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so today i started to think about trying to see if i could fit some of my spare disc brakes off my old disco onto my series front axle.

so far i have achieved not much, but food for thought:

i firat concerntrated on the hub caps, as i did not have access to the experimental land rover which im carrying out my investigation on. the problem i faced was the disco hub i need to use has 5 holes and the series hub cap i need to use has 6. i only mocked this up so i drilled 3 of the 5 holes and the origionals will be plugged later on.post-13725-0-89666600-1310602848_thumb.jpg

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i pressed a spare wheel nut into the disco hub cap as a centering device on the shaft as the thread is right and no damage was inflicted as the wheelnut was the perfect size.

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then i screwed it down onto the shaft like so, lining up the hole and putting relevant sized bolt in:

post-13725-0-32187300-1310602861_thumb.jpg

then marked the rest of the hole positioned

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like so:

post-13725-0-45109300-1310602870_thumb.jpg

and drilled

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hey presto (well half way there, dont want to waste too much time if it aint gonna work.)

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after messing about with both sets of swivels it became apparent that it wasnt just a case of swap some bits (didnt think it would be but hey ho) i managed to work out that the disco swivel fits just nicely onto the axle, just all the holes are out and there is a bit of a gap round the edge because of the lip on the axle casing. either a spacer could be made, or the lip could be ground down.

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as the disco swivel is slightly smaller in diameter than the series one the position of the holes means that it wont be possible to put a nut on the back of the axle flange, so i thought if the holes i drilled could be threaded then i could put studs in, then weld the back of the studs to the axle for extra strength, with minimal modification of the parts.

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here is a picture of the gap. note how the disco swivel is a good fit and there is no lateral play, it self centered itself onto the axle and will stay on on its own because of the good fit (obviously not with wheels on and weight on it :rolleyes: )

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next problem... the shaft on this series 3 is too wide at the point where it gies through the swivel, so it wont fit down to the diff. this could be lathed down to the diameter of the disco shaft, (surely if the thinner disco shaft is strong enough then it will be fine to lathe down?)

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amd heres the series 3 im experimenting on.

post-13725-0-77620600-1310603703_thumb.jpg

SO, in conclusion, here are my questions and confusions,

im sure the front halfshafts in my series 3 are the same diameter all the way down (like the disco ones), so are there two different types?

secondly, your thoughts on the swivel to axle mounting, re the space needed to be got rid of, and the stud idea.

next, i know its a reasonable amount of work, and i do have 2 complete disco axles sat around, but im not sure its worth removing both axles, cutting the flats off and welding new ones on in the exact right place, and reffitting the disco axles.

another problem with the disco axle problem is track width, my wheels are already flush with my body, i cant afford to buy defender eyebrows and sort out fitting them. this is why i want to try to fit the discovery hubs rather than just swap axles.

.... so is it worth drilling, tapping and welding 14 studs, possibly lathing down 2 halfshafts, fitting the discovery hubs and gaining disks or is it worth the work of swapping axles and fitting eyebrows to suit? (im not going to repaint it so the defender wing and part of the tub fixed on approach isnt really viable.)

watcha reckon?? :)

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I like the concept, safety concerns aside (for now - they deserve serious consideration when this moves from thought experiment to real road) I'd be concerned at the reduction in halfshaft diameter - but isn't the problem with the collar that the seal in the axle casing rests against?

I thought that collar was removable, or is that only series 1?

Would it be possible to lathe/turn out the swivel to take the seal? And whilst in the machine shop (I really must ship my lathe over to the UK) you could remove a bit of the swivel for the axle lip, as it provides a great deal of positive positioning for the swivel.

I've some concerns about the tapping out of the axle flange, mainly centred around the castor angle. If the holes are in the right "o'clock"/angle but the wrong diameter, then the weld, drill and tap arrangement is your only option. As the flange is steel, not cast, that would work, but you'd want to do some serious preheating before welding to ensure that you don't have any stress fatigue issues. At least that is what my sleep addled brain is thinking right now, it could be complete toss, of course.

What's your plan for steering? A LHD swivel?

G.

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surely the turning of the halfshaft wont affect safety, mainly because it is onlyt ever used in 4wd off road? so there will be no major stress on the shaft on the road?

the collar on the axle casing sticks out by around 3 or 4 mm too much, it is however the perfect diameter for the collar on the swivel to push into, creating the perfect center on the axle. so i thought grinding the collar on the axle flush would be an option to keep the centering affect that it has.

when the swivel is at the correct castor angle none of the existing holes are at the right o'clock which means holes would have to be drilled (very accurately) to take the studs like i was thinking. i never thought of the stress fatigue side, this is why i posted this up, because obviously safety is an issue and i didnt want to bodge it at all.

how would i get round this? is it just as simple as heating the collar before hand?

steering, the RHD swivel on the left side has 2 steering arms, one for the steering rod and one for the track rod. the track rod will be in the position that the disco track rod is at but the steering rod will obviously stay at the front of the axle.

