Series axle conversion

[Sports Lorry]

Hello, I'm looking at doing a diff/axle conversion in my 69 ex army IIa. I want to keep it in the family and use rover parts, so I'm thinking Discovery diffs. Does anyone know the difference between S1 and S2 diffs/axles and which are better? Or if the setup was different from V8 to Td versions? Any advice would be appreciated! Cheers

[isuzurover]

Tech issues:

D1 and D2 are basically the same, except that pre ~94(ish) D1s have 10-spline diffs and later model D2's swapped to P38 diffs. However the oem 24 spline are no stronger than 10-spline, and P38 diffs can have issues. No difference diesel-petrol, and they are all 3.54:1.

On the front, the track rod wants to be where the springs are. So you will need to (a) go SOA (spring over axle), (b) rotate the housing to a funny angle so the track rod clears - then index and rotate your swivels if you want correct caster, or (c) fit a double-arm RHS swivel housing from a post '99 model or a LHD vehicle, and move the track rod to the front using a toyota-style combined track rod and drag link. Note that option (c) will not give you proper ackerman steering.

Legal issues:

In most states converting to coiller axles on a series will be illegal as you will increase the track width by more than is allowable. Series are 55" drum-drum, coillers are 61" disc-disc.

Option (a) is illegal in many states.

[Sports Lorry]

Thanks mate! I bought a pair of complete D1 axles/diffs and brakes in good nick for ten bucks (bargain!) but I don't want to spend money modifying them for leaves until I know its a good option. I suppose my question should have been: "What is the easiest way to get disc brakes and stronger diffs on a IIa?" Any ideas?


Tech issues:

D1 and D2 are basically the same, except that pre ~94(ish) D1s have 10-spline diffs and later model D2's swapped to P38 diffs. However the oem 24 spline are no stronger than 10-spline, and P38 diffs can have issues. No difference diesel-petrol, and they are all 3.54:1.

On the front, the track rod wants to be where the springs are. So you will need to (a) go SOA (spring over axle), (b) rotate the housing to a funny angle so the track rod clears - then index and rotate your swivels if you want correct caster, or (c) fit a double-arm RHS swivel housing from a post '99 model or a LHD vehicle, and move the track rod to the front using a toyota-style combined track rod and drag link. Note that option (c) will not give you proper ackerman steering.

Legal issues:

In most states converting to coiller axles on a series will be illegal as you will increase the track width by more than is allowable. Series are 55" drum-drum, coillers are 61" disc-disc.

Option (a) is illegal in many states.

[isuzurover]

I suppose my question should have been: "What is the easiest way to get disc brakes and stronger diffs on a IIa?" Any ideas?

You may want to rephrase that again... Easiest would be to buy one of the bolt-on disc conversion kits available, and buy ARB/Jacmac/Truetrac diffs, Ashcroft ring and pinions, and strengthened axles from Hytuff, rovertracks or mercesesrover/seriestrek (preferred option for a series http://www.seriestrek.com/axles.html).

But I suspect you may not wish to spend that sort of $$$?

[Sports Lorry]

Thanks again! That looks like expensive fun, and I like the idea of keeping the unis, rather than using CVs. I've looked into the disc conversions, supposing the rear Salisbury is pretty much as good as a disco diff, but I assumed I'd have trouble finding a good diff that fitted into the IIa front housing. Are the ones you mentioned bolt-on units or does the housing need modification?


You may want to rephrase that again... Easiest would be to buy one of the bolt-on disc conversion kits available, and buy ARB/Jacmac/Truetrac diffs, Ashcroft ring and pinions, and strengthened axles from Hytuff, rovertracks or mercesesrover/seriestrek (preferred option for a series Extreme duty axles (http://www.seriestrek.com/axles.html)).

But I suspect you may not wish to spend that sort of $$$?

[isuzurover]

Thanks again! That looks like expensive fun, and I like the idea of keeping the unis, rather than using CVs. I've looked into the disc conversions, supposing the rear Salisbury is pretty much as good as a disco diff, but I assumed I'd have trouble finding a good diff that fitted into the IIa front housing. Are the ones you mentioned bolt-on units or does the housing need modification?

