ATB Diffs

I have just gone through this saga over the past month with my Tdci 110. This is how and why I made the decision to go with 2 ashcroft air lockers.

Firstly I had already gone to Ashcroft rear halfshafts and flanges as I had twisted the spline on one of the stock rears - still with open centres. The front will be getting Ashcroft gear while its all out to do the front diff centre. My original plan was to go a Detroit locker in the rear and ATB in the front but that changed when I priced a few options up. Taking postage out of the equation as all of the centres cost relatively the same to post these are the prices I got for the 4 options I looked at.
ATB - $584
Detroit locker - $756
Ashcroft air locker - $815
ARB air locker - $1258

Seeing as I could get an Ashcroft air locker for as little as $70 more than the Detroit that was a no brainer for me for the rear diff. Then it was a knock on effect from there. I figured that since I would have all the wiring and air already run for the rear locker I may aswell shell out the extra $250 bucks for the air locker for the front as I was already planning on going to Ashcroft halfshafts and cv’s up front anyway. ARB didn’t even enter into the thought process from reputation for air leaks and cost, and my local ARB dealer is a jerk.

In the end it cost me around $1000 per diff to get the lockers to my door.

In my opinion the cost of compressor is a non-issue as most people who are looking for a traction aid like ATB’s or lockers would already have one for airing up tyres, and all switching and solenoids required for the Ashcroft lockers is included in the kits so I don’t really think that should enter into the equation.

Admittedly I will save a bucket load on labour as I will be doing the work myself but for the install and setup of the actual centers I’d imagine it would all be pretty close between all the options (not allowing for wiring and air lines - just setting up the diff centres).

I know the guys with 1 or 2 ATB's will disagree and defend savagely their decision but this was how I decided on the setup I have. I would have liked the onroad benifits of 2 ATB's but I wanted at least one positively locked diff and the ability to just put her in bog cog and crawl over an obstacle like a twin locked setup lets you do. No input from ABS or driver just lockers in, 1st low and let it do its thing.

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Originally Posted by komaterpillar

I know the guys with 1 or 2 ATB's will disagree and defend savagely their decision but this was how I decided on the setup I have. I would have liked the onroad benifits of 2 ATB's but I wanted at least one positively locked diff and the ability to just put her in bog cog and crawl over an obstacle like a twin locked setup lets you do. No input from ABS or driver just lockers in, 1st low and let it do its thing.

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Absolutely no disagreement or savage defence coming your way from me.

You made a perfectly valid choice - you value "crawl over an obstacle like a twin locked setup lets you do" over a liking for "the onroad benifits of 2 ATB's" and that is a perfectly valid choice. ATB's will never quite work as well as full lockers in the situation you you care more about. Good decision.

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Originally Posted by Slunnie

IF the ATB does "90%" of what a locker does as some claim then it has to be nearing the forces of a locker, except that it also has the shock forces of the wheel spin required to make the ATB work and the ETC working on it. If the ATB isn't adding much additional stress to the driveline then its not doing much additional at all. Its not the general loading of the axle the breaks them, its the impact loading of when it grabs traction while spinning.

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Thats the thing. In the few places where a full locker reigns absolutely supreme, nothing else really will come very close. In steane's ranking ATB (with TC) may be No.2 - but its not necessarily a close second in my view.

To get an ATB equipped vehicle to be half as good as a locker, when staring up a steep rutted climb with a wheel or two hanging in air - one would have to be brutal on the drive line. (whereas, all things going well, fully locked may walk up). The key here though is the term "half as good" which:
a. is just my opinion related to just the scenario described
b. is why risk of breakage is less with an ATB. Your own turn of phrase is applicable here: If its 90% as good as a locker then it has to be nearing the forces on driveline as seen with a locker. I dont reckon its anywhere near 90% thus nowhere near the kinds of driveline loads that are seen with a locker.
(As always acknowledging: one can still break stuff running ATBs or open diffs if you try hard enough)

Then factor in reality: In this situation the ATB equipped vehicle may try a few times and not succeed, then its time to break out the tow strap or winch. A bother but you still get to the campsite eventually.

depends what you use your 4wd for.
i do many touring. so a locker is not needed 99.999% of the time.
if your a mud freak who only does offroad travel, a locker might be cost effective

