Has anyone broke a HF2AV transfer case? (1 Viewer)

[coaders]

I did a search and I didn't find this topic come up. Having taken apart my transfercase twice I know it is built extremely well. Once to rebuild it and the other to install 10% overdrive gears. The case seems similar to the np205 except with an aluminum housing opposed to cast iron.

I have a built Cummins 12v and am guessing it pushes 300-400hp & 600-700 ft/lbs. I have an a343 and a HF2AV behind it. The torque converter in the a343 has taken the brunt of the power up to now, being my drivetrain cushion, but I am swapping in a NV4500. Without that cushion I am now concerned about the t-case. Has anyone ever broken a HF2AV due to overpowering? Also, because the t-case has 10% overdrive gears installed, does that mean it is receiving 10% more power from the engine and the axles and are receiving 10% less? I am thinking about getting the t-case cyrogenically treated, any thoughts on that?

Now, with that said, most would say I need to worry more about my drive shafts and axles. I'm also concerned about these things, but to help soften the blow of the extra power to the shafts and axles, I am leaving the t-case full time to so the power is divided up 50/50 between them. I haven't had any issue so far, but has anyone else?

 

[Kaninja]

It is strong PERIOD. There are guys running Cummins with them and in Saudi Arabia they are running 1,000hp+ doing sand drags.

I have never met a guy who has wrecked one, or even heard of it. I'm sure it has happened.....but it seems VERY rare. I think you would grenade the front differential before the HF2A let go.

 

[mjosoba]

I honestly think the only issues I’ve heard of are running it many, many miles with not enough oil. I don’t know that I’ve ever heard of one breaking mechanically. You’ll be replacing birfs or flanges or something similar before you break your t case. That being said, there are quite a few guys running 6bts and nv4500/ls who don’t seem to be gentle with their rigs and haven’t had t case issues.

If you decide to sell your transmission controller and harness, etc shoot me a PM. I may knowa guy.

 

[coaders]

sounds good. Thank you both your replies! I'll be posting my adapter parts for the automatic once o pull the engine.

 

[mudgudgeon]

There's loads of hd-fte Toyota diesel guys pushing similar numbers through them in Aus for a while now. I haven't heard of any failures.

 

[BILT4ME]

Calling @cjmoon to the party for his input.

 

[cjmoon]

Calling @cjmoon to the party for his input.

Lots of power no issue....read on... But agree taking the TC out of the equation puts extra stress. Cases are cheap due to not many failing and can find themIn parts outs like mine.
TC is first weak link, but we’re pushing 30psi on simi built ve 6bt and 3.55 gears 4K gov spring Hamilton cam 35” wheeled, 30k no issues. Dyno run is on YouTube. Can’t remember details 240hp to the wheels and 500ftlbs something like that...

toasted TC lockup in 28k. Have a rebuild one in now with aftermarket parts. Well see how long it lasts.

I’d Wait to see how/if it failed to see what the weak link is. I’d see gears and shafts being the issue first. Otherwise chasing your tail

 

[coaders]

Cool, thank you @cjmoon, I appreciate you letting me know about your experience. My realistic HP numbers, to the wheels, are probably right around yours. With 3.55 gears, sounds like you're running different than stock axles?

 

[baldilocks]

But the axles................ especially if you run larger tires.

 

[coaders]

I'm running 34's. What do you think?

 

[cjmoon]

Gears from Aus in stock axles. Really that puts more stress on the trans and Tcase. TC OD gears where just hitting the market after I got the axle gears to get the cruise RPM right at 75-80 with the Cummins.

 

[coaders]

Cool, thank you @cjmoon, I appreciate you letting me know about your experience. My realistic HP numbers, to the wheels, are probably right around yours. With 3.55 gears, sounds like you're running different than stock axles?

@cjmoon, what parts did you install to beef up the transfer case? I have it out right now and this would be a good time to do it.