bespoke portal drop boxes/axles

[bill van snorkle]

I believe the reason that MaxiDrive Portals are no longer available was due to litigation concerns should a vehicle so equipped be involved in a road accident,not due to any failings in the design. A Rover axle can be suitably and strategically reinforced to cope with the bending and twisting forces imposed by the extra leverage of having portals bolted on. Maxidrive also developed a supplementary bottom swivel bearing that very effectively beefed up the undernourished R/Rover Defender swivel housing assemblies, and the larger Series LandRover swivels can be internally sleeved to handle the forces involved

Some versions of Russian UAZ 469 jeeps use a piniongear driving an internally toothed ring gear style of portal as Simon suggested, but this design does not offer much offset (drop) without resorting to extremely low ratios.

There is an enormous amount of work involved in making custom portal ends, even if one has all the equipment and machinary at their disposal. I won't go into the long winded details again here, as most of whats involved is covered in the thread on my truck in the members vehicles forum. At the time I built that vehicle it was easy to rationalise the work on the grounds that there were almost no 404 Unimogs or C303 Volvos ever sold in Australia, so cheap donor vehicles were non existant, and I couldn't afford the $4500Aus to import a set of Volvo axles from Malaysia, But I did have access to splining ,broaching and grinding equipment, and I had a centre lathe plus plenty of after hours free time to do the job.

These days I have neither the time nor the inclination to be bothered doing something like that again,and at any rate fully reconditioned 404 Mog axle assemblies are now available cheaply, and even complete Mogs can be picked up in Europe for not much money, that it just wouldn't make sense anymore to make my own.

Bill.

[ThreeSheds]

This thread is getting seriously out of whack. I'm no expert, but I've fiddled with my share of portals & axle ideas, and while I don't see much point to this compared to using something that has already been done, here are some thoughts:

Oh, I like this thread with it's pinpong ball ideas thrown into the enamel bath of discussion... Some of them bounce right out it's true, but all are worth hearing and new (or re-hashed) ideas are surely to be encouraged? After all, struggling against LR inadequacies is what defines us - it's what we do.. Otherwise maybe we should all just go out an buy a Unimog

instead?

1. Two Sheds - no offence mate, but that is not a good idea. The whole point of portals, apart from torque reduction on the drivetrain, is clearance. All you do by putting the drop boxes at the diff is lose it again, at the expense of a lot of weight. If you don't believe me, draw a piccy on squared paper of 2 undercarriages - both same size tyres, axles, diffs etc, one with dop boxes in the wheels, one with them at the diff. Count the squares under each.

Asto_Al - no offence mate, but (I love that phrase ) I stopped drawing on squared paper even before I used to design tandem warheads for anti-tank missiles, and that was many years ago. Oh I know that warhead design isn't rocket science (we used to leave that to the lads down in 'Flight System And Propulsion'), but I do have enough 3D modeling capability in my head to see that my idea would increase, not reduce, the clearance under the diff (although I admit that the clearance under the axle tubes would be the same). I think that what we have here is a failure on my part to paint an accurate word-picture of the idea - and for that I apologise.

Here is what I said:

How about putting the drop/reduction boxes next to the diff? This would effectively move the tubes down and remove the diff-bulge^* (or move the diff up depending on your viewpoint.

and I admit that my phraseology here is not the most elegant.. But I thought that it got the idea across. But here goes again:

Imagine that the diff (the actual diff gears - not the axle) is fixed relative to the vehicle. Now - right next to the diff, put your drop-boxes arranged so that the half-shafts are moved down relative to the diff making (say) the bottom of the axle tube now line up with the bottom of the diff casing. By this means you have removed the lower bulge of the diff housing and increased clearance under the diff casing by 3"-4" relative to the wheels (which line up with the half-shafts). Of course since the suspension attaches to the axle tubes (which are now 3"-4" lower relative to the vehicle, you will need to fit 3"-4" lifted springs/shocks, thus lifting the vehicle relative to the wheels.

So to summarise: The diff gears and vehicle stay in the same relative positions, the axle tubes, half-shafts, wheels and suspension move down relative to the diff casing and vehicle, and so clearance under the diff casing and vehicle is improved and at the same time you can introduce a reduction gear (or event a two speed axle) if you want.

The only place that you don't gain is under the axle tubes where the clearance stays the same.

TwoSheds

Oh, By the way - I am not saying that this is a cost effective solution either for volume, limited or even home manufacture - it's just a thought experiment...

[Astro_Al]

Two sheds - no offence mate, but...

I get it. I got it the first time. Its a bad idea. Use squared paper.

You add the weight and complexity of portals, but instead of using them to gain clearance everywhere, you use them only to gain clearance at the diff.

You also negate the torque reduction effect for the halfshafts - a classic weakspot which could well do with the help it gets from portals.

Also, if you need to lift the vehicle relative to the wheels to accomodate the higher diff, you are ruining any change of a decent COG.

