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Bolt on Portal box Project


Papa B
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Hi,

So i am reasonalby new to this forum, but i have recently just finished helping disty with his defender rebuild, went for a great drive in the snow just now!

Basically, I am a 4th year engineering student and for my final year project i am working on designing and commercialising a set of portal boxes to be bolted onto the end defender axle casings. Currently i am reserching a few options and trying to validate the strength of the defender axle casing (i have an exciting experiment in the lab a couple of weeks where we are going to test a casing to destruction in a torsion load cell)

I have had quite a god look around at the options availiable, mogs, volvo and projects people have undertaken as one offs. My aim is to have design fully validated, build them and test them and then begin marketing them.

Currently i am considering:

-tradition geared drop boxes

-Chain driven like that of land rover's very own Ag-rover

-Hyvo chain driven

-Belt driven (the crazy out there, but strangely attractive option)

Are people interested?

One of the options i am thinking through at the moment is the issue of hub reduction, obviously an attractive option for reduction of stress on half shafts etc but also reduces the top end speed of your defender. As defender owners, if you were to fit portals would you prefer it if the final drive ratio stayed the same(hence same top speed) or do you consider the hub reduction as more important?

cheers,

Luke

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First off I'd take a damn good look at all those who have stated almost exactly the same intention as you and how far they've got.

As far as I'm aware, only two or three people have actually succeeded in actually producing something that drives around.

Bill Van Snorkle's effort is well worthy of close attention, the other chap on here I forget but his boxes were made by Tibus. Maxi-Drive made some for a while back in the day but stopped.

IMHO it's a hiding to nothing if you are thinking of doing something that could become a saleable product - the cost & hassle involved will far outweigh other solutions like axle swaps or a ground-up design using the right bits for the job.

If you just want an interesting engineering challenge though, I'm sure there'd be quite a lot of interest in the project.

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I agree.

Have a look at just the immense cost of this. There was a guy in the US wanting to do the exact same thing but dropped the idea after pretty much everyone discouraged him to continue on as the scale of such a project is just immense.

Another thing that set him back was when he found out howmuch it is to have gears cut, that is very, very expensive!

Then you have to decide on having the portalboxes machined or cast, both not very cheap...

I would think long and hard before doing something like this. As if you would want to make it sell it would have to be either better or cheaper than the ones already out there. You'd be hard pressed I reckon.

Good luck anyway!

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I kinda agree with what others above have said, i.e. cost verses market. To add some info though:

The 'Tibus' axles FF mentioned are made by Wolfgang Tibus at Killer Axles. Oilworker on here fitted the first production set. Wolfgang has played with Unimog and Dana axles a lot over the years so understands what is needed to mod the LR axle.

Another option worth looking at are the Mark's Adaptors bolt on portals for Nissan axles. They seem to be popular in Oz.

To answer your question about gear ratio, then I would say anybody running a bolt on portal is going to want to run a 35" to 40" tyre, so if you drop the gear ratio by the same percentage as that is an increase from standard tyres then it would be attractive to buyers. Something like a 1.1:1 to 1.2:1 drop ratio could work well.

My major concern on the whole idea is using Landrover axles. They're a weak out of date design and don't have too many options for modifying and upgrading (not like a Dana 44 or 60 for example). I know there is an obvious market in the UK for an easy Landrover upgrade, but I think maybe looking at a complete axle solution, like Spidertrax may be a better way forward and widen the appeal to the European, US and Oz markets.

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My major concern on the whole idea is using Landrover axles. They're a weak out of date design and don't have too many options for modifying and upgrading (not like a Dana 44 or 60 for example). I know there is an obvious market in the UK for an easy Landrover upgrade, but I think maybe looking at a complete axle solution, like Spidertrax may be a better way forward and widen the appeal to the European, US and Oz markets.

That is all true, but spidertrax only represents about 1 percent of all ofroaders, whereas landrover axles would represent at least 50% I would have thought, even world wide.

