NP273 Coasting Downhill problem

Hotrodtractor · May 26, 2013

OK - I believe that I have an NP273 tcase right now that when coasting down to a stop and it downshifts with enough load it grinds/clicks. Its either the tcase or the transmission - and I have a good record with a fair amount of time on the transmission.... so I'm skeptical its the transmission.

Has anyone ever heard of that or seen that problem before? It sounds odd as all hell to me and I can't readily explain it. There are NO issues with acceleration only coasting/slowing down.

NEVRNF · May 26, 2013

Does it do it when you are at high speed? LIke when you are in between being on the power and coasting.

Hotrodtractor · May 26, 2013

Nope has to be coasting down to a stop - and near as I can tell it has to be downshifting into either first or second gear. I don't think it has ever done it to me in 3rd gear.

hawgdoctor · May 26, 2013

Wonder if you have a spring going weak and it doesn't make a sound till then letting the fork bounce around a bit. Have a spare 273 in pieces right now if you need anything Jason.

sent from the shop making things fly.....

rpm-inc · May 26, 2013

I have one if you ever get near chicago.

Hotrodtractor · May 26, 2013

Thanks guys - I'm going to take it to a party tonight and try it out in 4 high (I haven't installed the front driveshaft yet) - if its a loose spring/fork - I would think that it wouldn't do it in 4 high.

Thanks for the offers - I have a couple of cases in the shop though - its just that this one is freshly rebuilt and modified for a 263 shift actuator and a different input shaft so it bolts up to an Allison. This grinding noise is either the tcase or the transmission and my money is currently on the tcase......

Hotrodtractor · May 27, 2013

Still does it in 4hi although it seems to be much harder to do. This sucks. I'm pretty positive its the tcase now though - it just sounds like that is where the sound is coming from.

Powerstroked162 · May 27, 2013

Hotrodtractor said:
Still does it in 4hi although it seems to be much harder to do. This sucks. I'm pretty positive its the tcase now though - it just sounds like that is where the sound is coming from.

Do you have full coverage?...

.

Hotrodtractor · May 27, 2013

Powerstroked162 said:
Do you have full coverage?...

.

Ummm..... yes I have full coverage and no I don't intend on using it.... lol

Hotrodtractor · Jun 28, 2013

Well - I've been busy and haven't had much time to really diagnose this - but I have been forced to drive the truck for a bit while I do some repairs on my fuel sipper. This doesn't occur all that often, and it definitely can cause the trans to go into limp mode if it occurs long enough. The real odd thing is that if I hit the throttle it will re-engage - further pushing my concerns away from the trans and to the transfer case. I did manage to catch it on video tonight on the way home from work - it had just happened to me and popped it into limp mode so it was stuck in 3rd gear - no downshifting. I decided not to clear the code because there was a steep hill after it happened and I knew I had a good shot of catching it on video because of it.

https://www.facebook.com/photo.php?v=523588544362528&l=7147273876335427290

4.0l sahara · Jun 28, 2013

Bet the fluid has metal in it.

Hotrodtractor · Jun 28, 2013

4.0l sahara said:
Bet the fluid has metal in it.

I don't doubt it. I wish it was easy for me to check. lol

It sounds like my tcase has a high probability of being covered by the peeps that built it for me after they watched the video - so good news on that front.