I'm not sure why you think thats a good idea to be honest? Bit lost now.

I like ideas, don't get me wrong, I just don't see any reason why that one is worth pursuing? Can you enlighten my tired old brain?

Cheers, Al.

[carl hurst]

Well i have had some good suggestions about this topic,I seems like a bolt on option is the favorite amongst most people but if made to sell to public it would need to have a huge disclaimer stating OFF ROAD ONLY or gear it down so it would be impractical for on road use,

One thought i had was to put the front drop box between the axle end and the chrome swivel,steering may become venerable,someone will put me straight on this i am shure,

Carl.

[LandyManLuke]

Two sheds - no offence mate, but...

... I'm not sure why you think thats a good idea to be honest?

I'm with Al on this one - don't see any sense in putting the drop boxes near the diff. drop boxes at the wheel end lift the diff and the whole axle tube relative to the ground, (which is what you're after all along), whilst making the halfshafts 'stronger' by virtue of the drop box ratio.

And squared paper rocks!!

Luke

[dirtydiesel]

Well i have had some good suggestions about this topic,I seems like a bolt on option is the favorite amongst most people but if made to sell to public it would need to have a huge disclaimer stating OFF ROAD ONLY or gear it down so it would be impractical for on road use,

Stop being such a capitolist, and build what is best for you not what would potentially sell the most.

One thought i had was to put the front drop box between the axle end and the chrome swivel,steering may become venerable,someone will put me straight on this i am shure,

Carl.

Have a look at simca portals this is how they are constructed, the portal box sticks out a long way inside the wheel

I would second risla1's suggestion, in that if volvo rear axles are widely available you'd be daft to make your own.

IMHO volvo portal boxes are a thing of beauty, superior in many ways to 404 mog ones.

[BatGeorgeone a.k.a George]

Hello chaps,

My two cents here...

Russian guys have made quite a large number of "home made" portals, some of them even can last a LADOGA competiotion, so I presume they are strong enough...

I have spent quite a few sleepless nights thinking searching in the Inet and drawing portals and also spent talking(and drinking) many hours with some tech guys, guys that go to LADOGA and some profy 4x4 builders, so in brief all of them say - do not even think about it, its gonna be looooong time project, its gonna be tons of money and at the end of the day does not worth it!

Here you are some project that russian bros have done:

Bear in mind guys that most of them are budget ones, means most of the job is done at the work place or done by mates at their work...

http://www.mktb.ru/fotki/

BTW I am looking for a cheep MOG axles if anyone got some

Kind regards,

[dollythelw]

dobre den George - the last pictures are of Anatolys Spider, I know Anatoly and his car pretty well - he is a good guy. The spider finished last year but mostly on 3 cylinders and if I remember correctly it was the only home made portal axle to finish last year.

good luck to using rear volvo portal boxes to make front axles, which bit are you planning on using? just the drop gears? then you could get into casting stub axles, inner C's, CV joints etc - it will be a loooooooong process but interesting to do

[Night Train]

Anyone considered the front portal axle design that Mack Trucks used?

The axle falf shaft ended with a bevel gear that meshed with a corresponding bevel gear bushed over the steering king pin. The king pin served to provide steering and to carry a hollow drive shaft down a drop box and to another pair of bevel gears that drove the stub axle.

The bevel gears were set at the king pin angle so that the steering geometry still worked and the opposing torque from each end of the axle balanced out through the track rod.

It did away with the need for a cv joint and allowed a reasonable lift in the axle tube.

See parts diagram here.

Alternatively, just to raise the axle, how about using a diff and cv jointed drive shafts, as in an independent set, up but having the diff and king pins set in a frame so that the axle ends are at maximum drop and the diff is at its highest. The whole assembly can then be spring monted as an axle case.

[dollythelw]

theres a Russian van (Antelope/Gazelle something like that) that uses the same configuration Night train - I'll try and find a link, it was on the Offroad ru website sometime ago. massive floation tyres slung under a transit type thing

[Astro_Al]

Alternatively, just to raise the axle, how about using a diff and cv jointed drive shafts, as in an independent set, up but having the diff and king pins set in a frame so that the axle ends are at maximum drop and the diff is at its highest. The whole assembly can then be spring monted as an axle case.

That has been discussed here before. I brought it up on Pirate ages ago. A guy (Rusty I think) made a rear axle like that.

Good plan if you ask me. Not as good as portals though... Less clearance (in total), no torque reduction, more joints to go wrong.

Al.

[Night Train]

I know the WW2 Mack NM truck used that system for the front axle as does the current Kubota tractors but I can't find any detailed diagrams. It would allow a very tight steering lock as another advantage.

[Astro_Al]

There is a commercially available axle of this type. For custom fitment to 4x4s. Can't remember the name though - dyna-something...?

Just fit portals. Or work out the problems with indy, compensate and run that.

Al.

