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Where an application requires that the diff must be able to act as an "open" diff and a fully locked effect, the only solution is to fit a manual locking diff under the control of the driver.

These diffs need additional external parts, compressor/pipes/ solenoids, etc. and need to be plumed in carefully if damage to these ancillary parts is to be avoided. We supply the ARB air locker, which has been proved, over a number of years, to be a reliable option.

We sell a lot of ARB air lockers and are great fans of them, the older 24 spline version was the RD56, this was OK but had occasional problems with the plastic cage inside failing. This has now been superseeded by the RD128 which internally is a much better as this plastic cage is no longer used making it a stronger unit but the only drawback is the air feed pipe comes from the other side, the same side as the crown wheel. ARB recommend the air pipe is routed over the crown wheel but this makes is very fragile and when you put it in the axle housing you can"t be sure the pipe is not fouling the housing. we prefer to make some small mods to the diff casing and fit the air pipe on the same side as the crown wheel like this :

This is also a good place for the air pipe to come out when fitting to a 2.4 TDCi engined Defender as it"s too tight to the engine sump if you come out the top of the diff housing.

Spare Parts

We stock spares for the ARB, to find the part number of the parts you need click here and go to "ARB Lockers" then "Parts and Service" and click on the model you have to find exploded diagrams.

Install tips

When installing into the rover diff please note there are 2 types of journal end cap, the earlier diffs have a "hook" attached to the end cap that stops the side adjuster nut from unwinding under load, this works fine on the stock side adjuster nut and the new ARB side adjuster nut.

The later type diffs don"t have this "hook" but instead have a roll pin that goes through the end cap and locates in one of the cut outs on the stock side adjuster nut to stop it turning, the problem is that the ARB side adjuster nut sits further in board than the stock nut and this roll pin will not stop it coming undone, so on the air feed ring side there is no mechanical locking mechanism to stop this side adjuster nut coming undone. What we have found it that under heavy load the ARB nut comes undone, this puts pressure on the blue wire clip that holds the air feed ring on and this now forces the air feed ring off centre which results in a big air leak. I have spoken at length to ARB about this and the only option is to threadlock the ARB side adjuster nut to the end cap to stop it coming undone.

ARB Air compressor will be required at £150.

Tyre inflation kit can be supplied at £ 35.

The ARB"s do not come with bearings, we supply these at £20/pair.

Installation

if you bring us a good take out diff and would like the ARB centre built in the cost would be : £ 475 (ARB) + £ 20 (Bearings) + £ 75 (Fitting) = £570

If you would like the ARB assembled into a rebuilt diff the cost will be £ 695 exchange + £ 75 refundable core charge

If you fancy going to 4.11 ratio at the same time then add £150 to these prices.

ARB	From £475
Where an application requires that the diff must be able to act as an "open" diff and a fully locked effect, the only solution is to fit a manual locking diff under the control of the driver. These diffs need additional external parts, compressor/pipes/ solenoids, etc. and need to be plumed in carefully if damage to these ancillary parts is to be avoided. We supply the ARB air locker, which has been proved, over a number of years, to be a reliable option. We sell a lot of ARB air lockers and are great fans of them, the older 24 spline version was the RD56, this was OK but had occasional problems with the plastic cage inside failing. This has now been superseeded by the RD128 which internally is a much better as this plastic cage is no longer used making it a stronger unit but the only drawback is the air feed pipe comes from the other side, the same side as the crown wheel. ARB recommend the air pipe is routed over the crown wheel but this makes is very fragile and when you put it in the axle housing you can"t be sure the pipe is not fouling the housing. we prefer to make some small mods to the diff casing and fit the air pipe on the same side as the crown wheel like this : This is also a good place for the air pipe to come out when fitting to a 2.4 TDCi engined Defender as it"s too tight to the engine sump if you come out the top of the diff housing. Spare Parts We stock spares for the ARB, to find the part number of the parts you need click here and go to "ARB Lockers" then "Parts and Service" and click on the model you have to find exploded diagrams. Install tips When installing into the rover diff please note there are 2 types of journal end cap, the earlier diffs have a "hook" attached to the end cap that stops the side adjuster nut from unwinding under load, this works fine on the stock side adjuster nut and the new ARB side adjuster nut. The later type diffs don"t have this "hook" but instead have a roll pin that goes through the end cap and locates in one of the cut outs on the stock side adjuster nut to stop it turning, the problem is that the ARB side adjuster nut sits further in board than the stock nut and this roll pin will not stop it coming undone, so on the air feed ring side there is no mechanical locking mechanism to stop this side adjuster nut coming undone. What we have found it that under heavy load the ARB nut comes undone, this puts pressure on the blue wire clip that holds the air feed ring on and this now forces the air feed ring off centre which results in a big air leak. I have spoken at length to ARB about this and the only option is to threadlock the ARB side adjuster nut to the end cap to stop it coming undone. ARB Air compressor will be required at £150. Tyre inflation kit can be supplied at £ 35. The ARB"s do not come with bearings, we supply these at £20/pair. Installation if you bring us a good take out diff and would like the ARB centre built in the cost would be : £ 475 (ARB) + £ 20 (Bearings) + £ 75 (Fitting) = £570 If you would like the ARB assembled into a rebuilt diff the cost will be £ 695 exchange + £ 75 refundable core charge If you fancy going to 4.11 ratio at the same time then add £150 to these prices.