Thread: Portals & D3's

Originally Posted by gghaggis

Would possibly work on a coiler, but the added unsprung weight would play havoc with the air suspension - you'd need to fit a limiting drop-chain or similar to protect the bags, but the spring response time would still be shot to Hell.
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You could get a similar effect to a portal by adding a 2 ~ 3" block to the top mounts of the air springs, reset the camber and source up-rated CV's.

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I seriously doubt you could get it road-legal though, especially over East.

Cheers,

Gordon

There are air-sprung solid-axled vehicles with aftermarket portals out there which work fine.

I disagree it would be a "similar effect" - sure you would get a lift from both but that would be all. Portals reduce gearing, thereby reducing torque on all the componants inboard of the portal box - which means that the (marginal) D3 CVs should last longer - Mal used stock RRC CVs on his portal assemblies and stock crownwheels and pinions - they all held up fine. You would also get much worse response from the suspension as the links will be at steeper angles, and the track width will have been reduced, unlike the increase which portals usually give.

The modification rules in most states are now the same, or will be soon. Most states have adopted the NCOP/VSB and even stragglers like QLD have indicated they will soon as well.

I'm sure Gordon, others and myself will applaud you once you achieve it.
Good luck.

Originally Posted by gghaggis

Would possibly work on a coiler, but the added unsprung weight would play havoc with the air suspension - you'd need to fit a limiting drop-chain or similar to protect the bags, but the spring response time would still be shot to Hell.

Re the ABS, no reason why you couldn't refit the toothed hub-ring and piezio sensor to the new hubs.

You could get a similar effect to a portal by adding a 2 ~ 3" block to the top mounts of the air springs, reset the camber and source up-rated CV's.

I seriously doubt you could get it road-legal though, especially over East.

Cheers,

Gordon

Hi Gordon,

In my limited knowledge I would have thought putting a spacer on top of the airbag would extend the ark of the suspension before you even try to go over one obstacle and thus make it far less effective and it would dramatically increase the angle of the axles etc.

Adding portals you would be running standard suspension angles as the drop boxs don't change that at all. They would also help keep the centre of gravity lower where as adding a spacer to the top of the suspenion would only raise it.

I'm happy to stand corrected if my logic is incorrect, afterall I did say in my first post that I was asking these questions purely as a academic exercise.

cheers,
Terry

Originally Posted by TerryO

They would also help keep the centre of gravity lower where as adding a specer to the top of the suspenion would only raise it.

You are correct wrt suspension issues of "lifting" the current setup - the same as I have posted above.

However Wrt CofG, there won't be much in it either way. Lifted suspension will raise CofG, as will portals which raise the suspension by the same amount, but in the case of portals there will be a slight offset because of the weight of the portal boxes. But given that the Disco is 2.5T+, it won't make much practical difference.

However - what will make a big difference, is that your track will stay the same and/or increase with portals, whereas it would decrease with lifted suspension.

Another issue I forgot in my post above is CV joint angle. CV's tend to fail at higher angles, so lifting the suspension as a "poor man's portal" will mean CV's fail more often than on a standard D3.

Hi Isuzurover,

Surely if you widen the track do you not keep the centre of gravity lower than if you raised the vehicle and left the track the same as standard?

cheers,
Terry

Originally Posted by TerryO

Hi Isuzurover,

Surely if you widen the track do you not keep the centre of gravity lower thenif you raised the vehicle and left the track the same as standard?

cheers,
Terry

CofG no, roll-stability yes.

This post by SlugBurner explains it best:

Originally Posted by slug_burner

This image is exaggeratted but it serves to illustrate the point.



track width increases the base of the stability triangle i.e., you will need a bigger side slope to take the centre of gravity outside the track width for the same CoG height. You can see this by how much you would have to rotate the vehicle about the point at the edge of the track.

CoG is a point in space where the centre of all the mass can be though of as being present for the purposes of further analysis (usually static analysis). The only way I can change the CoG is by redistributing the mass. to lower the CoG I have to place more of the overall mass down lower. Increasing the track width will not significantly redistribute the weigth/mass.

a definition

"The point in or near a body at which the gravitational potential energy of the body is equal to that of a single particle of the same mass located at that point and through which the resultant of the gravitational forces on the component particles of the body acts." probably not much good unless you already know what it means.

Here is a better/simpler one
"The center of mass or mass center is the mean location of all the mass in a system"

The above assumes the mass of the axles is the same in both cases.

Originally Posted by ~Rich~

I'm sure Gordon, others and myself will applaud you once you achieve it.
Good luck.

Hello Rich,

Not sure why you feel the need to keep on making sarcastic comments towards me on this topic, this is the second time now.

Can I refer you to my original posting/comment on this topic.

Portals & D3's
This is really more of a academic question then anything else but one that follows on from my previous question regarding body lifts for a D3.

Question being, would it be possible / has it been done and what would be the potential downside of fitting portals to a D3?

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Personally I have found that the internet is a great place to learn all sorts of things and further expand ones chosen field of interest and knowledge.

Conversly there has always been one very simple way of dealing with topics that you have no interest in or don't like and that is to ignore them.

cheers,
Terry

Originally Posted by isuzurover

CofG no, roll-stability yes.

This post by SlugBurner explains it best:


The above assumes the mass of the axles is the same in both cases.

Thanks for explaining that Isuzurover,

what it does show is that a D3 with portals would be far more stable than a lifted D3/4 ...that makes a lot of sense.

cheers,
Terry