410 gears in an 04 D2

Shiftonthefly1

Well-known member
Aug 11, 2014
433
14
Las Vegas
I've got a set of matched locker/trutrac with 410s just sitting in my garage. I've also got an 04 with 32" tires. Has anyone run this combo? I'm a little worried about hwy RPMs. Debating weather or not to use the taller gears. I don't want to ruin my cruise RPM but I think the benefits may our way the costs. I do realize I have to upgrade the axles asap as well.

My truck sees about 50% off road and 50% on. I do take a few long hwy trips a year. So I don't want to give up my ability to take my trips.
 

Howski

Well-known member
Oct 19, 2009
1,483
209
Alabama
My buddy had 4.10's on his D2 with a 32" tire and I thought it ran a little high rpm on the highway. Certainly doable but be prepared to cruise slower or lose MPG
 

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
I've considered this as well, as I run 33" tires. I end up making some pretty long highway runs to find interesting offroad spots, and really don't want to be running at 3k+ RPM for hours at a time.

In truth, I'd rather get a better low-range gear for the T-case, so that high range is unaffected.

On the other hand, since you've got the spare diffs sitting in the garage, you can always give it a shot and see how it works for you.
 

Shiftonthefly1

Well-known member
Aug 11, 2014
433
14
Las Vegas
Yea that's kind of what I was afraid of. Dammit. I'll find one of those final drive calculators. I need to find out the ratio of the overdrive. Numbers are great I was just hoping to find someone actually running and driving this set up.
 

DiscoPhoto

Well-known member
Jul 23, 2012
2,581
76
Vermont
Yes, it was too high for me, it was slightly higher than I'd like when I switched to 33s afterwards. If I did it again, it'd be 3.9s
 

Nomar

Well-known member
Apr 23, 2004
6,078
13
Virginia
FWIW, one of my RRCs has 4.11s and 265/75s.

It's peppy around town and nice offroad but it eats up gas on the hiway.

Cant have it all.


.
 

Shiftonthefly1

Well-known member
Aug 11, 2014
433
14
Las Vegas
Thanks for the info gents. I was afraid of that answer. I was hoping the overdrive was enough to drop the RPM down enough for highway cruising. I read the build on Expedition Portal of that super clean white D1. He also praised the 3.9 gears. Seems like that's the sweet spot.

Fish I literally bought new tires a few days ago. I seriously considered a 33. But to get them to fit with little to know trimming...would require a 4" lift. Especially if I want the travel and flex. So I backed off to a 32. The 4" inch is a whole different animal. So 3" lift on 32s. Still a driver. Still capable. Reasonably priced. Allowing the budget for other odds and ends.
 

fishEH

Well-known member
Jan 26, 2009
6,927
201
Lake Villa, IL
Thanks for the info gents. I was afraid of that answer. I was hoping the overdrive was enough to drop the RPM down enough for highway cruising. I read the build on Expedition Portal of that super clean white D1. He also praised the 3.9 gears. Seems like that's the sweet spot.

Fish I literally bought new tires a few days ago. I seriously considered a 33. But to get them to fit with little to know trimming...would require a 4" lift. Especially if I want the travel and flex. So I backed off to a 32. The 4" inch is a whole different animal. So 3" lift on 32s. Still a driver. Still capable. Reasonably priced. Allowing the budget for other odds and ends.

33's should fit on a D2 with 2" lift pretty easily with little to no trimming involved.
 

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
33's should fit on a D2 with 2" lift pretty easily with little to no trimming involved.

I'd say it depends. There's a whole range of "2-inch lifts". Years ago, I had a used and admittedly tired OME setup that was widely accepted to give 3" of lift on a D2. I had plenty of rubbing in front on a 32" tire.

My latest D2 has a brand new 3" Terrafirma setup with true 33" tires, and had not a hint of rub with the stock bumpers (before I smashed them).
 

