I am tuned, PHP tunes in fact. Not going to turn this into a conversation over whose tunes are better. I'm not lacking power. But at 65-70mph in OD I am always right there on the verge of needing to downshift if I come up on a hill of any decent size. I also still get a bit of turbo surge because of the lower rpms, even with the wicked wheel. When I get up to about 75mph, the rpms are higher and the truck will pull just about any hill without needing to downshift, but I don't like pulling my load at that high of a speed. As was mentioned earlier, I can drop down out of OD, but then I am limited to about 60mph or the rpms get so high it is killing fuel mileage. Not long ago I went on a trip with the 5er that was mostly backroads and the speed limit was 55mph. Towing with OD off at that speed was perfect. Basically I am trying to get my truck to run like that at 65-70mph when I'm on the interstate (which is where most of my towing is done).

 

Interesting Robert - I know that feeling well. When pulling the camper to the Black Hills I know I need to be at or above 70mph/2000 rpms or I will slowly start to loose momentum when I come up on the grades. I guess it is always a bit of give and take when it come to the gear ratios - fuel milage - rpms, etc.....

Be safe over there man.......

 

Bob, I think the 4:30s would be perfect. Like you've said if you tow in OD the truck is always on the edge of wanting to downshift. IMHO this gear change will will move you up to the sweet spot(2200-2500) and no more worries. i know I can play with gear combos on mine and 67MPH at 2400 RPM will get me better MPG than 70 at 2000. we're not towing a boat here, so RPM is important to keep the truck efficient. you've got a load back there and alot of wind resistance. RPM is your friend.
Good idea about finding an axle off a V10 truck.

Barney

 

Sorry, I did not see you had a tuner, what RPM were you running with stock tires, verses 33'' tires you have now. I run a 265-70-16 on mine now, made a world of difference in pulling hills and towing.


Changing tire size from one size to another has direct effect on power and driveability. The following chart, in conjunction to my Gear Ratio Calculator, will help you select the optimum gear ratio to provide the same level of performance (power and torque) that you are experiencing today.
To use the chart, first determine your current gear ratio and actual tire diameter. Second, follow the rows and columns to locate your current (approximate) RPM at 65 mph. Third, find the row corresponding to your desired tire size on the chart and scan the row to find the RPM closest to your original. The gear ratio listed at the top of that column will provide you with the same performance your Jeep has today.

If want to use gears that will give more power or better fuel economy, use the gear ratio listed to the right or left of the optimal gear ration accordingly.


Tire Diameter Gear Ratio
2.35 2.73 2.94 3.07 3.21 3.31 3.42 3.55 3.73 3.91 4.11 4.27 4.56 4.88 5.13 5.29 5.38 5.71 6.17 7.17
22 2333 2710 2919 3048 3187 3286 3395 3524 3703 3882 4080 4239 4527 4845 5093 5252 5341 5668 6125 7118
23 2231 2592 2792 2915 3048 3143 3248 3371 3542 3713 3903 4055 4330 4634 4871 5023 5109 5422 5859 6808
24 2139 2484 2675 2794 2921 3012 3112 3231 3394 3558 3740 3886 4150 4441 4668 4814 4896 5196 5615 6525
25 2053 2385 2568 2682 2804 2892 2988 3101 3259 3416 3590 3730 3984 4263 4482 4621 4700 4988 5390 6264
26 1974 2293 2470 2579 2696 2780 2873 2982 3133 3284 3452 3587 3830 4099 4309 4444 4519 4796 5183 6023
27 1901 2208 2378 2483 2597 2677 2766 2872 3017 3163 3325 3454 3689 3947 4150 4279 4352 4619 4991 5800
28 1833 2129 2293 2395 2504 2582 2668 2769 2909 3050 3206 3331 3557 3806 4001 4126 4196 4454 4813 5593
29 1770 2056 2214 2312 2417 2493 2576 2674 2809 2945 3095 3216 3434 3675 3863 3984 4052 4300 4647 5400
30 1711 1987 2140 2235 2337 2410 2490 2584 2715 2846 2992 3109 3320 3553 3735 3851 3917 4157 4492 5220
31 1656 1923 2071 2163 2261 2332 2409 2501 2628 2755 2896 3008 3213 3438 3614 3727 3790 4023 4347 5051
32 1604 1863 2007 2095 2191 2259 2334 2423 2546 2669 2805 2914 3112 3331 3501 3610 3672 3897 4211 4894
33 1555 1807 1946 2032 2124 2191 2263 2349 2469 2588 2720 2826 3018 3230 3395 3501 3561 3779 4083 4745
34 1510 1754 1889 1972 2062 2126 2197 2280 2396 2512 2640 2743 2929 3135 3295 3398 3456 3668 3963 4606
35 1466 1704 1835 1916 2003 2065 2134 2215 2328 2440 2565 2664 2845 3045 3201 3301 3357 3563 3850 4474
36 1426 1656 1784 1862 1947 2008 2075 2154 2263 2372 2493 2590 2766 2961 3112 3209 3264 3464 3743 4350
37 1387 1611 1735 1812 1895 1954 2019 2095 2202 2308 2426 2520 2692 2881 3028 3123 3176 3370 3642 4232
38 1351 1569 1690 1764 1845 1902 1966 2040 2144 2247 2362 2454 2621 2805 2948 3040 3092 3282 3546 4121
39 1316 1529 1646 1719 1798 1854 1915 1988 2089 2190 2302 2391 2554 2733 2873 2962 3013 3198 3455 4015
40 1283 1491 1605 1676 1753 1807 1867 1938 2037 2135 2244 2331 2490 2664 2801 2888 2937 3118 3369 3915
41 1252 1454 1566 1635 1710 1763 1822 1891 1987 2083 2189 2275 2429 2599 2733 2818 2866 3042 3287 3819
42 1222 1420 1529 1596 1669 1721 1778 1846 1940 2033 2137 2220 2371 2538 2668 2751 2798 2969 3208 3728
43 1194 1387 1493 1559 1630 1681 1737 1803 1894 1986 2087 2169 2316 2479 2606 2687 2733 2900 3134 3642
44 1166 1355 1459 1524 1593 1643 1698 1762 1851 1941 2040 2119 2263 2422 2546 2626 2670 2834 3063 3559