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If you are not welding up the holes then there's no problem, but if you are welding then just put a torch on for a bit beforehand, I think. Then hammer the resultant weld so that all stresses are relieved. Again, I think.

What concerns me about the shafts is that it introduces a weak point, and that the stresses will focus there. I suppose if you made sure there was no shoulders to focus stress then it might be ok, as you say, it would only be used in 4x4.

On the otherhand I don't think the hardening is an issue, though I could be wrong, as the hardening is only against physical wear at the splines. I can't remember, and am too lazy to look at the parts diagram, but isn't there a bearing in the swivel housing that the inner shaft runs in? How does that fit together?

The track rod on the disco would have to be shortened, easy enough, but what about the leaf springs? does it sit above them? I've a funny feeling that they are in the same space, and you have to raise the axle relative to the springs, or bend the track rod somehow (and also avoid the diff at the same time).

Great work, keep at it!

G.

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is there another halfshaft, im sure ive seen a non tapered front halfshaft in a series 3 before? in which case it will fit, and yes there is a bearing in the swivel ball where it meets the axle.

i didnt get as far as offering the whole hub up to the series 3 last night so i didnt come across the steering problem. ill have to see. what i really want now is a spare axle to play with but i only have 2 spare disco axles lol

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I think quite a few people will be following this with interest.

I don't see major safety concerns turning down a halfshaft, there are more safety critical areas such as locating the swivel onto the axle and ensuring it bolts up OK & hasn't been affected by the process of drilling & welding the holes up. I'm not sure I like the idea of grinding the lip on the axle away, it's doing a useful job there.

I would also be inclined to keep the machining operation to as few components as possible - better to do 10 machining operations on one component than 1 operation on 10 components, that way you only have one custom bit and the rest are off-the-shelf. In other words, if you can just modify the swivel it's better than having to make custom shafts, hack the axle tube about, etc. etc. especially if you might need/want to do another one in future.

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the bit that i am thinking of grinding flat will still be doing its job, because there is a locating collar on the swivel that sits in the axle my CAD drawings may help you to visualise what i mean, unfortunately i couldnt suss mating them together on the system as its a couple of years since i played with it last.

the first drawings are models of the end of the series axle, and the modification re the studs that i am planning.

this one shows the holes i would have to drill into the axle

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these drawings show the lack of space to put a nut on the back side of the axle

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this one shows where the studs would fit, (imagine there is thread on them and they are threaded into the axle, then plug welded in place from behind)

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the studs are highlighted in this picture, the holes are the origional series holes. which i think the bottom 2 will have to be plug welded up.

would i have to plug the rest too or not??

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this is the standard disco swivel drawing showing the locating collar which fits very snugly into the axle end, thus perfectly centering.

now i need to find an old series casing to test on, id rather mock up first than bite the bullet and pull my series to bits.

post-13725-0-55088300-1310652510_thumb.png

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why dont you stick to the series swivels and graft the disk and caliper onto that. There are a few write up on that subject on this forum, and I think it involves less adapting.

Daan

i have read the write ups on these, my concerns are the cost of manufacturing the collar that is needed to mount the caliper, and getting the dimensions exactly right.

if i can fit the disovery hubs, it means i can use completely standard bits for ease of replacement, and the brakes are in effect "non modified", which means it is a succesful tried and tested unit developed by land rover themselves.

i may still go down that route yet, but i am investigating how it could be done with as little as possible modifications.

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secured myself an axle off another farmer down't road ill pick it up from under its chassis when i get back from holiday, get back 23rd so im sure ill be straight into it, meanwhile i will be doing more research and calculations to bore you lot.

im off tomorrow night.

when i get the axle i can start to modify the ends, and if all goes well and as planned, i will not bugger it up, and will be able to swap axle casings, leaving my other one to be sold as unmolescted.

im then going to still have two disco axles lying about. shame about the track width and bodywork problem eh.. but i want to keep trying at this as there are many poeple who have thought it pointless to try it this way... i am an awkward person at times so its fitting that i try this i think. :)

also gives you stuff to laugh at :)

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some more researching on the net has come up with some possible answers regarding steering links etc.

