This 6 Speed is...interesting.

[DanW]

Before I start...bear in mind this is going entirely off the screen that shows your immediate MPG...has the little green half circle for visual effect.

So now that I've had my JLU w/6 speed for 5 months, I felt like I had firmly settled in with where I want to shift gears, essentially shifting as the RPMs go above 2k. I almost never get above 55 mph in my daily commute so usually 4th is all I need. Something like this:

1st: 0-8 mph
2nd: 8-20 mph
3rd: 21-40 mph
4th: 40-55 mph
5th: 55-65 mph
6: All others

Then other day I'm driving on a solid 55 mph speed limit road and I'm drifting between 50-60 mph with no traffic. However, I noticed that it didn't quite feel right when I shifted into 5th...kinda like the Jeep didnt like it. Wasn't lugging or anything obviously but still didn't feel right. So I put it on the screen referenced at the beginning and I'm noticing I'm getting better instant mpg in 4th all the way up to 62 mph than I am in 5th. I've never had anything remotely considered a "high revving" vehicle...but a Jeep?

Anyways, I said all that to just ask what everyone else's shift patterns look like.

Cheers!

I'm not sure about the lower gears, as I go with feel, but I get into 5th around 48 to 50 and into 6th at 60. Lately, though, I feel like the engine has continued to free up (I'm at 22,500 miles) and I can pull 6th gear down to almost 55mph and still mildly accelerate, and it can pull 5th with no problem down to 45. Over time it has become smoother at lower rpm, especially in the lower gears. I'd still like to see 6th gear be a little shorter ratio, but I'm pretty confident that if I was still running a stock setup with 285's, it would be close to the sweet spot.

Keep in mind, you are running a taller final drive ratio in a Sahara. The Rubi's 4.10 gears give a little advantage in this realm.

My fuel economy settled in around 15k, but the engine has continually improved in power and free-revving feel. The oil analyses I've had seem to indicate break-in is in its final stages, at least in terms of the presence of wear metals. Note: I'm not talking initial break-in, as in piston rings setting, but just overall tolerances stabilizing. I've found 20k miles to be typical with most of the vehicles I've owned, with some being more noticeable than others in feel, power, and fuel economy.

Just keep driving it. Also, regearing is always an option, but it obviously won't effect the spread in ratios, but only final drive ratio. But, that can cause a big improvement in feel and use of 6th gear, too. I'd certainly consider it if I wasn't happy.

Sponsored

 

[snowtx1]

I find that I can't shift my Sahara to 5th until at least 70 mph, and 6th is useless below 80. The engine has no torque below 2,000 RPM, so you need to keep it above that speed. I usually need to downshift for hills unless I'm going fast enough to keep the RPM's above 2,000.

 

[Dogboyslim]

How much would regearing cost?

Definitely gonna keep that in mind

If you go with Dana, the ring/pinions will be 3-400 each, and the overhaul kit will be another 3-400 each, so $600-$800 + labor. I'd guess labor is a good 3-4 hours each axle with a typical shop rate around $70-80, so $420 to $640 for Labor. Grand total $1.3k - $1.9K if you have it done. I'm sure you could find cheaper if you look.

[Edit] forgot to add cost of all three, so maybe I was a bit low.

@Northridge4x4 has package for this:

https://www.northridge4x4.com/part/...on-210mm-220mm-gear-package-and-overhaul-kits

$898.99 (as of 9/20/2019) for the ring/pinions and the needed install kits. Note this is for the Rubicon, I suspect it is similar for the D30.

So my corrected range above seems reasonable. Sorry for the initial error. [/Edit]

 

[Rogues Gambit]

If you go with Dana, the ring/pinions will be 3-400 each, and the overhaul kit will be another 3-400 each, so $600-$800 + labor. I'd guess labor is a good 3-4 hours each axle with a typical shop rate around $70-80, so $420 to $640 for Labor. Grand total $1k - $1.5K if you have it done. I'm sure you could find cheaper if you look.

Why'd I think it'd be worse?

Sounds good, I'll definitely consider it

 

[8flat]

Now a rhetorical question for a rhetorical answer

Why are Rubi's and under 4.10 and 3.45's? Mpg's most likely

Good question. From what everyone is reporting for MPG, my rubi is doing just as well as the saharas, although this isn't very scientific.

 

[DanW]

Good question. From what everyone is reporting for MPG, my rubi is doing just as well as the saharas, although this isn't very scientific.

The main reason is that it compensates for 33" tires. A sport with base tires can handle a 3.29 or whatever the base ratio is because the tires are small diameter. If you throw 33's on that Sport, it robs power, so 4.10 compensates for the larger tire by allowing it to maintain performance. Where people are struggling is when they put 33's, 35's or even 37's onto a Jeep with 3.29 or 3.45 ratios.

Mine does great with 315's which are equivalent to a small 35. (Really a 34.5). If I ran 37's, I'd regear to a 4.56 to gain back the lost performance. Going from stock 33's to the 315's didn't rob enough to cause much of a loss, so I'm sticking with the stock Rubi 4.10. If I had 3.29 or even 3.45, I think it would feel like it was pulling a trailer. If in that boat, I'd probably go with 4.56 even with 35's, but for sure with 37's.

Hope that helps.

 

[Rogues Gambit]

The main reason is that it compensates for 33" tires. A sport with base tires can handle a 3.29 or whatever the base ratio is because the tires are small diameter. If you throw 33's on that Sport, it robs power, so 4.10 compensates for the larger tire by allowing it to maintain performance. Where people are struggling is when they put 33's, 35's or even 37's onto a Jeep with 3.29 or 3.45 ratios.

Mine does great with 315's which are equivalent to a small 35. (Really a 34.5). If I ran 37's, I'd regear to a 4.56 to gain back the lost performance. Going from stock 33's to the 315's didn't rob enough to cause much of a loss, so I'm sticking with the stock Rubi 4.10. If I had 3.29 or even 3.45, I think it would feel like it was pulling a trailer. If in that boat, I'd probably go with 4.56 even with 35's, but for sure with 37's.

Hope that helps.

It does

 

[8flat]

The main reason is that it compensates for 33" tires. A sport with base tires can handle a 3.29 or whatever the base ratio is because the tires are small diameter. If you throw 33's on that Sport, it robs power, so 4.10 compensates for the larger tire by allowing it to maintain performance. Where people are struggling is when they put 33's, 35's or even 37's onto a Jeep with 3.29 or 3.45 ratios.

Mine does great with 315's which are equivalent to a small 35. (Really a 34.5). If I ran 37's, I'd regear to a 4.56 to gain back the lost performance. Going from stock 33's to the 315's didn't rob enough to cause much of a loss, so I'm sticking with the stock Rubi 4.10. If I had 3.29 or even 3.45, I think it would feel like it was pulling a trailer. If in that boat, I'd probably go with 4.56 even with 35's, but for sure with 37's.

Hope that helps.

True, but pushing more tire down the road along with a little more height (increase in frontal drag coefficient), should equate to a little less MPG in a Rubicon....in theory. Was surprised to see it.

I think 35s would be the perfect size. But I'm so frustrated with the lack of torque/power below 5k RPM on this thing that I'd really like to go with at least 4:56 gears if not 4:88s haha this engine drives me crazy. Need a hemi.

Sponsored