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2003 chevy trailblazer_ls
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Discussion Starter · #1 ·
I know the title sounds funny, but it's true.

I had an idea that I've been thinking about for WEEKs. I have a gut feeling that it doesn't work, but I can't figure out WHY it wouldn't work.

Please, I am giving everyone permission to tear me down and tell me how I am wrong!!!


Lifting our vehicles is difficult because of the halfshaft/diff/oilpan design, right?

I mean, that seems to be the real problem why we can't do a basic drop-bracket lift, like any other IFS body-on-frame rig.

Generally, with a drop-bracket lift, the control arms get lowered, and the differential gets lowered, as well, to prevent extreme half-shaft angles.

Because the diff goes through our oil pan, we cannot easily lower it the few inches that we would like... And our half-shafts are unable to handle the extreme angles of more than a couple inches of lift -- which you can do with a spacer.

So, enough of the exposition.... Tell me why my idea will FAIL:

Create a new (longer) spindle to replace the OEM one. This spindle has a bearing and spline to accept the factory half-shafts at the factory angle. A chain (enclosed in a housing on the spindle) transfers the rotation to the hub, which is lower than the factory location (Let's say the popular 6" that is oh-so-common, today). You then leave the diff in the factory location. A bracket will drop the factory lower control arm down.

The new spindle would make the stance wider, and would eliminate the need for spacers -- and we could make the spindles in 6x5.5" offset.

Perhaps we'd need a new upper control arm... And we would probably need ABS extensions and brake-line extensions, but that's all basic stuff.

Surely it cannot be that simple? I know the new spindle with the housing, cover, and chain would be HEAVIER than the factory part... But tell my why it won't work?
 

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Create a new (longer) spindle to replace the OEM one. This spindle has a bearing and spline to accept the factory half-shafts at the factory angle. A chain (enclosed in a housing on the spindle) transfers the rotation to the hub, which is lower than the factory location (Let's say the popular 6" that is oh-so-common, today). You then leave the diff in the factory location. A bracket will drop the factory lower control arm down.
It's called a portal axle:



I've never seen one with chains. I think the issue there is the noise, however it's not a bad thought. Normally it requires at least 3 gears to provide the proper wheel rotation relative to the halfshaft.

Also, because the gears must by spur cut (to prevent extreme axial loading) portal axles are known for their noise.
 

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Discussion Starter · #3 ·
Thank you for your reply. I don't think noise would prevent people from buying it -- especially if we did manual hubs so you could disconnect the half-shafts instead of always having them rotate.


But you haven't talked me out of it... Now it seems even more feasable.

Why has no one else done it?
 

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Why has no one else done it?
Portal axles are used by vehicles such as the Hummer H1 and the Pinzgauer (http://www.volvoc303.co.uk/images/rear axle off ground 2.JPG)

One of the leading portal axle companies is Portal Tek http://www.portal-tek.com/. I had contacted them a while back, as I too was curious of this possibility. I found out that portal axles cost a pretty penny because the volume is so low.

I have never seen chain driven portal axles though. I assume it's because of the reliability issues. It's alot easier to properly design a gear to withstand the immense stresses of rock crawling than to deal with a chain.

A custom spindle would have to be milled out of a block of aluminum or stainless. If you can design the 3D parts, I'm sure there would be plenty of machine shops willing to take your money to do the machining.

So, with enough money, sure, its possible, but you're going to need deep pockets for custom portal axles on our truck.
 

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you mean the CV would turn the chain and that would turn the hub? Like a timing chain right?

You would need a carrier bearing to mount to the frame and new shorter CV axles plus solid shafts from the diff to the carrier.

Heres a MS Paint rendition but it'll take some $$$ to get it all done god and proper.

 

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Discussion Starter · #9 ·
the price and if your lifting it that much you have to upgrade the majority of the drivetrain
I don't buy that. There's endless Tahoe/Silverado/F150/Tacoma/Ram/Dakota/Durango owners out there running 6" lifts or even bigger!

Heck, even the H3 and Colorado/Canyon get decent-sized lift kits.

I think our powertrain would be no worse than any other vehicle.
 

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Discussion Starter · #11 ·
you mean the CV would turn the chain and that would turn the hub? Like a timing chain right?
Basically, yes. Although gears may be needed for strength... the concept is the same.

You would need a carrier bearing to mount to the frame and new shorter CV axles plus solid shafts from the diff to the carrier.
Why would I need this? Why can't I re-use the stock CV's and have the new spindle move everything outward a little bit. I personally don't see a problem with maintaining stock CV's and stock angles.

Heres a MS Paint rendition but it'll take some $$$ to get it all done god and proper.

http://i187.photobucket.com/albums/x224/LMMJ_TV/LIFT.jpg
I understand. I can do the cad work.
 

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Discussion Starter · #12 ·
the re-gearing possibilities would be almost endless. No more need for new ring and pinions.
Not true, unfortunately. You have to remember that the rear is a solid axle, and there's no need to change anything back there except the springs, and longer arms. So you'd still have to worry about traditional gear-sets.
 

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Discussion Starter · #14 ·
IIRC the old hummers had those they are geared hubs i believe
yes, they do. And when I got the idea and recall that the military has used it -- with great success -- even in extremely harsh conditions.



So it seems the consensus thus-far is that it is definitely a do-able endeavor. The main concern seems to be cost.
 

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Discussion Starter · #15 ·
What you should upgrade depends on what your application is. If you get a 6" lift and run fire roads, no reason to upgrade anything. But if you are crawling over boulders... you may want to upgrade a few items.
Right. I am mostly high-speed trails with only a little low-speed "crawling" mainly to get over areas that water has eroded away the trail.

But our vehicles are no different than others from the standpoint that "serious crawling" will require additional upgrades on all vehicles.

I'm simply worried about what changes we need to bring our suspension to the "average" in terms of functionality and aftermarket modability.
 

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i know absolutely nothing about mechanics...


but it sounds nice.

im sure somebody with deep pockets and a vehicle hobby will do it

TV's are getting older...are common,and therefore will become cheaper and such after awhile....which is when i feel the aftermarket parts will boom
 

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wouldnt it be cheaper to do a strait axle conversion on the front? then doing all the custom machining to create the parts you are talking about
 
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