I have 700's with NXT drives. I have twisted both output shafts off of each unit . Any ideas?

Please post a picture. A lot of people have much more power on or maybe were left loose.

Output shafts? you mean propshaft? Are you running merc props? I have almost 300 hrs on mine. The only issue I have is water leakage. The NXT is not vented...so...when you run hard the drive heats up a bit and must push some air out somewhere..then when it sits in the cool water overnight it cools and sucks small amounts of water in.....then rusts stuff, bearings ect. I,m not talking large amounts just enough over a season to cause a issue. I have pressure tested for days and no leakage when sitting so I think its a set of shaft seals that are weeping...

You could hang some #6 drives on your NXT transom assemeblys. You would gain speed and handling, dual vertical shafts and some stronger parts.

As of why you are breaking parts? Good question. Seems like ALL drives seem to let us down from our expectations of what they cost and what they should be able to handle.

Good luck

The transom helmet is different for the nxt....not that ez..The nxt upper is the M8 upper. These drives are stout. The 2nd downshaft is parasitic and not necesscary. The gears in the NXT are massive. The only issue I have is no venting.

#6 drives will absolutely bolt right onto the NXT transom assemblies with no modification, my boat is setup this way. However, you do need to change the input shaft on the #6 drive to Mercury part number 899866T to match up to the NXT transmission/carrier shaft. Fountain swapped all of the NXT drives on their HP700/NXT boats to #6 drives at the factory.

The upper gear sets on the NXT are exactly the same as the #6, all the part numbers match.

If you are twisting the vertical shaft then swapping to a #6 will definitely help because it has two vertical shafts and a second set of lower gears to spread the torque. Remember the torque on a vertical shaft is multiplied by the gear ratio of the upper gear set so they are under a higher load than the engine's rated torque output at the crankshaft.

The M8 uses the exact same NXT transom assembly and gimbal but the upper gear set is not the same which is why they are rated for more torque. It's bigger/stronger than a #6.

Of course the swap won't be inexpensive and the next weak link will be the NXT transmission which is only rated at 800 Ft-lbs of torque.

GF?

Mfulgum has not been here so we dont know what he means by "output shaft" ? The #6 is vented, the NXT is not. The vent on a #6 goes through the "helmet", NXT has no hole. Your right the drive could be mounted on a NXT gimbal but I dont know why....
If you have any ideas on venting the NXT I would like to hear? Thanks