4.56 or 4.88 gears?

Looking at the actual teeth in a 4.88 vs 5.13 there is a material difference. My gear guy indicated that he's seen a few 5.13's go bad with my set up but rarely any 4.88's. I have no plans for 37s either.

And yeah, its a little sluggish on hills but not much, and the lower RPMs are nice. I'd rather have the safety factor of the 4.88's I guess.

Honest question; how much stronger is the 4.88 pinion with 1 more tooth vs the 5.13?

The only pinion we ever considered "weak" was the Richmond Gear 5.71 in the Toyota 8" drop out. That thing was tiny and we replaced several. Of course the guys wanting 5.71 were running 35+ on the little Toy diffs which didn't help the situation. Our recommendation was the 5.29, which we did not have issues with.

Fun fact; the 4.56 was considered "much stronger" vs the 4.88 several years ago in the 30 due to pinion size. Now the 4.88 is considered "much stronger" than the 5.13, again due to pinion size.

If I paid to have a re-gear, I'd be pissed at "sluggish" performance.
 
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Your gear guy is guessing and making statements based solely on rumors he heard. 5.13's and 5.38's have been thoroughly tested and in use for years now in our Wrangler axles. No problems. Some claimed the same thing when 4.88's came out for the Dana 30 many years ago. If there were problems we wouldn't be installing 5.13 and 5.38 gearing, me included with 5.38's, and using our rigs strenuously with them.

5.38 gear teeth are actually the same size and strength as the 5.13. Some smart engineers figured out a way to change the 5.13 gear tooth count and spacing slightly to give the 5.38 ratio with no loss in strength.
Jerry, you are a valuable resource on this forum, but respectfully, I've learned to trust my long time, well respected 4x4 mechanic over internet information. His views are hardly based upon rumors. Its fine to have an informed view and even better to respect informed views of others as well, even if you dont agree.
 
I have the 42RLE, 35s, and 5.38 gears. Even with 5.38 gears, I feel it could still be a bit deeper. It's way better than the factory 4.10s, but still nowhere near perfect (which is in large part due to the stupid .69 OD on the 42RLE).

My thought is that when in doubt, it's ALWAYS better to gear deeper as oppose to not deep enough... especially with the 42RLE.
 
Isn't there an argument that (numerically) lower gears create less stress on the smaller pinion?
 
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So who wants to buy 4.56 yukon gears and a spartan locker? I just finished installing everything last night and I absolutely hate it. For the driving I do I'll just stick with the 3.73 gears.
 
What do you hate about it?

At 55mph it's at 3000rpms. I'd say 70 or above it would be 4 or more. And the locker makes it road walk. We have never built a jeep and just going by what a friend said. I daily drive it to much for these gears. And with my built 4.0 it did great with the other than steep hills and I had to drop it in second myself because it wouldn't down shift.
 
Jerry, you are a valuable resource on this forum, but respectfully, I've learned to trust my long time, well respected 4x4 mechanic over internet information. His views are hardly based upon rumors. Its fine to have an informed view and even better to respect informed views of others as well, even if you dont agree.
The only problem with that is your guy is just wrong. Here is a way to help you think through it perhaps. Not saying you need to take the info and go beat him up with it, but it should help your knowledge and put things in a different perspective.

If you take a rig with 35's and 3.07's and try to get it moving up a hill offroad, one thing that almost all can understand is the driveshaft u-joints are going to be under a lot more stress due to the higher gears than the same rig with 4.10's, 4.56's or lower.

The same principle applies to the lower gear ratios practically regardless of pinion head size or tooth count. As gear ratio moves lower, the forces the teeth see are much less due to the increase in leverage to get the rig moving.

That and almost every time we see a gear failure, it can be traced back to improper break in or set up. It is very rarely due to gear size unless the owner is doing something dumb like running 37's on a Dana 30. The rest of that is if you are breaking gears with your driving style and tire size, you don't have enough axle, go get enough axle.
 
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At 55mph it's at 3000rpms. I'd say 70 or above it would be 4 or more. And the locker makes it road walk. We have never built a jeep and just going by what a friend said. I daily drive it to much for these gears. And with my built 4.0 it did great with the other than steep hills and I had to drop it in second myself because it wouldn't down shift.
That doesn't add up. According to Grimmjeeper, Your tires have a rolling radius of 14", which is in the 29-30" tire territory.

32rh/28"/4.56 = 3010rpm @ 55mph
 
At 55mph it's at 3000rpms. I'd say 70 or above it would be 4 or more. And the locker makes it road walk. We have never built a jeep and just going by what a friend said. I daily drive it to much for these gears. And with my built 4.0 it did great with the other than steep hills and I had to drop it in second myself because it wouldn't down shift.
Fix the speedo. 3000 rpm is 68 miles per hour with that set up.
 
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Ignoring the incorrect speedo, what do you think of the gearing? Use your phone as a speedometer.
 
Use your phone as a speedometer.
:aplastao:

Phone.JPG
 
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Ignoring the incorrect speedo, what do you think of the gearing? Use your phone as a speedometer.


I have been using my phone for the speed. According to my phone this was around 66-67mph. I honestly can't tell a difference in the gears other than the rpms being different. I have yet to take it offroad. Well I guess I can tell it does pull big hills better. I can stay at higher speeds.

20181223_102500.jpg
 
I'm also considering regearing to either 4.56s or 4.88s. I have a 5 speed manual and my 5th gear is useless on the highway, can't hold speed. I've got a heavy right foot too so my usual 80mph on the highway is around 2900 RPMs, and I need to get that lower. I have 35's too, so we're in the same boat.
With the five speed I’d go 4.88’s I personally run 5.13’s but I’m on a true 36.7” tire and at high Altitude and run mountain passes all the time so the lower gearing helps a lot
 
I may get slammed for this....

I know grimmjeeper is considered scripture in the 4wd world, but your actual rpm is reality.

If your wife leaves a note she loves you and only you, and you see her walking into a motel with your neighbor, trust your eyes.

On a regear , people are often startled initially by the change.

Blaine is so right....proper gearing is really good for the the entire driveline.
 
I may get slammed for this....

I know grimmjeeper is considered scripture in the 4wd world, but your actual rpm is reality.

....

Grimmjeeper matches reality very well if the data you enter is accurate. Most get their tire size wrong.