Can 40lbs rears handle a high powered cat?

they will be fine as long as you drive it right, its not a race car... most mfg's use 40K rears in there 625HP 2350 tq set ups not big deal

 

I know of one guy that has a 6NZ cranked up to 725 hp and still has 40K rears. It is all about how you drive it. You can blow up anything doing it the wrong way.

 

I pulled trains in BC for a little while and had a similar question about my 40k rears.

As Coast Powertrain in New Westminster BC explained it to me, the trans and driveline are subjected the strain from the motor whereas the diffs are subjected to the load they are pulling.

Rockwell 40's are rated for something like 120K on a turnpike. You're probably OK in the prairies, The Coquihalla? Not so much.

But many have done it, just not sure for how long.

 

I dont think you have to worry about the torque on 40K rear just the weight you put on them

 

Is that 140 gross or product weight.

 

Looks like you already spotted the weak link, that 10 speed. You'd better buy the strongest clutch you can find. I glazed an 1850 clutch the first hill I came to. You probably already know this, but will say it anyway...

The way to make the drivetrain last is get into the power as get into the power as gently as possible. We had a tri-drive with 745 HP that drivers that werent used to driving powerful diesels would twist the driveshaft and snap the axles out of all the time.

I'm running the same engine you are. Havent broken anything in the drivetrain yet, and I have 40k rears. I have a buddy that runs a 95 kw and pulls a 2+3+2 trailer with an old E model and 3.70s. I had the same questions as you when I built my truck and he told me that his has held together for 11 years. I was like , "You are pulling a 2+3+2 with 3.70s???? 2 speed? No? And it has held together?" Amazing. You know he has to be running alot of HP. He says tho with the jeep, he doesnt see over 38k on the drives.

 

I'm sure the U-joint will give up its lunch money before the rears do. Failure always happens atthe weakest point. That 10spd is going to be a close runner up......

 

40's or 46,s i prefer 46 rears but i dont have a single truck with them all i have is 40,s average 140000 or more 95% of the time. never had a failure with this kind of weight. now if your trying to do wheelies or shift all your gears from light to light. then there isnt a rear out there that will hold up! yes 46,s are better by a long shot. but for what they cost i'll stick to my 40,s. some day when i get rich and famous i will probably run 46,s. like other post said you will have a failure somewhere else in the drive line before you rip a rear out. and thats with over 600hp from the motor.