2 pinion diff for mild wheeling

[cc93cruiser]

Here's another question, I am assuming all or most broken diffs have happend while wheelin in 4 low, any reports or incidents of diff breaking while on 4 hi or just traveling down dirt rds (high speeds low speeds?)? Thanks for all the comments suggestions. Great read so far!

 

[spressomon]

The issue arises with either enough torque applied to the front R&P and/or shock loading of same from one front wheel's slip-catch induced shock load to the carrier and/or from ATRAC in extreme situations.

Tires with plenty of grip go a long way in mitigating front tire slip...along with careful skinny pedal work...and using the brake pedal with skinny pedal to better control wheel slippage for more technical trail sections. If you are new to auto trannies getting used to applying brake and accelerator for more technical trail sections will be a huge benefit for you to learn.

For cruising down a gravel road...you won't have a problem.

 

[Cruiserdrew]

I find it interesting given how much money is typically spent on other mods, some more cosmetic than not, how much consternation is involved with the decision of whether or not to install the front locker on a 100-Series.

For most of us the front locker cost pales, if done proactively before damage occurs, in comparison to what gets spent on these rigs.

Amen, brother.

There seems to be this weird random element to it. People have broken backing up in driveways, driving in daisy covered fields, in parking lots, in the snow and some times while just idling in the garage. (OK, maybe I'm kidding a bit, but just a bit).

The two I have seen break were both "mild wheeling" one of them was crossing a 2 inch wide crack in the rock with minimal throttle and torque. THe other wis driving up a 20 degree slope that was otherwise smooth. The plans about driving home with the center locked and teh driveshaft off are fine, but you also have to pull the drive plates so the wheels are not trying to turn the now broken differential. Then with the driveplates off, you need to seal the bearing from dirt and water while you limp home.

This is a known and common failure point. Fix it before you inconvienience your friends. Especially since the fix seems to be permanent.

 

[corleykj]

To answer the question if the front diff only grenades in four low, no. Mine grenaded on the previous owner. If I recall, he was pulling a boat down a mountain pass, and he manually downshifted and heard it go. He pulled over and was towed. I think it was around 140 k miles. Luckily they replaced it with the newer 4 pinion.

 

[mcgaskins]

I personally believe more in the time value of money and keeping that $ in my pocket until the repair comes due to breakage IF it ever happens. I know that anecdotally it happens to everyone who wheels, but I am more comfortable with having some dough set aside if that day comes and then spend it on something else when I sell the 100. I think the people who have first hand experiences with the failure have a well founded right to think it's mandatory trail prep to do it asap, as I'm sure that would/will be my new opinion when/if it breaks on me too. I feel it's most important to (1) be educated that it can happen (2) know what do when it happens (3) be prepared financially to cover the cost of the repair.

 

[KlausVanWinkle]

That is a good point, lots of nice bumpers out there that have never touched a rock or lights that don't get used on trucks that still have 2-pinion diffs and old heater hose T's. You can buy handful of ARB lockers for what a set of bumpers cost.

However at the end of the day most of us WANT these trucks more than we actually NEED these trucks so I can't bash cosmetic mods too much. After all there are guys on here who have builds much more costly than mine but who don't really wheel much.

I don't know how true this is. Most with 98-02's regear when they add lockers. That's a $4000+ job. Front bumpers help stop a rock, deer, tree or BlueCruisers rear bumper from smashing your radiator and/or totaling your truck on the trail. But agree that rear bumpers are crazy expensive and mostly for utility/cosmetics.

 

[paflytyer]

Totally. if it breaks, then I will fix it...........

If it breaks "on the trail", then I will remove the front driveshaft, lock the center diff and drive it home in 2wd, then I will fix it.

I guess if it breaks in a place where 4wd is absolutely essential to get out, then I will remove the front driveshaft, have somebody tow me through the tough part, drive it home in 2wd, then I will fix it.
.

You will also need to remove the c-clip and drive flanges from each hub. Held on by 6 nuts, washers and cone washers. Otherwise, you'll still be spinning.

Clearly there are two different camps here. I don't think either is right or wrong. To the OP, I think some folks have given great advice on how/why the R&P lets go.

