Originally Posted by resharp001

Oh man, 3.73 with 37s sounds......miserable. When I first went to 37s I had 4.10 gearing. I went maybe 9-10 months like that before it wore me down. It was the top end that did it to me. I couldn't stand essentially losing 5th gear on the highway and having to downshift to 3rd if I had to pass or there was even a slight headwind.

Did you watch that video by motor city mechanic where he disassembles a phaser? There isn't much going on inside one of those to fail. I tore one apart myself. There is literally just a little spring and lock pin in those that the oil pressure is moving back and forth. Outside of some very random particle jamming that, or I guess the little plastic cap in there breaking, I think those failing is a lot less than people want to believe.

I just went out and performed that cleaning function on mine to compare results. RPMs surged a bit while cleaning intake phaser 1, they did nothing while cleaning intake phaser 2. These are the same results you saw, and I have no reason to believe my intake phaser on bank 2 has a problem. I can't explain why there is no rpm increase when cleaning intake on bank 2. I would think it would be the same as well but for some reason it is not.

I'm running a ~120 tire/wheel combo (37s on ATX beadlocks) with 4.88 gearing and have a heavy ass full float PR60 rear axle too. My Jeep is sure not a light thing, so I can relate to the engine being under a lot of load even when I'm not towing my camping trailer which adds another ~3k lbs loaded down. I used to only throw the code when I was towing but it got worse over time to when I'd throw it just driving the jeep on long road trips. I really think if it's not throwing the code on you even when you feel like it could, that is a good sign. I personally wouldn't do anything else until it starts throwing the code again. Regearing would certainly improve your driving experience, though your wallet would be lighter. TBH, it would make a big difference and really help both the engine and the transmission out, but I can see not wanting to put that money into it when you think there could be engine aggravations you still need to work out. My confidence level is running pretty high that my issues may finally be behind me.


Also, my impression of the phaser "cleaning" process is more that it's flushing oil through the oil control valve. There is not much space for oil to travel in the phaser itself and there's no direct path through that....it's essentially a dead end at the spring pin in there so the cleaning is more of the oil control valve passage way (the big bolt holding the phaser to the cam).

Originally Posted by 13JKUR

I appreciate all the first hand info you’ve been giving. I just bought the jeep about a month or so ago with the lift and wheel/tire combo and was told he did not change the gearing. Being new to jeeps I have no idea what a smooth running jeep even feels like. I’ve always had and currently have lifted Chevys but with v8s and duramax so power wasn't ever an issue. I really do need to tear the diff cover off to physically count to see what I have versus the “jacking up rear and counting rotations” method. I plan on regearing, contemplating the 4.56 or 4.88. Do you have any regrets with the 4.88? Wish you went lower or higher? Will it stay in 5th gear now on the highway? What would you say your rpms are at when driving 70?

Originally Posted by resharp001

First, you don't have to count the teeth really. Assuming you have your speedo calibrated for the tire size, you can just get going 70 mph and then look at the rpm's and compare to the gear charts that are littered on the web. If you don't have the speedo calibrated for the actual tire size measurement (not what is stamped on the sidewall, ground to hub x 2), then you certainly should. I presume since you have Jscan that you've done that.

I've had several tire/gear combos in the past:

3.73 with 35s (touch overgeared but nbd)
4.10 with 35s (swapped in rubi axles, nice combination even if still 1 gearset too high)
4.10 with Nitto 37s (getting back to sucky again, high end power lacking)
5.13 with Nitto 37s (regeared, no rubi TC so I went more aggressive for my wheelin. Perfect for the crawlin', touch aggressive for high end pavement for some)
4.88 with Toyo MT 37s (on paper this is ideal, but I kinda miss my 5.13 gears)

So, with 37s and 5.13, at 70 mph I'd run 3k rpm +/-. That sounds a bit aggressive, but i swear you gotta but up over 2700 rpm for power with the 3.6L. I got used to the hum of the engine and I appreciated the offroad benefits cuz I did a good bit of technical offroading then. My last axle swap was to a PR44 front with a hub conversion and a full float rear PR60. That rear axle is heavy as shit, and my beadlocks with the tires are ~120lbs at each corner. It's a lot of mass to move. I really kinda miss my 5.13 gears and they would probably make this combo perfect, but you simply can't justify spending the money or effort to regear 1 gearset......so it is what it is.

**all of this talk is regarding an automatic tranny**

Realistically, with 37s, 4.88 gearing with the auto would be equivalent to how it drove stock. with 35s it's 4.56. People get used to their "normal" and kinda forget what these drove like....simply chaulking things up to "it's a jeep....it's slow". It's not like regearing would ever feel like you just added horsepower, but it is nice to drive more like it should and shift right. With my old 5.13 gearing I'd rarely downshift on the highway unless I was really stomping on the peddle to pass. With 4.88's I downshift more often and when I'm towing, I'll be downshifting to 3rd to climb a hill on the interstate.

I do a bit of driving up in Colorado to see my dad. If you ever spend time in the mountains or big hills you start to realize that you can spend time cruising at higher rpm's due to proper gearing, or you can spend time downshifted to 3rd with screaming high rpm's at every hill.

Originally Posted by resharp001

Y, I didn't really consider that you have the 4:1 TC. 4.88 would be best I think. if you went 5:13, holy cow 4Lo would be really low with that TC. You likely have several hundreds of pounds less than me too.

Originally Posted by IceColeNH

Wow, I appreciate everything I've learned on this page. Having gone through the cleaning process. I found intake one doesn't clean. I amusing JScan and have successfully cleaned the other phasers. Any thoughts?