehicle at 55k miles and at that time I would get a slight "shudder" feel when shifting from first to second at WOT. Soon after the purchase I installed the supercharger and then a Transgo shift kit and an external transmission cooler. I flushed the transmission and torque converter and changed the filter when I installed the shift kit. At the bottom of the pan there was a 1 mm thick layer of black sludge. No metal pieces to speak of on the magnet. The shudder had gone away at some point and the transmission was performing great with nice, firm shifts. The vehicle is at 60k miles now.
On at least one occasion recently, when shifting from first to second at WOT, instead of getting a nice firm jolt I got a weird noise from the drivetrain and no jolt at all.
And finally (I know this is long and I'm surprised you're still reading), lately I've heard what sounded like a worn speedo cable when decelerating at low speeds except that it has a more metallic sound. I would never have thought this was related but found on other posts that this might be clutch plates that have worn to the metal.
When accelerating, the transmission will not shift from first to second unless I completely release the gas pedal. And, when it does, it does so with a clunk.
Also, when in second, and at speeds of up to 60 MPH, it will downshift into first with only moderate gas pedal travel.
I was beginning to suspect a Throttle Position Sensor or something like that but then I used the gear selector and put the transmission into 2nd and got a very weird response. It acts like it is in first as far as the RPM to vehicle speed, but once you gain a little speed, the engine will race around like it's in neutral until it rises to meet the vehicle speed and then it will engage. And when it does engage the RPM's suggest that it is in first. If I manually put it in first, it acts normal and engages throughout.
Additional info:
I purchased the vehicle at 55k miles and at that time I would get a slight "shudder" feel when shifting from first to second at WOT. Soon after the purchase I installed the supercharger and then a Transgo shift kit and an external transmission cooler. I flushed the transmission and torque converter and changed the filter when I installed the shift kit. At the bottom of the pan there was a 1 mm thick layer of black sludge. No metal pieces to speak of on the magnet. The shudder had gone away at some point and the transmission was performing great with nice, firm shifts. The vehicle is at 60k miles now.
On at least one occasion recently, when shifting from first to second at WOT, instead of getting a nice firm jolt I got a weird noise from the drivetrain and no jolt at all.
And finally (I know this is long and I'm surprised you're still reading), lately I've heard what sounded like a worn speedo cable when decelerating at low speeds except that it has a more metallic sound. I would never have thought this was related but found on other posts that this might be clutch plates that have worn to the metal.
#2
05-06-2003, 05:40 PM
Join Date: Nov 2002
Location: Plano, Texas
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Didn't know this forum was populated with so many helpful experts. 
After a considerable amount of reading I'm pretty sure that I've got a broken sprag similar to the problem that plagued the "mechanical diodes" on the 2001 4R100's.
I've ordered a Factory Tech Monster rebuild kit and will post results.
After a considerable amount of reading I'm pretty sure that I've got a broken sprag similar to the problem that plagued the "mechanical diodes" on the 2001 4R100's.
I've ordered a Factory Tech Monster rebuild kit and will post results.
#3
05-19-2003, 01:10 AM
Join Date: Nov 2002
Location: Plano, Texas
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I was right. It was the sprag. I also had to replace the direct drum ($55) which was apparently damaged by the broken sprag.
The stock 36 element sprag was replaced with a 45 element sprag in the Factory Tech Monster kit so I should be good there from now on.
So far, so good. The transmission is performing well and I'm working out some issues with the shifting. I had originally installed a Transgo shift kit in the transmission and the leftovers of that and possibly the increased fluid pressure from the Kenne Bell chip was causing harsh shifting. Under moderate acceleration I was getting a 2-3 chirp at 80 mph. For now, I have reinstalled my original, Transgo modified, accumulator valve body and the shifts are much softer. I still get a 1-2 chirp at WOT.
The stock 36 element sprag was replaced with a 45 element sprag in the Factory Tech Monster kit so I should be good there from now on.
So far, so good. The transmission is performing well and I'm working out some issues with the shifting. I had originally installed a Transgo shift kit in the transmission and the leftovers of that and possibly the increased fluid pressure from the Kenne Bell chip was causing harsh shifting. Under moderate acceleration I was getting a 2-3 chirp at 80 mph. For now, I have reinstalled my original, Transgo modified, accumulator valve body and the shifts are much softer. I still get a 1-2 chirp at WOT.