Life of NV5600

[ThomG]

Ok so it seems at this point, my NV5600 syncro's are bad for at least 3rd and 4th gears. I do not feel I abuse them, maybe down shifting to take advantage of the Pacbrake causes more wear?? At 230,000+ miles is it normal to have them wear out ? Just my wondering, comments from others with NV5600's anticipated. What life expectancy is "normal". I've changed transmission lube with Amsoil syncromesh about every 30,000 miles since I've had the truck. It had about 110,000 miles when I bought it in 2007.
To Mmier, I was assured getting parts would be no problem.

 

[Tuesdak]

Standard Transmissions (appear to a be good place to get a rebuild) and South Bend Clutch both don't recommend using using the engine and transmission for braking. Clutches are designed to torque one way only so compression braking is said to reduce life. Standard Transmission also said they had a transmission in the shop for 5th gear and blamed the braking. Cheaper to use and wear out the service brakes. I was also told syncro life is approx 200K depending on use.

That said when service brakes are not enough... It's a better choice than a slushbox for these years.

What oil were you running before and did you have issues? If not change back to that oil. NV5600's are sensitive to oil and an oil change (change of oil and change of brand) can be felt immediately.

 

[6speed]

I have 235K on my NV5600. I tow heavy (26K). Run Amsoil Syncromesh and change it about 30-35K. I do not tow in 6th, it gets way to hot. Installed the GV at about 100K to take advantage of the dbl overdrive when empty and to be able run decent mph in 5th over. I run my fluid approximately 1 & 1/2 qts over filled. I use my pacbrake all the time and I have a South Bend Dual disc. I do what I can for service and hope to get plenty more miles. Of course how one drives determines the life of things. I watch temps in everything. I believe that is the key to longevity.

 

[ThomG]

To JDOREMIRE If yhe engine and transmission are't to be used for braking, what do you use your pacbrake for or is it just for show? Just trying to understand your post.

 

[BLNRAY]

Built my NV5600 at 350,000mi due to pilot bushing screwing up the input shaft.trans still worked ok but with the miles on it I should go through it while it was out.most of its life I used Royal Purple Synchro-max oil,tried amsoil after the build but went back to RP,it seemed to shift better on RP

 

[CKelley1]

the exhaust brake does not effect the nv5600 in any way, the disc is affected, the spring's are setup for heavy torque in the forward direction with only compression torque in reverse, the good brakes like the pac or bd add 165 hp to the reverse load. after many miles of heavy use the rivets holding the center section wear into. we have peter at southbend build the disc using a center piece for a clutch using a engine brake. attached is a pix of one that this happened to and left my driver stranded in Oklahoma. use a blend of royal purple synchromax and sae 50 wt synthetic Transmission Fluid like delvac from ww granger or castrol synguard from o'rileys. you need to overfill the transmission to lube and cool the rear bearing and some upper shift parts, we have transcools on ours so they hold more fluid than yours. i think without the trans-cool ten quarts will be about right, this is double.
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[Prairie Dog]

Agreed. The EB doesn't hurt the big NV at all. Many, many of us have been using them for hundreds of thousands of miles without any issues.

 

[mikeyb]

Personally there's just too many variables to determine the life span of the syncros. Operator, the design it's self, fluid used and the usage. Other issues like weak clutch hydraulics, dragging clutches and pilot bearings can take it's toll on the syncros too.

For about 6 months I had shifting issues with my NV5600, changed fluid and hydraulics, no change. Finally ditched the stock clutch setup for a HD South Bend and found the pilot bearing (needle bearing) was the issue. Now the NV shifts better than ever (actually better than I could ever remember). The syncros probably lost some of their life with this issue.

 

[CKelley1]

mikeyb made a good point about the pilot bearing, also had this happen

 

[HHhuntitall]

As for service, the few NV5600s I've been lucky enough to keep around, have all ran around 200k before starting to show some signs of needing some work. The one in my '97 runs behind a 50+psi boost 12v (yes, it's a NV5600, I installed with a new built engine). It's been there just over 255k miles and is starting to make a lot of noise, so it's due. I've run Synchromesh in it until about 6 years ago when I went to Blumenthal's oil. 3rd gear synchro is argumentative. The two in my '03s are both about 140k, and running strong. The one in the '04 was rebuilt at around 250k, as it wouldn't shift into 3rd at all anymore. Mostly, I've run Synchromesh over the years, until Blumenthal's started making an oil, which I started running. Seems to run cooler and certainly makes less noise under high boost.

 

[mikeyb]

Can you tell us more about Blumenthal's oil? Is it still a 5w-30 or something else?

I've tried Pennzoil Synchromesh and Amsoil MTF, but keep coming back to Pennzoil due to price and it's seems to shift better.

