Loss of power in overdrive. - JeepForum.com
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post #1 of 9 Old 06-12-2021, 07:34 PM Thread Starter
maintman40
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Loss of power in overdrive.

2004 4.0
Starts and runs good. Wont gain speed in overdrive. Seems very sluggish. New air filter, spark plugs.

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post #2 of 9 Old 06-13-2021, 10:38 AM
Jerry Bransford
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Your 42RLE's overdrive ratio reduces the engine rpms so much that it will barely accelerate in overdrive. Its OD ratio is .69 so the engine rpms are reduced to 69% of what they were in 3rd gear. To really accelerate you need to get out of Overdrive by either stepping hard on the gas or temporarily switching the Overdrive off.

Something else that will cause a lack of power is having installed larger tires which further reduces engine rpms. Bigger tires can kill performance and the only fix is to regear both axles to a lower ratio to get the engine rpms back up to where they should be.

What size tires are you running?

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post #3 of 9 Old 06-13-2021, 02:09 PM
TheBoogieman
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You might have 3.07 gears also.
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Quote:
Originally Posted by jeepinmichguy_ View Post
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2003' Rubicon/Zone 4.25" combo lift with Rancho RS5000X shocks/ Zone hydro shocks/5.13 gears/35" Mickey Thompson MTZ P3 tires/Black Magic brakes. Jeep #17 & 19.
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post #4 of 9 Old 06-13-2021, 02:16 PM
Jerry Bransford
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Quote:
Originally Posted by TheBoogieman View Post
You might have 3.07 gears also.
X2, your TJ would be a real dog acceleration-wise with 3.07 in the axles.

You should be able to tell what your axle ratio is by looking at the steel ratio tag bolted onto the 9 o'clock position of your diff covers. This tag is indicating a 3.73 ratio inside the axle. No worries if yours says 3.08 or 3.74, the front and rear axle ratios are .01 different on all but Rubicons.
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post #5 of 9 Old 06-13-2021, 02:33 PM
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Add to that above too, that maybe the transmission kick-down cable (I forgot the name right now) may not be adjusted correctly.

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post #6 of 9 Old 06-13-2021, 04:33 PM
Jerry Bransford
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Quote:
Originally Posted by dbbd1 View Post
Add to that above too, that maybe the transmission kick-down cable (I forgot the name right now) may not be adjusted correctly.
While the earlier 32RH had a TV (throttle valve) aka kickdown cable, the OP's 42RLE is fully electronic/computer controlled and has no kickdown cable.
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post #7 of 9 Old 06-14-2021, 12:10 PM
rsurran
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My 2003 had 3.07 gears on 33 inch tires. Luckily it was a 5 speed stick. I posted similar to you when I first got it. After I got educated I never ran it in 5th gear (OD) except on rare occasions of flat level roads. Jeep did fine in 4th.

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post #8 of 9 Old 06-14-2021, 12:48 PM
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Jerry pointed out the 0.69 overdrive ratio.

In other words, you are only putting 69% power to the wheels when in overdrive.

You are around 130hp at the rear wheels stock and this is around 4,500 RPM. In overdrive you'll put about 90hp to the rear wheels at 4,500 RPM, but you'll never see that RPM in overdrive. 4,500 rpm is 190mph with 3.07 gears or 155mph with 3.73 gears.

Long story short, you're below 90hp at the rear wheels in overdrive.
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post #9 of 9 Old 06-14-2021, 04:45 PM
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Quote:
Originally Posted by Wheelin98TJ View Post
Jerry pointed out the 0.69 overdrive ratio.

In other words, you are only putting 69% power to the wheels when in overdrive.

You are around 130hp at the rear wheels stock and this is around 4,500 RPM. In overdrive you'll put about 90hp to the rear wheels at 4,500 RPM, but you'll never see that RPM in overdrive. 4,500 rpm is 190mph with 3.07 gears or 155mph with 3.73 gears.

Long story short, you're below 90hp at the rear wheels in overdrive.
Well that's depressing info.

Quote:
Originally Posted by jeepinmichguy_ View Post
TheBoogieman is a jerk.
2003' Rubicon/Zone 4.25" combo lift with Rancho RS5000X shocks/ Zone hydro shocks/5.13 gears/35" Mickey Thompson MTZ P3 tires/Black Magic brakes. Jeep #17 & 19.
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