I'm about to order a 1500 Hemi automatic and found these ratios in an old post (deciding on rearend ratio). Can anyone please tell me if they are still correct?

5-45RFE:
1st - 3.00:1
2nd - 1.67:1 (upshift)
2nd - 1.50:1 (downshift)
3rd - 1.00:1
4th - 0.75:1
5th - 0.67:1

Many thanks in advance!

 

Yup, those look correct. If I could do it over again, I'd get the manual trans. The ratios in the 545RFE auto. suck in my opinion and hurt fuel economy, not help it. Why? Because with those tall ratios, the tranny is constantly shifting.

 

WXman:

Thanks for the reply.

I was going to get a stick but was told that only automatics will be built to finish out '05 production and that I'd have to wait for an '06 at some point down the road.

Since I'm in need of a tow truck for my wife's Salt Flats Racer and can get an incredible deal at this time, I decided I'll go ahead. The thing will be used as a truck at most 1.5 weeks out of the typical year.

It would seem the 3.92 rearend would be some help.

I appreciate your input and any other comments.

 

Well I definitely think you are making the right decision by paying $900 extra for the 5.7L. My 4.7L is OK, but my truck weighs 5,500 lbs. empty and you can tell out on the highway that it's a little too much for the 4.7L. You'll be happier towing with the Hemi.

And the 545RFE is supposed to be a much higher quality tranny than Dodge is known for putting in trucks. So it should hold up well for a long while. I would also recommend the 3.92 gears. I have them and I turn 1,600 RPM at 60 mph. So they aren't going to hurt you on the highway any at all, and in town you'll be much better off with them instead of the taller 3.55s.

Good luck.

 

I did a lot of research before I ordered my truck...your trans. ratios are correct but the options for gears are very limited. If you get the 20"s 3.92 is ll you can get. If you could get the 3.55 with the 20"s it would pull about 250 RPM off the tach at 75 MPH. I personally think I may change out my 3.92 for th 3:55. My thoughts are to install the 3.55 and reprogram the truck with hyper tech to bring on the torque ASAP. I think this would improve mileage in town and highway.

 

Thanks for the additional info.

I ordered the truck today. I got the ST hemi, auto, tow package, cruise, and limited-slip with the 3.92. No other options or extra weight. I got vinyl seats and rubber mats because the Bonneville salt is a killer to get out of carpet and cloth, soaks right through and rusts everything unless carpet is removed and all flushed out each year. I'll toss in mats and put a sheepskin on the driver's seat the rest of the year.

I've driven my race car builder's '04 Hemi 4x4 with this setup and the 2x should be a lot lighter and a nice semi-daily driver in town and suffice for two weeks of long distance towing each year from what I read here. Next project is to buy an aluminum car trailer--another 500+ pounds saved (never know I was a racer at heart, huh). I drive performance cars (daily driver's a C-5 Vette--only GM I've owned in 43 years of vehicles--but don't worry, I've a '58 392 Hemi-powered NY convertible, among other things) and race, so I need a truck that will get out of its own tracks when I decide to toddle around town in it... he, he!

Again, I appreciate your help and just discovered this forum, though I've been active on others for years.