Like the title says, my transmission is hard to shift. Real notchy, and sometimes a bastard to put into gear or reverse. It's rebuilt, and has maybe 400 miles on it. Running Lucas 50wt oil as recommended. But it just doesn't feel right. In another post I stated I had the clutch pedal adjusted way our to get rid of the slop of no bushing. The clutch seems to release ok, it doesn't crawl when in gear. But I worry it's something else. I will say when I put the transmission back in I fought to put it in the last tiny bit in the pilot bearing. Had to torque it down, but I did it as slowly and gently as I could,and the gap was less than half an inch when I started. Not sure if it was hung up on air or just such a tight fit. Also has a Sb dd clutch, and had the big input shaft put in. Stock shifter. No noise from the clutches, and no noise from the transmission. But I can kinda feel the teeth in third sometimes, is this normal?

Anywho, tell me I'm paranoid and it's all ok. I'm terrified to blow up this transmission, or hurt this truck in any way. I waited seven and a half years to get another cummins, don't want to ruin this one. 

5 minutes ago, Mopar1973Man said:

Being 50 WT transmission fluid is designed around the Eaton Fuller transmissions and hauling 80,000-pound loads. It should be a piece of cake for the 50 WT to do its job for a mere 8,000-pound truck.

I would definitely consider using Valvoline 50wt synthetic that claims to work on synchromesh if I was 100% sure about no long-term damage. But now knowing people are run 15-40 motor oil in nv5600 maybe I will try the 50weigh next time I change it. 

Carbon syncro's require a Synthetic GL-4 lubricant.

 

WARNING: GL-5 lubricants will damage carbon fiber syncro's.

 

I can't speak for engine oils or ATF+4 for a transmission lubricant. Might be too thin for good protection. Like during my rebuild on my transmission the 5th gear itself was worn and required replacement. The hard facing was gone. I ran strictly the 75w-85 Mopar Fluid and it failed to protect. Which is the same values of 15w-40 engine oil.

 

When I reach 362k miles will be 100k miles on this transmission with 50 WT. Take me 8 more trips to Ontario, OR and I'll have 100k miles. My morning temperatures are dropping in the teens through New Meadows and Tamarack Mill. Very cold and the transmission temp is not even moving the transmission temp gauge off 100*F at all. I need at least 50*F outside temperature to even reach 110*F transmission temperature. Here before long, I'll be down in the -20*F realm for winter time.

 

Edited November 16, 20186 yr by Mopar1973Man

1 hour ago, Ravewolf said:

I tried that trick, it seems to work somewhat at first. But still sometimes it's kinda hard, and I have to keep playing with the clutch to get it to go in

 

Sometimes, when the transmission input shaft comes to a stop, two teeth are lined up and contacting each other head on making it hard to shift into gear - that is normal.  If a pilot bearing is dragging, it will be hard to get into gear every time.

 

1 hour ago, Ravewolf said:

I doubled clutched all day yesterday, and she shifted beautifully

 

Double clutching allows you to use the throttle to control engine rpm's while passing through neutral to better match engine speed to road speed, as well.

 

Good to hear that the clutch and transmission are working okay.

 

- John

I can attest to the shift quality of an NV5600 with a southbend double disc. Really you just have to get used to shifting slower. Dont force it. 

 

If your having doubts about the hydraulics you can use an H bar puller to actuate the clutch fork manually. A call to south bend will also give you that information and i think it says so somewhere in the paperwork they give you with the clutch as well. 

 

We had a heck of a time trying to install a south bend in a customers truck here in the shop. Ended up going with a factory one instead but never could figure out what was wrong with the south bend one but it just flat out was not going into gear. Tried everything