Front Diff - How robust is it?

[bugnout]

I just bought a 2004 Crewcab
Question about the front axle. I have a Jeep Liberty, they come stock with Aluminum front diff, and it was very common for them to grenade. All it took was to have the one of the front tires to be digging and have only one tire get traction. Input shaft would climb the ring gear and big bang,with gear lube on the ground. This was fairly common, and I know of owners that have replaced the diff 3 - 4 times. Aluminim diffs could be had for a couple hundred dollars. I've replaced my Liberty's diff with an iron diff when I regeared.

I've done a quick search but didn't find a lot of horror stories for the S10. Is it common? common only for offroaders or do you know of owners that have experiences with front diff grenading while driving in snow and ice?

[HenryJ]

The only cases of ring gear failure that I am aware of are those where related to a "lunchbox locker" that was installed in the front diff.
I have seen the stock diff take quite a bit for the size. If you exceed 33" tires , I think SFA might be a better idea. Adding a V-8 also might warrant the change.
Personally , I did not fear the front after many many years wheeling my old first gen and then the crew. Easy on the skinny and you will be fine.

[bugnout]

Thanks, good to know that there isn't a history of failures other than hard duty.

Another question on the front diff...
I'm confused on how 4wd works on the S10. Please correct any misconception I have.

Pushing the 4 Hi button engages the transfer case AND the right front axle is engaged via the vacuum actuator. I've read that the vacuum system can get week and when that happens the front right axle engagement collar can get stuck or not fully engage or disengage.

Any idea what the logic was for creating this disconnect for the right front axle? Doesn't make a lot of sense to me. Maybe an attempt at fuel mileage improvement.

I found a how-to on replacing the vacuum actuation of the front diff with a cable actuator. I've also read that the bravada axle is one piece and eliminates the need to engage the right front axle at all.

Do I have this right?

[HenryJ]

...Pushing the 4 Hi button engages the transfer case AND the right front axle is engaged via the vacuum actuator. I've read that the vacuum system can get week and when that happens the front right axle engagement collar can get stuck or not fully engage or disengage.

I think you have it right. A bad cable or vacuum leaks seem to be the problem spots.

Any idea what the logic was for creating this disconnect for the right front axle? Doesn't make a lot of sense to me. Maybe an attempt at fuel mileage improvement.

That and turning, as well as wear and tear.

I've also read that the bravada axle is one piece and eliminates the need to engage the right front axle at all.

Do I have this right?

Yes. Keep in mind the autotrac transfercase has a viscous clutch system allowing it to slip inside the transfercase. Ours is direct. No give at all.

[ApproachMedium]

If the cable gets stuck locked in, like mine did, you will blow out your CV joints making tight maneuvers. This is why I personally don't recommend doing the bravada solid axle swap unless you plan to only use it for wheeling and loose ground/snow. With both axles spinning together and 4x4 off turning is not easy and the front end will hop since the wheels are binding up. Of course this is what I have found thru the circumstance of cable failure.

I recommend if you just got the truck checking out your vac lines. Grab some new hose from the parts store and replace as much of it as you can if you find any cracks or tears. The lines down to the T case switch tend to be OK usually, but the ones around the engine usually get destroyed over time from oil and the heat from the engine. I replaced all of mine on the engine area and it helped quite a bit. Take your battery out and check the vac actuator and see if its OK. Cleaning any battery acid off of it if its still intact could help extend the life of it. Mine was totally torn up when I bought my truck and had to be replaced. It was $125 from the dealer. Another part you will want to change for about $7-10 is the vac switch on the T case. Many of the ones on these trucks would let transmision fluid past and cause problems with the HVAC systems. Replacing that now if everything is working OK could also save you some trouble down the road.

[crew cab sonoma]

The Bravadas use the same CV axles as the 4wd's do, and they don't
seem to have any higher CV failure rate.
If the transfer case is disengaged, there's really no significant difference in work load
on the CV's wether the front front axle is engaged or not, as long as its a stock open front differential.

Now if you have a "locker" modified front diff, that's another matter...

[crew cab sonoma]

Keep in mind the autotrac transfercase has a viscous clutch system allowing it to slip inside the transfercase. Ours is direct. No give at all.

97-older Bravadas had the viscous clutch transfer cases, made by Borg Warner. Model 4472, IIRC.
Basically the same t-case that was used in the Cyclone/Typhoon.
98-up use electromechanically controlled multiplate wet clutches, like in an automatic transmission.
This is the NV-136 case, which is a derivative of the Blazers 4-button "Autotrac" NV-236 t-case, minus the
low range components.
There is a beefed up NV-246 case used in the full size trucks, which had a extra planet gear and a couple
more clutch plates added for greater torque capacity.
In the 136, the "encoder motor" applied pressure to the clutches, as dictated by the TCCM.
The older Borg Warner viscous clutch was all mechanical, with no electronic control.