How difficult is it to shift with the NV5600? Should it slip right into the next gear with zero hesitation? Can you downshift with zero hesitation? Or should it be somewhat difficult to get it into the gear?

Please let me know how your's shifts and what oil you're using.

I'm using 6 quarts of the Pennzoil stuff designed for the NV5600.

 

Mine shifts slow when the trans oil temp is below ~110 degrees, but after it warms up it shifts better. I am using 6 quarts of Penzoil Syncromesh and I just changed the oil in the tranny last weekend.

 

mine shifts like a PIG and always has I have tried other oils but still the same its just a slow notchy pig but it shifts better with a load behind it

 

I've never changed oil, and as long as its somewhat warm, I can shift with 2 fingers and my thumb

 

175k on it now on my 6-speed it seemed to like redline MT fluid better than penz, never tried amsoil. I also have added the filter that goes on the pto cover at 90k it does collect alot of gunk also added bigger square magnets on the pto covers. when I went to a DD clutch the shifting was alittle more notchy but told its common. I dont have a issue with cold/warm shifting doesn't get cold enough in winter here that often.

 

How SHOULD it shift? Like butter. How does mine shift? Sometimes it plays nice, and sometimes it shifts like a truck, since new. Original blew its guts out @ 237k. Replaced with used box and that shifts much better. My 06 6 speed blows it away though...

 

Well...mine shifts smooth, once I get passed the syncros.

All of the following is with the truck standing still. I will push in the clutch and it's difficult to put into gear. Once into the initial gear and the clutch pushed in, I can row through each of the gears. If I put in Neutral and release the clutch, it is again difficult to get back into any gear when I push the clutch back in. I understand that releasing the clutch gets the transmission internals spinning again.

I need to test it again, but I believe it is difficult to put into any gear when initially pushing in the clutch. Whether I'm trying to put it in 6th, 1st, or whatever. Obviously I'm not going to start out in 6th, I'm just saying that it's difficult to put into any gear when initially pushing in the clutch.

When driving the truck, there is very noticeable resistance when trying to downshift and it just doesn't easily slip into the next gear when upshifting either.

The shifting is smooth once I get the shifter passed the initial difficult resistance. Sure, there is the gear rub if the transmission oil is cold from the truck sitting all night, but overall, the truck shifts nicely. Just a very difficult initial resistance. Yes, the plastic cup is on the shifter ball.

If I had a specific worn syncro, I could see it difficult to put into that specific gear, but since (if I remember correctly) it's difficult to get into any gear, perhaps it's just an oil issue. Even if incorrect oil was used sometime in the truck's past, I can't imagine that ALL the syncros would be worn, just the ones that are used frequently. For instance, wouldn't it still be easy to get into 1st, since 1st is rarely used?


I bought the truck with 99,875 miles on 3/6 and I've put less than 1000 miles on it since then. I changed the transmission oil with 6 quarts of Pennzoil Synchromesh within the first 150 miles of buying the truck. I assumed the fresh oil would improve the initial resistance to shifting. It hasn't.

Ideas?

 

Your blocker rings (synchros) are worn out. When new the teeth are like a rounded point, when worn they are like a flat point.

When I finally got mine overhauled, I could barely get it into reverse without shutting the truck down.

They aren't meant to speed shift like a car five speed and can't really ever be made to do so. They are big and heavy and the synchros need time to match the speeds of the gears for a smooth slip.

Mine hates the cold, BTW. even in the 40's overnight is enough to need to go a little farther than usual to get it warmed up.

It is what it is.

 

Non synthetic can cause problems. This transmission is cast iron which is TERRIBLE at dissipating heat. Virtually no thermal conduction at all.

I don't know why, but non-synthetic+heavy load makes transmission difficult (sometimes impossible once hot) to shift. Put in a full synthetic, and eventually it will start shifting right again. Every time you get the transmission hot it will shift a *tiny* bit better.

Use a full synthetic, and put in an extra quart through the top pto bolt or the shift tower. I use Royal Purple and was shocked at how much better it shifted than the OE stuff. I've heard that Redline is the best, though.

 

I changed out mine to Redline the week I bought it and it shifted a lot better once it was warmed up. However, trying to get it into gear at a dead stop was getting worse and worse. Turned out to be the blocker rings, ie synchros. The drained fluid was pretty clean with tiny bits of yellow metal, which is normal.
After tearing it down as far as possible we discoverd that the damage had been done before I bought the truck. After leafing thru the owners manual I found the PO's notes in the back re: service. He had the trans serviced at a quick lube and my trans guy said its highly possible the tech saw a big cast iron case and filled it with gear oil, thus starting the destruction process.
The gears were pretty much fused to the mainshaft, probably from overheating.
My warranty says the stock fluid only. After its up, I'm going back to the Redline MTL.

 

I had a similar situation with my NV4500. Hard to get into any gear from a stop in neutral, then shifts fine.

Turned out to be the clutch needed replaced. Worn clutch surface was draging on the pressure plate even with the clutch depressed.

 

I am close to 300k on the 5600 since the swap. Changed fluid for first time back in Jan 2010, put in penz synchromesh and lucas. 3rd gear is rough when cold.

 

Royta, the wrong fluid at any time in the past is sure to junk the blocker rings. The incorrect fluid is a death sentence to the 5600.

Towing the truck without disconnecting the rear d-shaft any distance is enough to damage the trans also. Towing should be done by flatbed or by the front end with the driveshaft removed, even for what seems like a short distance.

I'd check the clutch first and see if you can adjust it a little to make a difference, if not, you are probably in need of a new clutch or worst case, a rebuild....

 

my old tranny you could not get into 6 od rev with out a grind. my new one shifts like a g56 minus the stiffness. and with the new one i have to use the clutch all the time. you will always have to wait on the 6 speed. found out that a stock clutch makes it shift really different than my dd clutch. the stock one shifts alot better. amsoil fluid with the fast coolers with a oil cooler.

 

I had exactly the same issue when I switched to Redline MTL. In fact, I had a grind when going into third gear (when cold).

I switched to Amsoil and all the problems disappeared.