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 Post subject: Re: Differential explained
PostPosted: Mon Nov 25, 2013 9:50 am 
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Your concern about your front axle is common.

If you have an open diffed front, and you HAD to pull the entire truck, it would mean the rear has zero traction...and if the one front tire slipped, you would still have zero traction, and slide down the hill....etc.

If the front is locked, you probably would STILL slide down the hill, because if going uphill, the rears carry most of the weigh due to the rearward weight transfer....so if the rear had zero, the front would not have more unless the front was on something different. On most uphills, the rear is carrying ~ 70% of the truck's weight.

If the front WAS on something different, say, with traction, and you had an open diff, and no tires slipped, the two front tires would be able to potentially hold you in position, or, potentially pull you over.

This would be the same if locked.

If the front had more traction that the rear (Again, it would need to be on something else than the better weighted rear...), it would typically have only about 30% of the truck's weight available TO pull.

So the fronts are almost never in a position where they are bearing the entire truck's weight, in practice, due to the rear weight transfer.

The fronts are typically used more like a hiker going up a steep trail uses his hands to grab a branch, etc, to help him up the hill. IE: His FEET might slip, but the hand gives enough purchase to hold position/gain enough boost to make it.

An open diff is like having hands that let go if the other hand slips.

A locker is like having two hands that can grab what they can.

If you are in a situation where you need to drag your self up a hill in FWD, that's usually an exercise in futility.


When I used to get a FWD company car once in a while, and I had to get up a steep icy driveway, etc...I'd turn around and BACK up the slope instead...to avoid that "drag".

:D



I also love that diff video, its perfect for explaining how it works....I remember posting it several times over the years myself. Its the best one I'd seen so far, despite the corny acrobats, etc.

:D

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 Post subject: Re: Differential explained
PostPosted: Mon Nov 25, 2013 11:40 am 
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Thanks TJ - The hiker example is pretty good... makes it easier to understand when you might want to use the front locker.

And Jus' video was excellent too.


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 Post subject: Re: Differential explained
PostPosted: Mon Nov 25, 2013 11:45 am 
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[quote="brunkhorse
Check out these vids of Pizza Rock in Rausch Creek. We take the same line one had lockers the other was open. Though the higher lift and bigger tires on the 2nd vid don't hurt either. :D [/quote]

Were you locked rear & front while doing Pizza rock in that video? Thx.


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 Post subject: Re: Differential explained
PostPosted: Tue Nov 26, 2013 12:27 pm 
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DirtySocks wrote:
[quote="brunkhorse
Check out these vids of Pizza Rock in Rausch Creek. We take the same line one had lockers the other was open. Though the higher lift and bigger tires on the 2nd vid don't hurt either. :D


Were you locked rear & front while doing Pizza rock in that video? Thx.[/quote]


It looked like the front was locked, but its hard to tell if you have a good line like that.

One way to tell sometimes is the "tire shake" you see on one tire that is idled while the other is spinning and the wheel is sawed to nibble for traction...in the unlocked version, you do see that...and in the locked version, you do see the fronts pull him over better.

The fronts can pull you better if you have them pointed straight ahead on a rock so one is less likely to slip in the first place.

For example, here is an open diffed X approaching Pizza Rock from the side, and then swinging in to set the line up, so that the tire can be cut to gain clearance on first contact, and then straightened to help pull the rig up and over.

The rear line was set up to allow a little bounce momentum to help prevent a spin and stuck and get the front end launched going the right way at the right angle to pop over that ledge.

http://www.youtube.com/watch?v=NjUobrS2ujM



Here's the same Pizza Rock with another open diffed X, and you can see the tire spin and the bounce technique being used to work its way over...but by an initially more tentative driver.

Watch the front rear spin and how the alternating hook up is used to maintain momentum, so that when the rear loses traction the momentum is maintained by the front and visa versa.

http://www.youtube.com/watch?v=dqr8DCEY4-Y



And, finally, here is an open diffed X that has a hard line, and, the spin on opposite ends is killing the momentum, and, who's line never lets him break free.

http://www.youtube.com/watch?v=bnCAjTOByG4



Its three ways to do the same Pizza Rock....with open diffs.


Compare the speed and spin going on for all three open diffed rigs to the smooth easy roll over of the locked rig....he COULD go slower and just crawl over it, as he didn't have any spin or need to get the line to make the tires work, to worry about.