Shiftonthefly1

Well-known member
Aug 11, 2014
433
14
Las Vegas
I had these exact tires with a 3" TF lift on my last 04 D2. It fit perfectly. I am pretty sure that they'd rub at full lock and during full compression. The rears were always an issue with that stupid over hang quarter panel. But eventually I'd be doing a Greg Davis bumper and that would be trimmed up any way. I just don't want to get into my door or wheel arcs.
 

Shiftonthefly1

Well-known member
Aug 11, 2014
433
14
Las Vegas
I found a calculator and it asks for some basic info. I found that the ZF auto has a final OD ratio of .72:1. Sound right?

If so I'm doing something wrong. It says the engine RPM at 70 w a 33 inch tire and 4.10 gears is 2104. That's way off.
 

Blue

Well-known member
Mar 26, 2004
10,043
856
AZ
About a year ago I upped from 265/75/16 to 285/75/16s (about a 33") on my 2004 D2 with OME HD springs & OME shocks front & rear. Net lift when new was about 2.75-3" and no rub with the 265s. Springs have about 90,000 miles on them so they are far from fresh. Newer 285 front tires rubbed a bit on the forward plastic fender liner and on the back edges of my SG steel bumper. Also took out the stock windshield washer fluid bottle pretty quick. I filed down the SG bumper ends, trimmed the fender liner, and replaced the washer bottle with a genuine plumber pipe. Rear tires rubbed the exposed rubber seals on the rear door arch over the wheel well and the sharp metal edge bit into the tires a bit on full stuff. I just hammered down the metal edge. I had already trimmed the rear aluminum panel behind the rear tire for the GD steel rear bumper.
 

Olip

Member
Feb 11, 2016
9
0
PA
My D1 is running 32" tires with 4.11 gearing as well as a defender t-case with the 1:1.4 reduction. RPMs are over 3K at 80mph.
 

Shiftonthefly1

Well-known member
Aug 11, 2014
433
14
Las Vegas
My D1 is running 32" tires with 4.11 gearing as well as a defender t-case with the 1:1.4 reduction. RPMs are over 3K at 80mph.

That's it. I'm forgetting the damn transfer case is actually the final ratio. Not the transmission. So I would subtract the final ratio of the transmission from the final ratio of the transfer case correct?

*edit*

I found the Ashcroft website. That preloads everything. What a great tool.

So it looks like with a 33" tire final RPM at 80 is 2954. With a 32" it's 3054. 2900 isn't too bad I don't think. It's about 26-27 stock? Ish?
 
Last edited:

fishEH

Well-known member
Jan 26, 2009
6,927
201
Lake Villa, IL
That's it. I'm forgetting the damn transfer case is actually the final ratio. Not the transmission. So why would subtract the final ratio of the transmission from the final ratio of the transfer case correct?

What calculator are you using? The Ashcroft one is pretty straightforward.
Run it the first time as a stock truck with stock gearing on stock sized tires to get a baseline. Then start changing the variables and decide if you can live with the RPM difference.
 

Frank4

Well-known member
Jul 10, 2012
61
1
Memphis
I've got a set of matched locker/trutrac with 410s just sitting in my garage. I've also got an 04 with 32" tires. Has anyone run this combo? I'm a little worried about hwy RPMs. Debating weather or not to use the taller gears. I don't want to ruin my cruise RPM but I think the benefits may our way the costs. I do realize I have to upgrade the axles asap as well.

My truck sees about 50% off road and 50% on. I do take a few long hwy trips a year. So I don't want to give up my ability to take my trips.

410's and 32" tires? Is this a joke? You would be running 3500rpm + doing 55mph with a that set up. Was this a joke? Seriously, 410 gears and 32" tires?
 

Blue

Well-known member
Mar 26, 2004
10,043
856
AZ
Maybe the question is, "Why in the hell would you need 4:10s with 32s?"
 

Shiftonthefly1

Well-known member
Aug 11, 2014
433
14
Las Vegas
This set was intended for a different truck. So I have them all set up and ready to bolt in. Plus the Detroit and Trutrac are an obvious upgrade over the open diffs