-Excessive "bouncing" going uphill

-Wheel slip brought on by a slick spot and then subsequent traction as that wheels grabs

-Wheel lift and power applied as that wheel touches back down

-35's (the added weight and force required to turn them in the above situations)

-Any combination of the above. Let's say.... a wheel lifts, light power is applied, ATRAC "searches" for the correct wheel to apply power to, tire touches down just as power is being applied...that sends a shock wave of force that has to find a weak spot somewhere.

Here's Skidoo's video of his breaking. IMO, that is A LOT of force before it breaks. Again, it was the ring gear that broke, not the spider gears.
https://forum.ih8mud.com/100-series-cruisers/736305-stock-front-4-pinion-diff-how-strong-video.html

 

[cc93cruiser]

Thanks for the video! That clearly summed it up. I believe it's I fairly common problem and happens more often than not with a hundy series because of the nature of its IFS. It obviously dosen't have nearly as much flex as a solid axle rig and therefore it's very common to have a wheel in the air. And in this case, a considerable amount of throttle was given in order to try and climb the obstacle.. NO Wheels in the air for me!

 

[LandCruiserPhil]

What is hard wheeling???

I have flogged my 99 on countless sand hills pinned, done just about ever pass in Co. and numerous trails in AZ on the same 99 diff. But I had no problem breaking a birf on my 80 backing up in sand without wheel spin. Go figure YMMV

But then again I dont have ATRAC

 

[Skidoo]

Keeping the front wheels on the ground will go a long ways towards keeping it unbroken. The other one to avoid is snow/ice, can get a lot of front wheel spin before you know it in a stuck situation, have to be real careful. I had six years of off-roading, before I broke it. It was the first time I had pushed it hard enough to bounce and missed what was going on until too late.

 

[Junglejack]

What is hard wheeling???

I have flogged my 99 on countless sand hills pinned, done just about ever pass in Co. and numerous trails in AZ on the same 99 diff. But I had no problem breaking a birf on my 80 backing up in sand without wheel spin. Go figure YMMV

But then again I dont have ATRAC

I really think that is a key point. It certainly says something to me that the 4 pinion front differential was added when ATRAC was. Given how much testing was done in designing the 100 Series. I would not be surprised if front diff blowouts were pretty even between <2000 and 2000+ hundies.

 

[bamachem]

Ends up costing you 4 CV boot kits but its a WHOLE lot quicker and easier to drop the lower control arm from the spindle and cut the inner and outer CV boots then pull the center shaft out. Leave the inner and outer splined sections on the truck and reconnect the lower control arm. This is easier than pulling drive flanges and trying to protect wheel bearings, and you can easily drive highway speeds with zero issues.

 

[paflytyer]

Ends up costing you 4 CV boot kits but its a WHOLE lot quicker and easier to drop the lower control arm from the spindle and cut the inner and outer CV boots then pull the center shaft out. Leave the inner and outer splined sections on the truck and reconnect the lower control arm. This is easier than pulling drive flanges and trying to protect wheel bearings, and you can easily drive highway speeds with zero issues.

I have to disagree. I've done 3 front diff isolations to get me and two other people off the trail after a blown diff. It takes less than 30 minutes from start to finish, no need to even raise the vehicle (unless there are wheel spacers installed)

I drove 60mph+ for almost an hour in 2wd, flanges and driveshaft removed.

 

[Skidoo]

Ends up costing you 4 CV boot kits but its a WHOLE lot quicker and easier to drop the lower control arm from the spindle and cut the inner and outer CV boots then pull the center shaft out. Leave the inner and outer splined sections on the truck and reconnect the lower control arm. This is easier than pulling drive flanges and trying to protect wheel bearings, and you can easily drive highway speeds with zero issues.

WHAT!!!!! I must be missing the sarcasm here.
I have pulled CV's to repack, and in video mentioned a few posts back, I pulled the drive flanges. No way is pulling center shafts easier and quicker. I Duck taped some plastic to rim to keep stuff out and done. Drove at highway speeds to Grand Junction from Moab. Was talking to Paul May and he took his 1000 miles highway speed like that without issues. Number of folks have gone drive flange route without issues.