Mile Marker for NP203 transfer case conversion….thoughts ?

[57NAPCO]

Just wondering how many folks have done this, I’m getting ready to order the kit for my 74 K20. Does it work OK, has it held up? Seems like a pretty straight forward job.

Thanks

[kwmech]

I was doing these back in the 80's, but with a better kit. But with this kit you have to pull the 4x lever into 4x every couple of days to spin the fluid around to lubricate the drive box since the chain is not flinging fluid up, and also overfill the t-case a little. The fluid will still fling around in the gear box but doesn't quite make it to the rear output bearing in the chain box like it should.

[57NAPCO]

[cadillac_al]

They don't save hardly any gas and isn't worth the trouble. I can roll 75-80 in AWD and my truck has 180k on it. It's always ready to steer off road at any time.

[57NAPCO]

It’s just my stupid logic I guess….

[SilverMiner]

Originally Posted by cadillac_al

They don't save hardly any gas and isn't worth the trouble. I can roll 75-80 in AWD and my truck has 180k on it. It's always ready to steer off road at any time.

I agree with cadillac_al 100%. There was never a compelling reason to perform this change to the 203 back when they came out in the 70's, and there are even less reasons today. In fact, I would suggest that neutering the unique characteristics of an NP203 is in fact a downgrade rather than an upgrade.

Additionally, this particular kit will require extra attention and care so as not to starve the drive box of lubricant. Who needs that kind of headache? Spending money on our rigs should make them better and more reliable, not the opposite.

[52napco]

Switch it to a 205..they're still out there

[kwmech]

Originally Posted by SilverMiner

I agree with cadillac_al 100%. There was never a compelling reason to perform this change to the 203 back when they came out in the 70's, and there are even less reasons today. In fact, I would suggest that neutering the unique characteristics of an NP203 is in fact a downgrade rather than an upgrade.

Additionally, this particular kit will require extra attention and care so as not to starve the drive box of lubricant. Who needs that kind of headache? Spending money on our rigs should make them better and more reliable, not the opposite.

One of the main issues ---back in the day-- was of course the continual spinning of the chain with a heavy truck which managed (believe it or not) to stretch the chain to the point of it being able to jump the gear and eventually break, blowing the chain case part of the t-case out of the bottom.

http://67-72chevytrucks.com/vboard/s...d.php?t=545961

[SilverMiner]

Originally Posted by kwmech

One of the main issues ---back in the day-- was of course the continual spinning of the chain with a heavy truck which managed (believe it or not) to stretch the chain to the point of it being able to jump the gear and eventually break, blowing the chain case part of the t-case out of the bottom.

http://67-72chevytrucks.com/vboard/s...d.php?t=545961

In the 80's I inherited via my job the responsibility for a 16 vehicle fleet of mining exploration vehicles that mainly consisted of 70's squarebody trucks, Blazers and a couple of Suburbans. All were extremely high mileage with a sketchy prior maintenance and all were abused in the way that only mining company rigs used in the Norther Rockies can be. All had original and unmodified NP203's. Although a number of the 100K mile + rigs eventually had chain problems, none resulted in a blown chain case. I do believe such things have happened to other people, but it has never happened in my experience which is odd given how poorly geologists and mining engineers traditionally treat company trucks.

You would have to have absolutely zero mechanical sympathy to allow a loose chain noise to persist long enough for it to result in a blown case. That is a level of abuse I have fortunately never experienced. I can only imagine those same idiots would listen to an NP205 with drained lubricant whine until the gears fused together.

Neither fault can be attributed to the transfer case - abnormal use brings about abnormal results.