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Old 06-24-2014, 10:27 PM   #1
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Disabling overdrive?

Is there a way to have the overdrive off when the jeep starts up, instead of automatically being on? Also, what exactly does overdrive do on an '03?

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Old 06-24-2014, 10:42 PM   #2
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Also, what exactly does overdrive do on an '03?
So...you don't know what it does, but you want to disable it?

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Old 06-24-2014, 11:40 PM   #3
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Here is how one guy did it.

Overdrive off at start up.
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Old 06-25-2014, 05:26 AM   #4
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I know what it does, but I would like more technical information about it, such as what gear or rpm limit does it change, can it be adjusted, or disabled. I have factory 3.73's and I would rather not re-gear if I'm goin to 35's. So if you don't have anything to add to the thread, stay off of it.
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2003 TJ Sahara automatic
3" Bilstein Shocks and progressive springs
Factory Dana 44 HD w 3.73 rears
31 x 10.5 Firestone A/T's 15 x 8 M/T Sidebiter II's
330 watt Delta Skybar Xenon
Koolertron DVD/GPS head unit 7 factory speakers
Custom matte decals from 46graphics.com
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Old 06-25-2014, 05:35 AM   #5
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I have factory 3.73's and I would rather not re-gear if I'm goin to 35's.
With a 42rle transmission that would be a very terrible mistake. The deepest gearing you can fit into the front Dana 30 is 4.88, which still isn't deep enough to properly run 35" tires on that transmission.

I have the same transmission and I removed the previous owner's heavy ~32x11x16's and put on 31x10.5x15's. World of difference. I think 3.73 is barely tolerable on 31's, and the math of 35's on 3.73 is frightening really. I plan to run 33" tires and 4.88 gearing on my rig, but I wasn't going to buy the tires until the rig is properly set up to run them. I'm a function over fashion kind of guy.
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Old 06-25-2014, 03:52 PM   #6
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My rig originally had 33 x 12.5 x 15 BFG all terrains on it and it ran great on the stock 3.73s. They had a bit of dry rot so I decided to change them to Firestone destination a /t 31 x 10.5 x 15 and it runs well, but it seems less peppy. I thought it would have been even more torquey w smaller shoes but maybe its just in my brain.
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Factory Dana 44 HD w 3.73 rears
31 x 10.5 Firestone A/T's 15 x 8 M/T Sidebiter II's
330 watt Delta Skybar Xenon
Koolertron DVD/GPS head unit 7 factory speakers
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Old 06-25-2014, 04:37 PM   #7
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Larger tires are harder for the engine to turn. This is why we regear to numerically higher gear sets to counteract the increased tire diameter.

If you went down in size, you effectively made it easier for your drivetrain to turn the tires. The only factor could be the weight of the tire. If you went from a very light tire in a 33" to a very heavy 31" it is possible that you feel that difference but its unlikely this applies. AT's will be heavier than the firestones.

Probably just in your head
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Old 06-25-2014, 05:37 PM   #8
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Forgot to release parking brake after tire change?

Don't know why a smaller diameter would feel less powerful

Also note your speedo odometer readings change with tire diameter
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Old 06-25-2014, 07:58 PM   #9
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Also, the technical (ish) data on the OD is:

.69 drive ratio
It kicks in around 40 mph with appropriate gearing.


