How many RPM's at 70 w/ 4:10's and factory 20's?
But hopefully someone will chime in, forgot his name but he has 4:10's w/ factory 20's.
ok so i was doing the math to figure this out for you.
in my truck with 3.55's doing 65 MPH the chart says i would be doing 2349 RPM obviously thats not the case so if you minus that by 32% it will give you the right rpm's
2349 - 32% = 1597.32 RPM
so then if you move to the 4.11's it says you will be running 2720 RPM so again minus that by 32 %
2720 - 32% = 1849.6 RPM
so thats about what you should be running at 65 MPH
in my truck with 3.55's doing 65 MPH the chart says i would be doing 2349 RPM obviously thats not the case so if you minus that by 32% it will give you the right rpm's
2349 - 32% = 1597.32 RPM
so then if you move to the 4.11's it says you will be running 2720 RPM so again minus that by 32 %
2720 - 32% = 1849.6 RPM
so thats about what you should be running at 65 MPH
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(5)45RFE
1 3.0:1
2 1.67:1
2P 1.5:1
3 1.0:1
4 0.75:1
5 0.67:1 (545RFE only)
R 3.0:1
There are the numbers for the tranny.
Here is another calculator.
http://www.angelfire.com/fl/procrastination/rear.html
Calculates mine to 1800. In the real world my truck with 3:92's turns 2000 or so..analog... at 70 mph.
I will aslo say I am taking mine in soon for a tranny check. 3:55 I drove had much more get up than this 3:92.
I wish Dodge has not dropped the Getrag 238 6 speed auto that was initially planned for the 2009.
1 3.0:1
2 1.67:1
2P 1.5:1
3 1.0:1
4 0.75:1
5 0.67:1 (545RFE only)
R 3.0:1
There are the numbers for the tranny.
Here is another calculator.
http://www.angelfire.com/fl/procrastination/rear.html
Calculates mine to 1800. In the real world my truck with 3:92's turns 2000 or so..analog... at 70 mph.
I will aslo say I am taking mine in soon for a tranny check. 3:55 I drove had much more get up than this 3:92.
I wish Dodge has not dropped the Getrag 238 6 speed auto that was initially planned for the 2009.
Last edited by blue2050; May 29, 2009 at 09:23 AM.
(5)45RFE
1 3.0:1
2 1.67:1
2P 1.5:1
3 1.0:1
4 0.75:1
5 0.67:1 (545RFE only)
R 3.0:1
There are the numbers for the tranny.
Here is another calculator.
http://www.angelfire.com/fl/procrastination/rear.html
Calculates mine to 1800. In the real world my truck with 3:92's turns 2000 or so..analog... at 70 mph.
I will aslo say I am taking mine in soon for a tranny check. 3:55 I drove had much more get up than this 3:92.
I wish Dodge has not dropped the Getrag 238 6 speed auto that was initially planned for the 2009.
1 3.0:1
2 1.67:1
2P 1.5:1
3 1.0:1
4 0.75:1
5 0.67:1 (545RFE only)
R 3.0:1
There are the numbers for the tranny.
Here is another calculator.
http://www.angelfire.com/fl/procrastination/rear.html
Calculates mine to 1800. In the real world my truck with 3:92's turns 2000 or so..analog... at 70 mph.
I will aslo say I am taking mine in soon for a tranny check. 3:55 I drove had much more get up than this 3:92.
I wish Dodge has not dropped the Getrag 238 6 speed auto that was initially planned for the 2009.
Wasn't the Getrag 238 a 6 speed manual that was on the 4.7's pre '09? A friend has that setup and it is sweet; boy do I miss my old handshaker in a Dakota...
Speaking of 6 speed autos, this is where Dodge is really lacking IMO. The Ford 6 speed ala F150 is one sweet piece; it is really nice having that extra gear before your double O/D. After putting 2500 miles on a Rental Expedition in the Rockies with the 6 speed, I'm seriously considering the F150