i first thought of "shaping" the track rod, which could mean more effort and less adjustment come tracking time.

then i found a few posts on a few other sites where poeple doing the coiler axle conversion have fitted a 20mm spacer to the spring seat, then using military shackles. Easily made and would sort the steering issue and would be fine for my project because i have parabolics, otherwise the u bolts arent long enuff for average springs.

i also found that the shock bottom mounts may be too far away, easy enough, +2" shocks would do, or aparently the rear bottom plate has much less of an offset and the origionl shock is long enough.

so a cyber scavenge leaves me with this:

  • steering can be sorted with spacers and shackles
  • shocks can be sorted with rear bottom mounts
  • my modifications to the axle ends should work provided i am careful and precise and double, then triple check measurements
  • brake pipes simple enough.
  • hub caps have a good solution

now all i need is to work out if i can get the right shaft, and earlier it occurred to me, will the UJ fit in the disco housing as the disco housing is slightly smaller.. if not, im sure a stage1 v8 shaft will fit.

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some more researching on the net has come up with some possible answers regarding steering links etc.

i first thought of "shaping" the track rod, which could mean more effort and less adjustment come tracking time.

then i found a few posts on a few other sites where poeple doing the coiler axle conversion have fitted a 20mm spacer to the spring seat, then using military shackles. Easily made and would sort the steering issue and would be fine for my project because i have parabolics, otherwise the u bolts arent long enuff for average springs.

i also found that the shock bottom mounts may be too far away, easy enough, +2" shocks would do, or aparently the rear bottom plate has much less of an offset and the origionl shock is long enough.

so a cyber scavenge leaves me with this:

  • steering can be sorted with spacers and shackles
  • shocks can be sorted with rear bottom mounts
  • my modifications to the axle ends should work provided i am careful and precise and double, then triple check measurements
  • brake pipes simple enough.
  • hub caps have a good solution

now all i need is to work out if i can get the right shaft, and earlier it occurred to me, will the UJ fit in the disco housing as the disco housing is slightly smaller.. if not, im sure a stage1 v8 shaft will fit.

Stage 1 v8 shaft?! Got any spare?

G.

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ive just been reading up about halfshafts and yes it seems they will slot straight into the disco hub ends, but im not sure if the inner shaft is still tapered like the earlier ones? if not then great but if yes some lathing will be required. (i know that sounds abit extreme but i will only lathe it to the diameter of the disco halfshaft)

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I have a spare set of Stage One Front shafts. You don't want to use them as they are rare and very spendy.

My recommmendation if you want to go down the Disco Hub route would be to crop the matching flanges of the disco axle and graft them to the series casing at the correct castor angle.

Make a jig first to ensure paralleism of the two ends. Set the diff face of the axle vertical and then mark the flange top and bottom so you can reproduce it when refitting. The diff flange face, line through end flange centres and diff bore centre are your datums (I know a little bit about making Land Rover axles lol).

You will need to be good with the old welder for this of course. The compromise comes with steering and the oft mentioned Ackerman issue. Many people just go with it.

I don't think turning down shafts will help their strength much. Rakeway will make a shaft for you of the correct length to go from diff to CV, at a price which will be cheaper than a stage one shaft!

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There must be a smarter way around the steering track issue, too. I'd hate to lose the ground clearance the parabolics have gained.

The shaped disco track rod is an option - I don't quite like the idea of applying heat sufficient to allow a bend on a steering component, but could be persuaded otherwise.

I suppose that it would have to be curved up over the spring, long enough lock-to-lock clearance, and then curved under the diff. Would the bending of it make it less rigid? Or would one of the heavy duty steering bar manufacturers be able to make them up?

An alternative is to hang both the track rod and the drag link out of the front arm, suzuki style:

http://bulletproofsteering.com/steeringsystems.html

Not entirely convinced by this approach, the loss of the taper concerns me, but I don't know why. It should work, and the change to the hole and bolt style tie rod is probably an upgrade.

You'd have to use a LHD drivers side swivel, but as you'd be buying new anyway there is no additional hassle.

G.

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There must be a smarter way around the steering track issue, too. I'd hate to lose the ground clearance the parabolics have gained.

The shaped disco track rod is an option - I don't quite like the idea of applying heat sufficient to allow a bend on a steering component, but could be persuaded otherwise.

I suppose that it would have to be curved up over the spring, long enough lock-to-lock clearance, and then curved under the diff. Would the bending of it make it less rigid? Or would one of the heavy duty steering bar manufacturers be able to make them up?

