Opinions on gearing?

[SSR]

Looking for some opinions...

Yesterday we tore into the front axle going under my low budget build (not sure I can rightfully refer to it as a "build" because nothing's happening), the 4.10 gears are trashed. So I have a gear decision to make, unfortunately decisions that cost $$$ are not my strong suite.

So here's the scenario, I can install a cheap set of used 4.10's and spend the money saved toward a decent front locker, doubler/atlas, or shocks. Alternatively, I use this opportunity to go to 5.13 gears and cheap out elsewhere on the project with the intent to loop back and address them later. So the question is, how big of a difference is there between 4.10 and 4.88/5.13 off road?

Background information / project objectives are, a low budget but very capable vehicle that my family can wheel trails like HT, Price, Pritchett. Project vehicle is a 91 yj, I have already frame/body stretched to 109" wheelbase. Motor/trans/t-case is undecided but will likely be SBC/700r4 or 400, I have a 14 bolt with detroit for the rear, front is currently open gm 60, targeting 38-40" tires. I don't plan for this yj to spend much time on the street, but ideally it is street legal and can perform well enough on the hiway to get to the trail head or back to the truck & trailer.

So what would you do?

 

[mbryson]

38" tires, I'd go 4.88 with planned power train. 40", I'd go 5.13 gears


I have 4.56 with 350/700 and 4:1 tcase. It's PLENTY low off-road, not ideal on road. In my opinion, 4.10 is about right for 33-35" tires depending on powertrain.

 

[Pile of parts]

No matter how you achieve the lower gearing (t-case or axles) I think you'll want them in the axles if your objective is to have 38"-40" tires. You might get away with higher gearing with the auto and may not have to address the t-case. I run a manual and prefer lower gearing options for control so I have addressed both the axles and t-case. I'm running 14b/60 5.38, 39.5" tires, 350 TBI, t-18 and 4 speed Atlas with 3.8. I run 99% of the time in the 2.7 range but on very technical sections of some trails it's nice to shift into 3.8 range. The 10:1 range is ridiculous and really unusable. With your auto you wouldn't need that kind of gearing - no clutch/no stalling.

However, the 5.38 allow me to buzz down the hiway to and from the trail. I can do 60 mph +- and the jeep has enough get up and go.

The only argument I can think of for staying 4.10 and addressing the t-case gearing is ring and pinion strength. I sacrifice a little but I figure that's why I went with tons anyway.

Just my opinion to a tough question. Good luck!

 

[bobdog]

I have used 4.10s if you decide to go that route. Out of a front end. $30.00

 

[SSR]

38" tires, I'd go 4.88 with planned power train. 40", I'd go 5.13 gears


I have 4.56 with 350/700 and 4:1 tcase. It's PLENTY low off-road, not ideal on road. In my opinion, 4.10 is about right for 33-35" tires depending on powertrain.

mbryson / Pile of Parts, thanks for the comments.

I am estimating the cost difference between the two gear options at $700-750, so it's not an huge expense, but worth weighing options. I found a online calculator to compare highway performance of 4.10's & 5.13's. Using a Th400, 40" tires, and 65/mph inputs for both gear ratios, calculator shows 4.10's running @ 2365rpm and 5.13's running @ 2959rpm. Looking at highway performance isn't the 4.10 ratio a better fit? Of course off road performance would have to corrected, I think a 5.0 or maybe even 4 speed Atlas would be required. Cost of a 4 speed Atlas is significantly greater than a 2-speed, so cost of gearing becomes the cheaper route.

I used a TH400 in the calculator thinking it provides the cheaper, reliable, solution over the 700r4 or 4l60e. What's your thoughts here, is the 400 cheaper or more reliable in a crawler application? If a 700r4 is a better or suitable route, I suppose as previously mentioned 5.13 or maybe even 5.38's gearing would be needed.

 

[mesha]

I always vote for lower gears in axles. That doesn't make me right

 

[Herzog]

I vote for gearing at the axles first too. It puts less stress on the drivetrain behind the axles (drive-line -> tcase), but will put more stress/torque on your axle shafts & axle u-joints.

 

[mbryson]

mbryson / Pile of Parts, thanks for the comments.

I am estimating the cost difference between the two gear options at $700-750, so it's not an huge expense, but worth weighing options. I found a online calculator to compare highway performance of 4.10's & 5.13's. Using a Th400, 40" tires, and 65/mph inputs for both gear ratios, calculator shows 4.10's running @ 2365rpm and 5.13's running @ 2959rpm. Looking at highway performance isn't the 4.10 ratio a better fit? Of course off road performance would have to corrected, I think a 5.0 or maybe even 4 speed Atlas would be required. Cost of a 4 speed Atlas is significantly greater than a 2-speed, so cost of gearing becomes the cheaper route.

