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 Post subject: Re: AWD Locost?
PostPosted: Tue Aug 09, 2011 7:13 pm 
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Joined: Wed Mar 30, 2011 7:18 am
Posts: 457
Location: central Arkansas
A normal 2-3/4 or 3" shaft could run over the transmission, as long as the shifter was offset. If you were already using a shift linkage extending to the rear you could do that easily.


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 Post subject: Re: AWD Locost?
PostPosted: Tue Aug 09, 2011 7:32 pm 
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Joined: Sat Apr 16, 2011 11:05 pm
Posts: 237
Location: Melbourne, Australia.
Problem will be getting it around the flywheel and bellhousing, it is equally huge in every direction.
That is why I would rather go under the floorpan with a really skinny rigidly located shaft.
In my case, the output of my transfer case, and front diff are both offset ten inches from the vehicle centre line.


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 Post subject: Re: AWD Locost?
PostPosted: Tue Aug 09, 2011 7:41 pm 
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Location: central Arkansas
That's why I suggested going over the bellhousing. Then the shaft would run down to the front differential. If the diff was inverted, the angle would be small.

The passenger would lose a top corner of his footwell, maybe.


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 Post subject: Re: AWD Locost?
PostPosted: Tue Aug 09, 2011 7:43 pm 
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Location: Melbourne, Australia.
How do you go over the bellhousing, that is where the cylinder head will be ?


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 Post subject: Re: AWD Locost?
PostPosted: Wed Aug 10, 2011 4:34 am 
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Location: central Arkansas
Up and over the top-right corner of the housing (assuming the front diff is on that side), however far is needed to clear the head.

Like I said, it's not pretty, but it allows a passenger, and you could cobble it up out of standard bits.


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 Post subject: Re: AWD Locost?
PostPosted: Wed Aug 10, 2011 11:11 pm 
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Joined: Sat Mar 19, 2011 2:05 pm
Posts: 50
On the topic of transfer cases, I remember my friend's Samurai had one that was pretty small as far as truck ones go. Not sure what it weighed, but couldn't have been more than 50 lb.

After some googling, apparently the nissan xterra (maybe frontier as well?) has a fairly small one (http://www.courtesyparts.com/images/n50/n50_331-2.gif) which looks fairly promising. My concern would be the extra weight, since they're all made for heavy trucks and off-roading, but something made for a small, light-duty truck may be right up our alley. If they're cable-controlled, turning it on its side wouldn't present too much of a control challenge, as opposed to a direct stick-shifted one.


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 Post subject: Re: AWD Locost?
PostPosted: Thu Aug 11, 2011 3:18 am 
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Location: Melbourne, Australia.
Transfer cases are about as simple as it gets.
You could always gut one, and just use the centre diff type of your dreams, and throw the low range and all the other unnecessary heavy crap into the dumpster.

Fabricate a reasonably light weight box to support the various bearings and you have a Locost light weight minimalist transfer case.

Remember, we don't need a low range, and that cuts the torque handling requirement considerably.
It is not the actual gears that are heavy, but usually the hugely robust outer casing that serious off roading in low range first gear requires.

In my case, anxiety about weight saving increases exponentially for anything that lives closer to the front of the car.

As the transfer case is located well behind the CG, a few extra pounds there do not seem to be such a huge concern.


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 Post subject: Re: AWD Locost?
PostPosted: Thu Aug 11, 2011 1:45 pm 
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Joined: Tue Dec 21, 2010 11:01 pm
Posts: 188
Location: Sidney, NE
The weight of a transfer case tends to vary. The one I swapped out of my Grand Cherokee weighed almost 90 lbs. Although a TC in a Jeep is going to be a lot different than one in a Subaru.

The TC in my Jeep had a viscous coupling that linked the front and back together. Basically a large hockey puck with steel plates and goo. When they turned at different speeds, the goo heated up and thickened to lock the two output shafts together. Problem is that the viscous coupling burned out, so I was essentially locked all the time. I ordered a salvage yard TC for $100 and it cost $120 to ship it. When it came in, the aluminum housing had a nice big crack down the side, which made me pretty mad, as it would cost more to ship it back than it cost for the unit to begin with. The one I ordered did away with the viscous coupling and gave me a real mechanical linkage between front and rear, and gave me the bonus of a real selectable 2WD option. Fortunately, the casings of the two units was almost identical and I was able to transplant parts. I bought a rebuild kit and had it up and running for about $100.

I always thought it would be cool to buy a salvage yard Jeep and build a car around it. Although, if it were a car, I would want to get rid of the live axles and go independent front and rear so that there's no differential movement. Although producing just 190hp, it wouldn't be speedy unless it was stroked. A 4.7L could make 275hp.

