Rear axel gearing

[reelchef67]

I have 3,73 on 2wd with 245's is that ok?

[BajaSportsmobile]

Originally Posted by reelchef67

I have 3,73 on 2wd with 245's is that ok?

Absolutely!

[torboschen]

I have to agree with Ramsey (as usual)... my 2001 4x4 GTRV E250 (4.10) with 33" rubber really struggled to get off the line with a trailer. It also had trouble staying in OD down the highway. I dropped tire size to 265 70 17s and it seems far happier off the line. interestingly, fuel economy improved slightly from 12.5 mpg at 75mph to over 13 (yes I corrected for the speedo being a couple off).
Im not sure if its the narrower profile of the tire or the engine just being more in its torque range... Flip side is I now have to use 4x4 in the sand where previously it floated better.... Still the rig spends 99.8 of its miles on the highway....
I'm sure thats a topic with many opinions.
T

[mkuper]

My van is a 1998, motor is the same. 4.56 just seems pretty deep, I won't be pulling a trailer of any significant weight. I still think I am going to go with 4.10

[Chance]

Originally Posted by mkuper

joeH the calculator and info in the trutrack was helpful. I am more concerned with gear ratio selection. Currently with the 3.55 gears @ 70 MPH the engine runs about 1800 RPM. I don't think the converter is even locking up and I cant use overdrive unless I am driving on a perfectly flat road with nonexistent headwind. From the aforementioned calculator @70MPH 4.10=2046 RPM, 4.30=2145 RPM, 4.56=2275.
Which one would be the best choice?
Mike

In my opinion using RPMs alone to determine best gearing is not very effective. There's a lot more to it than matching someone else's engine speed.

Beyond that I'd say you have to define what "best" means to you. Best fuel economy isn't achieved with same gear that prevents frequent downshifts out of OD, or offers best acceleration, etc... What do you want to accomplish?

If you know what MPGs you get at 70 MPH, you can then do a little reverse engineering to find out how hard your engine is working while cruising at 70 MPH. If you have a scan gauge even better. From that you can then choose a good overall compromise based on your personal objectives (i.e. -- fuel economy vs acceleration, etc..).

Personally, I'd go with the lowest gears that won't make a huge difference in fuel economy.

[mkuper]

Took me a while to get the $$ together for the gears, locker, install kit. A few home improvements took priority. I went to Moab last weekend. The 4.10 gears and locker combo worked great. I maintained 70-75 on the interstate at about 2150 to 2300 rpm. The shifting was much improved and is stayed in OD much better then before.
Thanks for the advice.
Mike