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Rough shifting nv4500

5K views 9 replies 4 participants last post by  20valve 
#1 ·
Just had my nv4500 rebuilt by Moonlight Diesel, put the SB HD hydraulics in, and a new input shaft to boot. The trans was filled with a little over 4 quarts of the mopar fluid that was recommended. Truck has a 13" valair kevlar/ceramic clutch with about 4k miles on it, at which time the clutch fork pivot and spring were replaced, too.

Problem is, it's kind of tough to shift between the gears. To get the truck into 1st or 2nd, you have to put a fair bit of pressure on it to go in. I would hate to ruin the synchros early, too. It's been a long time since I've driven a good nv4500 (the previous one had bad synchros), so I don't remember if this is normal or not. I adjusted the rod for the master cylinder up quite a bit, but the pedal was very "sticky". It wouldn't release smooth, but rather in 1/4" increments. Adjusting it back down to the factory pedal position seemed to help, but it's still sticky.

I didn't grease the input shaft retainer when I put it back together. Not sure if that was a critical step or not. I didn't check the throwout or input shaft bearings, but seeing as how they had 4k easy miles on them, I didn't think they would be bad.

I can't think of where to start, seeing as how everything is either new, or nearly new. Any thoughts? 3rd to 4th is smooth, just not coming back to 1st or 2nd. Is it because the kevlar/ceramic clutch has more drag to it, even when released? I did call Terry at Moonlight, who said dual disks tend to wear out synchros sooner, which lead me to believe they may have the same problem my single disc does.
 
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#2 ·
My truck is the same way. I have a PPE dual disk clutch and it is hard to get into 1st and 2nd but shifts easier after that. Sometimes it feels like the shifter is going to break before it goes into gear. I even tried letting out on the clutch a little to make it pop in gear easier but it does not always work, but I did find out if I go to 2nd gear and let out the clutch enough to get the truck to barely move it will go right into 1st.
 
#3 ·
I've had bad problems with notchy shifting since I put my southbend DD clutch in. I'm about to pull the clutch back out and send them pictures of what my clutch components look like. Apparently, they've come up with some new parts since my clutch was built, and they're willing to hook me up with some of the improvements for not much money. It's bad enough that I think I could lose a race to an automatic truck with 150 hp less than me unless that race went on for about a mile. My truck is a screamin retard in gear once it spools the turbo, but then I have to wait until the 15th coming of Jesus to get the next gear, especially from 2nd to 3rd.
 
#4 ·
did you add the extra washer under the pivot fork ball?

That allows for a little more movement of the throwout bearing....

It sounds like your clutch is not fully disengaging. It could also be a pilot bearing/bushing issue or a warped clutch disc causing some drag and keeping the shaft spinning.
 
#6 ·
Now that I think of it, I don't remember. I believe I did, because the donor truck the bellhousing/trans come out of had all the factory parts in it. The only things I replaced were the pivot ball and spring. Chances are if it was in there before, it went back in. The pilot bearing should be good, but then again, it probably wouldn't be the first failed bearing. The only possible thing I could think of was I didn't grease the input shaft retainer. Terry didn't think it was a HUGE deal, or a critical step, but he also didn't think that alone would cause the problem. The clutch disk should be flat and straight, as I didn't drop it, and it hasn't had any boosted launches, or high HP running through it (certainly not enough to tax even a stock clutch).

I was thinking it may just take a little bit to wear everything evenly, so I will give it another thousand miles or so. Also, the clutch could still have some breaking in to do. Kevin at Valair said the ceramic is pretty tough to break in, and a long process. Seeing as how this truck has been driven easily, it could be that the ceramic isn't fully seated. Just my theory, though.
 
#5 ·
I have tried everything on mine, and nothing has worked. I pulled it earlier this spring because I was flat tired of it, and I took it to the man who was one of the first to build the dual disk for the Cummins as he live 2 houses down from my mom and he found 1 disk warped in which we got it straightened back out.

I then put the clutch back in and it drove great for about an hour then went right back to the same old thing. What we figured out is the nuts on the bolts that hold the arms for the release on the PP will not stay adjusted and vibrate loose a little. Yes these nuts were staked, now staked in 2 different places and still did not hold for some reason. My plans are to pull the NV4500 and replace with a 5600 if I ever find a wrecked truck, then I will redo the clutch again.
 
#7 ·
just because you didnt drop the discs doesnt mean they werent factory defects or get beat up somewhere between the factory and you!

I would pull the trans once again, check the runout on the discs and see if that extra washer is installed beind the pivot ball.
 
#8 ·
How does one go about checking the runout of a clutch disc? I can get ahold of a dial indicator, but that's about it. Not sure what kind of setup or tools I would need.
 
#9 · (Edited)
easiest way would be to have it out of the truck and in a stationary jig so that no 'outside forces' (ie, wobbling on the splines of the input shaft)will obscure the reading.

Magnetic base/stand for the dial indicator would be the way to go.

Runout of the disc is usually pretty large, less than 40 thou is usually fine. the flywheel on the other hand should be MUCH less, idealy under 5 thou
 
#10 ·
Okay, on quad4x4's website, it says new or rebuilt nv4500's may be hard to shift, until the synchronizers wear in, especially if they are brass; new venture rings are the only way to cure it, according to the site. I wonder if this is the cause. Not sure what kit Terry used, but it sounds like genuine New Venture parts are scarce. It doesn't grind, doesn't jump (even in 1st downhill with the brakes off), or make any funny noises. Just have to give it some force to put into 1st or 2nd from a stop.

I'm not sure how long it would take to screw up a fresh rebuild, but I was going to give it another 1000 miles before I pull it back out to inspect, just in case there is some breaking in to do. I'm also going to play with the adjustable rod for the master cylinder a little bit, to see if maybe I can find a sweet spot. Anyone see any problems?
 
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