 

I started off this thread thinking that 4:10s would be the best, but Barney you have me convinced as well.
I vote the 4:30s. The engine will thank you very much by pulling like a freight train for you.
Especially if 95% of the trucks use is pulling the trailer.
If it were more of a 50-50 thing then I would say 4:10s or even 3.91.

 

GREAT information guys! Thanks a ton. I dont really want to drop back to 265's. I have a leveling kit installed and really love the way my truck looks. 265's would be too small on my truck. I realize it would affect my rpms in a positive manner if I did go back, but I'm more willing to regear than do that. Dan, thanks for chiming in, the 4.30's are sounding more appealling and the reason I started this thread. I don't want to go to all this trouble and not feel like the gains were significant enough. That being said, I would think it would be easier for me to find a used axle with 4.10 than with 4.30, right? What is the most common ratio in these gas trucks? If you compare total miles, I would say 80-85% is towing the 5er. I do use the truck for other things around town, but we generally go on trips with the 5er that are hundreds of miles away, so it takes probably 10 around town trips to equal one RV trip.

Rich, thanks for the support, I'm keeping my head on a swivel, haha !

 

Not sure how me having a manual differs from your automatic....but for me....(4.10 gear)...at 70mph the rpm needle is pointing straight up (2200-2300) which is about perfect....if I see a bigger hill up ahead I may up the rpms a bit but don't have to. Having said that....I wish I had 4.30s because at 50-60 mph on back roads it struggles a bit in 6th gear (1800-1900rpm) and in 5th the rpms are a little high for my taste (2500+).

 

Shawn, what size tires do you have? I'm thinking they are smaller than my 285's, right? I think that would drop my RPMs off of your 22-2300 in OD.

 

yep...265's

 

Can anyone confirm whether the final drive ratio is the same between a manual and an auto trans?

 

Bob,
I can relate to everything you describe about towing your load. If I didn't know any better I would say you must be driving my truck around.

Sounds like good advice that you've been getting. I'll throw in my $0.02 if you don't mind...

I've towed my trailer with 3.73 and 4.10 gears. The 4.10 set is much nicer for pulling. With the lower gear set, the power band around 68 mph was ideal and pulled up and over small hills with ease. That truck had the stock 265 series tires though. Since you are running larger tires, I think 4.30 would put you right where you want to be.

 

They are pretty close.
3rd on the 4R100 is 1:1 (same as 5th gear on the ZF6)
4th on the 4R100 is 0.71:1 with 6th gear in the ZF6 being 0.72:1

 

Awesome input Greg, thanks!

 

Is there a difference between an 01 and an 03 as far as D50 or D60? I have a D50 https://www.ford-trucks.com/forums/1...est-gears.html heres another thread I started a long time ago and most of the guys on this thread were on that one too. Clay on post #12 said to make sure I got a D50 and not a D60. Can someone set me straight here?

 

I agree with Dan and Barney. The King Ranch went to 4.30 and my boy was going there to but he has 35 tires so he's going 4.56. He also pulls 18000# when fully loaded so it is a big help. His story is a different deal he has a 6.0 riased truck and has spent everything to make it do this. I told him he needs 550. Chet