Sahara vs Rubicon JL Technicals

[zogby]

I know the Sahara vs. Rubicon discussion has already taken place a couple of times on this forum, but I wanted to understand the differences at a more technical level. I like to understand the details, even when it's academic for my actual use (mostly on-road; light off-road).

I'm going to state everything following as fact to avoid cluttering with "My understanding is...", but in actuality much of this is my guesswork from what I've read -- I've never owned any 4x4 vehicle before. Please correct as necessary.

Transfer case: Rock vs SelecTrac

The Rubicon transfer case physically locks the front/rear axles when in 4H or 4L with a chain. The 4L ratio is 4:1, which is shorter than the Sahara's 4L, for improved hill descent control and severe rock climbing.

The Sahara's optional SelecTrac uses a clutch between the front and rear axles. In full-time 4H, it uses stability control to decide how to route the torque between the two, and tries to send torque to axles with traction. In part-time 4H and 4L, it locks the axles with the clutch.

Result: The Sahara should offer more convenience and superior drivability in mixed traction situations (e.g. light snow on-road, light off-road). The Rubicon offers a sturdier t-case and higher ratios for rock climbing.

Questions:

• Is there any reason to believe a clutch-based t-case is inferior to a chain? After all, there's already one clutch between the engine and the wheels in the transmission. Why is a clutch in the t-case bad?

Axle Locking
Both the Sahara and Rubicon use open diffs with brake-locking, controlled by stability control, by default. Because the car has to brake one tire to route torque to the other tire with traction, some engine torque is wasted. Further, brake locking takes some time to respond to changing grip conditions, and could in theory fail in extreme conditions if the brakes overheat.

The Rubicon, in addition, offers e-lockers for both front and rear axles, which physically lock the wheels on the axle. In this mode, no torque is wasted by braking, the torque is instantaneous, and it is a more robust system. However, this can not be used in high-traction situations, as it will cause binding in turns.

The Sahara offers an LSD on the rear axle. The advantages of this system over the brake differential aren't immediately clear, but presumably it offers a smoother or more robust transfer of torque to the rear tire with grip.

Summary: both cars should route torque to the tire with grip (on a given axle) effectively in normal circumstances via the brake lock differential. The e-lockers on the Rubicon will be more effective when large amounts of torque are required to a single wheel (i.e. rock climbing) and may be able to sustain longer. The rear LSD on the Sahara may respond better then the brake locker in situations when an e-locker is not acceptable (mixed-traction on-road).

Questions:

• Are the e-lockers always on in 4L on a Rubicon?
• How bad is it to use e-lockers in mixed-traction scenarios? Though in such cases, the brake lockers seem like they'd be fine.

Upgrades and Modifications

• Physical e-lockers are relatively easy to install for perhaps a couple of thousand dollars.
• The 4L crawl ratio is not easy to change
• Full-time 4H is not easy to add
• Increasing up to 35" on a Rubicon is trivial (just put 'em on)
• Increasing up to 33" on a Sahara may take further modification. Is the stock front axle is sturdy enough?

Capability
Overall, the Rubicon has higher absolute capability, both in terms of which obstacles it can overcome (via more torque from e-lockers and shorter crawl ratios, and better tires), and how much punishment it can take (less reliance on clutches and brakes to provide traction). The Sahara is more convenient and pleasant, and possibly more capable, in the less severe hurdles, as LSDs and clutch-based transfer cases can readily deal with mixed-traction scenarios.

Subtext
You probably can tell I'm trying to figure out what I want to get. As I said, I do not need severe capability, and I very much like the idea of having SelecTrac for both on-road driving, and light off-road. It seems to me SelecTrac + brake lockers is perfectly fine for off-road use except when sustained abuse or extreme torque at a single wheel is needed. I admit I don't like the Sahara wheels or tires, and would prefer for no real reason to have options that makes the vehicle more sturdy (beefier axles, skid plates, steel bumpers), "just in case". Other than the wheels/tires, I think both the Rubicon and Sahara look great. SelecTrac will probably trump the other considerations.

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[Jeepsterfreak]

I'm in a similar situation. If you don't plan to do any serious off-roading or rock crawling it sounds like you would get more benefit with the sahara selec-trac vs. rubi 4:1 and diff lockers. That is if selec-trac proves to be a reliable system and works as advertised.

 

[Mac]

The lockers on a Rubicon have a couple limiting factors, they can only be used in 4 low and only up to 25mph. They can be turned on, rear and rear and front only. As they only work in 4 low using them in a mixed traction situation is probably out, by mixed traction I would think of snowy roads with occasional bare spots.

 

[AZCrawl]

The lockers on a Rubicon have a couple limiting factors, they can only be used in 4 low and only up to 25mph. They can be turned on, rear and rear and front only. As they only work in 4 low using them in a mixed traction situation is probably out, by mixed traction I would think of snowy roads with occasional bare spots.

You can do an aftermarket flash that will allow them to be used in 4HI as well, but I doubt I will do that.

 

[Spank]

As I said, I do not need severe capability, and I very much like the idea of having SelecTrac for both on-road driving, and light off-road. It seems to me SelecTrac + brake lockers is perfectly fine for off-road use except when sustained abuse or extreme torque at a single wheel is needed. I admit I don't like the Sahara wheels or tires, and would prefer for no real reason to have options that makes the vehicle more sturdy (beefier axles, skid plates, steel bumpers), "just in case". Other than the wheels/tires, I think both the Rubicon and Sahara look great. SelecTrac will probably trump the other considerations.

Just slap some KO2s on your Sahara and you'll have the best of both worlds. You'll have more than enough capability for moderate wheeling while enjoying its not-so-extreme features. The KO2 is a fantastic tire and they're fairly quiet on the road. As I mentioned in another thread, I'd put some transparent paint protection film over the front of the rear fenders because they will eat rocks on even the most basic trails.

 

[zogby]

The lockers on a Rubicon have a couple limiting factors, they can only be used in 4 low and only up to 25mph. They can be turned on, rear and rear and front only. As they only work in 4 low using them in a mixed traction situation is probably out, by mixed traction I would think of snowy roads with occasional bare spots.

Oh, I didn't realize they were 4L only.

 

[zogby]

Just slap some KO2s on your Sahara and you'll have the best of both worlds. You'll have more than enough capability for moderate wheeling while enjoying its not-so-extreme features. The KO2 is a fantastic tire and they're fairly quiet on the road. As I mentioned in another thread, I'd put some transparent paint protection film over the front of the rear fenders because they will eat rocks on even the most basic trails.

Putting on KO2s does seem reasonable. I wonder if the Sahara will be able to take the stock Rubicon tires.

 

[Schmeegz]

My biggest dilemma here is that in order to throw 35’s on the Sahara you would need to pay just as much as if not more than the $3K price difference between models. Not to mention you’re already eating up $1200 of the difference in the select-trac and LSD.

Stock rubi’s are 33” and they said you’d even need a lift and hiline fenders to fit a 32” on the Sahara.

Resale id imagine would be better on the Rubicon. More so an afterthought but still...

 

[Mid-life Wrangler]

I’m glad I am not the only one struggling with this decision. I know Selec Trac better fits my needs and what I will be willing to attempt in a brand new Jeep, but the configurations I have drawn up only leaves a $2000 difference between the Rubi and the Sahara, so I am leaning towards the Rubicon. Decisions decisions. #1stworldproblems.

 

[Schmeegz]

I’m glad I am not the only one struggling with this decision. I know Selec Trac better fits my needs and what I will be willing to attempt in a brand new Jeep, but the configurations I have drawn up only leaves a $2000 difference between the Rubi and the Sahara, so I am leaning towards the Rubicon. Decisions decisions. #1stworldproblems.

Friggen Exactly! I’m losing sleep over this decision. Good thing is waiting for the Blue gives me time to debate. I fully plan on throwing 35’s on so it should be a no brainer to go Rubicon. (That red dash tho... yuck).
Being in Buffalo, NY I will see a healthy amount of snowy roads tho, but at the same time 4-hi should be plenty good enough. And maybe, having a Rubi, will encourage me to go out and try off-roading a bit.

 

[Jeepsterfreak]

Stock rubi’s are 33” and they said you’d even need a lift and hiline fenders to fit a 32” on the Sahara.
.

The stock sahara 255/70-18 is a 32" tire.

 

[Andy2434]

This is a timely discussion. I was some 80/20 with my decision. This helps to totally seal the deal with my decision to go with the JLUR.

 

[Spank]

Putting on KO2s does seem reasonable. I wonder if the Sahara will be able to take the stock Rubicon tires.

I think it'd be fine. Bare in mind that all BF Goodrich tires typically are an inch smaller than their rated size. The JL Sport that ACE has has 35's installed on it and despite having little remaining space between the tires and the fenders, they claim they fit just fine and don't bind or rub on anything. I don't see why you couldn't slap some 33's on the Sahara without any issues or it looking goofy, either.

 

[Mac]

My biggest dilemma here is that in order to throw 35’s on the Sahara you would need to pay just as much as if not more than the $3K price difference between models. Not to mention you’re already eating up $1200 of the difference in the select-trac and LSD.

Stock rubi’s are 33” and they said you’d even need a lift and hiline fenders to fit a 32” on the Sahara.

Resale id imagine would be better on the Rubicon. More so an afterthought but still...

Ace engineering said 35s fit on the Sport they had with no issues, I would assume the Sahara would be same, you will also probably be able to get the Rubicon fenders and put those on the Sahara for extra clearance. As far as resale, all the Wranglers have great resale the difference between a Sahara and Rubicon will be minimal. As far as the wider axles that is great but there is no 17" diameter 35" tall tire that will fit on the factory Rubicon 7.5" wide wheels so you can just buy a aftermarket wheel with less backspacing.

 

[JDaPP]

So I have a jeep liberty with selec-trac (original one not the this new one) and a JKU Rubicon. I am in to overlanding (going off the beat and path to camp/explore) and I got the Rubicon for that as I wanted to get all the tools in one package. In the 5 years I have had it, I have yet to find myself in a spot where I truly needed the lockers and crawl ratio (have used them and they are nice...). Most of my exploring has been fire roads and an rock/dried up river beds for reference where skids, tires and clearance were the bigger issues.
During the 12 years of owning the liberty I have used the selec-trac in full 4x4 on a almost daily basis in rainy season (Florida) and snow/ice season (Northern Nevada) as well as for towing in mountainous areas.

My point is look at what you are going to use it for. If you truly believe that you will take the Jeep off-road regularly there is no better option than the Rubicon. For most the
Rubicon is probably overkill and push come to shove you could add additional features (lockers, sway bar disconnects, lift, etc.) if it came to it, albeit at a more expensive price.

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