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As a commercial venture a no no,though I assume you have access to a good university workshop so machining shouldnt be a problem and if your design uses straight cut gears again a simple machining operation, though the correct heat treatment is vital and should be sent to a specialist in heat treatment. As for castings they are not that expensive in low temp alloys though casting steel is a different matter.

I think most people are afraid of this sort of project due to the inability to workout loading both shock and running, gear design spec meshing depth etc etc.

Do it!(I am ex drivetrain engineer, R&D by the way)

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Engineering student , obviously not marketing :rolleyes: , as mentioned a technically very interesting project , but in view of the possible market (minute) a real non starter from an economics point of view. The landrover mods market is huge (and very profitable) with the right items , If you want to take the project all the way , do a bit of marketing research first ;) eg landrover lightweight snow plough in view of current conditions :lol: JMHO

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Thanks for the input guys,

i started with a reasonably similar view to all of you, that actually its been done and its been expensive. i think one of the biggest reasons people dont buy them is because they are so expensive, which is offcourse because gears are so expensive to cut. If i could bring the cost down with a fundementally differnt design ie: to use a belt/chain drive,bringing down the cost on gears and in the case of a belt it would not need lubrication...

another option is to use existing gears, ie like those that bill van snorkel used (if i remember correctly)

However, i am still in the early stages, i think its safe to say that its definatly more of a technical project with a marketing bit tagged on, in some ways it doesnt matter if it doesnt go to market, as long as i can understand why... We can make thinks much more cheply with the university workshop, its staffed with about 20 guys who's job it is to make things for projects.

With regards to land rover axle strenght i am wokring on assesing thier strength through testing in the next couple of weeks. This will either yeild a confident yes, or a project stopping no!

I have spent a while reading various threads, i saw the american guy on pirate 4x4, i think the main problem with his concept was that he limited himself to a typical gear mechanism, one of the beauties of a final year project is that it pushes you to explore new concepts and problems that have previously not been overcome, i dont want to just copy something that is too expensive, i want to make it cheap enough to be popular...i am pretty sure lots of people would have them over a lift, if they were cheaper???

loving the input!

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Engineering student , obviously not marketing :rolleyes: , as mentioned a technically very interesting project , but in view of the possible market (minute) a real non starter from an economics point of view. The landrover mods market is huge (and very profitable) with the right items , If you want to take the project all the way , do a bit of marketing research first ;) eg landrover lightweight snow plough in view of current conditions :lol: JMHO

Just into December is too late to change his final year project!

Totally agree about the economics, an interesting engineering challenge though, provided it is not just a straight copy of an existing design.

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I don't think we should be poo-pooing the idea, Papa B is right, if these could be made cost effectively then there would be a good market for them and perhaps that's where you should be trying pitch the engineering side.

Looking a cost effective and simple production technique and therefore making the end product more accessible would certainly put a good spin on the project. Maxi drive, Killer axles, Mark's Adaptors all prove that there is a market, how big could that market become if the product was cheaper?

Out of interest Mark's GU Patrol Portals are £9,900.00 approx for a set, Killer Axles Landrover Portals are £5,000.00 approx for a set. The Mark's system is for a modified axle assembly, rather than the Killer Axles system which is bolt on.

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I don't think we should be poo-pooing the idea, Papa B is right, if these could be made cost effectively then there would be a good market for them and perhaps that's where you should be trying pitch the engineering side.

Looking a cost effective and simple production technique and therefore making the end product more accessible would certainly put a good spin on the project. Maxi drive, Killer axles, Mark's Adaptors all prove that there is a market, how big could that market become if the product was cheaper?

Out of interest Mark's GU Patrol Portals are £9,900.00 approx for a set, Killer Axles Landrover Portals are £5,000.00 approx for a set. The Mark's system is for a modified axle assembly, rather than the Killer Axles system which is bolt on.

