Are Super 10's weak?

No. Structurally, they are the same as a 13/18. Yes, they're missing two gears in the main box, and they do the range shift based on lever position; but there is no inherent weakness in the transmission.

The problem with Super 10s is that if you allow the shifter to leave the right gate, the transmission attempts to shift to low range. Not a problem at any appropriate low range speed; however, if it's done at too high a road speed, it will fubar the synchro on the range shift. Just make sure you have geared down to at least sixth before kicking the lever to neutral when stopping.

I haven't driven anything newer than '99 Super 10s, so they may have rigged up some sort of interlock on the newer models, but I know that was the issue with the early models.

 

I was once told either the input shaft or the output shaft (forget which) is a weak link with super 10's - no idea if it is true.

 

We've ran super 10s on all our trucks for years, probably 200 trucks in total, never had a problem. Seems pretty bullet proof to me.

 

a trans is only as good as the nut behind the steering wheel-nuff said.

 

Every one that failed where I worked had been driven by a driver who thought it reasonable to kick the tranny into neutral ~40mph coming down ramps or up to redlights. The trucks he never drove where all still going strong after 500K plus.

 

So is that what stresses one and makes them break?

 

Yep! The mechanic told us it screws the synchro (spits the pins, or something like that,) and exactly what had caused it. He said normally they hung in high range ( as ours had) when they finally let loose. He actually told us what he'd find before the trans ever hit the floor, and he was right. Basically the same as if you took a 13/18 and range shifted it at high speed multiple times; it would fail the same way.

 

over 1.4 mil miles on my super 10 never touched. original clutch went to 1.2 million miles