[Escape]

theres a Russian van (Antelope/Gazelle something like that) that uses the same configuration Night train - I'll try and find a link, it was on the Offroad ru website sometime ago. massive floation tyres slung under a transit type thing

You mean this:

There are lots more pictures, but very few specs.

[dollythelw]

thats the kiddy

[simonr]

Why did nobody show me this when I was looking for a van for X-Eng? It would look good with a big X on the side!

Si

[sheeppimp]

Why did nobody show me this when I was looking for a van for X-Eng? It would look good with a big X on the side!

Si

It'd look cracking but the load bed at around 5 foot high would be a pig to load/unload at shows (I'm sure you could find a forklift for loading at home )

[Night Train]

You mean this:

There are lots more pictures, but very few specs.

Imagine that bearing down on you at 90mph on the motorway with with Van Hire written on the side!

[deepmud]

the huge leverage on the axle scares me but I've seen this on tractors - farmers break stuff if it's weak lol

[deepmud]

Suspension? We don't NEED no stinkin' suspension.

[robhybrid]

How about using narrower series axles with rr diffs fitted and then making a portal box to fit on the end of them.

The width would then end up only marginally wider than original.

Std series shafts and uj swivels could be used and the lack of strength compensated for by the gear reduction in the drop box.

Somebody earlyer had a similar idea to me in that the stub axle would un bolt off the axle then bolt onto the drop box.

This is what I have considered and as such done many a fag packed drawing only to think I havent got enough spare time as it is.

Would it be possible to modify a cv joint (weld a sprocket to it) and use that as your drop box output shaft, the input would be a similar modified std drive member.

I was tempted by the idea of running a duplex?/triplex chain and sprocket type drop box.

I thought manufacture may be cheeper acuracy not needed to be as good ang if the box bot damaged there would be a chance it could still run.

I thought you wouldnt need to make different casings to alter the gear ratio, chust change sprocet sizes.

When I win the lotttery

[Escape]

Suspension? We don't NEED no stinkin' suspension.

I read somewhere the suspension is supposed to be inside the portal drop box, perhaps a torsion set-up like on trailers.

Haven't quite figured it out though...

[dollythelw]

its a tractor axle

[sheeppimp]

I was tempted by the idea of running a duplex?/triplex chain and sprocket type drop box.

I thought manufacture may be cheeper acuracy not needed to be as good ang if the box bot damaged there would be a chance it could still run.

I thought you wouldnt need to make different casings to alter the gear ratio, chust change sprocet sizes.

When I win the lotttery

that was the system used on the Agrover created in the eighties, here Never seen one but I vaguely recall that there were issues with power losses due to chain stretch. On an unrelated note I know a guy who used a duplex chain drive arrangement on a Volvo engined bike and that suffered horrendously from chain wear - 2000 miles a chain was good going.

I have wondered if these drop boxes could be obtained though?

Personally I've always fancied going down the earlier Roadless Traction 109", just to be different

[bill van snorkle]

Anyone considered the front portal axle design that Mack Trucks used?

The axle falf shaft ended with a bevel gear that meshed with a corresponding bevel gear bushed over the steering king pin. The king pin served to provide steering and to carry a hollow drive shaft down a drop box and to another pair of bevel gears that drove the stub axle.

The bevel gears were set at the king pin angle so that the steering geometry still worked and the opposing torque from each end of the axle balanced out through the track rod.

It did away with the need for a cv joint and allowed a reasonable lift in the axle tube.

See parts diagram here.

Alternatively, just to raise the axle, how about using a diff and cv jointed drive shafts, as in an independent set, up but having the diff and king pins set in a frame so that the axle ends are at maximum drop and the diff is at its highest. The whole assembly can then be spring monted as an axle case.

I think you are referring to the WW2 Mack NO that employed that system. A firm in the USA called Assam in the 1920's I think made front axle assemblies of that design, known as ''turret drive'' IIRC to convert Ford cars and trucks to 4wd. Strangely they reversed the design so that the offset actually lowered the differential so as to maintain standard ride height.

I'd imagine these designs are very suitable for low speed tractor style work and the relatively low speeds that the old Fords and Macks were capable of,also bearing in mind that the drive to the front axle would also be disengaged at these speeds,so the bevel gears would not be under pressure and therefore not generating much heat.My guess is that for rear axle and constant 4wd applications, the designs I have seen in the flesh, mainly on 4wd tractors would probably generate too much heat at highway type speeds, possibly leading to premature wear and failure.

It occasionally gets reported on Pirate that Humvee portal boxes can be picked up at scrap metal prices. If this is true then I don't see why the gears, shafts,Cv's,(early models that will fit inside LR swivel balls), bearings and bearing carriers etc can't be used and incorporated into custom fabricated housings, designed around LandRover swivel housing and disc brake fitment. As mentioned in my first post, both Series and coiler type swivel balls need extra assistance or reinforcement to cope with the extra leverage, and the banjo housings can be easily reinforced to cope with the bending and twisting forces.

Bill.