Gear Ratio Suggestions
Thread Starter
|
5th Wheeling
Joined: Mar 2024
Posts: 39
Likes: 3
Gear Ratio Suggestions
Hello everyone, i currently have a 73’ f100 paired with a 390fe and a NP435 on 3.25 open differential. I am wondering if it’s a smart option to bump it up to a helicol 3.50 ratio? Currently I have 265/65/16 wheels on the truck and it does 80mph at around 3,000rpms on the highway but I do feel the acceleration is quite slow to get up to higher speeds at 4th gear anything after 2.8k rpms. If anyone had any suggestions on what you guys run or what you guys would recommend thank you all for reading.
Logistics Pro
Joined: Jun 2004
Posts: 4,840
Likes: 3,455
From: South Central Utah
What are you looking for or what is the primary use of your truck?
Traveling, power, towing???
I think 3.73 are ideal gears for a truck.
With you 29.5" tall tires,
3.73 gears
80 mph 3400 rpm
65 mph 2750 rpm
45 mph 1900 rpm
4.10 gears
80 mph 3700 rpm
65 mph 3000 rpm
45 mph 2100 rpm
Traveling, power, towing???
I think 3.73 are ideal gears for a truck.
With you 29.5" tall tires,
3.73 gears
80 mph 3400 rpm
65 mph 2750 rpm
45 mph 1900 rpm
4.10 gears
80 mph 3700 rpm
65 mph 3000 rpm
45 mph 2100 rpm
Last edited by Rubiranch; Mar 22, 2026 at 05:17 PM.
Thread Starter
|
5th Wheeling
Joined: Mar 2024
Posts: 39
Likes: 3
I use the truck for occasional uses like 4-5 times a month but no hauling, the truck is mainly on the highway but I would like to feel some power throughout the gears from time to time. I’ve read some people stick with the 3.25 gears because the highway friendly rpms but like I said I really don’t feel much of a punch when in street use although I understand I can’t have both low rpms at highway and very punchy off the line.
Hotshot
Joined: Feb 2004
Posts: 10,861
Likes: 2,624
From: The Shenandoah Valley
I think mine hit 80 once in the 1980s. It was a long pass, knocked down a couple TTs and a white PU pulling a camper on one of the few passing zones of that road ... in Georgia.
3.50 gear, Auto, 31" tires, 2,450 rpm = ~60 mph.
3.50 gear, Auto, 31" tires, 2,450 rpm = ~60 mph.
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,271
Likes: 5,822
From: S/W Missouri, Polk county
Trending Topics
Tuned
Joined: Dec 2012
Posts: 345
Likes: 184
If it’s mostly hwy, sounds like an overdrive should be in your future.
Im running 3.54:1 on 32.5” tires with 1:1 final, and turn 2200 rpm at 60, 2550 at 70, and just shy of 3k at 80. Plenty of scoot with a rebuilt big block and 4spd.
Try playing with your numbers here: Novak Conversions
Im running 3.54:1 on 32.5” tires with 1:1 final, and turn 2200 rpm at 60, 2550 at 70, and just shy of 3k at 80. Plenty of scoot with a rebuilt big block and 4spd.
Try playing with your numbers here: Novak Conversions
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Hotshot
Joined: Feb 2004
Posts: 10,861
Likes: 2,624
From: The Shenandoah Valley
.......Im running 3.54:1 on 32.5” tires with 1:1 final, and turn 2200 rpm at 60, 2550 at 70, and just shy of 3k at 80. Plenty of scoot with a rebuilt big block and 4spd.
Try playing with your numbers here: Novak Conversions
Try playing with your numbers here: Novak Conversions
OK, so I guess it's close enough, my tach and speedo needles are some bit wider.
Last edited by tbear853; Mar 25, 2026 at 01:16 PM.
Thread
Thread Starter
Forum
Replies
Last Post
jowilker
1961 - 1966 F-100 & Larger F-Series Trucks
2
Nov 8, 1999 09:06 AM