Disco axles.

I know this is a well discussed topic, anyhow heres my input.
My tdi project is nearing completion, however my rear axle needs replacing so I looked at disco, well deffy axles.
In a cheap moment I actually got both front and rear axles.

The rear isnt hard to swap, the front is another story, but I'm gonna try.
There are 3 issues with disco front axles, steering track rods hitting the leaf springs (discos have the steering link rod at the back not the front), the diff nose angle is incorrect as the disco is a leading link susp front axle where as the series is effectively a trailing link, this means that the castor angle is well diffo, and the steering control rod from the relay to the n/s wheel is a diffo length.

Firstly the steering control rod is going to have to be made (at a local machine shop).
Then to clear the springs and steering link rod a spacer between spring and axle, there is a bracket available on ebay that lifts a disco 40mm, well I'm gonna see if it will work on the series to lower it 40mm (as the bracket goes over the spring and under the axle) giving me the clearance for the steering rod over the leafs, these brackets have been used before for fitting rear disco axles, the front one is slightly diffo from the rear, heres one:

The next issue is the diff nose angle, teflon gave me an idea for that, loosen the swivels and flanges for the steering, weld up the holes on one side, position the axle for correct diff nose angle then clamp and re-drill the flange holes with the castor angle set up, no major hardship.

To correct for the drop in ride height, 1 ton spring hangers can be used, which mine allready has, compensation for screw up in castor caused by these can be reduced when re-drilling the flanges.

All in all this mod as far as I can see reasonbly maintains susp geometry and will keep good steering and wont shred prop shafts like some of these mods do, and the whole thing isnt a major task, well for a skilled basher.
The only compromise is that the steering control rod sticking out the disco/deffy axle is a bit shorter, so the steering will be a bit quicker, therefore a bit harder, no major hardship.

I'm gonna be doin this mod some time next year so will be good to see what you do
Loads of pics please mate

Have done it although it's not on the road yet.
- 1-ton shackles to drop the rear of the springs
- Re-drilled flanges to sort out the castor/diffnose angle
- 30mm solid steel spacers underneath Series axle mounts to lift axle enough for rear track rod to clear springs
- Range Rover HD aftermarket track rod kit. This gets rid of the clamps on the behind-axle track rod which could otherwise snag the spring, plus the RR track rod that goes from relay to N/S wheel is longer than you need it to be on the new Series so it can be turned down in a lathe and re-tapped. I haven't done this bit yet and am hoping the metal isn't too hard!

This method has been scrounged off someone who'd had success on another forum.

This is mine, but on this pic ignore the fact that the diff is on the wrong side ...

...PS, if using Series axle mounts, the axle mount that goes nearest the diff (offside on yours) needs major mods as the RR/Disco diff is closer to the leaf spring than on the Series axle. You also need to have an odd-shaped U-bolt made up for the mount nearest the diff, you'll see why when you do it.

If you use parabolics, the seat area of the spring is thinner so you can use standard U-bolts for the other three U-bolts despite the +30mm thicker spacer.

Probably very silly idea but
What about moding the ralco pin/steering arm from a series to fit the r/r swivel housing
That would sort the steering arm clearance prob just have to make steering arms to fit the lengh

Thanks smithy, ere you couldnt measure up the length of that steering rod to th'nearest mil you pictured by any chance, I'll make one up.
Did you weld up the old holes and redrill the flanges, or did you just redrill?
Yeah I was wondering about the inboard u bolt on the o/s, is it sort of a u bolt with the top kinked over.
Pobs not sure what you meant, could you elaborate, do you mean something with rubber bushes?
I'll keep piccies coming, allthough the job might get postponed till I finished some brackets and the 'lectrics, anyways heres some of my axles I just got, you can see things now I've pressure washed them, you can see the deff/disco axle has the track rod at the back, and you can also see the mounts for the springs pointing up, if these were ground off and welded upside down on the other side of the tube then they'd become spring hangers, you just need to drill a hole for the leaf locating pin, the 40mm lift, or in this case lower ones will give me clearance without the packers, not that theres owt wrong with packers.

so will this end up giving you less ground clearance?

Kinell you lot must badly need something to do of an evening. What a load of hassle.

If you use mil spring hangers then the ride height goes up a little, if not you lose about 30mm.
Not wanting to open a can of worms here, if you use mil hangers with a standard axle, then as far as I know the castor is screwed up tending to make the steering wobbly, and/or cause prop vibration.
This mod can take that into account, in fact its a help as with mil springs the swivel flange faces are shifted far enough to drill new holes without breaking into the old ones making a mess.
Done correctly the vehicle is just a little higher, or the same if you make your own spacers, the small tradeoff being the spring clamp beneath the axle is an inch lower to the ground.

Smithy, did you make those shackles, are they 2" londer than stock?

Those track rods weren't expensive to buy, think it was a paddocks HD offroady type kit. Will measure for you, but 'fraid you'll have to give me a bit of time, we just had our first daughter born earlier this week .. and the landy is currently buried at the back of the shed as we're also in the middle of building a new house!

The only place you lose a smidge of ground clearance is under the spring seats, and the diff is lower than that anyway.

The shackles I think are 1-ton ones, they came on an old believed ex-mil chassis I took in for scrap.

I actually reversed my axle to put the diff on the left, and found that I only had to re-drill 6 out of the 7 flange holes. I'm not welding up the original holes as the new holes are in really good meaty areas.

I hope your neighbours like the sound of your angle grinder. It takes hours and hours to clear all the old bracketry off. I had the use of a plasma cutter to slice most of it off, made a big difference.

