Looking for input on gear ratio and lockers

[gosborne]

1999 Jeep TJ. Dana 35 rear & Dana 30. Looking for the right gear ratio and for the best of both worlds. In Montana there is lots of icy roads on and offroad. Traveling to hunting areas can involve lots of highway travel. I'm running 33" tires and right now open diff. with 3.73 gears. 5 speed manual 4.0l (runs 2000 RPM at 65mph). After lots of research on lots of Forums. It gets pretty confusing. Moderate off roading. old logging roads.deep snow and narrow icy inclines/declines. Loose rocky travel. I'm upgrading to chromoly axles front and rear. Thinking about Detroit Trutrac LSD front and rear. 4:10 or 4:56 gear change.

My upgrades already are: RC 4" coil springs, Advance Adapter SYE , Adams drive shafts (front & rear),Core4x4 front and rear control arms (upper & lower),RC adjustable track bars, rear disc brakes

Not going to any bigger tires,no rock crawling (nothing extreme anyways). Not upgrading to a rear dana 44.

I know this has been gone over time and time again but would appreciate your input and suggestions on gears & lockers/limited slip for My driving conditions!

 

[Rubicon88]

1999 Jeep TJ. Dana 35 rear & Dana 30. Looking for the right gear ratio and for the best of both worlds. In Montana there is lots of icy roads on and offroad. Traveling to hunting areas can involve lots of highway travel. I'm running 33" tires and right now open diff. with 3.73 gears. 5 speed manual 4.0l (runs 2000 RPM at 65mph). After lots of research on lots of Forums. It gets pretty confusing. Moderate off roading. old logging roads.deep snow and narrow icy inclines/declines. Loose rocky travel. I'm upgrading to chromoly axles front and rear. Thinking about Detroit Trutrac LSD front and rear. 4:10 or 4:56 gear change.
My upgrades already are: RC 4" coil springs, Advance Adapter SYE , Adams drive shafts (front & rear),Core4x4 front and rear control arms (upper & lower),RC adjustable track bars, rear disc brakes
Not going to any bigger tires,no rock crawling (nothing extreme anyways). Not upgrading to a rear dana 44.
I know this has been gone over time and time again but would appreciate your input and suggestions on gears & lockers/limited slip for My driving conditions!

Selectable locker and if you've no intention on bigger tires go with 4.56 gears. 4.10 is better than 3.73 but 4.56 is better. 4.88 would be too much if you're never going higher than a 33.

Go with a Selectable locker. There are several to choose from. Very strong. Open diff behavior when not engaged.

 

[gosborne]

Thank you for reply ! Trutrac LSD rear and Detriot Elocker front ??

 

[Rubicon88]

Whatever you want but if it were me I'd get two selectable true lockers front and back. Eaton, ARB, OX...etc.

You said about spending a decent time on the road...and since you will have both differentials completely apart...selectable lockers are wonderful...and strong.

 

[Jerry Bransford]

Thank you for reply ! Trutrac LSD rear and Detriot Elocker front ??

For your winter conditions there in Montana that would be a good combination.

 

[astjp2]

For your winter conditions there in Montana that would be a good combination.

I would be more into elocker front and rear, not a fan of lsd on ice.

 

[Jerry Bransford]

I would be more into elocker front and rear, not a fan of lsd on ice.

While the clutch-based Traclock has a tendency to slid/skid on ice, the gear based Truetrac does not.

 

[gosborne]

For your winter conditions there in Montana that would be a good combination.

For your winter conditions there in Montana that would be a good combination.

That's what I'll be going to: Trutrac LSD rear and Detriot Elocker front. I've had rear LSD on other rigs in the past and have had good luck. I would like to go 30 spline on the dana 35 but can't fine a 30 spline Limited Slip to match up. Just 27 spline

 

[Wildman]

That's what I'll be going to: Trutrac LSD rear and Detriot Elocker front. I've had rear LSD on other rigs in the past and have had good luck. I would like to go 30 spline on the dana 35 but can't fine a 30 spline Limited Slip to match up. Just 27 spline

Yes the TruTrac is only offered in stock spline count (27) but you can get some 1541H shafts like this if you want a little stronger shafts.

https://www.revolutiongear.com/prod..._tj_yj_and_93_98_zj_rear_axle_revolution_gear
Do not go with axle shafts that are 4140 hardened shafts as they don't play well with the axle bearings.

 

[IAmTodd]

I have yet to drive in winter with my Trutrac but in the wet and mild dirt I've been happy. I can't comment on gears as I have an auto. I used the link below to figure out what was best for me.

http://www.grimmjeeper.com/gears.html

 

[gosborne]

Yes the TruTrac is only offered in stock spline count (27) but you can get some 1541H shafts like this if you want a little stronger shafts.

https://www.revolutiongear.com/prod..._tj_yj_and_93_98_zj_rear_axle_revolution_gear
Do not go with axle shafts that are 4140 hardened shafts as they don't play well with the axle bearings.

