Fixing an UN-broke NV5600

[Cattletrkr]

I've been thinking about finding a reliable transmission shop and having them go thru my NV5600. There's nothing wrong with it now, but I don't have anything against preventative maintenance. With 143K of heavy work, what should I look for if anything?

 

[jelag]

I did this a couple of years ago... and wish I hadn't... the transmission was never the same and we later had to replace it with a factory re-maned unit... I'd suggest that you change the fluid and take one of the side covers off and inspect the gears... . if its not making any noises and the fluid is clean and no chipped teeth... I'd leave it...



Our problem has been a noise at idle with the clutch engaged... and with shifting problems when we up or down shift... you put it one gear and take it back to N and it makes one noise... . you shift to another gear and take it back to N and the noise changes...



One thing we did find is that this transmission is not designed for heavy hauling in 6th gear... we pull a 22K trailer and often the total load is close to 30K with the truck and fuel... and the path for 6th gear is just not designed for this load other than driving down the freeway at speed... we not down shift to 5th right off the bat on all hills... Our trucks have the 4:10 and had I know of this problem I'd put the other rear end in the truck and would drive it in 5th most of the time with a load...



When we did the re-man transmission the noises got worse and we were told that from the factory the gear boxes were set up too tight... and that they now have more clearance... . after 10K miles in about 3 or 4 weeks the noise from the transmission was getting worse... we had to go back in have it set back up... .



I'd just not go there again unless I have to... but I'd be good about the inspection and oil changes...



BTW - I have 3 trucks... 04 with 240K miles, 04. 5 with 60K and 05 with 50K and at this point only the 04 has given us problems... .

 

[Cattletrkr]

Unfortunately I have the same setup as you and I pull much heavier than that, one way. My trailer weight usually doesn't run under 23K too often. I do run in 6th gear a lot, but I don't "lug" it. I've gotten better at downshifting into 5th.



I do regular oil changes. I used to change at 30K or so, but the oil comes out so clean I'm stretching that to 40K.



What can all be seen thru the pto holes. I could pull the fastcooler off next time and look, but I wouldn't know what I'm looking at.



Hindsight being 20/20 I screwed up getting the 4. 10's again, my '01 had the same setup. I'm kinda waiting for rear-end troubles so I can do a swap. Until something goes wrong with the rear end, it really doesn't pay to swap a 4x4.



I suppose I could just trade for a new CC auto, but where's the fun in that?

 

[jelag]

I have never seen this rear end give any problems... . and I until the new transmission came out I haven't seen an auto that would handle the load... Just my thoughts...



Jim

 

[rbattelle]

If it isn't broke, don't fix it! I'd take Jim's advice and leave the transmission alone. Just change the fluid.



Ryan

 

[Gary - K7GLD]

I agree with Ryan - unless you have a KNOWN issue - and a pretty good idea what you are looking at and for - and maybe have the transmission out for other work anyway, leave it alone!



About all you will see from the side cover or top shifter area is gears - and pretty limited view at that - to actually make a meaningful inspection requires a teardown and inspection by someone well experience with transmissions in general - and the 5600 in particular.

When we did the re-man transmission the noises got worse and we were told that from the factory the gear boxes were set up too tight...

That I can believe! Since new, my transmission will quite noticeably momentarily drop engine RPM when the clutch is released in neutral - and I mean MORE than you might reasonably expect from the mass and inertia of the gear assembly itself. No issues with mine, it shifts as perfectly hot or cold as I would expect from a transmission of this nature, and makes no noises I am able to hear under any circumstances - and I am using the stock lube specified for the 5600...

 

[Cattletrkr]

OK, I'll just leave the transmission alone, fluid changes aside. Thanks for the input.

 

[Cattletrkr]

I have never seen this rear end give any problems... . and I until the new transmission came out I haven't seen an auto that would handle the load... Just my thoughts...



Jim

Every now and then I'll get a little bit of filings on the Mag's dipstick. The first 50K there were a lot of filings, I mean a lot. But since then, not much.



I'll let dad borrow my trailer to haul his own cattle. His '03 CTD 3500 DRW has an auto. Pulls the load just fine, but I can't stand trying to get things moving. His auto is all stock and I'm sure upgrades are in the relative near future at 93k. I think there's a pic in my gallery of what he pulls.

 

[Diesel Nut]

Just make sure you overfill the transmission by 1 quart when you service it. I just replaced a NV5600 for a guy because the bearings went south. the extra quarts can help to eliminate that problem.