Just something I would like to add.
One of the things that make an ATB more effective as well as open diffs I guess is suspension travel most notably articulation.
I had an Quaife ATB in the front of my RRC and I would remove the sway bar when I was planning a long dirt trip like Cape York. The added articulation would ensure the dropped wheel had some ground contact and energise the ATB.
If I ever have enough dosh to put one in my D2 I would get front swaybar disconnects as well as the front swaybar is humungous.
Please can the complacent" I have ACE" comments. I have nice reliable springs unlike the poor bloke I met outside of Mildura topping up his ACE oil every couple of ks to get to a workshop. LOL
Regards Philip A

Part of the fun of ETC or ETC with ATB's is being honestly able to tell onlookers "No mate she hasn't got lockers fitted" when you go places most 4wds can't go unless locked front and rear...[emoji41]

Cheers

Even if that is something of an untruth [emoji14]

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Originally Posted by ozscott

Part of the fun of ETC or ETC with ATB's is being honestly able to tell onlookers "No mate she hasn't got lockers fitted" when you go places most 4wds can't go unless locked front and rear...[emoji41]

Cheers

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hehehe I hear ya! Guilty of that too. (and its COMPLETELY true, Disco Muppet. [biggrin] they aren't "lockers").

One trip in particular comes to mind - the first trip into the Malaysian jungle for my barge was to a trail I hadn't travelled before. The vehicle was only a year old and had been treated with kid gloves til then. The group I used to hang with told me the trail is not hard at all, and not to worry about my stock standard Defender making it. They lied. It was a set up.

We hit the first serious obstacle about 15 min after leaving the tarmac. It was about 1am. I was in the middle of a convoy of 7 vehicles (none of the others were land rovers). Couldn't see the obstacle but could hear the screaming engines and chatter on the radios as the three big lifted and locked trucks ahead of me struggled and thrashed about trying to get through. Was parked up for about 30 min waiting blindly for my turn.

Then the radio crackles "Land rover next - all come look!". The crews of the three vehicles behind me all ran forward past me to join the three crews ahead of me at the obstacle. I idled forward in low 2nd til the obstacle came into view. Oops! That section is affectionately nicknamed "The rock garden". Big rocks, gullies, side slopes and plenty of ways to get cross axled. Selected low 1st, feet off. Focus only on picking line. Idled through it entirely. Disappointed the entire convoy who were evidently hoping to see the Landy perform hopelessly.

Of course it wasn't the ATBs that got me through. Pure driver skill and excellent lines, not to mention my greatest virtue - a modest and unassuming demeanour.

And the point of the story: I felt no grief or guilt at all in rubbing it in that my STOCK STANDARD(!) Defender shamed all their rigs with their 35" or 37" tyres, lockers, and horsepower.

Much like Tact the thing i love most is my standard height 110 on 33s fully locked idling over almost everything whilst patrols and cruisers on 35 amd 37 inch tyres struggle. The standard articulation complimemted with my lockers makes for an excellent all round set up.

The front and rear lockers allow me to have a extremely capable offraod vehicle that can tackle any track and the centre diff atb allows it to be an excellent tourer offering the added safety of locking in slippery fast terrain. Persoanlly i think my setup offers the best of both worlds and thats what i set it up for.

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Originally Posted by tact

KAM lockers used to have an ATB diff that was a selectably lockable. Obviously when these are "unlocked" one does not have an open diff, one has an ATB.)

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That would be the ultimate for all situations.

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Originally Posted by Eevo

whata the general price for ATB's? say ashcroft

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Ashcroft Transmissions
Ashcroft ATB

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Originally Posted by Robmacca

Good to know.... One would assume that it would be advisable to run H/D axles due to the extra stress of applying the brakes to gain traction??

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Personally I upgraded my shafts and front CVs to HD to avoid any future issues with the extra stress and I'd recommend it.

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Originally Posted by komaterpillar

Seeing as I could get an Ashcroft air locker for as little as $70 more than the Detroit that was a no brainer for me for the rear diff.

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I'm interested to know more, why the preference for the air locker over an auto locker? I had always wondered if I should have put an auto locker in the back with the ATB in the front, but riding passenger in a D1 with a Detroit locker in the back the bang was nasty as we went around a round about. I don't know much about them though. The guys I go wheeling with either have air lockers or torsion diffs.