High RPM Shifting Problems - NV5600

xDiesel03

xDiesel03

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Oct 29, 2013
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When I try to shift at higher RPM (3500-4500) under heavy throttle its really hard to get into gear. Within the last few weeks its happened on two occasions where I can't get into fourth at all- it grinds and I have to wait a few seconds before it will go into gear. When shifting during normal driving and medium acceleration with mainly 1500-2500rpm shifts it shifts normal for a NV5600 with a dual disk. Since moving to a dual disk it's always been hard to get into gear from a stop and hard to get into reverse. I have around 32k on my fluid (6qts Redline MTF).

Do you think it's the fluid, the syncros, or the clutch?
 
I have found the redline fluid seems to make a little harder shift compared to factory fluid, the nv5600s don't like high rpm shifts with dual discs anyways usually but it seems as some are different than others. If it's getting worse I would almost bet the syncros are just getting wore.
 
If it is the syncros, wouldn't I experience grinding into gear regardless of RPM?
 
Do you know where you make the most power with in your hp curve? Have you tried staying with in that?

Also, the NV5600 will never shift fast, ever. Go auto.
 
Peak power happens around 3100rpm and carries out till around 3800rpm. After 4000rpm power starts dropping because of the small 68mm turbine wheel and CP3 limitations. I'm going to compounds within the next year so I've started considering going to an auto vs getting a street triple and eventually rebuilding the manual.
 
I have had some higher mileage trucks with start scraping slightly going into gear in higher rpm or when trying to shift quickly when the syncros are getting wore, usually if you wait for it to drop rpms a little more or double clutch is won't but tearing it down and inspecting is the only way to know for sure if syncros are damaged or not.
 
I'm going to start with a fluid change and see how it feels. I pulled the shifter to add some MotorKote Hyperlube and saw this. Not looking to healthy in there. I have some Amsoil on the way.

image_zpskt04ptpy.jpeg
 
I was always told if I tried to shift fast, I'd break it. Mines not a race truck by any means, so I just let it take its time.
 
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