Just wondering what kind of rpm you guys with 3.92 gears in the rear end are turning at 60 mph. I'm looking at an 07 right now and it seems to want to run 2000 rpm at 60mph. I'm figuring it should be around 1850 or so. It has 20" rims with 275/60x20" tires. I just wanna make sure everyhting is working alright with it before I pick it up. Still has plenty of warranty but if there something wrong I'd like it fixed before I picked it up.

Thanks
Tim

 

1725 rpm @55 MPH

06 RAM 5.7 with 20" tires

 

2000 RPMs at 60 mph with a 33" tire is high, I'd suspect it's been re-geared at some point. I'm running 4.56 gears with 35" tires and run that rpm at about 65 mph...

 

Does sound a bit off. You might want to lift the rear axle and turn the tires, counting the drive shaft turns. If it turns out to be ~4:1, there might be a tranny issue.

 

Yea I turn around 1800 at 60. But then I have 3.55's

 

1950rpm @ 70mph with 275/60R20's and 3.92 gears.

 

2k @ 60 is 4.88 territory for the 5 speed auto and 33" tires. This is based on 0.67 final gear ratio.

 

Yea I turn 2000 rpm at 70

 

same here

 

Sounds like your still in 4th gear. If you ease into it up to 60 you won't kick into 5th until you go down a slight decline, or let up on the gas. If you accelerate more aggressively ~ 2.5k rpm it will drop right in. It is an odd thing that I learned with my 07 with 3.92's as well. the PCM wants to see a certain % load reduction, or throttle position change before dropping into 5th.

I have had it were I accelerate very easily up to 70 and it will stay in 4th gear for almost 2 miles before finally deciding to drop into 5th. The PCM knows that the Hemi likes the higher RPM's so it will hold 4th longer than you may expect.

of course all of this can be remedied via SuperChips trans tunes to where it shifts however you like it.

best of luck

nateroach