cost to upgrade a sport to rubi spec
 

My beloved WJ is just causing me too many problems so im looking into buying a JK and im trying to work out if i want a sport or rubicon. The car will be my daily driver but ill be taking it on as difficult trails as im personally able to drive. I will use the full features of the rubi, and if i bought a sport i'd want to modify it over time to the same or better capability as the rubi.

I have the option of a very low km sport with the 3.6 motor or a rubi with the 3.8 with 80,000 ks.

My question is: If i want to modify the drivetrain of the sport to a similar or better capability as the rubi, how much will it cost, ballpark? the aim is to run 35s.

My understanding is that i'll have to re-gear both diffs and add lockers. Am i right in believing that if i re-gear the diffs, i wont really need to re-gear the t-case? Will i want to replace the front axle of the sport if i go for 35s? if so, how much would this cost?

Thanks for your insights!

Main differences are front and rear Dana 44 axles, front and rear lockers, and a 4:1 transfer case, electronic disconnects.

If you want Rubi spec just buy a Rubi, if you want better than Rubi spec than a Sports with mods might be the right avenue.

Having said that, look into you state laws for running 35s, in some states its either illegal or require major mods to get it engineered. Which state are you in?

Im in Vic, but not too worried about pushing the limits legally.

I forgot about the axle. So for the front im going to need a complete new D44, or otherwise, beef up the D30 as well as re-gear and locker.

If i got the rubi would i run into any road blocks in terms of modding? i want a very capable truck, but itll still be a DD so im not after a comp truck. Will i want anything better than what the Rubi has to offer do you reckon? Are the lockers up to scratch? Are there any weak points in the Rubi that you'd probably want to replace with aftermarket?

My 2009 JKU Rubicon is my DD - 40mm lift and 33's - all legal. No issues at all and while I don't off-road nearly as hard as I used to, I would reckon you won't find a spot a Rubicon won't get you through with no problems. Even a sport, while it has a D33 and no lockers will get you through most things you'll face.

Also, since Rubicons come with slightly different factory specs it allows you more wiggle room to mod in terms of tires etc.

If your wrangler will become your DD, you ought to test drive the Pentastar v the minivan donk. Try it in traffic and on the open road if the vendor allows.

Methinks the daily driver bit will be the determining factor.

If you go the sport, can add anything aftermarket to your liking and budget. The older the car gets, the less likely you will be to source stealer parts and service. The more vanilla it is, the better to explore after market options like a crate axle, lockers, suspension etc.

If you're in Vic, you're looking at about $20k to run 35s legally (D2s + AEV lift). Which is why most people just take their chance with the police. A Rubi with 35s on will get you to most places and if taken care of should be relatively bulletproof.

New housing will add to your total weight, if you are hard on your drivetrain, upgrading the housing, gearing and axle shafts will help. If you are reasonably sympathetic to the mechanicals of your Jeep, maybe beef up the D30. Perhaps a donor front axle from a wrecked Rubicon would suffice?

The e-lockers that come with the Rubicon are good, not subject to leaks as airlockers I have seen tend to be. The big difference is the disconnecting sway bar from inside the cabin, but there are a multitude of aftermarket options that allow for the front axle to articulate further in the sport models.

I'd avoid the Rubicon electronic sway bar disconnect system unless you are buying rubicon, as it is not as sealed as they suggest, is prone to periodic malfunction ,and I have pulled mine off and cleaned/regreased it a few times to offset this.

There are a few aftermarket items that are supposed to remedy this, I think EVO have a air based system that can be operate from inside the cabin.

dont forget diff ratios 4.11...if u want 35s, 4.56 is prolly better suited

I would say 3.6 Pentastar vs 3.8 V6 would be important, not to mention the nearly bullet proof NAG1 transmission behind the Pentastar.

You don't mention the prices of the 2 options so I'm going to assume they're roughly the same price?

3.8 vs 3.6.....This means new vs old interior....I have the old interior and it's ok, I think the newer one is probably better and you'd have things like iPhone input for music etc

3.8 vs 3.6......speed......3.6 will obliterate the 3.8 and use less fuel while you're at it

Are they both auto or manual? Think about that, I have auto and its great until it gets hot or you need to push start it (haven't needed to yet).

The transfer case is a big choice as it's most likely going to stay put in the jeep....the sport transfer case is probably better on sand....I'm in Perth so a lot of off-road is beach stuff and I've heard the Rubi t-case is too slow on the beach. The sport t-case with 35s and 4.88 gearing (I have CRD) is good on rocks, but I have an auto, so that makes it easy (autos can sometimes get away from you going down steep hills though, the new interior jeeps have hill descent control I believe, the old interior ones don't).

Lockers....I have eaton e-lockers and they're brilliant, the Rubi ones are also e-lockers (don't bother with air). The Rubi lockers can only be engaged when in 4Lo (I believe), mine can be turned on anytime (pros and cons...you have to make sure you don't knock the switches at 70km/h in a corner! But you can use them in 2/4Hi)

I think a fully built front D44 is about $8k, not a bad idea, the rubi D44 is a d44 ring and pinion but uses the same axel tubes and C's as the sport...i.e the diff gears are stronger (and less likely to shatter if a spinning wheel grips) but the axle would still be prone to bending. Use lockers and you'll never have a spinning wheel anyway.

Teraflex make replacement housings for the D44 and D30, where you can simply swap over your internals. I run 35s on a factory D30 with some re-enforcement internal sleeves, never had a problem but I also know its a weak point so I take it easy on sharp turns and dropping off big ledges. If it bends...I would need to decide on a full D44 swap of a Teraflex D30 housing (as I already have the lockers, gears and RCV axel shafts)

RCV axel shafts are great, they are technically weaker mechanically but have a lifetime guarantee. U-joints create a jerking motion at close to full lock which stresses the diff gears, CV joints are constant velocity and feel so smooth. Look at some animations on youtube if you need more info.

the Rubi has an electronic disconnecting front anti-roll bar....I have heard the electronics can be temperamental. You can add quick disconnects to the sport for about $150 I think. Its a really simple mod and gives you something like 30% more flex (best bang for buck mod out there)....I use it on rocks but not on sand.

The Rubi dosn't get side steps, it gets basic rock rails...I replaced my steps with some HD side armour in anticipation of damaging the steps. I haven't really damaged the armour with 35s and a lift....I should have kept the steps until I damaged them (if it ever happened...the steps would be nice sometimes as the Jeep is quite high for small people).

Advice....embrace the JK thing and take the modification route...there's no other vehicle like it and you can pick and choose exactly what you want. Get the nice new interior and newer engine, put in a Teraflex D30 housing or a fully built D44 if you can afford it. Re-gear the diffs so you're happy with highway RPM and low range crawl speed (this might be a trade-off) and put in eaton lockers while you're at it.

Have one of the big name Jeep modifiers do all the mods in one session to avoid incompatibility between parts. In Perth, SBR Offroad are brilliant. Murchison in QLD are good too (and sell really good suspension coils). Get some decent headlights installed while you're at it.

AEV and Teraflex are really good brands. AEV is like factory quality. Teraflex are really good value. I have Synergy suspension components and they're completely solid. I expect Teraflex are just as good but a bit cheaper.

Last tip...Once you have the lifts in and it's settled. Speak to Airbag-man and get airbags for the rear coils. I haven't noticed any downsides but if you want to load the Jeep up with decent weight, you can level it out so easily.

The 2011 model with the 3.8L comes with the updated interior so that's not quite correct.

ah crap, yep I forgot about that 3.6 was 2012

What kind of wheeling did you do in the WJ? The JK will drive completely different on and offroad. The WJ is much nicer to drive IMO, the v8 and auto are nice. Offroad a WJ with QuadraDrive is about the same as a stock JKU Sport with no lockers, in sand the WJ is much better. But the JK can be built into anything you want it to be.

Re Sport vs Rubi. A JKU Sport is an extremely capable vehicle offroad with traction control only, Jeep's TC system is much better than most other companies, in most cases lockers are not required. People think they need them because the Rubi has them, or because everyone talks about ARB air lockers etc, but a JK with TC is very capable out of the box. Might be true for other vehicles, but not a JK. Look up Ronny Dahl's earlier vids on Youtube, his dad drives a JKU Sport with no lockers on 33" tyres and went everywhere Ronny and his mates went on their 70 Series LC's with 4" lifts and 35"s and twin locked.

As a DD, I would 100% go for the 3.6. Throwing money into your fuel tank if you get the 3.8.

The only thing you will find difficult to get in a Sport later on, is swapping in the Rubi transfer case, but as others have said, although great in the rocks, for anything else (beach, mud, mild tracks, majority of offroading) the ratios are too slow, so you need to swap back to high range, but then high range might be too fast etc, the normal 2.72:1 low range in (non Rubi) Jeeps is perfect for pretty much everything except for technical rock crawling.

Everything else on a Rubi is debatable. Rubi's are great if all you want to do is maybe 33-35" tyres and possibly a 2" lift and be done. Great, the Rubi is the best 4wd you can buy off the showroom for that. With the Sport you can buld it over time, some parts will cost less to achieve the same (sway bar disconnects) and some you will prob build even better than the Rubi (replacement front axle housing, correct diff gearing for your application), etc. And its not like your starting point with a Sport is rubbish offroad, you can still drive 95% of the tracks in Aust like that stock.