 

[RVTRKN]

the exhaust brake does not effect the nv5600 in any way, the disc is affected, the spring's are setup for heavy torque in the forward direction with only compression torque in reverse, the good brakes like the pac or bd add 165 hp to the reverse load. after many miles of heavy use the rivets holding the center section wear into. we have peter at southbend build the disc using a center piece for a clutch using a engine brake. attached is a pix of one that this happened to and left my driver stranded in Oklahoma. use a blend of royal purple synchromax and sae 50 wt synthetic Transmission Fluid like delvac from ww granger or castrol synguard from o'rileys. you need to overfill the transmission to lube and cool the rear bearing and some upper shift parts, we have transcools on ours so they hold more fluid than yours. i think without the trans-cool ten quarts will be about right, this is double.
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CKelly1, are you saying that the spline slipped within the 4 rivets that clamp it down in the center? I'm not seeing the damage.

 

[HHhuntitall]

Can you tell us more about Blumenthal's oil? Is it still a 5w-30 or something else?

I've tried Pennzoil Synchromesh and Amsoil MTF, but keep coming back to Pennzoil due to price and it's seems to shift better.

I wish I could get a spec sheet on it, but they want to keep it a secret for some reason. I do know it's refined locally either in OKC or Tulsa, but can't find out any more than that, as of yet. It appears to be 30w. I wanted to try it, seeing as how they machine a lot of parts in house for the NV4500 and 5600, and certainly know a lot about why they fail. I've never been sold on Amsoil.

 

[Tuesdak]

To JDOREMIRE If yhe engine and transmission are't to be used for braking, what do you use your pacbrake for or is it just for show? Just trying to understand your post.

Well it came with the truck when I got it... Yes, I use it component life reduction be dammed. Mainly because I find trailers that the trailer brakes quit working when I need them. So unless I am towing I don't use the exhaust brake. So keeping component life in mind I can make a better decision and not use the brake unloaded for "show". (I am already 2 clutches into this truck due to a dowel pin missing so I just don't see where the extra wear is going to shorten the already short clutch life I get...)

More shifting from downshifting = more syncro wear. Other than that I just recall Standard Transmission saying it does cause problems. Does it matter in the long run is hard to say.

I wish the info on the different clutch design in this thread for engine braking was presented earlier as I would have asked for this design too!

2nd to the last question says it.

http://www.southbendclutch.com/troubleshooting.html

 

[NIsaacs]

CKelly1, are you saying that the spline slipped within the 4 rivets that clamp it down in the center? I'm not seeing the damage.

I don't see the damage either. That is a picture of a bone stock clutch, I don't think I would use one on a modified Cummins. In all fairness mine lasted 210k miles. I changed to this one, note the beefy hub. I use the exhaust brake all the time and down shift.



Nick

 

[HHhuntitall]

I know in the older Dodge 5spds, we would destroy a factory type clutch in an instant when we'd bump the throttle or try to back up a big trailer in reverse. The metal tabs that connect the center section of the hub to the pad sections would bend. It would literally lock them up so they wouldn't disengage, too, with the metal tabs "S" shaping over themselves, pressing the clutch disk into the flywheel.

Referring to the Southbends FAQ section, yes, a clutch is designed to go one way. So is a ring and pinion, for that matter. And the helical gears cut in the transmission. The direction of cuts add strength in the direction torque was designed to go, but can be inherently weak when going the other direction. The more torque you add in a reverse direction, the quicker you will wear out, weaken, or potentially break the components. Not that that fact has ever stopped me......

 

[GCroyle]

Guys,

Just for grins, take a look at an OE stock style disc damper. It has 6 stop pins that hold the damper assy to the drive plate. They are at the outer edge. Now, look at the edge of the damper at a stop pin. See the hub flange? Notice that it is about 1" from the flange to the edge of the stop pin and about 1/2" on the opposite side. The 1" is the range of damper spring compression in DRIVE, the 1/2" is the COAST direction, easy peasy. Now look at the edges of the stop pins? See any witness marks, are they just a touch or slightly notched or really notched?

No marks, never fully compressed the damper. Just a witness mark, you touched it a few times. nice imprint? you've held it on the pins, fully compressing the damper springs. Deeply gouged, been having some fun ain't it grand.

One other damper reading issue, if the hub pilot is washed out and all loosey goosey, got pilot dowel sleeves in the engine to trans adapter plate? Missing dowel sleeves don't allow the damper to float and relax, causes premature damper failure. That disc does have a floating nugget hub and it will feel loose if you put it on a shaft and check it at the facings.

Dowel sleeves are critical to the long service life of the torsion damper, pilot bearing and even the input shaft and trans bearings.