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_________________
Cost to date: $203.62
Projected cost:$12,000.00
Expected completion: Spring 2017


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 Post subject: Re: AWD Locost?
PostPosted: Thu Aug 11, 2011 3:30 pm 
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Joined: Mon Aug 16, 2010 5:03 pm
Posts: 352
Location: Whitby, Ontario
Off topic, but thanks for those pics! I am thinking of getting a TJ soon as a precursor to my build and just yesterday I was trying to learn all about the 4wd system on it and was curious about this chain business. Your pics cleared that all up for me :)

Tom...


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 Post subject: Re: AWD Locost?
PostPosted: Thu Aug 11, 2011 7:07 pm 
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Joined: Sat Apr 16, 2011 11:05 pm
Posts: 237
Location: Melbourne, Australia.
I was curious about gears versus chains, because "New Process" make both types with otherwise very similar internal guts.
From what I have read, gears are preferable for high speed very high mileage road use, but chains are considered more desirable for serious off road work.
It is not the chain that is itself stronger than gears, but the stresses put into the transfer case outer casing are very different.
Gears try to force themselves apart under extreme shock loads and may try to burst a light weight outer gear casing.
A chain under tension pulls things together, and may survive shock loads that may crack a light alloy gear casing wide open.
Chains do have the disadvantage of stretch, and there is usually no means of re tensioning.
The chain must be replaced when it goes slack.
Like overhead cam timing belts, transfer case chains have a recommended life and should be changed on schedule.
It is also interesting that some chain drive transfer cases designed for sustained highway speeds have provision for external oil cooling, where the gear drive transfer cases just run fully closed lubrication.

Anyhow, here's mine.
A New Process 124, fully open epicyclic centre diff, gear drive, with no low range.
Total weight 21 Kg (46 Lbs)
They put these behind 400Hp LS3 engines with 4L65 auto, they are plenty strong inside.
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 Post subject: Re: AWD Locost?
PostPosted: Fri Sep 02, 2011 11:46 am 
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Joined: Wed Feb 06, 2008 10:36 am
Posts: 62
Can you post a picture of the other side? Does it look adaptable to any manuals?


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 Post subject: Re: AWD Locost?
PostPosted: Fri Sep 02, 2011 5:16 pm 
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Joined: Sat Apr 16, 2011 11:05 pm
Posts: 237
Location: Melbourne, Australia.
This particular transfer case came off the back of a 4L60 Auto, but they are also fitted behind the Asin Warner D173 six speed manual fitted to Alloytech 3.6 litre V6. Ratios are as follows:
4.48
2.58
1.63
1.19
1.00
0.75

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 Post subject: Re: AWD Locost?
PostPosted: Sun Sep 04, 2011 12:51 am 
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Joined: Tue Dec 21, 2010 11:01 pm
Posts: 188
Location: Sidney, NE
I was looking for pictures for the possibility of inboard brakes on a Ford 8.8, kind of like the Jag IRS and found something totally unrelated, but interesting. A builder posted a few pictures on a Discovery website in 2009 about their Locost build. In the picture below, notice that this is the front end. Unfortunately, they don't list a lot of information about the build.

http://community.discovery.com/eve/foru ... 9219607301

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_________________
Cost to date: $203.62
Projected cost:$12,000.00
Expected completion: Spring 2017


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 Post subject: Re: AWD Locost?
PostPosted: Sun Sep 04, 2011 1:34 am 
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Joined: Sat Apr 16, 2011 11:05 pm
Posts: 237
Location: Melbourne, Australia.
I looked into the possibility of inboard front brakes for my 4WD front suspension build.

The problems boil down to getting the steering rack past two large enough diameter discs, and unless you mount the diff right in the middle, not really enough width either, unless you run very short front suspension links and driveshafts.
Inboard front brakes ended up having far more undesirable compromises than leaving the existing outboard brakes right where they were.
Mounting inboard calipers can be fun too, which is why I went for a Jag diff at the rear in mine.

Outboard brakes at the front are unfortunate, but I am sure there will be enough other interesting problems at the front to keep you entertained for quite a while.


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 Post subject: Re: AWD Locost?
PostPosted: Sun Sep 04, 2011 7:43 am 
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Joined: Wed Mar 30, 2011 7:18 am
Posts: 457
Location: central Arkansas
Interesting. The chassis seems to be an ordinary IRS Locost with a front engine, other than the use of round tubing everywhere. The front driveshaft would go right through the engine, though.

Perhaps he's building a single-seater with an FWD driveline sitting in the passenger seat area.


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