S10 front axle swap

[Owly]

Anybody swap out their front differential for one from an S10 with the axle that disengages?

I have a 2000 AWD, and am looking at all the little things I can do to up my mileage. The actual time I need active AWD is minimal, so it makes sense to simply install a shut off switch and put in clean new fluid. There is always going to be some bind / drag, I suspect. I can see no reason to have the auto engage enabled unless conditions warrant it.

The front differential obviously is turning all the time, and this constitutes some drag. The logical solution is to use a differential assembly for an S10 or something, that has the axle release dog clutch. Can these be substituted? I assume that the same ratios are used...... 3.43:1 or something like that in this case.

Howard

[Owly]

On further thought, releasing the front axle is a bad idea with this transfer case. This will result in clutches always wanting to slip past each other as the font end will not be turning and the rear will. Even with no pressure on the clutch pack, there will be significant drag from this. The ONLY way to make things work the way I would like them to work is to completely swap out the transfer case with an in and out transfer case, and modify the front axle or replace it accordingly. It was a dumb idea.

Howard

[Herbie]

It's my understanding that the S10 front diff with the disconnect only separates one (passenger's side?) CV axle. The front driveshaft and the other axle would still be connected.

Details here:
http://northeastoverland.forumotion.com ... ed-s10-ifs


All of that said, anecdotal evidence from those who've fitted the S10 axle is that there's no (or negligible) increase in MPG, so it's probably only worth it if you wanted to fit a locker into the front and use the disconnect to make it driveable the rest of the time.

[photo_van]

What Herbie said. I have one in mine,not sure it makes much difference. There are rare times when 2wd low is handy though.

[Owly]

It's my understanding that the S10 front diff with the disconnect only separates one (passenger's side?) CV axle. The front driveshaft and the other axle would still be connected.

Details here:
http://northeastoverland.forumotion.com ... ed-s10-ifs


All of that said, anecdotal evidence from those who've fitted the S10 axle is that there's no (or negligible) increase in MPG, so it's probably only worth it if you wanted to fit a locker into the front and use the disconnect to make it driveable the rest of the time.

Your understanding is correct in terms of disconnecting only one axle............However the spider gears do the rest. With one front axle disconnected, the other spins freely without turning the ring and pinion and driveshaft. it's the same principle as spinning one tire on ice while the other sits there and does nothing.......... Note that some of what is stated at the URL you gave is absolute bunk............. The sequence of events should be as follows. First the transfer case goes into gear. This starts the driveshaft turning. The left and right front wheel are turning at approximately the same speed as everything else, so the sliding collar is connecting two splines that are turning approximately the same speed. The guy who wrote that bit didn't know what he was talking about! Wear in the engagement splines is due to trying to engage 4x4 while spinning....... not "while moving" as he stated. Intelligent drivers do NOT do that. They engage 4x4 BEFORE the wheels start spinning, or stop and engage. I've run 4x4 vehicles all my life. The world is full of idiots!!

Howard

[photo_van]

The left and right front wheel are turning at approximately the same speed as everything else, so the sliding collar is connecting two splines that are turning approximately the same speed. The guy who wrote that bit didn't know what he was talking about! Wear in the engagement splines is due to trying to engage 4x4 while spinning....... not "while moving" as he stated. Intelligent drivers do NOT do that. They engage 4x4 BEFORE the wheels start spinning, or stop and engage. I've run 4x4 vehicles all my life. The world is full of idiots!! Howard

Well I have to say, as an owner of this particular set up, I can tell you this is how it works (I didn't read the previous link, so I'm not sure what the "idiot" said).

You will never get the axle engaged if all the components are spinning at the same speed because the splines won't be aligned (unless you're very lucky). You need to be rolling slowly w/o the transfer case engaged in 4wd for the splines to mesh. The opposite holds true if you are stuck (front wheels aren't spinning). You need to engage the transfer case so that the front driveshaft starts to turn (as rear wheels spin and the front wheels are stationary) as you pull on the front connect cable, this allows the splines to mesh. Otherwise, the collar will never line up and you will never get into 4wd.

BTW, I've had 4wd all my life as well (I'm closer to 60 than 50 and still have two) and this setup is unlike any others I've owned.

