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Running diffs in odd positions......


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10 replies to this topic

#1 NVBigBlue

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Posted 23 April 2005 - 07:29 PM

Hey guys!

If this is in the wrong spot....somebody please move it.

I'm interested if any of you out there have ever run a suby rear end in any kind of "odd" position. By odd I mean things like:

drive shaft running in a vertical position (pumpkin down, shaft up, etc.)....
vent plugged, diff flipped upside down.....
input running in a reverse direction as a normal direction....

What I'm getting at here is that I have a project in mind that suby diffs would be perfect for, but would require that one of them be flipped over. I won't go into too many details, but....
imagine taking a drive shaft and putting flanges on both ends....then bolting up a diff to each end of the shaft. Now obviously, if the shaft turns one diff the "right" way, the other is going to get turned the "wrong" way. That is, the output shafts off the rear diff would turn forward, and the output shafts of the front diff would turn backwards. BUT.....if you flip the front diff over (left to right)...now the output shafts off the front diff would also turn forward.
Now I was thinking that if you plugged the vent and drilled a new hole in the bottom of the diff (now the top...) for a new vent, things would still run correctly. I think you might have to adjust the oil level to a correct level though. I think this would be better than flipping the diff over front to rear and running the input in reverse. Anyone see a flaw in this logic?
And before someone asks.....
the shaft would be driven via a gear bolted onto one of the flanges.
AND
I thought about running the imput shaft in a vertical up position (and connecting them via a wide drive chain), but then there'd be no oil to the pinion bearings and slop in the chain would cause problems.....:-\
To summerize......
I want to get four (4) output shafts turning forward using diffs from the rear of suby's, using one (1) drive shaft.
Thanks...
NV

#2 NorthWet

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Posted 23 April 2005 - 07:36 PM

Find a front diff off of a Nissan 4WD that has the same gear ratio. Same maker, same flange, opposite rotation already. Qman ran a Nissan front diff, and probably others have done something similar.

#3 mikie

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Posted 24 April 2005 - 04:10 PM

You dont have to flip it upside down. When you turn the front one around it 'sees' the driveshaft as rotating in the opposite direction to normal, and drives backwards, effectively forwards. Get 2 diffs and lay them out and rotate the flanges if you cant visualise it.

Chain drive rotating driveshaft in normal direction:
http://webhost1.insp...nsfer chain.htm

Rear diff right-way-up and in the front, turning in the right direction:
http://webhost1.insp... suspension.htm

To answer youre question a lot of folks have done this with their T-case swap and front diff fitment without hassle, and mine has been fine so far.

#4 Snowman

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Posted 24 April 2005 - 04:34 PM

What the heck is that beast that the pics are from?!!!!

#5 NVBigBlue

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Posted 24 April 2005 - 09:08 PM

[quote name='mikie']You dont have to flip it upside down. When you turn the front one around it 'sees' the driveshaft as rotating in the opposite direction to normal, and drives backwards, effectively forwards. Get 2 diffs and lay them out and rotate the flanges if you cant visualise it.

mikie,
I get what you're saying.....it would work that way..... but that makes the pinion drive on the back side of the ring gear. BUT I'm glad to hear someone is running things this way. :) That is one of my concerns...that running on the back side of the gears might cause a large amount of wear. Have you seen any increase in gear wear running it this way?

If not, then my problem is solved.
Thanks,
NV

#6 mikie

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Posted 25 April 2005 - 12:46 AM

It does make the gearset run backward, and i'm aware thats not the designers intention. But diffs must be designed to handle a small amount of reverse use during their lifetime, and i have no problems here yet. Otheres with the T-case mod on this board have done more miles than i without hassle. The lash should be the same either way, and I presume the case hardening or heat treatment on the gears would be over the entire surface, not just one side.

#7 VaporTrail

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Posted 25 April 2005 - 01:54 PM

awesome!!

http://webhost1.insp...~nyloc/Toybaru/

#8 MorganM

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Posted 25 April 2005 - 03:06 PM

Not trying to put words in Mudrat's mouth here but I recall him mentioning a lack of proper lubrication if you tip the rear diff upward.

Something to consider. Maybe shoot him a PM on this.

#9 mudrat79

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Posted 25 April 2005 - 07:21 PM

Diff Needs to stay as flat as possible if you are running it in normal position.....If you lean it up any you will need to raise the oil level......If however you want to turn one upside down, all you need to do for Venting is pull the back cover off, and Rotate it 180, so the vent is at what was bottom of diff....It will do that you know......:-p

I once had the opportunity to play with a sand rail that was 4x4 using a Very Modified Subaru Drive train....They had Taken a EA-81 and Auto 4x4 trans, had it in the rear, with final drive in the Auto reversed..as well they had run the drive line to the front, and HAd a rear diff sitting there upside down, with vent tube up, and fully functional......They had To fill the rear Diff quite high to keep the Pinion bearing at the front of diff oiled..., But no biggy....

Also yes many of us have run the Rear Diff up front backwards to its intended Direction.....Now, As I understand it , the Nissan T-case turns the front Drive line in reverse order to rear drive line, so Even though the Front diff is positioned backwards, it thinks it is Driving forward due to t-case rotation to the front........

But as The ToyBaru plainly shows, , he is truely running it in reverse, with no ill effect so far......Try it, worse that can happen is a blown gear set....:)

Hope this helps clear things a bit for you.....

John

#10 Adam N.D.J.

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Posted 26 April 2005 - 12:02 AM

ya, the front output of the Nissan T-case is reversed, all of us with rear diff for from diffs now know this. It's a matter of lubrication what it come to positioning a diff, as long as all the bearings get lubed, it should work fine.

#11 NVBigBlue

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Posted 09 May 2005 - 05:32 PM

Thanks for all the input guys!




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