TheSmiths88 said:

I actually reversed my axle to put the diff on the left, .

Click to expand...

just out of interest, how does the diff on the left now line up with the gearbox?
when you say reversed it, is it now upside down? (cos it'll drive backwards)

or have i completely misread all this?

not misread. it now lines up with the new gearbox - which came out of a mitsubishi - the prop is on the left of the vehicle. and i had to re-invert the diff to make it drive the right way again ... easier said than done as the bolting pattern is asymmetric. seemed like a really good idea when I started it!

lol, thought i'd gone round the bend with this one!
cheers for confirming i havent!

Just recently fitted disco 300tdi axles to my 2a and I can't believe I didn't do this ten years ago! Better brakes/steering/handling on road and no more oily patches on my drive!(not from axles anyway)
a few pics for ya

looks ok jonno, did you correct for the diff nose angle, or compromise?, congrats on the sprog smithy!

I've been trawling through paperwork and threads on various forums on the topic, this is what I found spec wise.

The standard series front axle is 'square', as in if you set the spring mounts level with a spirit level, then the diff nose angle will be 90 degrees horizontal, and the castor will be 0 degrees, ie no castor.
Apparently the 3 degree castor on the series come from the springs, they tilt the axle forward at the top to create the angle.

Disco/deffy axles with coils are diffo, if you set the axle so that the susp spring mount is dead level (ie the spring would be vertical), then the diff nose angle will be 12 degrees up from horizontal (like it is in the vehicle), and the castor will be the req 3 degrees.

So what we need to do is to weld on the leaf spring mounts horizontal on the disco axle so that the diff nose is also 90 degrees horizontal, then re-drill the holes for the swivel mounts and rotate them 12 degrees so that the req castor is back to 3 degrees.
If you dont re-drill the holes, the castor would be 9 degrees negative and the vehicle would drive like balancing a pencil on your finger, another way would be to postion the axle as it would be in the disco/deffy with the diff nose at 12 degrees, that would put strain on the prop shaft and running gear, if you were to do this you could use wide angle prop uj's and put them 45 degrees out of phase to compensate for the 'box and diff being at diffo angles.

The hardest part seems to be grinding and cleaning up the old brackets for the coiler setup on the deffy/disco axle.

What I did was have a good look at a standard disco and a standard defender and found that the spring seats were level(horizontal)when the vehicles were sat in a normal position,only thing is you have to cut these off in order to fit leaf spring seats but discovered that the top bolt for the swivel was right at the top when in the correct position for castor angle.as for the redrilling of the swivels I didn't bother because when I fitted the V8 I lifted the engine up at least 2" so the oil filter would clear the diff casing and I also have long shackles which lower the rear of the spring and diff anyway,if anything the disco axle made it better because before the front prop was so far out it was hitting the crossmember when offroad and now because the diff is pointing up(as it is meant to on a disco) the prop angle is more or less back in the original position. If your gonna redrill the swivels to bring the diff nose down I don't think you can, the track rod will want to be where the diff is because the track rod is very close to the bottom of the diff at the back on a disco axle.also to get the right castor angle the track rod will be where the leaf springs are so even if you redrill it won't solve this problem, you will have to fit about an inch spacer between the spring and axle. Good luck! Jon

that is one fun toy.

peppers, forgot to mention you'll need to use spring seat/shock mounts off the rear of a SWB which pull the bottom shock mount a lot closer to the axle ... otherwise the shock wants to be where the trailing track rod is.

Jonno, yes I am gonna use the spacers so I can redrill the flanges, I could have lifted the motor up a couple of inches if I'd known, I recently put a 300tdi in, ah well.

Thanks for that smithy, I dont really want to buy an swb axle just for the mounts, do you think I'd be able to do summat with the mounts of the disco rear axle, looks possible.

With mi new inclinometer gizmo I've been measuring up the series salisbury rear axle, with the spring mounts level, the diff nose is 2 degrees up (the spring must cause the diff to point nose down, as this would compensate for 'windup'), the shocker mounts are at 36 degrees forward, I've ground these off carefully and I'm gonna weld them on the disco axle, the spring centres are 35 1/4", and the shocker centres are 35 1/2", the diff drive flange on the disco axle is 1 3/4" further back than the salisbury so I'll need a longer prop, or a spacer-eek!.
I have new shatpart spring mounts for the disco, as said I'm gonna drill a 12.5mm hole for the leaf locater and weld them on upside down for the spring mounts.
Think that'll sort out the rear, dunno if I'm gonna need arches yet or not.
Heres some pics of bashings and measuring with the salisbury:

dr pepper said:

Thanks for that smithy, I dont really want to buy an swb axle just for the mounts, do you think I'd be able to do summat with the mounts of the disco rear axle, looks possible.

Click to expand...

I don't mean the axle perch mount things - I mean the plate that goes underneath the spring that has the 4 U-bolt ends poking through it. You need ones off the back of a SWB for the front axle of your new set-up, it pulls the bottom shock mount in close to the axle to stop it fouling the aft track rod. (The plate I think is quite different between 88" and 109")

My prop was modded by 'the propshaft clinic' for about £55 - albeit a little while ago - including postage back to me. tidy job.

Ok, yep I knew you meant shock mounts not spring perch, from what you say though the shockers on a swb bolt onto the spring clamp plate, that could be a usefull way of making life easier, I'll see if I can get a couple for sensible readies, if not I'll search for a pic and fab some the same style.
I spose I'd be better having the prop done, might see how much it'd be nowadays, then theres the messing about working how much longer it needs to be, because the shaft is on an angle then the actual lengthening will be slightly les than the diffo in drive flange distance.