[doyoulikeithere]

I have one in mine. I'm 50 and have had 4x4s all my life too. Its hooked to a pull cable.
I like mine because I wanna run in 2WD 95% of the time and I figure the less resistance the better.
That being said, I've installed an NP231C Transfer case, so its a different story than AWD trying to disconnect.
4 Hi-Lo on occasion is nice to have

[racrx7]

The NP236 and 246 are clutch based units. The vehicles that use these two units come standard with front axle disconnect. The NP136 is near identical to the 236 minus the low range. The clutches in these units, (with the exception of the later year model units), use a pre load clutch pack. With a front axle disconnected, the path of least resistance will be the free spinning spider gears. Therefore, I can't see where the clutches would actually be forced to slip. Even if the rear wheels overran the front wheels and the TCCM activated AWD, the spiders would still be the point of lowest resistance. After all, this is how the 236 and 246 work in 2wheel drive. Only difference is the AWD command prompt to the encoder motor is disabled. im looking to replace my axle with an S10 set up as soon as I find the ratio I want.

[Snowgeek]

Racrx7 - have you made any motion on installing this S10 disconnect? I am starting to brainstorm the ability to get 2wd low... there is no way to make that happen with our np236 cases.... so I have been thinking about the disconnect to make that happen.

My though process is this. I like my tall gears because my highway milage is great but I have been pulling a trailer through the mountains and the van is just under geared for that.

I have tested and found that I could drive in low range and with my current gearing and easily drive 35 mph..... which would get me up my winding 2 lane mountain roads just fine.

Thanks for your thoughts!

[Astrophysics]

Hi,

You could get the Atlas gear driven T Case from Advance Adapters in Paso Robles , Ca.

It has twin stick manual shift and allows 2 low as I recall.

It is about $1,500 for a brand new Atlas T case. And you can select the low range ratio, 2:1, 3:1, 4:1 etc.

The Atlas T case does not have 4 Wheel Auto mode.

AP

The Atlas is available to fit Astros.

Check out their web site.

The old S10 axle disconnect is a weaker axle than our AWD Astro front axles.

It should be less labor to swap T case than mess around with front axle and differential and the linkage or vacuum to engage and disengage the axle slide gear spline gizmo.

[Mmusicman]

On further thought, releasing the front axle is a bad idea with this transfer case. This will result in clutches always wanting to slip past each other as the font end will not be turning and the rear will.

I have spent time contemplating the same thing.. and came to the same conclusion. Unless "everything" turns.. there will be damaging drag on the clutch-packs. If the free-wheeling parts have minimal drag, then there's minimal gains. The S10 "axle disconnect" that I am familiar with uses a transfer case that doesn't use clutches (such as the NP233) and has no pre-load. Otherwise, there's not much point in disconnecting the axle if everything else is still turning.

One thing for sure.. any possible gains would be minimal at best... it would take years to recoup your loss.. just to break even.

[Snowgeek]

ok so the caviat to my thoughts here is that I am running a np236 transfer case which is the same as a 136 but with a low range gear and when switched into 4wd vs AWD locks the clutch pack up so that there is fully split power and no slipping of the clutch pack. If I were to drive in 4low with my front axle disconnect open the power would go through the spider gears and go out the disconnected side of the diff.

This would give me the freedom to use 2low in situations like maneuvering a trailer or even pulling the trailer up a couple of steep mountain passes that are typically below 30 mph.

With 3.42 gears in the diffs and 245/75/16 tires I am just geared too high for some of these things. I love the highway milage that I realize because of the gearing and it also means that in low range I can do 35 ish miles an hour in overdirve and be below 3200 rpm.

I would love others thoughts on this as I haven’t attempted this set up before and I can’t find much info out there reguarding this set up.

As to the atlas transfer case AWD in this 236 t-case is of up most importance..... and it is the very last thing that I would give up. In snow country that is the key!!

Thanks for your thoughts!

Ryan

[Mmusicman]

This would give me the freedom to use 2low in situations like maneuvering a trailer or even pulling the trailer up a couple of steep mountain passes that are typically below 30 mph...

Yes.. this could certainly be one use for this application.. where you'd want to use the low range on pavement (where 4x4 would be damaging) in a very steep incline. But realistically, 1st gear is already quite low for most road applications.

[Captn. Crunch]

I know this is an old thread but I’d just like to clarify that GM did pair the two piece axle and the np236 transfer case so clutch pack wear shouldn’t be an issue