How would you make this cost effective? It's not without reason that all options out there are expensive. And I don't reckon many people would be interested in belt driven portals for example. No way I would want anything else but gears for strenght and reliability. Belts 'could' be reliable, just as the Td5 is so reliable ;)

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Actually, if it was for competition then going belt isn't a bad idea really. The reason you use oil bathed gears is for heat equalization. Many things use belts strong enough, the final drive on Harley Davidson are almost all belts. If it could make it cheap 'enough' it would be worth looking at... however I suspect it cannot be made cheaply since you end up still needing toothed wheels etc.

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Many things use belts strong enough, the final drive on Harley Davidson are almost all belts.

Yes, and have you seen how crazy wide/big they are? And they don't see anywhere near the torque the belt in a portal box would see which means it would have to be massive to be able to handle it reliably. Whatever it is a belt is made off, it's not as strong as steel.

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I'd go hydraulic drive. I know, I know, keeping oil in a landrover is a big challenge!

Some sort of torque converter or pump driven by the drive shafts?

You could also incorporate a traction control system, perhaps with an electronic switched valve block, so that if a wheel is slipping then the drive would be diverted to another wheel by locking up the pump on that wheel? Via an ECU. You could even have a cab mounted control unit!

I know, I'm bluesky idea bouncing, but you never know the little kernel that grows into the BIG idea!

If you've any access to agri-engineers who deal with final drives in modern tractors, then pick their brains, torque drives and multipliers, and multi plate clutches are all in there - and might be source components for you.

G.

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There's got to be a market- loads of people love the concept of portals but the technical challenge of fitting them means most (like me) don't have the skills or budget.

Whenever I come unstuck offroad it's usually down to ground clearance- having a way of raising my diffs without resulting to huge tyres has got to be a good thing.

Having the gearing remain standard would definately appeal to me- I guess my 90 is an "expedition" type vehicle so I dont want super low gearing for massive horsepower.

The Killer axle solution is great but too expensive- make them for half that and I reckon you've got a go'er.

(Market research provided by me, having polled one person= me)

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How would you make this cost effective? It's not without reason that all options out there are expensive.

That would be the challenge which would make the project interesting! If you look at some of the other options then you can see that the bolt on option is cheaper than a completely modified axle. Also the construction could make a huge difference in price, for example if you could source existing mass produced gears to use (Billvansnorkle use transfer case gears I think) then you can make a big difference. Like wise a 3 part casing with 2 laser cut plates and a milled centre piece could be cheaper than two custom cast parts to the casing.

Also you could look at 2 different ratios, a 1.15:1 or similar to suit the expedition crowd, then a 1.2:1 or 1.25:1 for the challenge crowd.

I think it's an interesting project.

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The gears are really not a problem, its all straight forward machining operations. Keeping the gears modular helps ie on a 2 axle set you will have8 identical idlers etc.Being a prototype the internal splines can be hobbed or edm ,no need to have a broach made.

Infact Ill back myself up that if you come up with a viable design ill cut you the gears!

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I thought that one of the concerns about a "Bolt on" to stanadard axles was the fixing point.

The systems that were shown before IIRC had the axle modified to include an extra brace to the bottom of the drop box whereas a purpose built axle has the strenght built in to the design?

Marc.

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The gears are really not a problem, its all straight forward machining operations. Keeping the gears modular helps ie on a 2 axle set you will have8 identical idlers etc.Being a prototype the internal splines can be hobbed or edm ,no need to have a broach made.

Infact Ill back myself up that if you come up with a viable design ill cut you the gears!

i may well take you up on that! thanks!

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Project progressing well, i am getting the flanges made up to load the my defender axle on the torsion machine, basically see how much it can handle before it snaps!

So i am thinking that there is space for a viable product if its cheap enough, so dream with me... if i could make them using an alternative method, which afterall is the basis of the project (exploring new methods)what value would people be willing to pay to add them to thier truck? someone mentioned half the price of the killer axles?

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