4.88 or 5.13 Gears?

[Honor2afault]

5.13 for 37's

 

[RockinAZJK]

If you're running 37s try looking at the RPM for 36" tires or even between 36" and 35" tires.

This.
Those charts are for true measurements - not what's on the sidewall. So measure your tire and then reference the chart again

 

[TormentedCrawler]

Everywhere I've researched showed people running 3.8L switching to 5:38 for 37" tires. Not sure what's everyone thoughts are

 

[Colorado2003]

Same as Ddays on the RPMs.

 

[PabloK]

Now this might be a really stupid question but an honest one that I would appreciate some feedback from you guys.

Is running our Jeep's at higher rpms really that bad for them? Yes your putting more stress on the engine and some of the components but if she stays cool and your good about changing fluids is it really that bad for it? Are they designed by the factory to run 90% of their life under 3,000 rmps?

Just curious... I run 4.56 gears with a ripp supercharged and I drive the shit out of it. I'll cruise at 80 (3100-3200 rpms) for 200-300 miles stretches.... am I asking for trouble?

I personally wish the engineers would be accounting for us folks that regear and design the engine according... but who knows.

Any thoughts?

Pete

 

[JohnnyWest]

We have 5.38 gears on our 3.8 with 37's and 5.13 on our 3.6 with 37's. I don't think you can run 5.38 on a D30 though, not sure.

Here is the chart for a 3.8-

 

[jknikos]

Everywhere I've researched showed people running 3.8L switching to 5:38 for 37" tires. Not sure what's everyone thoughts are

5.38s are not available for a d30 and even on a d44 the pinion will be tiny! As far as the gear ratio itself i think if you have a 3.8 auto you should use 5.38s for 37inch tires and 5.13 for 35inches.