RPMs with different rear axles and trans

[JWerkheiser]

Thought I would post this info for those interested in deciding which rear axle ratios to go with, if others chime in with their observations for their particular configurations that would be great. I have the 4. 10 and 48RE. Cruising at 70mph, the RPMs sit right at 2150. Stock BFGoodrich on/off road tires.



Trying to remember what my '03 with 6 speed and 3. 73 ran for RPMs at that speed but I don't think it was much less.

 

[klenger]

The 48RE has a higher top gear than the 6 speed which makes up some of the difference.

 

[pecandude1]

what rpms would you be running with a 6spd a 3. 73s at 70mph?

 

[Kurt Henzler]

rpm

2000 rpm 70mph 3. 73 rear end

 

[XJSuperman]

Just to add... with my 48RE 3. 73's with the 315's... sits at 1800 RPM's at 70.

 

[thejeepdude]

Originally posted by XJSuperman

Just to add... with my 48RE 3. 73's with the 315's... sits at 1800 RPM's at 70.

That's corrected 70mph, right? You had your speedo adjusted, I presume? So does that mean you're only at ~1450 at 55mph? Hmmm... maybe I do need those 4. 10's...

 

[Kirk_B]

http://www.klenger.net/dodge/general-reference/gear-speed-calculator.xls This is the best calculator I have found.

 

[Kirk_B]

Surprised you didnt post your own sheet klenger

 

[klenger]

I was being modest, ... or was it lazy?

 

[JWerkheiser]

Kelnger, that's great. Didn't know that existed. Thanks!

 

[XJSuperman]

Yes I had my speedo corrected. In OD I am at what was said (1450 I think) at 55. BUT I don;t run OD unless I'm doing better than 60 MPH. Works great for me.