Gear ratio upgrade
Thread Starter
|
Tuned
Joined: Nov 2004
Posts: 444
Likes: 1
From: Nelson, BC, Canada
Gear ratio upgrade
Hi all!!!
Looking for some advice and/or experience from someone who may have gone through this.
My truck has stock 3.73's, as you can well imagine this doesn't bode well with 38 inch tires. At any rate, it was time to do my brakes (rotors and pads) front and rear as well as my ball joints. WELL!!!!! I take off my first rear wheel and what do I see, gear oil on the emergency brake shoes. UGH!
So, since I have to look at seals anyway, and should get the right gear ratio in the diffs for these tires, I figure I may as well rebuild the diffs while I'm at it.
So, the question is this. Are there any implications parts wise in going from 3.73's to say 4.56's? Do I have to change the carrier to accomodate gear sets over 4.10's?
The reason I ask is that when I went to pick up the rotors, I was asked if the ratio was 3.73 or 4.10, cause if the ratio was higher it was a different set of rotors needed. So this got me thinking, if I do rebuild the diffs and go with 4.56's, what else may need to be changed aside from the rotors?
Your help, as ALWAYS, is greatly appreciated.
Cheers!
:-)
Looking for some advice and/or experience from someone who may have gone through this.
My truck has stock 3.73's, as you can well imagine this doesn't bode well with 38 inch tires. At any rate, it was time to do my brakes (rotors and pads) front and rear as well as my ball joints. WELL!!!!! I take off my first rear wheel and what do I see, gear oil on the emergency brake shoes. UGH!
So, since I have to look at seals anyway, and should get the right gear ratio in the diffs for these tires, I figure I may as well rebuild the diffs while I'm at it.
So, the question is this. Are there any implications parts wise in going from 3.73's to say 4.56's? Do I have to change the carrier to accomodate gear sets over 4.10's?
The reason I ask is that when I went to pick up the rotors, I was asked if the ratio was 3.73 or 4.10, cause if the ratio was higher it was a different set of rotors needed. So this got me thinking, if I do rebuild the diffs and go with 4.56's, what else may need to be changed aside from the rotors?
Your help, as ALWAYS, is greatly appreciated.
Cheers!
:-)
Post Fiend
Joined: Jul 2005
Posts: 14,582
Likes: 12
From: 21791
my only educated guess would be the fact that all SRW diesels had the 3.73, and the duallies had different ratios, most common being 4.10. the rotors on the D80 axle are EXTREMELY different from the Sterling 10.25 axle, and i should know.
but to the gearing, i dont think you need anything more than a ring and pinion, and a master rebuild kit (or whatever they call it). i would have a shop do my gearing just because it is hard to measure backlash and the gear mesh patterns. i do not have tools for that so that is why i would have it done for me, not that i am incapabe or anything. new bearings and seals are usually used.
but to the gearing, i dont think you need anything more than a ring and pinion, and a master rebuild kit (or whatever they call it). i would have a shop do my gearing just because it is hard to measure backlash and the gear mesh patterns. i do not have tools for that so that is why i would have it done for me, not that i am incapabe or anything. new bearings and seals are usually used.
Posting Guru
Joined: May 2006
Posts: 2,274
Likes: 1
From: Milroy, PA
strokins pretty much got it i would say, if you changed gears in your rear differential, yuo deffinetly would not hav eto change any of the brakes, i would replace all carrier/ pinion bearings, but from there out nothing changes, besides the fluid that is. Nice thing about changing gears ina full floating rear such as these, dont need to take apart brakes to change gears, although since you need to replace seals, you however will have to remove brakes. I replaced a gearset in a 1/2 ton chevy, its not a big deal so long as you have the proper tools!
Thread Starter
|
Tuned
Joined: Nov 2004
Posts: 444
Likes: 1
From: Nelson, BC, Canada
Thanks guys. On another note, what ratio are people running with 38's to get the RPM back in the stock range (read: proper power band)?
It seems to me that there are specific carriers to support different gear ratio ranges. For example, Detroit locker states different diffs for 4.10 and down as opposed to 4.56 and up, hence my question, the liklihood of my needing to change my stock carrier (currently set up with 3.73's falling in the 4.10 and down category) to a different carrier to support 4.56 (or greater) is pretty high hey?
Which lends itself to the next question of who's running which ratios with 38's and how do you like it? Are 4.10's enough or are 4.56's better?
Thanks again. :-)
It seems to me that there are specific carriers to support different gear ratio ranges. For example, Detroit locker states different diffs for 4.10 and down as opposed to 4.56 and up, hence my question, the liklihood of my needing to change my stock carrier (currently set up with 3.73's falling in the 4.10 and down category) to a different carrier to support 4.56 (or greater) is pretty high hey?
Which lends itself to the next question of who's running which ratios with 38's and how do you like it? Are 4.10's enough or are 4.56's better?
Thanks again. :-)
Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
I know of at least one guy (not a member) who has 37" tires and went with 4.56 gears. As far as I know, he's pretty pleased with them. I'd imagine there is some sort of equation or online calculator that you could use to tell you what gears would bring you back in line with stock, given the tire size.
Thread Starter
|
Tuned
Joined: Nov 2004
Posts: 444
Likes: 1
From: Nelson, BC, Canada
I know 4lo.com has some good calculators on it AND, according to the one, with 38 inch tires, running in overdrive (.71 for the E4OD), at 60mph with the transfercase at 1:1, it suggests I need 5:13's to get at 1932 RPM?!?!?! Is that right? 5.13's sounds a bit odd. For you guys running 38's with 4.10's and liking it, what are your RPM's in overdrive at 60 mph? (Automatics chime in).
Cheers!
:-)
PS - Anyone have thoughts on the different carrier for different gear ratio ranges?
:-)
Cheers!
:-)
PS - Anyone have thoughts on the different carrier for different gear ratio ranges?
:-)
Trending Topics
Thread Starter
|
Tuned
Joined: Nov 2004
Posts: 444
Likes: 1
From: Nelson, BC, Canada
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
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
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski