42RLE Opinions

[matt4wheels]

Curious what the opinions are on this transmission or running an automatic in general for fairly serious offroad use (3/4 - 1T, 37-40s)? Vehicle in quesiton is a 04 LJ. Curious about things such as overheating, engine braking, water intrusion/susceptibility, crawl ratio considerations/feedback, upgrades/rebuild updates, etc....

[Matt Brown]

Autos are supposed to be nice going up hill, but not so much for going down.... If I were to seriously wheel a 42rle, I would look into replacing it with a built one from ATS with their t/c. Then also a trans programmer to control torque management and lockup rpm. Water intrusion should be easy to fix with raising vent lines and using a good dielectric grease on all connections. 1st gear isn't extremely low, but the t/c will make up for most of that with slip, but that also creates heat. But a deep pan and a good plate style cooler with fan put in before the radiator should keep temps in check.

I know Brian Montgomery has one and didn't like the no compression braking, but not sure if that was before he swapped to lower gears and how it is now.

[wdln]

I saw a big improvement in compression braking when I went from 3.31 to 4.56 gearing in the axles, but it's still nothing like what you get with a manual in a low gear. Mine (a TF-727) particularly seems to loosen up its grip as the engine revs down to 1200-1000 rpm, like when you're close to the bottom of a hill. A controllable torque converter with full lockup would be the way to go if you really want good compression braking. I upgraded the rear brakes to disc and I've never been too puckered going down hills.

Going up hills is indeed nice, although I'm almost always downshifted to 1st gear. The automatic is particularly nice if you're stopped on an incline and need to transition from stop to go. Two pedals for two feet.

[matt4wheels]

Matt/Dave, great thoughts and insight. I've been kicking around the idea of an LJ but the majority I seem to find are autos. That and the price on these seem to be climbing. But I was also surprised to find so many built LJ's running the auto. Crawl Magazine's Larry Nickell ran his in KOH with the stock auto and Poison Spyder owner Larry McRae runs the stock auto in Daddy Longlegs. Curious if any other TJ/LJ owners had any feedback? Al, I believe you own one and possibly Bill and Will. Any rubicon owners that can comment on the 4.0/auto/4:1 t case? Not really looking for a rubicon but curious of any feedback from someone using that power train on the trail.

[alkat]

Sorry Matt, mine's a 6 speed manual and rubicon. I've also changed to 5:13 gearing and I really like it on downhills. Never tried an auto so I really don't have much of an opinion on them.

[vlucdog]

Sorry Matt, my Rubicon hasn't seen any trails. YET.

I think Rubicrawler, a member here would be a good one to ask. He runs a auto with I believe 4.88 gears. IIRC he told me at Will's Missouri ranch that he had to increase RPM's on downhills.

Hope Lisa, the little one and you are doing well.

Bill