Samft that was an epic response man. So much info. Thank you!

Tourismo the grand has 4” lift plus long arms front and rear so I’d been getting into some pretty serious tracks. The bloody thing is just off the road so often that it’s almost not worth having.

So all advice is pointing to the 3.6. Just to throw another question in there while we’re at it, how does the diesel rate against the 3.6?

Dear god...don't ask that ;) or this will become another 'are CRDs worth it thread' haha

Nah, I'm a CRD owner, and we all seem to love them until something goes wrong, then it's like F'ing CRDs. I have a great mechanic who eases my nerves of parts availability or engine issues but not all are so lucky.

Mine is auto, fully locked with 35s and about 4inches of lift. It's largely unstoppable, and I still get 11.5L/100kms on long flat drives (with all terrains and a roof top tent).

I haven't driven the equivalent in a 3.6 but I doubt they have the low RPM chug along ability and I know they become fuel hungry with 35s.

CRD's can be a bit limited for engine parts (and online advice) because the US doesn't get a CRD JK

I think if you care about how they feel on the road, the CRD drives like a truck but I think the 3.6 revs up more like a car.

I'm not convinced either engine will last longer than the other. The CRDs are meant to be better engines for towing and will use significantly less fuel, however they do get hot (the manual less so, but I believe their clutches are a weak point)

Most people are quite happy with the 3.6 though so long as they don't regularly tow (only the 3.8 was available when I bought mine FYI). You also get all the US engine parts (superchargers!) and can do a V8 swap a lot more easily if you ever wanted.

I believe the easiest way to decide if a CRD is worth it for you is if you're particularly bothered about fuel economy, or sometimes more importantly 'range on a full tank'....or if you will tow much.

Otherwise I reckon the pros and cons of either engine are fairly well balanced.

Beautiful! Thank you very much to everyone who contributed. I came very close to buying a 3.8 rubi with 80,000 ks but it had a bit of rust and a rear diff noise so I let it go. I think I’ll keep an eye out for a low k 3.6 and put the work into building it. It’s not what I really want to do at this stage, but it’s the most far sighted option. Hopefully I can find something and get it track ready in the not too distant future!

Just keep in mind the 3.6 and NAG1 auto are really good together, but the actual performance is still dependent on the diff gear being right for the Tyre size.

I have a Rubicon 2-door which is slightly lighter. 4.11 gearing has worked well with bigger tyres. 3.27 diffs and 4-door would make it feel underpowered.

Kiwi- yeah so I guess what I was really asking in my OP was, do I get the rubi and suffer with the 3.8 or do I get a 3.6 sport and then install lockers. If I was putting lockers in I’d regear while I was there so it’ll end up being an expensive upgrade.

Anyway, my decision is made. Yesterday I put a deposit down on a bright yellow 2015 sport with 45,000ks for $28k. It’s very clean, never been off-road and came with a stubby bar and rear bar, lights, winch and a bunch of internal additions. It’s more than I’d intended on spending but I’m very happy with it and it’ll make a great platform to build on.

So given that I’ve already overspent, does this sound reasonable to start with? Pick up a second hand 2” spacer lift, put on some 35s a snorkel and some discos. From there I can put a bit of research in and work out a permanent solution to the lift. Would it be silly to go straight for 35s without regearing or strengthening the front diff/axle?

Congrats on the purchase
auto or manual and 2 or 4 door?

not sure you can go to 35s on stock rims?

FYI the AEV rims are made to be hub centric on the wranglers

wranglers are prone to shakes and wobbles (especially with 35 inch muds) so having a hub centric rim removes one point of unbalance. I didn't get AEV but I would have if I had known this.

I have no experience with spacer lifts but a 2 inch coil and shocks lift might last you a few years and wouldn't cost much more, it might be worth doing that while you sort your diffs and lockers.

2 inch lifts are incredibly simple, but as soon as you go to 3 inch you begin needing to change geometry etc.

If you're going to 35s, a 2 inch lift will probably do you well for a long time.

You could always grab some new rims and 35s and trial them. If you're cautious I think the D30 will be fine. that way you can swap back to the stock tyres easily if the 35s sap too much power (before re-gearing diffs).

You need to decide if you're going to stick with the D30 (meaning strengthening and re-gearing) or buy a built to order D44 with the gearing / lockers built in

Modifying the D30 will mean more time in the shop for your vehicle i suspect

I personally would save up for a built D44, it probably wont end up costing much more (especially when you consider labour and time in the shop) and you'll have piece of mind that it's significantly tougher (which it sounds like you'd make the most of).