need help on ring and pinion selection 2004 f350 5.4 stock tires 265/75/16
auto 3.73 4x4 I pull a 10000 lbs trailer looking for more low end torque.looking to pull hills better. don't no if 4.10 would make too much of a differences or 4.30 would be too much.

 

ring and pinion

 

I believe 4:30 is the way you want to go. Those 5.4's like to spin.

 

I went with 4:30 but if I had to do it again I would have went 4:56..

 

thinking 4.30 is the way to go how did the 4.30 change your rpms and mpgs

 

My rpm if I remember correctly went up 500 rpm and my mileage really didn't change much it actually got a little better when pulling..

 

thanks Chris really nice talking to someone thats been through this before

 

The 4.10 in mine feels like a world of difference to the ones I have driven with a 3.73, but if you are going through the expense of changing gears then I would go with at least a 4.30. 4.56 is a little steep for me, but others seem to really like it.

 

If you plan on changing tire size go with the 4.56. 4.30 does cost more as well. 4.56 gives you a bit more room as Big Pipes said in case you upgrade tire sizes as well.

 

My Ex has a V-10 but I think the 5.4 and 6.8 have enough in common to mention my experience with a gear change.
The Ex came with 3.73s and 265/75R16s (31.5"), we pulled a 31' 9500lb+ ToyHauler. Tires were upgraded to 275/70R18s (32"). On several towing trips to/from NC, SC and GA from home just outside Philly the rig averaged from a worst of 6.5 to a best of 7.5 MPG. Average solo highway was about 14MPG.
I swapped in a new set of axle housing with 4.88 gears and left the 32" tires in place. On a trip to/from Savannah GA from Philly the EX got 9 MPG pulling the exact same trailer over the same route as before at the same speeds (61-63 MPH). And the beast pulled like a locomotive! Solo mileage has dropped down about 1 MPG to around 13 or so, not a lot of solo miles to collect good data. The deeper gears and higher revs allowed the trans to stay in OD and locked up much much more, OD = MPGs
With the 32"s and 4.88s my revs were 55MPH = 2075RPM, 60MPH = 2280RPM and 65MPH = 2430RPM. I recently moved up to some 35.24" tires so my effective ratio dropped back down to 4.39 and I haven't towed enough highway miles with them to gather good data yet. The RPMs with the 35"s for the above speeds are now 1900, 2055 and 2230 or so, all speeds are from a GPS as the speedo is/was a bit off.

 

thanks for all the info.very helpful. next question what name brand of gear would you recommend? been hearing Yukon is pretty good

 

I went OEM but I don't think they have 4:56, I have heard Randys ring and pinion is a good source..

 

went with 4.56 rears know have to get speedometer re calibrated any help with this cant seen to find a programmer to do ring and pinion change

 

I dont think you need a programmer for ring and pinion change but more the tire size difference. Otherwise Auto Enginuity may help. I think you need someone to program the computer. Contact the local dealer and see if they can change it.

 

You don't need the speedo recalibrated for a gear change, only if you are changing tire size. The speedo reads off of the ring gear which is turning the same speed regardless of the gear ratio..