42RLE doesn't always lock up in 4th

[toximus]

I noticed today that the 42RLE was varying RPMs in 4th gear between 2.3k and 2.7k trying to go 60mph up an incline to 11k feet. It would also drop down into 3rd gear at 3.1k rpm so I'm positive that it was in 4th while that happened.

I thought that it was always supposed to be locked in 4th? Anyone know the answer?

Also, I learned that the transmission doesn't like running at 4400rpm in 3rd at 85mph... When I sprayed someone with ATF passed someone.

 

[pagrey]

The 42RLE isn't always supposed to be locked in 4th. It lets go all the time to fake a shift or do whatever fuckery they had in mind when they programmed it. Lockup happens more often when you have O/D off but obviously 4th isn't in that picture. The thing unlocks when the A/C cycles, it unlocks all the time really. Anyway 4th isn't always locked, definitely not.

 

[mousehunter]

I have 35" tires with 3.73 gears - what is this overdrive you speak of. I have only occasionally seen it when going down hills.

 

[tonywrangler07]

Hey guys, new to the forum and just trying to chip in where I can. I can also vouch that overdrive is very selective with our transmission. I just got a newly rebuilt 42rle from these guys, https://reman-transmission.com/transmission-codes/?code=42RLE, and its OD shift patterns are exactly the same as the old one before it went kaput. I am rocking a 4in lift with 33s though

 

[txbemis69]

I have 35" tires with 3.73 gears - what is this overdrive you speak of. I have only occasionally seen it when going down hills.

i can only imagine how bad 35’s & 3.73 gears are. i’m only on33’s with 3.73 gears and it sucks bad.

 

[Terry Tiemeyer]

When in 4th the converter can be locked but when loaded just right it will unlock and stay in 4 th. That’s the variance in rpm your seeing. When it goes into 3rdyou will notice a big swing in rpms. 4th is a very high ratio in this transmission. I have 5.13 s and 33” tires it is a game changer in how this works.