LOST JEEPS :: View topic - Intalled rear ARB Locker higher fuel consumtion?

Marry X-mas everybody!!

I recently installed an ARB air locker, replacing the limited slip in my rear diff.

The locker locks and works great, no funny sounds coming from the diff or anything,
but I have noticed an increase in fuel consumption.
Aprox 1 Lit/100 Km for my '05 2.4 export.

Is this normal?

m_volyrakis wrote:

Not unheard of when getting rid of the awful trashloc and going to a ARB as your not having any of the friction causing undue drag from the clutch based LSD when turning.The ARB when unlocked has no such added friction so you actually gain a tad bit of mpg's,it could also be due to new gear oil also.

Did you adjust pre-tension and backlash 100% to JEEP specs? (these do NOT come with the ARB install instructions, they refer to the FSM!)

Author:	m_volyrakis [ Sun Dec 26, 2010 2:53 pm ]
Post subject:	Intalled rear ARB Locker higher fuel consumtion?
Marry X-mas everybody!! I recently installed an ARB air locker, replacing the limited slip in my rear diff. The locker locks and works great, no funny sounds coming from the diff or anything, but I have noticed an increase in fuel consumption. Aprox 1 Lit/100 Km for my '05 2.4 export. Is this normal?

Author:	CRD Joe [ Sun Dec 26, 2010 5:01 pm ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
It shouldnt be. When the locker is OPEN it in effect does not exist.

Author:	m_volyrakis [ Sun Dec 26, 2010 5:04 pm ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
I know!! So, it should theoretically contribute to a lower consumption...

Author:	tjkj2002 [ Sun Dec 26, 2010 8:20 pm ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
m_volyrakis wrote: Marry X-mas everybody!! I recently installed an ARB air locker, replacing the limited slip in my rear diff. The locker locks and works great, no funny sounds coming from the diff or anything, but I have noticed an increase in fuel consumption. Aprox 1 Lit/100 Km for my '05 2.4 export. Is this normal? Not unheard of when getting rid of the awful trashloc and going to a ARB as your not having any of the friction causing undue drag from the clutch based LSD when turning.The ARB when unlocked has no such added friction so you actually gain a tad bit of mpg's,it could also be due to new gear oil also.

Author:	Tokyojoe [ Mon Dec 27, 2010 1:03 am ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
Have you checked to make sure your ARB is not installed incorrectly and is actually engaged full time? Just asking.

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Author:	JeepinJarhead03 [ Mon Dec 27, 2010 3:45 am ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
tjkj2002 wrote: m_volyrakis wrote: Marry X-mas everybody!! I recently installed an ARB air locker, replacing the limited slip in my rear diff. The locker locks and works great, no funny sounds coming from the diff or anything, but I have noticed an increase in fuel consumption. Aprox 1 Lit/100 Km for my '05 2.4 export. Is this normal? Not unheard of when getting rid of the awful trashloc and going to a ARB as your not having any of the friction causing undue drag from the clutch based LSD when turning.The ARB when unlocked has no such added friction so you actually gain a tad bit of mpg's,it could also be due to new gear oil also. he's reporting the opposite, increase in fuel consumption

Author:	tonycrd [ Mon Dec 27, 2010 8:51 am ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
m_volyrakis wrote: Marry X-mas everybody!! I recently installed an ARB air locker, replacing the limited slip in my rear diff. The locker locks and works great, no funny sounds coming from the diff or anything, but I have noticed an increase in fuel consumption. Aprox 1 Lit/100 Km for my '05 2.4 export. Is this normal? Did you adjust pre-tension and backlash 100% to JEEP specs? (these do NOT come with the ARB install instructions, they refer to the FSM!) If not..you could have to much tension on the diff bearings, so it rotates with dificulty. Or, there is to much pinion/gear contact pressure. This won't go away by itself, will end up in destroying the bearings, (possibly diff), gear and pinion. I'd doublecheck my settings.

Author:	m_volyrakis [ Mon Dec 27, 2010 11:08 am ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
Tokyojoe I'm sure that the ARB is locking, but how can I be sure it's a 100% lock? Yeap! JeepinJarhead03 got it right it's an increase in fuel consumption alright. I was expecting a slight decrease for the exact reasons mentioned by TJ. tonycrd wrote: Did you adjust pre-tension and backlash 100% to JEEP specs? (these do NOT come with the ARB install instructions, they refer to the FSM!) I'm not sure it was 100% to jeep standarts, I dont recall the mecanic measuring before pulling the old diff out.. Point well taken... will have a look and see if I can locate the needed info in the FSM... BUT.. checking will mean that I'll have to go back to the shop, re-open the diff and measure... right?

Author:	m_volyrakis [ Mon Dec 27, 2010 11:24 am ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
Just went throught the FSM I don't think that I now posses have a definite knowledge of what the correct specs are.. I has hoping that I would find something clear like a specific number or chart or sthg to take with me to the shop. Any help?

Author:	tonycrd [ Mon Dec 27, 2010 11:27 am ]
Post subject:	Re: Intalled rear ARB Locker higher fuel consumtion?
Yep..you will have to take the rear cover off. Then measure. But I would start all over again. Ask your mechanic if he adjusted the bearings in the right way... There are several pages in the FSM about fitting a diff int the 8.25 rear axle. Here's some of it. It's in chapter 3, differential&driveline.

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