Best use of a 31-spline posi carrier?

[ZMan]

If you're gonna do occasional off roading then switchin to 3.73s would be a plus. I too have a '92 4.0l that came factory with 3.08s, funny thing is I too got a 31 spline carrier by mistake, except I didn't pay for it.

I switched to 3.73s in mine, the ONLY thing it did for me was drop my gas mileage considerably (I only got 19mpg highway at 70mph), didn't make a bit of difference at the track. So if its mostly a street truck, keep your tall gears.

 

['92Custom]

If you're gonna do occasional off roading then switchin to 3.73s would be a plus. I too have a '92 4.0l that came factory with 3.08s, funny thing is I too got a 31 spline carrier by mistake, except I didn't pay for it.

I switched to 3.73s in mine, the ONLY thing it did for me was drop my gas mileage considerably (I only got 19mpg highway at 70mph), didn't make a bit of difference at the track. So if its mostly a street truck, keep your tall gears.

What were you getting before the gear change?

I can get 20 to 24 at 65-75 depending on wind and temperature. But it really sucks around town, usually 16 to 20 but sometimes as low as 14 in the winter. Granted, this is an economy car compared to my Land Rover, I pray for double digits on that one.

There is a strong probability that I will fit it with larger tires to fill up the wheel wells in the future, probably 235/75-R15s or maybe just a 27x8.50R14... But if I get the tools and learn to regear it myself, perhaps you are right that I should keep the 3.08s for now, save on parts and keep my MPGs. If I need new gears later, do it again...

My friend has 3.73s in his '98 and he's going to 31s and 4.56s soon. Just figured I'd snag his gears and use them in mine. Were you faster off the line but just had to shift more? Surprising the gear change wouldn't help your trap times.

 

[ZMan]

What were you getting before the gear change?

I can get 20 to 24 at 65-75 depending on wind and temperature. But it really sucks around town, usually 16 to 20 but sometimes as low as 14 in the winter. Granted, this is an economy car compared to my Land Rover, I pray for double digits on that one.

There is a strong probability that I will fit it with larger tires to fill up the wheel wells in the future, probably 235/75-R15s or maybe just a 27x8.50R14... But if I get the tools and learn to regear it myself, perhaps you are right that I should keep the 3.08s for now, save on parts and keep my MPGs. If I need new gears later, do it again...

My friend has 3.73s in his '98 and he's going to 31s and 4.56s soon. Just figured I'd snag his gears and use them in mine. Were you faster off the line but just had to shift more? Surprising the gear change wouldn't help your trap times.

I averaged 20 with normal country road driving before the gear change, and higher on the highway. If youre going bigger tires than yes def upgrade the gears. these engines definitely do not like spinning 3k rpms at highway speeds though, which is why they had 3.08s.

Changing gears took .2 off my 60ft time, that is literally the only thing it did, trap times and speeds were the same.

 

[94 lngbd]

92 CUSTOM: My friend has 3.73s in his '98 and he's going to 31s and 4.56s soon.


He shouldn't need to go to 4.56 for 31s, even his 3.73s should be fine ,but a more suited gear would be 4.10s