RPM at 65 mph on 3.73 gears
Thread Starter
JK Enthusiast
Joined: Sep 2008
Posts: 100
Likes: 0
From: Chicago, IL
RPM at 65 mph on 3.73 gears
So I am getting a new set of 33's, moving up from the stock 32's on my Sahara. I understand that most say you shouldn't have to change gears from the 3.73's that are on the Sahara as I have. But I have a question.
Having looked around, I found the RPM chart in the 4WD catalog. At 65 MPH, the RPM for 3.73's with 32" tires is listed at 2546. I understand that this is for a manual, whereas my Sahara is an automatic, so there will be a difference. However, just today, I was checking out what my JK runs when hitting 65 MPH. The Tach is reading around 1750. While accelerating through 60 MPH it does reach ~2500 RPM, but as it passes 60 MPH, it shifts and then drops to ~1500 building up to ~1750 RPM once it reaches 65 MPH. Is this correct?
I hope that there isn't something going on that I actually have 3.21 gears on here. Any thoughts?
Having looked around, I found the RPM chart in the 4WD catalog. At 65 MPH, the RPM for 3.73's with 32" tires is listed at 2546. I understand that this is for a manual, whereas my Sahara is an automatic, so there will be a difference. However, just today, I was checking out what my JK runs when hitting 65 MPH. The Tach is reading around 1750. While accelerating through 60 MPH it does reach ~2500 RPM, but as it passes 60 MPH, it shifts and then drops to ~1500 building up to ~1750 RPM once it reaches 65 MPH. Is this correct?
I hope that there isn't something going on that I actually have 3.21 gears on here. Any thoughts?
JK Jedi
Joined: Feb 2008
Posts: 7,215
Likes: 10
From: Georgia
So I am getting a new set of 33's, moving up from the stock 32's on my Sahara. I understand that most say you shouldn't have to change gears from the 3.73's that are on the Sahara as I have. But I have a question.
Having looked around, I found the RPM chart in the 4WD catalog. At 65 MPH, the RPM for 3.73's with 32" tires is listed at 2546. I understand that this is for a manual, whereas my Sahara is an automatic, so there will be a difference. However, just today, I was checking out what my JK runs when hitting 65 MPH. The Tach is reading around 1750. While accelerating through 60 MPH it does reach ~2500 RPM, but as it passes 60 MPH, it shifts and then drops to ~1500 building up to ~1750 RPM once it reaches 65 MPH. Is this correct?
I hope that there isn't something going on that I actually have 3.21 gears on here. Any thoughts?
Having looked around, I found the RPM chart in the 4WD catalog. At 65 MPH, the RPM for 3.73's with 32" tires is listed at 2546. I understand that this is for a manual, whereas my Sahara is an automatic, so there will be a difference. However, just today, I was checking out what my JK runs when hitting 65 MPH. The Tach is reading around 1750. While accelerating through 60 MPH it does reach ~2500 RPM, but as it passes 60 MPH, it shifts and then drops to ~1500 building up to ~1750 RPM once it reaches 65 MPH. Is this correct?
I hope that there isn't something going on that I actually have 3.21 gears on here. Any thoughts?
Thread Starter
JK Enthusiast
Joined: Sep 2008
Posts: 100
Likes: 0
From: Chicago, IL
Sounds like I could be all right...but just really wasn't sure. Especially since it said that automatics would have higher RPM than manuals.
@Yamaha90 -- do you have 3.73s or 3.21s?
@Yamaha90 -- do you have 3.73s or 3.21s?
JK Enthusiast
Joined: Jun 2008
Posts: 150
Likes: 0
From: Eastern NE
My Rubicon with a manual and 4:10 on stock 32’s run around 2300 @ 60, and about 2700 @ 70-75. I generally set the cruise about 63 when on road trips regardless of the speed limit, much faster than this and my MPG’s go down quite a bit.
Trending Topics
JK Freak
Joined: Sep 2008
Posts: 916
Likes: 3
From: Terryville, LI, NY
I'm running 3.73 gears, 32" rubber with the automatic. With overdrive enabled, I see around 1,600 rpm at 65 mph. I would expect to see about 100 rpm less than the Rubi with its 4.10 gears.
Make sure you haven't disabled the OD, or your revs will be much higher.
My regards,
Widewing
Make sure you haven't disabled the OD, or your revs will be much higher.
My regards,
Widewing
