Why driver side axle shaft? 4x4 to AWD

R

Rinkrat456

Got LS1?
Excuse me if this question is going to be answered in pages 60-112...I've been reading little by little covering this entire forum and so far I'm only on page 59 of 112 in the drivetrain tech forum. Lots of 4L80E questions by the way... Anyways, I have searched, just nothing came up with a definitive answer. I have a Sonoma 4x4 project under way, parts collecting to make it AWD. In the threads, I keep reading that in order to go AWD, the drive side axle shaft from the 4x4 needs to be swapped out for an AWD driver side axle shaft, and I'm wondering why? What's the difference between the two, or pro's and con's of one or the other?

I guess my end goal is worth mentioning, both rear tires will turn equally with the Eaton posi, and in the front I'd like the power to be sent to the tire with the greatest drag, aka, traction. I'm not looking for a locked front end. I'm perfectly adjusted to deal with torque-steer, as I've had plenty of practice counteracting it in all the little front wheel drive sports cars I've driven over the years, especially my most current DD. Any ideas or answers would be greatly appreciated. I don't think I'm the only one with this question, as other threads have seemed to go unanswered when this questions arises.
 
JSM

JSM

Active member
Re: Why driver side axle shaft? 4x4 to AWD

It is the pass side axle tube that needs changed.

4x4 style can be turned on/off via a cable or electric solenoid.

AWD is on all the time, a lot less parts inside an AWD axle tube.
 
R

Rinkrat456

Got LS1?
Re: Why driver side axle shaft? 4x4 to AWD

So if I understand this right, 4x4 trucks could potentially have a 2wd, and AWD setup? As I've read in other threads, detaching the front propshaft sends 100% of the power to the rear tires, would that be like me staying in 2HI? Then when I push the 4HI button, it'll become AWD, 35% front 65% rear sending power to the rear wheels and alternating between front tires? There's an electronic solenoid that engages the front differential on a 4x4 right? So in a way would that be just like engaging or disengaging the propshaft..?

Or am I totally out to lunch on that theory? :rotf:
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: Why driver side axle shaft? 4x4 to AWD

Loeryder said:
Here is a very detail oriented post by Waller.

http://www.syty.net/forums/showthread.php?t=39567&highlight=passenger+axle

That should clear it up.

And driving in 2wd for long periods of tie will wear the viscous clutch.
If you park on an incline with the propshaft disconnected your vehicle will roll.
There isn't enough resistance in the transfercase/ VC alone to hold the truck.
Click to expand...

I believe if I understand what he said, he means using a truck with a standard 4x4 case with an AWD front diff. In this case, you would in fact have a truck that could be 100% 2wd, but 4wd trucks split power 50/50 in 4wd. so you could do it, but it wouldn't be the same. Also, the reason for having the disconnectable axle shaft in the 4x4 trucks is so the propshaft stops spinning when the truck is in 2wd, because even if it is disconnected from the case, it's still being driven by the front wheels
 
R

Rinkrat456

Got LS1?
Re: Why driver side axle shaft? 4x4 to AWD

Gotchya...that post has been bookmarked. So I can ditch the 2HI, 4HI and 4LO buttons in my dash. So I'll be 3wd the whole time with the 4472, and with that cable kit I can lock in the front for 4wd AWD? Did I read that right?
 
R

Rinkrat456

Got LS1?
Re: Why driver side axle shaft? 4x4 to AWD

jjorgensen52 said:
I believe if I understand what he said, he means using a truck with a standard 4x4 case with an AWD front diff. In this case, you would in fact have a truck that could be 100% 2wd, but 4wd trucks split power 50/50 in 4wd. so you could do it, but it wouldn't be the same. Also, the reason for having the disconnectable axle shaft in the 4x4 trucks is so the propshaft stops spinning when the truck is in 2wd, because even if it is disconnected from the case, it's still being driven by the front wheels
Click to expand...
I have the 4472 case and 4x4 front diff currently, but haven't swapped anything out yet, still parts chasing.
 
J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: Why driver side axle shaft? 4x4 to AWD

For S10 platform trucks, there are a couple of different transfer case mechanics, and associated drivetrains....

Standard 4wd stuff uses transfer cases that you can't / shouldn't engage at speed (from 2wd). Nor should they be used on hard surfaces, because the front and rear driveshafts will turn at the same speed (mechanically locked, anytime in 4wd), meaning binding and unhappy driveline parts when turning. Since you can't engage it at speed and are looking for fuel economy, they disconnect the Pass front axle shaft, allow the differential gears in the differential to spin like mad, and idle the driveshaft. Keeps you from having to backdrive the driveshaft, allowing slightly better fuel economy.

Now on to AWD stuff:
1st Gen Bravada's & Astro's, Sy's, and Ty's all use a viscous coupling transfer case. The VC allows the tcase to manage slip front to rear (to allow turning corners, etc without significant binding) and splits the torque front to rear (35% / 65% is the nominal ratio, but probably isn't accurate most of the time). Due to the mechanics involved, the front propshaft has to be running or there are funny consequences (drifting while parked, burned up / damaged VC's, etc). So, you want to have a front axle assembly that is always on. For Drag racing, it might be useful to be able to turn the front end off to do a burnout (heat rear tires) or to heat up the VC and maybe get it to lock quicker. But I'm not sure if that would be desirable.