Checked out your build Wildman. Awesome job. Thank You for your service!

 

[Wildman]

Checked out your build Wildman. Awesome job. Thank You for your service!

Thank you on both.

Good luck with your regear & LSD & Locker install. And not that it matters but I like your plan for a TruTrac in the rear and selectable locker in the front.

 

[Jerry Bransford]

27 spline shafts are typically enough for 33's and a Truetrac but replacement 27 spline 1541H shafts would be a nice easily installed upgrade to give a little added insurance.

 

[gosborne]

For your winter conditions there in Montana that would be a good combination.

Well I got the bucks for my upgrades to the Dana 35 & Dana 30. Going with Chromoly axles front and rear. Eaton
Trutrac LS on the rear and a cable shift OX locker on the front. 4.56 gears (Revolution) . I do almost all my own work on my jeep but not set up to do ring and pinions. Local offroad shop doing the work.

 

[BugoutJeep]

1541H material is the shaft material you want for at least the rear. The revolution axles are nice, those are about to go into mine. I went selectable front and rear, but my needs are different than yours. I rarely need to lock my axles, but it might save me from winching a small percentage of time.

I think the 4.56 gears with the 5speed and 4.0 will be good. I've been playing around with tire size before my gear change and I'm in the wagon of people saying, larger gear ratios are better than too little and I think the 4.0 needs to really get up in the RPMs to move well on the highway with heavy tires and equipment most of us have.

I used to look at charts and picked my ratios that way, but when swapping tires to "simulate" gear ratios, I really like going a bit higher and from my experience for normal driving, the MPG will be a little bit better. I went from wanting 3.55s to 3.73s (running 33s) and I kind of want to go with 4.10s for my setup, but instead, I'm going to just have 2 sets of tires for the different seasons around here (and 1 season I tow a lot on backroads). My engine torque curve is completely different, so NO ONE should match my gearing.

 

[gosborne]

1541H material is the shaft material you want for at least the rear. The revolution axles are nice, those are about to go into mine. I went selectable front and rear, but my needs are different than yours. I rarely need to lock my axles, but it might save me from winching a small percentage of time.

I think the 4.56 gears with the 5speed and 4.0 will be good. I've been playing around with tire size before my gear change and I'm in the wagon of people saying, larger gear ratios are better than too little and I think the 4.0 needs to really get up in the RPMs to move well on the highway with heavy tires and equipment most of us have.

I used to look at charts and picked my ratios that way, but when swapping tires to "simulate" gear ratios, I really like going a bit higher and from my experience for normal driving, the MPG will be a little bit better. I went from wanting 3.55s to 3.73s (running 33s) and I kind of want to go with 4.10s for my setup, but instead, I'm going to just have 2 sets of tires for the different seasons around here (and 1 season I tow a lot on backroads). My engine torque curve is completely different, so NO ONE should match my gearing.

1541H over Chromoly for the rear? Is there a reason

 

[BugoutJeep]

If I recall correctly, it's the way they harden the section of the shaft where the bearings run. I guess the chromoly shafts aren't as hard as they need to be in that area.

Also 1541H material is very similar in strength as chromoly.

In my experience though with chromoly, we have stuff hardened to whatever we want and in whatever locations we want, but I work on industrial equipment that regularly run bolts multiple sizes larger in diameter than these axle shafts and almost everything is custom made.

 

[SvtLdr]

If I recall correctly, it's the way they harden the section of the shaft where the bearings run. I guess the chromoly shafts aren't as hard as they need to be in that area.

Also 1541H material is very similar in strength as chromoly.

Correct. It has to do with chromoly not being suitable as a bearing surface. I stumbled upon an in depth explanation of this at one point. I wanna say it was either @Jerry Bransford or @mrblaine that was doing the schooling...

 

[BugoutJeep]

Correct. It has to do with chromoly not being suitable as a bearing surface. I stumbled upon an in depth explanation of this at one point. I wanna say it was either @Jerry Bransford or @mrblaine that was doing the schooling...

Yeah I'm guessing their eyes are rolling from this discussion again. I do still wonder why that area isn't induction hardened or something with the Chromoly. We do that all the time with gear teeth. Granted it might not be through hardened, but once you've worn through a few thousandths per side, you're spinning your bearing on the shaft and it'll fail.

Maybe all these shafts are just heat treated complete and more than 1 at a time, so it's a price/process thing.

 

[SvtLdr]

I found an explanation from Revolution Gear explaining the difference between chromoly alloys and 1541H. The question was why choose 1541 material over chromoly for this application?

1541H is used since it's a c/clip axle. 4140 or 4340 is just too hard for the bearing surface. Fundamentally not sound for that application. It would wear out the bearing surface in a few hundred miles.