All the ones I mentioned are bolt-in centres which would completely replace your centre. They are many times stronger than either your series or a D1/D2 centre.

Keep in mind the D1/D2 diff centre is no stronger (and almost identical) than the centres you have now. Just the 3.54:1 D1 ring and pinion is stronger than the series 4.7:1 ring and pinion. 3.54's are far too high unless you want to drive most places in 3rd and never go offroad.

The strongest ring and pinions available for a rover diff are here:
Ashcroft Transmissions (http://www.ashcroft-transmissions.co.uk/index.php?act=viewCat&catId=12)

I forgot they also make lockers which I left out from the list.

[Sports Lorry]

Cheers mate, I really appreciate your advice.




All the ones I mentioned are bolt-in centres which would completely replace your centre. They are many times stronger than either your series or a D1/D2 centre.

Keep in mind the D1/D2 diff centre is no stronger (and almost identical) than the centres you have now. Just the 3.54:1 D1 ring and pinion is stronger than the series 4.7:1 ring and pinion. 3.54's are far too high unless you want to drive most places in 3rd and never go offroad.

The strongest ring and pinions available for a rover diff are here:
Ashcroft Transmissions (http://www.ashcroft-transmissions.co.uk/index.php?act=viewCat&catId=12)

I forgot they also make lockers which I left out from the list.

[boot]

P38 have 4 pinion diff heads which are much stronger than the std series ones. but are 3.54 and a different stud pattern, but the smaller stud pattern is more common making mags cheaper. just another line you could look at.

[Dougal]

P38 have 4 pinion diff heads which are much stronger than the std series ones. but are 3.54 and a different stud pattern, but the smaller stud pattern is more common making mags cheaper. just another line you could look at.

Diff heads are on the other side of the P38 axles too.

[Sports Lorry]

Thanks. Dougal makes a good point, but do you know if the centres will fit into a series housing?


P38 have 4 pinion diff heads which are much stronger than the std series ones. but are 3.54 and a different stud pattern, but the smaller stud pattern is more common making mags cheaper. just another line you could look at.

[Dougal]

Thanks. Dougal makes a good point, but do you know if the centres will fit into a series housing?

I've never tried, but apparently the bolt pattern is different. It could certainly be overcome, but for the same effort you might find something more suitable.

A locker is the easiest way to get a very strong diff-centre.

[boot]

from what Ive been told the bolt pattern is the same pcd but yo need to extend the pan out 15mm. and obviously custom axles.
Im going to look at the path for my rrc as i like open diffs and don't see the need for lockers if you can keep ya wheels on the ground.
Locker also mean you can get further than your mates with out them. Sounds great until you get stuck and they cant reach you!

[isuzurover]

from what Ive been told the bolt pattern is the same pcd but yo need to extend the pan out 15mm. and obviously custom axles.
Im going to look at the path for my rrc as i like open diffs and don't see the need for lockers if you can keep ya wheels on the ground.
Locker also mean you can get further than your mates with out them. Sounds great until you get stuck and they cant reach you!

Maxi-Drive used to make heavy duty carriers - Basically a solid 4-pinion rover diff (must stronger than oem 24-spline or P38 diffs). MR Auto may be making these if they are making MD lockers again.

Rover have had LOTS of issues with P38 ring and pinions - personally I would stay away.

For the same or less $$$ you could buy a couple of true tracks from lucky 8. True-tracks should be as strong as a MD 4-pin diff centre, and while they do act as an LSD when both wheels (on an axle) are on the ground, when you lift a wheel it will spin like an open diff. So you can still claim you don't have lockers.

[boot]

been on the new today and KAM also do a four pin head to fit the series with lsd
Landrover Tuning :: Home (http://www.landrovertuning.com.au) have them for everything else so should be able to do a series one.

[isuzurover]

been on the new today and KAM also do a four pin head to fit the series with lsd
Landrover Tuning :: Home (http://www.landrovertuning.com.au) have them for everything else so should be able to do a series one.

They may make them, but unlike MD, Ashcroft, Rovertracks, etc they won't tell you what materials they are actually made from.