:D

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 Post subject: Re: Differential explained
PostPosted: Tue Nov 26, 2013 12:58 pm 
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ummm, are we gona have homework on this? haha :guns:

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 Post subject: Re: Differential explained
PostPosted: Tue Nov 26, 2013 6:43 pm 
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If there's a test are we allowed a cheat sheet? Really though, thank you all for this information. Basically answered a lot of questions I had without the fear of getting flamed. I'll have to delete memories of high school so I can store all this information in my head.


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 Post subject: Re: Differential explained
PostPosted: Tue Nov 26, 2013 7:57 pm 
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Ha

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 Post subject: Re: Differential explained
PostPosted: Wed Nov 27, 2013 1:06 am 
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Bklyn.X wrote:

Lockers cause wear on any truck and I do not feel the front axles, IFS and steering in my Xterra are strong enough to handle being locked up by itself or for any length of time (one of my concerns with the Lokka). The front axles in my truck cannot push or pull the full weight of my truck. :cry:


Sorry if I'm hijacking this further...
While I'm sure lockers will cause extra torque and wear...The R200 diff in the front of the 1st gens was used as the rear diff in the 280Z and 300Z in both open and limited slip versions. While we know it is strong in the Xterra, apparently it is the "go to" in the Z car crowd. Of that era anyway. Some Nissan Performance guy had apparently said it would handle a V8 conversion and that "you would have to be doing something really stupid to break an R200".
Interestingly, the R180 that's in the front of the 2nd gen was used in the rear of the 240Z. Until the owner opts to swap it out for a R200, because they had trouble with the R180 then too...
So I'm not sure about the front driveshaft, but the front differential is quite capable of moving the Xterra by itself IMO. It makes me wonder what sort of hybrid we could come up with if we started researching axle shafts and CV's...if they might be stronger in the Z cars. It's interesting to me how Nissan used the same components in different applications over that long of a period of time.

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 Post subject: Re: Differential explained
PostPosted: Wed Nov 27, 2013 9:03 am 
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I never said anything about the diff. The diff can take a bomb blast.
IFS is weak, steering needs to be upgraded and then maintained for off road use even when open. The CV is weak and and breaks unless you are an expert like TJ.
Years ago I seem to remember someone finding upgraded axles from a Porsche that fit but the cost was prohibitive.

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 Post subject: Re: Differential explained
PostPosted: Wed Nov 27, 2013 10:21 am 
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Ok, a few comments to be added.

One thing TJ did not mention when talking about a locked front is that when confronting an obstacle that has a verticle or near verticle face, the locked front helps pull you up and over, whereas without the extra traction on the front the rear has a tendency to mash you more into the vertical face.

While the front diffs on the 1st gen are strong, they are not indestructable. I know of several people (myself included) that have blown front diffs. Usually it is the result a spinning front wheel (e.g., in mud) suddenly getting traction (eg., encountering a rock or other solid surface). An ARB is stronger that the OEM, but obviously much more expensive.

Tom does make a good point. A locked front will put a lot more strain on the steering components of a 1st gen. Plan on destroying and replacing you centerlink, and at least adding an idler arm brace (if not doing a full steering upgrade).

k_enn


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 Post subject: Re: Differential explained
PostPosted: Thu Nov 28, 2013 7:35 am 
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I was locked front and rear in that video. Definitely makes for an easier time crawling up over

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 Post subject: Re: Differential explained
PostPosted: Mon Feb 10, 2014 4:01 pm 
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 Post subject: Re: Differential explained
PostPosted: Mon Feb 10, 2014 5:03 pm 
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Great video, Tom.

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 Post subject: Re: Differential explained
PostPosted: Mon Feb 10, 2014 5:05 pm 
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Missing some video of my truck...


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 Post subject: Re: Differential explained
PostPosted: Sat Oct 13, 2018 11:49 am 
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Holy old thread revival batman!

I have an ARB Locker in my H233b and had one in the R200 before it shit the bed. With the truck wired and plumbed plus a great deal I got from a friend I dropped one into the D44.
Following the wiring instructions from ARB I have them wired so that SOLENOID 2 (front locker) can be actuated only if SOLENOID 1 (rear locker) is already on.

They say this is done “for safety reasons” and I understand the safety concern.

Just out of curiosity, do any of you have them wired independently?

I’ve never had a situation arise when I thought “I wish I had rewired this thing…” and cannot think of when would one possibly need the front locker alone?

I’m just wondering if I should rewire the system or just leave it be…

Thanks.

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