A driveshaft disconnect, twin stick, or the marlin prototype doesn't cause anything, they ALLOW you to have front wheel drive only. Basically, he's turning using only the giant front tires on cement. You know what happens when you try to make a sharp turn on dry pavement in 4wd...lots of fun noises.

this happened because i was being an idiot, and was trying to spin my front tires on wet asphalt with only 5psi in them=lots of traction, but i do believe that this failure was caused by some existing damage, last time out wheeling, i had the front end in the air a couple of feet trying to make it over a ledge, with a lot of wheel spin when i landed, i did that at least 5 times, oh well

Cool.

You can see the case hardening of the pinion shaft at the failure surface. The outer 0.05" of the shaft is smooth indicating a brittle failure while the interior is more ductile.

Thanks for some of the explanations, but I am still a lil confused. If you are front digging (with a twin stick - dual tcases) means 1st tcase is in 4low and second is in N, right? So why would there be any binding unless the front is locked?

I am very sorry for the Q's, I am just trying to get this straight in my head.

ok, my rear driveshaft was not in the truck when i did this, i just had the rear case in 4LO, the front case was in high, so only the front wheels were driving, and on a high traction surface like asphalt something has to give, and in my case it was the ring & pinion, marlin crawler is working on making a Toyota t-case capable of disconnecting the rear shaft so you can use only FWD to help pull you around an obstacle, usually you only see d-line disconnects on buggy's or comp rigs

I get it all now, I was only confused because I didn't understand the two different typed of stress. In my setup, I cause binding because of not having a center differential, in your case, you just had too much traction and the gear couldn't handle it. I kept trying to apply "my" type of binding to your scenario which just doesn't apply.

Thanks for the explanations and patience!

no problem

(I apologise if this got a clear answer later in the thread, I haven't read to the end yet.) edit: LOL, I was so close to the end....

Marko - nothing was binding. Nothing was wrong really. It happened because with all the gear reduction available, plus not splitting the increased torque between the front and rear wheels like normal, plus the super traction available on pavement with aired down tires - he simply grossly applied much more torque than the axle could take. Pilot error.
If it hadn't broke there it surely would have broken something else - in fact it did damage the gear teeth - but it could have snapped an axle or snapped an outer joint or busted the hubs or twisted the driveshaft or something - something was gonna go bust.

Superjoe - 2 questions?
1 -is your torque arm still installed? I've seen this exact failure before on rigs without the front torque arm - high torque and axle wrap...
2- did you follow the time honored tradition before you perfromed this standard-mil-spec-clutch-drop test - and utter the invocation "Hold my beer and watch this." ?

:lol: Heh - Heh...Nice pics Superjoe, if I may ask, what kind of camera do you use? those are some clear closeups.
[Hijack Off]

torque rod has been gone for about a year now, the u-joint at the axle showed no signs of binding
not really i was by myself being an idiot, costing myself money :pat: