Question on Gears

[NickRanger89]

I have a 93 Ranger STX 4.0L 4x4. I'm currently running 3.73 gears on 33" Thornbirds. I'm planning on going with 35" BFG A/T's and was wondering what/if I should upgrade gears? If so what ratio would work best? The truck is used for daily driving (I don't drive much) and going out once a month. Also would I have to change ratio in the front as well? Thanks and any help would be great!

 

[Rifleman]

I have a 93 Ranger STX 4.0L 4x4. I'm currently running 3.73 gears on 33" Thornbirds. I'm planning on going with 35" BFG A/T's and was wondering what/if I should upgrade gears? If so what ratio would work best? The truck is used for daily driving (I don't drive much) and going out once a month. Also would I have to change ratio in the front as well? Thanks and any help would be great!

On a 4x4 you are best to keep all tires sizes and gear ratios the same all the way around, changes to the front and rear ratios must be made to match and all four tires should be the same diameter to prevent axle failure.

 

[NickRanger89]

^I understand that, all the tires will be the same size, 35x12.50x15 What is a good ratio for that size? I read on this forum that some guy went to 35's with 3.73 gears and the tranny lasted 5k miles before it went. Now thats got me thinkin! lol

 

[Rifleman]

His tranny would have failed anyway. He was likely enjoying the new found torque a little too much. My 275.75.R16 on my 2006 4.0 are easily enough to tear stuff up. I've got a 4.10 LSD...

 

[NickRanger89]

It would of failed anyway? Why is that? I have 106k on my tranny ikes!

 

[Rifleman]

It would of failed anyway? Why is that? I have 106k on my tranny ikes!

It is just unlikely the gearing and tires had much to do with it as many many many others have done it without issue. The higher the ratio number is, the more torque (wheelspin power) you put to the ground. Spinning the rubber off big tires is not what the drivetrain of a Ranger was meant to do. Not to mention the larger tires increase traction which stresses the components more. When doing wheelspins, if the tire is grabbing more traction than the clutches in the transmission, BOOM. He probably was putting his new-found torque to improper uses.

I don't know the specific post you're talking about, but many folk have done what you are doing without issue and that one seems to be more of a random incident.

 

[NickRanger89]

Geeze that went right over my head! Haha idk why but I completly forgot about everything else that can happen. Ugh I feel stupid, I'll go sit in the corner now. Thanks! Oh and Rep'd!

 

[4x4junkie]

Deeper axle gears do take a tremendous load off the transmission (NOT regearing for bigger tires will increase your chances of the trans failing, not to mention will put your MPG deep into the crapper).

For 35" tires on the 4.0L V6, I would suggest 4.88:1 gears. These should put your RPM at the engine's torque peak for best power and MPG during highway use. If you do a lot of offroading (or towing), you might also consider 5.13 gears.

 

[Dieselinjected]

With a 35'' tire a 4.56 gear ratio would pretty much almost put you back to the same as stock. Having said this I agree with 4x4junkie that 5.13's would be an excellent gear ratio if you were doing lots of 4x4ing and want the most out of your truck.

 

[4x4junkie]

That is true, but 'stock' is already geared a bit too tall on many of these trucks (an extreme example is those having 3.27 gears, which just sucks donkey nuts). Then you're adding some extra wind drag from the truck being taller and the tires being wider. 4.88-5.13 is pretty much the ideal when all these factors are considered together.