I used a TH400 in the calculator thinking it provides the cheaper, reliable, solution over the 700r4 or 4l60e. What's your thoughts here, is the 400 cheaper or more reliable in a crawler application? If a 700r4 is a better or suitable route, I suppose as previously mentioned 5.13 or maybe even 5.38's gearing would be needed.

To me, a 700 is my choice. Lighter and a WAY lower first gear ratio. You're welcome to come take a spin in my Jeep and see what you think with 38" tires and 4.56 gears. Might give you a good guinea pig?

I always vote for lower gears in axles. That doesn't make me right

I vote for gearing at the axles first too. It puts less stress on the drivetrain behind the axles (drive-line -> tcase), but will put more stress/torque on your axle shafts & axle u-joints.

Less stress is ideal always

 

[SSR]

You're welcome to come take a spin in my Jeep and see what you think with 38" tires and 4.56 gears. Might give you a good guinea pig?

I think the best evaluation of your setup would be to try it in as many conditions as possible. With that in mind, maybe I could pickup your jeep in March, and drop it off in November? Seriously though, next time I run into you Ill gratefully take you up on this offer, as it looks now it might be EJS.

 

[mbryson]

I think the best evaluation of your setup would be to try it in as many conditions as possible. With that in mind, maybe I could pickup your jeep in March, and drop it off in November? Seriously though, next time I run into you Ill gratefully take you up on this offer, as it looks now it might be EJS.

March to November should be ideal

 

[SSR]

This build is going to cost FAR more than I budgeted and saved for, I failed to plan for several items that I now realize should have been assumed going in. I'm now considering a revised two stage plan in a effort to keep progressing and prevent the project from stalling out. Stage 1 being "keep it super cheap, but get it functional", taking place as quickly as possible, mostly limited by my time, I have many of the parts at my disposal and I'm only out what they are worth in horse trades. Stage 2 target is 2-4 years allowing me additional time to save $$$ and gather parts, but hopefully allows use of the jeep for a few trips while I'm saving/gathering.

Stage 1
-4.10 gears
-Dana 44 front, lincoln locked, leaf springs
-14 bolt with Detroit, triangulated uppers
-37" tires (need)
-TBI or Vortec 350 (need)
-SM465
-TC needs solution(I have a NP208 bolted to the SM465, but not sure it's worth even trying to run?)
-109" wheel base

Stage 2
-5.13 gears (need)
-Dana 60 (have stock housing, knuckles, hubs)
-locker to be determined (need)
-40" tires (need)
-700R4 (need)
-Atlas 3.8 or 4.3 (need, hey a guy can dream)
-Hydraulic assist

I'm not interested in wasting lots of money doing things twice to go this route, financially I'm limited to what I have saved and my allowance money (there's a possibility of some bonus money in the next few months, but not much). I'm determined not to spend family savings money to speed up Stage 2.

One big question in my mind is powertrain lengths. If I start with a SM465 and want to switch to 700R4 is there a difference in powertrain length or position? If so, how much? I don't want to be building drivelines twice or have cross-member position change significantly.

What are your thoughts?

 

[mbryson]

I like the phased build idea. You will not be able re-use 100% of what you do in Stage 1 vs Stage 2 (or 3?). I think your Stage 1 thoughts are fine. While 208 aren't used much, it's worth a shot to run. I assume an SYE will be needed for one and that's $300 you don't need to spend on it. I swapped a 27 spline 241 input into a Dodge 241 (passenger drop...not sure if you're drivers drop or passenger?) with fixed yoke front/rear for the cost of a core from the junkyard. That'd give you a pretty strong case to work with going fwd. You may decide you don't need the twin stick? If you're set on a 700r4, I'd just go there right off the bat.

You might even "settle" into 38" tires vs the 37" tires and swapping to 40" tires?

I don't think there's a way around shortening lengthening drivelines. That's not a huge expense if all your components are still good.

 

[Pile of parts]

I'm sure you'll see a difference in drivetrain lengths between the 700 and 465. Then you're into cross member/drive line expense and modifications.

 

[mesha]

I would spend money first on things you won't be switching out.


If the building in stages part gets you out wheeling more, then that is the way to go. If you are one of those guys that wont go out and wheel because you are afraid your 44 or 208 will break then it is a bad idea.

