Sheep Shagger
Adventurer
I'm keeping my eye out for a new rear axle since I think my semi-floater is on it's way out and want to change to a full floater.
At the moment I've got 4.10's in a quigly running 33.5" tires. I really want to reduce my freeway RPM's and after looking at the OD units out there (and driven a few), I can't see myself going the Gearvendors or equiv route, so I'm wondering about 3.73 or 3.55. I very much doubt I'll run anything bigger than 34 or 35" tires, there is always 4low so I'm wondering why people don't do 3.55?
If I could be at or under 2k rpm at 80mph that would be perfect for freeway MPG, but I don;t think I'll achieve that, considering there is only a 200 rpm difference between 4.10 & 3.73 or 3.73 & 3.55, so best I could do it 400 rpm drop between 4.10 and 3.55 with 33" tires. I read a lot of people saying you'll trash your trans running 3.73 and big tires, but the 06 F350 (same year as my van same trans & ratios) came with 33" tires and 3.73 gearing, so not sure I believe that.
So what are the disadvantages for going from 4.10 to 3.73 or 3.55 ?
At the moment I've got 4.10's in a quigly running 33.5" tires. I really want to reduce my freeway RPM's and after looking at the OD units out there (and driven a few), I can't see myself going the Gearvendors or equiv route, so I'm wondering about 3.73 or 3.55. I very much doubt I'll run anything bigger than 34 or 35" tires, there is always 4low so I'm wondering why people don't do 3.55?
If I could be at or under 2k rpm at 80mph that would be perfect for freeway MPG, but I don;t think I'll achieve that, considering there is only a 200 rpm difference between 4.10 & 3.73 or 3.73 & 3.55, so best I could do it 400 rpm drop between 4.10 and 3.55 with 33" tires. I read a lot of people saying you'll trash your trans running 3.73 and big tires, but the 06 F350 (same year as my van same trans & ratios) came with 33" tires and 3.73 gearing, so not sure I believe that.
So what are the disadvantages for going from 4.10 to 3.73 or 3.55 ?