Turning it off is something I do all the time under 60 mph because the engine will just run at 1500 rpm which is not something I want it to do. Again, that is with 31's (30.8" fairly light KM2 tires), 3.73 gearing, 42rle 4spd auto. You'd have to go over 80 to even want 4th gear with 35" tires, and first gear would be a joke. It may tear up the clutches a bit too depending on how you drove it. Lotta headache for zero gain, other than being able to say you have 35" tires.
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Old 06-30-2014, 07:41 PM   #10
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35's are probably not practical with it being my daily driver (for now). I notice that if i hit the overdrive when I'm driving it seems to give me a higher drive line on the RPM gauge. That's all well and good but even when I'm highway driving i need it off for me to keep up with traffic. I think my fan clutch is shot too, which making me feel like I'm dragging something around all the time. 3.73s should really be giving me a nice pep with 31's on it.
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2003 TJ Sahara automatic
3" Bilstein Shocks and progressive springs
Factory Dana 44 HD w 3.73 rears
31 x 10.5 Firestone A/T's 15 x 8 M/T Sidebiter II's
330 watt Delta Skybar Xenon
Koolertron DVD/GPS head unit 7 factory speakers
Custom matte decals from 46graphics.com
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Old 07-01-2014, 10:44 AM   #11
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they should be giving you more than a little pep, ive got 33/12.5/15 goodyear mtr kevlars on my 97 and i can race around better than most. im also in manual with control over my torque zones so thats a difference.
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Old 07-01-2014, 08:51 PM   #12
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im also in manual with completely different gear ratios, and more forward gears so thats a difference.

Fixed that for you.
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Old 07-02-2014, 07:46 AM   #13
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I know what it does, but I would like more technical information about it, such as what gear or rpm limit does it change, can it be adjusted, or disabled.
i'll bet all you think it does is lock out overdrive. It does that, but more importantly disabling it also changes the lockup pattern of the torque converter. Enabling the OD-Off button (disabling OD) will also prevent the TC from unlocking (allowing "slip") in lower gears as well. When driving below 45-50mph, this is noticeable because you will no longer have the extra 300-800rpm boost that TC unlocking provides. Basically, at lower than highway speeds & climbing up hills in the mountains, it will feel like it has less gears. You be in locked-up TC 2nd gear with higher RPMs, instead of unlocked TC 3rd gear with less RPMs.

you can not change the transmission programming. the only way to make the 42RLE tolerable is throw deep gears at it.

Quote:
Originally Posted by NoBoat0429 View Post
My rig originally had 33 x 12.5 x 15 BFG all terrains on it and it ran great on the stock 3.73s.
if you think 3.73s/33s with the 42RLE "ran great", you should feel 4.88s with 33s. I ran 33s with 3.73s for a week and it was terrible. personally, I'd run 4.56s or 4.88s with 31s without thinking twice.

for 35s you want at least 5.13s, preferably 5.38s or maybe even 5.89s.
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Old 07-02-2014, 11:06 AM   #14
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How big of a deal is a gear swap to 4.10's or 4.88's? What if i run 33 x 10.5 BFG's.
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3" Bilstein Shocks and progressive springs
Factory Dana 44 HD w 3.73 rears
31 x 10.5 Firestone A/T's 15 x 8 M/T Sidebiter II's
330 watt Delta Skybar Xenon
Koolertron DVD/GPS head unit 7 factory speakers
Custom matte decals from 46graphics.com
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Old 07-02-2014, 01:50 PM   #15
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Originally Posted by NoBoat0429 View Post
How big of a deal is a gear swap to 4.10's or 4.88's? What if i run 33 x 10.5 BFG's.
tire diameter is what matters here...those are still 33s, going to need at least 4.88s.

generally, if you have to ask how big of a job a gear swap is, then you aren't ready to do it yourself. You're much better off paying somebody that does this stuff all day everyday. Full regear costs about $1200-1800, depending on geographical location, labor rates and parts chosen.

you have to understand the 42RLE equipped jeeps are grossly undergeared from the factory. For comparison, a jeep bone stock with 4.0L/42RLE/3.73s/30s, feels like a 4.0L/NSG370 (6-speed)/3.73s/35s while losing two gears (1st and 3rd).
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Old 07-03-2014, 07:39 AM   #16
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This is the type of info I was looking for. Thank you.

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2003 TJ Sahara automatic
3" Bilstein Shocks and progressive springs
Factory Dana 44 HD w 3.73 rears
31 x 10.5 Firestone A/T's 15 x 8 M/T Sidebiter II's
330 watt Delta Skybar Xenon
Koolertron DVD/GPS head unit 7 factory speakers
Custom matte decals from 46graphics.com
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