Do whatever gets you out.

 

[SSR]

If the building in stages part gets you out wheeling more, then that is the way to go. If you are one of those guys that wont go out and wheel because you are afraid your 44 or 208 will break then it is a bad idea.

Do whatever gets you out.

I still have the red TJ I wheeled Hanging Tree last May with you guys. That TJ is a lot of fun, but I have a mental block about wheeling it to its potential out of fear of damaging it, silly, I know. I also feel the wheelbase and tire size somewhat limit its fun potential. I did heavily consider stretching the TJ and going to bigger tires with a front 60, but i estimated the amount of work and money involved was not too far off from just starting over with a clean (dirty faded yj) slate. It also provides me the ability to keep wheeling while I over analyze every aspect of this build In the end, if the YJ turns out well I plan to sell the TJ.

I have no worry or fear of breaking any of the stuff listed other than the unwanted potential of interupting a day of fun.

 

[thenag]

"build is going to cost far more..."

sounds like every build lol

a d44 welded diff with a v8 and 37's. that seems weak to me, I know people run it without much issues for a while...

hydro-assist could be added to the "stage 1" and almost completely transfer over to a d60, if you plan your steering linkage. Something like the Ruff Stuff 1 ton tie rod setup could swap right over.

I will have 2 of the old style goodyear wrangler 37x12.50x15's mounted on 8 lug wheels that will be laying around soon. If you want one for a spare or both they will be cheap.

I also have barley used set of 4.88's for a gm 14 bolt and never installed set of 4.88's for a ford d60. I used to think that I would never do my own gear installs, but I now have the tools to do it and it is actually kind of fun to do. since you will be changing gears in your 14 bolt and re-gearing the 60 you buy, you might want to consider learning to setup gears.

As far as the length switch from the drive trains, you will have to move/modify cross members and get drive shafts re-done, that is a minimal cost. Something else to consider is that for OEM motors, they have a different EEC for a manual and an auto, so make sure you are aware of any cost for too.

Nathan

 

[SSR]

I swapped a 27 spline 241 input into a Dodge 241 (passenger drop...not sure if you're drivers drop or passenger?) with fixed yoke front/rear for the cost of a core from the junkyard. That'd give you a pretty strong case to work with going fwd.

I'm VERY interested in this approach, I think these are 2.72 ratio? Can you give me more info on how to build this tcase for a passenger drop?

What dodge truck models and years tcase can I use? It looks like I can buy a 241 27-spline input from ebay or Bearingkit.com for around $50-120, but I read there is difference in early vs. late teeth cuts, apparently it breaks at 94/95', which do I need? Do I simply try to match the tcase years both dodge/Gm? What about bearings and seals? Thanks.

 

[mesha]

I still have the red TJ I wheeled Hanging Tree last May with you guys. That TJ is a lot of fun, but I have a mental block about wheeling it to its potential out of fear of damaging it, silly, I know. I also feel the wheelbase and tire size somewhat limit its fun potential. I did heavily consider stretching the TJ and going to bigger tires with a front 60, but i estimated the amount of work and money involved was not too far off from just starting over with a clean (dirty faded yj) slate. It also provides me the ability to keep wheeling while I over analyze every aspect of this build In the end, if the YJ turns out well I plan to sell the TJ.

I have no worry or fear of breaking any of the stuff listed other than the unwanted potential of interupting a day of fun.

That TJ flat out works and you know how to drive it. If you have that to wheel while you build then BUILD AWAY! I am excited to see what you come up with.

 

[mbryson]

I'm VERY interested in this approach, I think these are 2.72 ratio? Can you give me more info on how to build this tcase for a passenger drop?

What dodge truck models and years tcase can I use? It looks like I can buy a 241 27-spline input from ebay or Bearingkit.com for around $50-120, but I read there is difference in early vs. late teeth cuts, apparently it breaks at 94/95', which do I need? Do I simply try to match the tcase years both dodge/Gm? What about bearings and seals? Thanks.

Check out post #105
http://www.expeditionportal.com/forum/threads/70072-70-C-20-4x4-Suburban-Father-Son-project/page11

 

[SSR]

Check out post #105
http://www.expeditionportal.com/forum/threads/70072-70-C-20-4x4-Suburban-Father-Son-project/page11

Thanks for the link. Bummer the Dodge 241 with fixed yoke aren't more common, post 110 says they came in 87-93 dodge gassers if anyone knows of one getting parted out.