2nd Gen Bravada's, Astro's, and some other GM products use a different method of tcase activation to achieve AWD. Basically its a full time 4wd box with a big electronically activated clutch pack for the front propshaft. A computer monitors wheelspeeds, and turns on the clutch pack as needed, sending power to the front propshaft. But the front propshaft needs to be turning or you'd have a tremendous "Thunk" as you sent power (started spinning) a shaft that wasn't spinning and probably wasn't fully engaged. Advantage of that type of tcase is you can run in 2wd without damage to the tcase (my truck has a tcase but currently doesn't have a front axle / propshaft but won't hurt anything, nor will it drift when parked, because 100% of the power goes to the rears.). I'm not sure if it technically qualifies as AWD or if its really electronically managed 4wd.....But regardless, it works.

I don't know if that helps explain or just muddies the waters. Hope it helps.

'JustDreamin'
 
J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: Why driver side axle shaft? 4x4 to AWD

Rinkrat456 said:
So I'll be 3wd the whole time with the 4472, and with that cable kit I can lock in the front for 4wd AWD? Did I read that right?
Click to expand...
Um...Not really.

If you use the cable kit, you've got 2wd with it disengaged, and 3wd (no posi up front) with it engaged.

If you were to find a posi for the front, then you'd come up with 4wd. There is / was a "locker" made by Powertrax (I think) for the 7.25" IFS front end, but I think its been discontinued. Don't know of anything else.

Some other front axles do have a limited slip available, like the 8.8" Ford IFS setup has an Eaton True-Trac available, meaning one could have real 4wd with that axle.

'JustDreamin'
 
R

Rinkrat456

Got LS1?
Re: Why driver side axle shaft? 4x4 to AWD

The water has cleared up, not quite Aquafina clear yet.

I think from my posts you can tell I'm making a fun vehicle to drive on weekends and whenever buddies come over. I will occasionally go to the track monthly. How would you set up my driveline for the intended application? I double checked the year of the case, the junkyard had the 4472 listed as a 95 Bravada case mated with a 700R4, I crossed the case number with google and it says it's a 93.

The current setup right now is NP231 4x4 t-case, 4x4 front differential, stock driveline pretty much except the motor and tranny right now. Ford 8.8 rear, GM 7.25" front. 3.42 front ratio, 3.55 rear ratio...as stated in my other thread.
 
J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: Why driver side axle shaft? 4x4 to AWD

I'd set it up as follows:

4x4 front axle with axle mechanically locked on (bolt / weld / whatever)

Use the BW4472. It's a stout box, given that there are guys running 9's (and maybe 8's) on it. Was used on the Bravada through '96 or '97 (which is a 2nd gen, but the 2nd Gen Autotrac system came out in '97 or '98, can't remember which year). The later cases require computer control and wheelspeed sensors, so as a retrofit is expensive and a pain....Stick with simple mechanical....

Do plan on upgrading the trans. 4L80E is a good choice. Trans choice really will come down to a bunch of things, including power output, driving style, performance goals, how often you are willing to take the trans out for service, etc.

I'd leave the front axle alone and see how it runs. Sadly, besides the Powertrax, there really ins't any offering to make it better.


I didn't mentioned the 8.8" Ford IFS to suggest it as a swap idea. It's found in the Expedition / F150, so I doubt it'd be an easy fit (track widths are off, Ford parts vs GM (so shafts / splines / hubs probably won't play nice) etc). I've dreamt about building a tube frame AWD toy, with LSx power, T56, 8.8" IFS & IRS rears, maybe as a mid engine application, and that would be my front axle of choice. Fairly stout, available, and such. But I doubt it'd be an easy swap into an S10.

'JustDreamin'
 
R

Rinkrat456

Got LS1?
Re: Why driver side axle shaft? 4x4 to AWD

I found the Lock-Right locker everyone still thinks isn't being made anymore. All my gears I get from Randy's Ring and Pinion website (ringpinion.com) and I found this.
http://www.ringpinion.com/ProductDetails.aspx?ProdID=869

So that'll be the method I use to lock the front 7.25". Then all that needs to be done is just bolt the 4472 to the 4L60E. Is it a straight bolt up? I haven't looked yet.

I have a level 3 Raptor 4L60E, which has 0 miles on it, still in the wood crate it was shipped in ready to be bolted to the LS1. It's a stout transmission, not built for the average drive train requirements. In comparisson, it's stronger than a stock 4L70E which I know is just a beefed up 60E, but it should hold up to my abuse until I start spraying N2O at the track with slicks. On top of the extra strength, the pan is 1 quart deeper and I have a fan cooled transmission cooler. I understand AWD breaks parts though, where normal rear wheel drive burns out clutches...if this tranny goes, I'll start researching into the 6L90E, hopefully by then the aftermarket will catch up with a stand-alone control unit.

I just really don't like the 4L80E, or at least in a sporty S-truck. It's overkill in my opinion, with gear ratios not suitable for a true sports oriented vehicle, with even worse daily driveability aspects; and for the total cost of the swap I personally would rather rebuild a 4L60E twice...but that's because I know and like these tranny's and have a full coverage 3 year 30k mile warranty. It all comes down to knowing what one is willing to do for a performance edge, and I don't mind the extra work involved. After all, this isn't my daily, it's just a fun, expensive toy.

8.8's front and rear sound fun.
 
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