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Unread 04-12-2004, 05:33 PM   #1
Scott B
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Does my 3 speed auto have a overdrive?

I have a 99 tj with a 3 speed automatic and just wondering if it has an overdrive, at about 30 mph it shifts into drive, and at about 40 mph it shifts again and drops the rpms down. I don't think it has a overdrive but cofused what the shift is at 40.

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Unread 04-12-2004, 05:46 PM   #2
airduds
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No overdrive. What you feel/see is the torque converter locking up.
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Unread 04-12-2004, 05:49 PM   #3
KaiserJeep
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There is no overdrive in a 3-speed auto. However all modern Jeep automatics utilize a locking torque converter. When it locks it will indeed drop a few engine RPMs - the same amount as the converter slippage at that speed. Once locked, the exact 3rd gear ratio is in use, which in the case of the 3-speed TJ transmission is 1:1, but not overdrive. You are not the first to mistake this for another gear - and many Jeep owners never seem to notice this at all.
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Unread 04-12-2004, 06:21 PM   #4
Scott B
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Hey thanks, that answered alot of my questions.
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Unread 04-12-2004, 08:39 PM   #5
CobraKhan
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I definately notice it. I wasn't sure what was causing it until now. But, I really notice it at 50 mph, I feel a little kick down in the rpm. Like said above, it is only a few hundred rpm though.

Does this only happen in third gear, or in all three gears?
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Unread 04-14-2004, 04:08 PM   #6
KaiserJeep
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Only in 3rd gear for '97-'02s or in 4th gear on the newer TJs.
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Unread 04-14-2004, 06:54 PM   #7
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Quote:
Originally Posted by KaiserJeep
There is no overdrive in a 3-speed auto. However all modern Jeep automatics utilize a locking torque converter. When it locks it will indeed drop a few engine RPMs - the same amount as the converter slippage at that speed. Once locked, the exact 3rd gear ratio is in use, which in the case of the 3-speed TJ transmission is 1:1, but not overdrive. You are not the first to mistake this for another gear - and many Jeep owners never seem to notice this at all.
I noticed it day one in ours...but I DEFINITELY think there still needs to be another gear, PLUS the lockup...

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Unread 10-31-2004, 06:07 AM   #8
Gary Gill
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Would this be true for my 98 TJ as well?
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Unread 10-31-2004, 07:14 AM   #9
jessejames
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2003 - first year for 4 speed automatics....that is why I bought an auto.
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Unread 10-31-2004, 07:50 AM   #10
StealthTJ
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Quote:
Originally Posted by Gary Gill
Would this be true for my 98 TJ as well?
Yes, '97's ~ 2002 all use the same 3 speed auto tranny.




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Unread 10-31-2004, 09:56 AM   #11
Gary Gill
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Thanks for the info.
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Unread 05-31-2005, 05:56 PM   #12
FloridaJeeping
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Damn, I just found this old thread and had been scratching my head for some time now... I have "counted" 4 gears over and over when I get my TJ up to highway speed and could have sworn it had a 4th or OD gear. Duh do I feel kinda dumb now. But this shows what a search will turn up.
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Unread 05-31-2005, 06:12 PM   #13
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I'm sure that 30 years later, I still have friends that would swear in court my old Triumph TR-6 British-made 2-seat sportscar had an 8-speed manual transmission. It didn't of course but I could sure fool them into thinking it did with its electrically controlled 2-speed rear axle. To this day I don't know how that 2-speed rear axle worked but it was fun fooling my friends into thinking my TR-6 (kind of like an MG) had an 8 speed transmission by secretly shifting the axle back and forth via a turn-signal like lever on the steering column between High and Low as I shifted the 4-speed trannie.

Just goes to show that trannies and how many speeds they really have can fool the best of us.
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