Choosing a Gear Ratio for 36s

[ozziemo27]

I am SAS'ing my 99' Ranger with a 4.0 with an auto tranny sooner or later (manual tranny someday). I have a set of 36x12.50x15 TSL Radials I am going to run. I am torn between 4.88s and 5.13s. This rig is/will be my daily driver so I want to gain back some fuel economy (4.10 gears and 33s has been getting me about 12 at best) as well as decent performance. I talked to a gentleman with an exploder who was getting between 15-17 mpg with 5.13s (which i could definitely live with and would be fantastic). I want to see what anybody else has gotten with 36s for fuel econ with 4.88s? How is the performance with the 4.88s? I did the calculator in the tech library and it pointed to 4.88s. I am just looking for some other opinions. Anybody got anything? I do some highway driving occasionally so that needs to be considered.
- thanks for any input fellas.


Edit: Wow, I'm such a n00b. If a mod sees this, can you move this to a more appropriate forum, like general? If not, I'll contact somebody.

 

[MAranger]

The biggest variable in fuel mileage will be how you use your foot. Do you have a sitck or an auto?

I'd suggest doing a little math. For best highway fuel econ, you'll want to be cruisin 65 mph at 1500-2000k rpms.

So here comes some math:

engine rpm x (1/ 5th gear trans ratio) x (1/ r&p) x (pi x tire diameter) x
= ____ inches per minute

Convert that to mph by:

in/min x (1 ft /12in) x (1 mi /5280 ft) x (1 hr /60 min) = mph (at ____rpm with____ tires and ____blank r&p gears in _____ trans gear, tcase in hi range 1;1)

Also look at your low range, is your current setup low enough for you, or do you want a little lower. Keep in mind of you want way lower than you will sacrifice highway performance.

The low range calculation is the same as above, but you need to factor in the low gear reduction, insert { x (1/ low range ratio) } after thrans ratio.

Do these for your 4.10's and 33's first, then your 36's and 4.88/5.13. I think the low range on the 54 is 2.4:1. The ratios are in the tech library for whatever trans and tcase you have. Just to clarify, the (1/_____) means one divided by ______. I did it this way to keep track of the units and make sure i'm feeding you the right bs.

 

[pillen140]

I have 3.73's with 33s. its a dog, but not that bad, and i only have a 3.0! i get about 15/16mpg. gonna do 35's and 4.10s pretty soon here. i know itll be a dog. not that its a ranger, but my friend has a wrangler with 36's, and 4.88's, he says it revs too high on the highway for his liking, so i dont know how 5.13's would do..... i know its a jeep, but hope it will help.

 

[Sasquatch_Ryda]

5.13's.

Better safe than sorry. You might want to go larger with the tire seize eventually.

 

[wahlstrom1]

5.13's, no point in wasting the money on 4.88's when your gonna want more gear later..... ask me how I know...

 

[ozziemo27]

The biggest variable in fuel mileage will be how you use your foot. Do you have a sitck or an auto?

I'd suggest doing a little math. For best highway fuel econ, you'll want to be cruisin 65 mph at 1500-2000k rpms.

So here comes some math:

engine rpm x (1/ 5th gear trans ratio) x (1/ r&p) x (pi x tire diameter) x
= ____ inches per minute

Convert that to mph by:

in/min x (1 ft /12in) x (1 mi /5280 ft) x (1 hr /60 min) = mph (at ____rpm with____ tires and ____blank r&p gears in _____ trans gear, tcase in hi range 1;1)

Also look at your low range, is your current setup low enough for you, or do you want a little lower. Keep in mind of you want way lower than you will sacrifice highway performance.

The low range calculation is the same as above, but you need to factor in the low gear reduction, insert { x (1/ low range ratio) } after thrans ratio.

Do these for your 4.10's and 33's first, then your 36's and 4.88/5.13. I think the low range on the 54 is 2.4:1. The ratios are in the tech library for whatever trans and tcase you have. Just to clarify, the (1/_____) means one divided by ______. I did it this way to keep track of the units and make sure i'm feeding you the right bs.

I guess I'll have to try that out, thats alot of math =O.

5.13's.

Better safe than sorry. You might want to go larger with the tire seize eventually.

Yea, I was thinking that, I can still milk some fuel econ out of that.

5.13's, no point in wasting the money on 4.88's when your gonna want more gear later..... ask me how I know...

Yea. True.

 

[feellnfroggy]

I run 33's now with 3.55's. I would like 4.10's. More gear is better, you can always go to a bigger tire if you have to much gear.

 

[Sasquatch_Ryda]

33's should have 4.56's.

 

[Andres629]

5.13

I wish I did.

 

[ozziemo27]

5.13

I wish I did.

I can imagine 4.56s with 35s and a 2.9 would suck! 4.56s with 33s and a 4.0 is prime.

 

[Andres629]

Well... it doesn't SUCK... but 5.13 would be much better.

 

[CheapThrillB2]

I can imagine 4.56s with 35s and a 2.9 would suck! 4.56s with 33s and a 4.0 is prime.

Try bias 36's, a clapped out 4.0L with 350K on it, and 3.73s and a 5spd...

It was 4-lo or don't even bother trying to drive it down hill


5.13's get my vote.

 

[ozziemo27]

Try bias 36's, a clapped out 4.0L with 350K on it, and 3.73s and a 5spd...

It was 4-lo or don't even bother trying to drive it down hill


5.13's get my vote.

Lol, that sounds horrible....! Jeff's Bronco Graveyard has my stuff shipped!

 

[The Jester Race]

5.13's.

Better safe than sorry. You might want to go larger with the tire seize eventually.

Agreed. I'm glad I went with 5.13's. I only dropped 2MPG going from a 2" lift on 31"s to a full width SAS on 37"s. I'm getting just over 15MPG city. FWIW

-Jester

 

[scarface]

agreed

Agreed. I'm glad I went with 5.13's. I only dropped 2MPG going from a 2" lift on 31"s to a full width SAS on 37"s. I'm getting just over 15MPG city. FWIW

-Jester

5.13 in my 89 2.9 with the original speedo gear and 35"yokahamas gps's my speed exactly as the speedo shows