An alternative is to hang both the track rod and the drag link out of the front arm, suzuki style:

http://bulletproofsteering.com/steeringsystems.html

Not entirely convinced by this approach, the loss of the taper concerns me, but I don't know why. It should work, and the change to the hole and bolt style tie rod is probably an upgrade.

You'd have to use a LHD drivers side swivel, but as you'd be buying new anyway there is no additional hassle.

G.

THAT, given a bit of work could do well. but then i would have to source a lhd swivel housing, i am using the existing housings as there is nothihng wrong with them, its the safety critical components i will be renewing. i thought about putting the series LH steering link from the series swivel onto the disco but i dont think it would work. still, i think i still have my old springs so i will mount them to the axle i am getting and work out clearances and ways round the steering system. My only concerns is that the insurance company would see that as a steering modification?

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THAT, given a bit of work could do well. but then i would have to source a lhd swivel housing, i am using the existing housings as there is nothihng wrong with them, its the safety critical components i will be renewing. i thought about putting the series LH steering link from the series swivel onto the disco but i dont think it would work. still, i think i still have my old springs so i will mount them to the axle i am getting and work out clearances and ways round the steering system. My only concerns is that the insurance company would see that as a steering modification?

If you turned the bleedin' steering wheel they'd view THAT as a modification! Insurance companies. Pah.

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There must be a smarter way around the steering track issue, too. I'd hate to lose the ground clearance the parabolics have gained.

The shaped disco track rod is an option - I don't quite like the idea of applying heat sufficient to allow a bend on a steering component, but could be persuaded otherwise.

I suppose that it would have to be curved up over the spring, long enough lock-to-lock clearance, and then curved under the diff. Would the bending of it make it less rigid? Or would one of the heavy duty steering bar manufacturers be able to make them up?

An alternative is to hang both the track rod and the drag link out of the front arm, suzuki style:

http://bulletproofsteering.com/steeringsystems.html

Not entirely convinced by this approach, the loss of the taper concerns me, but I don't know why. It should work, and the change to the hole and bolt style tie rod is probably an upgrade.

You'd have to use a LHD drivers side swivel, but as you'd be buying new anyway there is no additional hassle.

G.

Hi,

I have been waiting to see the responses as I expected a lot of negatives as lots of people have looked at this. It is pleasing to see that the answers are positive and taking it seriously.

Firstly I am just a LR owner not an engineer so my comments are completely unproven and are offered for discussion.

I started off looking at narrowing a RRC axle using custom half-shafts, Then I talked to a reputable engineering company who work on LR products, they suggested cutting down KAM long spline H/S. I now have 2 sets though it is arguable if I needed the rears. I may still need a shorter H/S in one side and I see that Rakeway has been suggested in a couple of topics and at a reasonable price.

Next I wanted to look at the swivel swap as you have. I hoped but have not tried yet that the lip on the swivel could be made to fit inside the axle tube. It is great news that it does and sounds like it is perfect? Grinding off the axle lip is a pain but not major.

The key is that you retain the lip in one half (axle or swivel and that it is a good fit) as the sheer loading will be higher than on the back axle due to the width of the swivel and stub axle tubes etc..

You have made your work much more difficult though by using 7 bolt swivels, if you use RRC 6 bolt swivels then you can re-drill the holes as Series have the bolt pattern rotated by 90 deg which leaves the room to re-rill. Also why use studs, by using a 6 bolt swivel you can tap the holes and use the standard bolts. This way you have reduced the modifications down to one on the axle ends and one on the spring mounts.

One aspect that I have not measured yet is the resulting track width. If this does not work then I would suggest going down the narrowing route, this is very common in the US. I planned to cut and prepare the axle then just tack it up before getting a coded welder to do the final welding. This should solve the insurance / legal issues then apart from the H/S and width all is standard and you can use your 7 bolt axle. Some/one person on this forum has done this without a jig so it is possible but jigs are available to buy in the US or to make.

One aspect of LR products is that in the US the axle flange is a casting that is a push fit and then welded in place, therefore it is really easy to narrow them, LR use friction to but weld the flange on ans is much more difficult. another option is to use a Salisbury axle as the tubes are I believe a push fit into the pigs head (diff case)then welded like I described for US axles so maybe easier to narrow? There are a number of fabrication companies that do this kind of work for Drag Racing and the custom cars.

Bizarrely it had not occurred to me to use a Rose joint on the standard swivel arm and a LHD Swivel for the drag link this will solve the problem completely. :D

I hope that this makes sense and is useful, if I have missed something important then I hope that someone notices and tells me.

Good luck.

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