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Drum or disk for the back of the 90?


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Hi,

I've got an exmil 90 with the drum brake rear axle and 4 pin diff. I've got a ARB locker on the way and am debating wheather to fit it to the extisting drum axle or to build it into a used Disco axle that I have kicking around. The Disco axle has weaker shafts and closer spaced wheel bearings, neither of these strike me as being good but disk brakes would be nice. I can get stronger shafts for the disco axle but that still leaves me with suspect looking wheel bearings. In the perfect world I'd fit 110 front stubs and hubs to the disco axle, they fit fine, but then I'd need custom made shafts which is no good if I brake them. I use the truck for long distance trips in Canada and some heavyish off roading, tires are 255/85R16. Any ideas?

Thanks.

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is the Disco axle 10 or 24 spline?

the Disk braked axle is a far better bet.

ideally a 24spline as the shafts are stronger as standard.

the wheel bearings are not an issue IMHO whatsoever

They are both 24 spline but the drum shafts are much thicker like a Salisbury shaft.

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Salisbury/Rover Shafts are nigh on the same Diameter it is the diff centre that differs greatly:

10 SPLINE: Used for axle shaft to diff side gear in ROVER Type diffs from the first L/R in 1948 to app 1992. Also used in L/R series 1 & 11 vehicles at drive flange and early R/R & Disco CV joints.

Square form (40 o included angle) Major dia 28.2 (1.11") Root dia 25.3 (.997") Zp ( polar section) .212

App torque capability for axle of 1500 Mpa UTS Hytuf 5635 Nm (4160 ft lbs)

24 SPLINE: Commonly referred to as "Salisbury" spline as it first came into rover use in the Salisbury diff fitted to series 111 long wheel base. Also used at drive flange on series 111 onwards. From app 1994 the Rover Type diff also uses this spline in the side gear although this gear is about .004" tighter than the Salisbury diff gear. The side gear spline in all Maxi-Drive 24 spline diffs is also the same as the Salisbury. (Why Rover decided to depart from industry standard and make the Rover diff tighter is anyone's guess)

Involute form, flat root side fit, 20/40 DP, 30 o PA,

Major dia 31.4 (1.24") Root dia 29.2 (1.15") Zp (polar section) .294

App torque capability for axle of 1500 Mpa UTS Hytuf 7835 Nm (5780 ft lbs)

23 SPLINE: Only used as the inner axle to CV connection on the three decent CV joints, namely R606665 R/R ; AEU1828 stage one 111 and AEU2522 early county

Involute form, flat root, side fit 20/40 DP, 30 o PA,

Major dia. 30.1 (1.18") Root dia 27.9 (1.10") Zp (polar section) .281

App torque capacity of axle of 1500 Mpa UTS Hytuf 7450 Nm (5500 ft lbs)

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I fitted a Disco rear axle to my ex-MOD 90 but retained my original 4-pinion diff & 24-spline halfshafts so I have the best of both worlds. If I fit LR alloys in the future I will of course have to change over to 1-piece half-shafts on the rear but that isn't an issue at the moment.

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Ok, anyway the 90 24 spline shafts that I have are thicker in the main body than the Disco 24 spline shafts that I have (disco shafts are wasted the 90 shafts are not). I've seen the disco ones brake in the main body or at the flange. I've not seen the 90 ones brake yet hence my thinking that they are stronger.

Now that that is out of the way my main interest is the relative strenghts of the wheel bearings between the two axles. The Disco bearing are about 0.5 to 1 inch closer together than the drum set up. This seems like it would be less durable to me... thoughts?

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I fitted a Disco rear axle to my ex-MOD 90 but retained my original 4-pinion diff & 24-spline halfshafts so I have the best of both worlds. If I fit LR alloys in the future I will of course have to change over to 1-piece half-shafts on the rear but that isn't an issue at the moment.

You used the 90 halfshafts? What drive members did you use? The disc and drum hubs have a different bolt circle for the flange bolts and the pilot.

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I used all the standard Disco components apart from the diff, halfshafts & drive-flanges (obviously I had to use the drive-flanges that came with the halfshafts). Apparently you can't fit the 10-spline/1-piece halfshafts to a 90 hub but it works the other way without any modification whatsoever. :D

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there is No issue with the wheel bearing spacing widths whatsoever

all 300TDI> inc the TD5 model has the narrower hubs

L/R wheel bearings are plenty man enough for any wheel/tyre combo you will be choosing to fit.

If the narrower bearing are fine then I guess it makes sense for me to use the disco axle if I want disc brakes. Thanks for the input guys :)

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