Rpm's @50 mph

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

eradicator006

Full Access Member
Joined
Apr 18, 2009
Messages
175
Reaction score
2
Location
Canada
Is 2000-2200 RPM normal @ 50 MPH for the 3.7L V6?

Stock size tires? That seems kind of high. That's about where mine is at 100km/h (62mph)

EDIT: Wait a sec. Mine is about 2k at 110km/h. I find that's where I get the best mileage at and it doesn't have to downshift to get up a hill.
 
Last edited:

lejeep

Full Access Member
Joined
Feb 16, 2013
Messages
31
Reaction score
0
Location
Ohio
Mine is at about 1500 RPM at 50 MPH in 4th gear/overdrive with a 3.7L V6. I have the stock tire size. At 55 (normal speed around here), it is around 1650 RPM.
 

CactusJacked

Full Access Member
Joined
Dec 12, 2013
Messages
2,407
Reaction score
11
Location
Chicago Suburbs
His 02 has the 45RFE trans, and 4th gear is a .75:1 overdrive. With the factory 3.73 gears and factory 235 70R16 tires (29"), at 50 mph in 4th the rpm's would be 1,622. If 4.10 gears were swapped in, rpm's would be 1,778.
However, in 3rd gear (1:1) with 3.73 gears, rpm's would be 2,161. With 4.10 gears, rpm's would be 2,375.
Can you feel the trans going into all 4 gears? Because if you have a factory setup (tires & gears), it's pointing to the trans staying in 3rd, or it's slipping.
 

dude1116

Full Access Member
Joined
May 31, 2011
Messages
3,373
Reaction score
13
Location
Pompton Plains, NJ
Mine doesn't like to lock the TC at 50MPH which actually causes it to sit at 2k RPM. It locks the TC at 55 and RPMs are down to about 16-1700. I have an 04 with a 42RLE.
 

streetglideok

Full Access Member
Joined
Jul 27, 2011
Messages
413
Reaction score
1
Location
Colorado Springs
Ok based on him having a 45RFE, and 235/70r16 tires and stock gearing, according to the gear calculator sticky'd at the top of this forum section, at 50mph it calculates 1623rpm in fourth gear. 2165rpm in third gear. So mx3, sounds to us if all that info matches, your ****** isn't shifting into fourth. I'd check to see what the rpms are at 70mph. At 70mph in fourth gear, it should be 2273rpm, and if it's in third, 3030rpm. That's in the ballpark at least.
Gear Ratio Calculator
 

mx3_ryder

Full Access Member
Joined
Jan 27, 2014
Messages
351
Reaction score
1
Location
troy VT
Yes, I have the 45RFE ******, stock gearing and tires and no fourth gear. What could be the problem? No slipping, just never shifts into fourth.
 

mx3_ryder

Full Access Member
Joined
Jan 27, 2014
Messages
351
Reaction score
1
Location
troy VT
Might be a dumb question, but am new to my jeep. Is there an overdrive button somewhere that I might need to turn on? Where is it located?
 

Gyro

Full Access Member
Joined
Sep 12, 2012
Messages
408
Reaction score
154
Location
Nova Scotia
Drivers side of shift lever.
Should be a yellow light on cluster OD off.

Gyro
 

mx3_ryder

Full Access Member
Joined
Jan 27, 2014
Messages
351
Reaction score
1
Location
troy VT
Thanks, guess it resets its self when vehicle is turned off, so that wasn't it. Any suggestions is to why I don't have 4th gear?

Edit: I just went out at break and ****** does shift all 4 gears, guess I wasn't noticing 4th before as it does shift really smooth. My overdrive button works perfect to. Also when going 50 MPH, I can get RPM ranges of 1600-2000 depending on accelerator position and road surface. So I guess nothing wrong other than she's a gas guzzler.
 
Last edited:

streetglideok

Full Access Member
Joined
Jul 27, 2011
Messages
413
Reaction score
1
Location
Colorado Springs
Darn if all that ^ doesn't sound familiar!!! ;)
This is a quick and easy calculator that doesn't cause migraines nor take minutes to get the answer like the stickied one: Speed/RPM Calculator

I didn't think the one that got stickied was all that complicated. Gives you some pretty exact numbers. At the bottom with the spreadsheets it gets a bit cluttered but that was all.
 

streetglideok

Full Access Member
Joined
Jul 27, 2011
Messages
413
Reaction score
1
Location
Colorado Springs
Thanks, guess it resets its self when vehicle is turned off, so that wasn't it. Any suggestions is to why I don't have 4th gear?

Edit: I just went out at break and ****** does shift all 4 gears, guess I wasn't noticing 4th before as it does shift really smooth. My overdrive button works perfect to. Also when going 50 MPH, I can get RPM ranges of 1600-2000 depending on accelerator position and road surface. So I guess nothing wrong other than she's a gas guzzler.

Honestly, at 50mph, I would click off the overdrive button. Too low of RPMs, will hurt fuel economy as the engine is below the torque band, and puts undo stress on the overdrive clutch pack.
 

tommudd

Moderator
Staff member
Moderator
Joined
Jul 14, 2005
Messages
22,450
Reaction score
3,650
Location
Southeastern Ohio
My setup is far from stock
BUT I never run 50 mph with the overdrive on, its always off at that speed, lugs down too much for me.
Did try it this morning worn down 265-75-16 tires with 4.10s at 50 in overdrive its about 1680/1700. More for those ever considering going to 4.10s and larger tires.
 

Latest posts

Members online

Top