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2006 Jeep Wrangler Unlimited Rubicon
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Discussion Starter · #1 ·
I have an 06 LJR auto that shudders/vibrates when shifting into OD but it only happens around 45-50 when the RPMS are lower anyone have any suggestions as to what might be causing it? Thanks
 

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Hard to say it could be a lot of things, but I'm wondering if it could just be the engine is suddenly lugging from the rpms being too low for the tire size? What size tires are you running and have you regeared your axles if the tires are significantly larger than the factory installed? The 42RLE has a very steep .69 overdrive ratio that drops the rpms WAY down once it gets into overdrive. With large tires those rpms will be too low.
 

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2006 Jeep Wrangler Unlimited Rubicon
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Discussion Starter · #3 ·
I'm running 33's on stock gears. Nothing too crazy I don't think.
 

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I agree with Gerry. Based on his experience, I normally would anyway, but based on driving my 05 Rubicon with 33's...
Anything under 60 is too slow for a Rubicon in 6th gear.
I don't go into 6th gear until I hit 65, right about 3k RPM. At the time I go to 6th, the RPMs drop from 3k to about 2750, still maintaining 65 MPH.
If traffic in my lane slows a bit I can drop to 60 and climb out of that hole without lugging.

As a general rule, I would not want to be below 60 in 6th gear.
 

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OP said he had auto tranny so no sixth gear

But do agree probably just to slow engine speed for auto OD with those tires and stock gears


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I have an 06 LJR auto that shudders/vibrates when shifting into OD but it only happens around 45-50 when the RPMS are lower anyone have any suggestions as to what might be causing it? Thanks
That's the damn 42RLE and it's EMCC. While the 42RLE was somewhat of a pioneer with it's adaptive memory and electronically modulated converter clutch, it is by far the worst transmission ever offered in a 4.0L Jeep. What your feeling between 3rd and 4th is the PCM modulating the Low/Reverse solenoid which regulates the pressure to the torque converter clutch. It was designed this way to soften the 3/4 shift via hydraulic pressure. It probably works fine in light weight cars with small tires and small motors. It is the absolute worst in a Jeep, especially when the 42RLE final drive ratio is .069. The combination of a long/soft shift and a super steep 4th gear (extreme drop in RPM) equates to vibration and lugging.
Most 42RLE Jeep owners just shut the O/D off unless running on the highway. Regearing the differentials to at least 4.88 or 5.13 will definitely decrease the amount of time you spend lugging between 3rd & 4th gear. The EMCC will always be there though, to annoy you to some degree. It annoyed me so much that I pulled the 42RLE out of my LJ and threw it in the scrap yard. Imagine if all TJs/LJs had AW4s like the Cherokees.

4506886
 
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