My NV5600...how much I hate it!

[steved]

Before synchromesh fluids were available aftermarket, a lot of guys ran 5w30 Amsoil Motor Oil... the only thought at the time was that the oil isn't as shear stable as a gear oil...



If you look at Amsoil's MTF, it is a 5w30 weight oil, and if you look at Red Line MTL, it is a 70w80 weight oil!



I'm pretty sure the pilot bearing is one of my problems... I've actually felt that might have been a problem since the first winter. It was good to see that it is a common problem... and one that has a "fix".



steved

 

[Cattletrkr]

If you look at Amsoil's MTF, it is a 5w30 weight oil, and if you look at Red Line MTL, it is a 70w80 weight oil!

No wonder I'm a little confused about the oil viscosities. I ran the Amsoil engine oil in mt 5600 once, with a little Lucas too. No difference.

I'm pretty sure the pilot bearing is one of my problems... I've actually felt that might have been a problem since the first winter. It was good to see that it is a common problem... and one that has a "fix".

My pilot bearing was a little loose iirc, but the throwout was dang near seized.

Does your pedal feel different than when the truck was new? Have you ever had a pedal that isn't smooth all the way down?

 

[steved]

My pilot bearing was a little loose iirc, but the throwout was dang near seized.



Does your pedal feel different than when the truck was new? Have you ever had a pedal that isn't smooth all the way down?

Nope, it feels the same as the day I drove it from the lot...



steved

 

[rbattelle]

This is hard to NOT notice... when you can't catch a gear WITHOUT getting tooth-to-tooth contact, its more than annoying.

I've never had any real problems with mine I guess. I thought the gear clash was normal for such a huge trans.

I'm confused on the tooth-to-tooth contact and gear clash. How can you get gear clash in a constant-mesh transmission?



During the cold months, 2nd and 3rd frequently have what I'd describe as "push back" from the dogs during the shift. I think this is the dogs popping out of their engagements. Below 30°F, 2nd can be very bad.



My theory is that this arises from the uneven nature of an arm pulling on the shift lever. If constant speed and force could be applied, the dogs would slip right in. A momentary lapse in shift pressure or speed will knock off a tiny bit from the sharp edge of the dog. Over time, the edge becomes more rounded, which will tend to create a force parallel to the shaft in the opposite direction you're moving the dog for the shift.



I'm attaching a drawing of a friction cone (this one happens to be 5th gear) from the service manual. Note the square edges of the dogs. That's what I'm talking about - those get worn slightly, causing them to "push back" a bit during engagement if the engaging isn't done quickly and with even pressure (after the synchro has been given time enough to do its job). Poor shift methods ("grinding the gears" as they say) will accelerate the wear.



Just how bad this is in terms of transmission life, I don't know.

The only small issue I have noticed ... is if I am in a hurry going through the gears is I have a loud drive line clunk aka slop... usually from the 2 to 3 shift if I don’t let off and re-apply fuel pedal just right.

Check your universal joints in the rear driveshaft.



Ryan

 

[steved]

I get tooth on tooth contact during morning (cold) shifts, sometimes worse than others. You can tell it is a grind, and not the dogs jumping.

It is impossible to pull 2nd out of my driveway most mornings (no gear clash, just won't go into gear). I usually end up looking like a fool, out of the driveway in 1st, then come to a dead stop trying to get second. Pump the clutch, grab second, then get some clash going into 3rd as I shift less than 100 feet from my driveway.

Even after driving 50 miles, I get some difficulty into 2nd/3rd/5th... albeit a lot less than when its stone cold. And the trans shifts the best at around 180*F... which I never see during the winter. The only gear that I never have trouble getting is 6th.

I do not force the gears... just put it into the correct "slot" and hold a slight pressure on the shifter until it drops (or tries to drop) into gear. I do not horse on it...

I'd like to see anyone drive my 5600 with any better results... I can make it work, as I know what I have to do to make the gear changes without a clash... but it isn't anything near push a clutch and grab a gear. I usually have to pump the clutch to get into gear, double clutch 2nd, double clutch 3rd, pull 4th, take a long time (clutch depressed) before trying 5th, pull 6th.

steved

 

[rbattelle]

I get tooth on tooth contact during morning (cold) shifts, sometimes worse than others.

I cannot understand this. How do you explain this in a constant-mesh transmission? Are you thinking you've lost some teeth on 2nd gear? (Remember what Cattletrkr found in his transmission!)



Ryan

 

[betterthanstock]

Before synchromesh fluids were available aftermarket, a lot of guys ran 5w30 Amsoil Motor Oil... the only thought at the time was that the oil isn't as shear stable as a gear oil...



If you look at Amsoil's MTF, it is a 5w30 weight oil, and if you look at Red Line MTL, it is a 70w80 weight oil!

5w-30 would be notchy when cold (too thick compared to synchromesh).



0w-30 is a lot better, especially if you can find it synthetic without VI (viscosity improvers), which is what breaks down.

Actually, the synchromesh is even thinner when cold than 0w oil, so I don't know if they make a double zero viscosity, that would look like 00W-30.



I know a lot of ATF comes close, but the additives are all wrong, except for Type F, which is too thick when cold, and too thin when hot.

 

[kkreigh]

I have 94 K on my 2001. 5 My NV5600 is smooth as silk. I use the factory fluid. I change it around 25,000 miles. I used Lubrication Engineers trnas fluid for one change and felt no change went back to factory. I occasionally haul 14 k triler in extremely hot weather and have had no problems with my trans

 

[Cattletrkr]

I cannot understand this. How do you explain this in a constant-mesh transmission? Are you thinking you've lost some teeth on 2nd gear? (Remember what Cattletrkr found in his transmission!)

Ryan

I have a grinding when going to 4th when cold. I might get a "new" rebuild out of the deal. I'm thinking it's synchros that are shot.

For those of us who have no idea, please go back to your drawing and tell us what's what on there.

 

[rbattelle]

For those of us who have no idea, please go back to your drawing and tell us what's what on there.

Sorry about that. There's only one part I'm highlighting in that drawing - the friction cone.



I believe (someone correct me if I'm wrong), that the dogs on that shift cone (the little square protrusions) are what's engaging each gear on the shaft.



The gears are constant-mesh. That means all the gears are spinning at all times. But only the one gear that has been locked to the shaft by the friction cone is actually providing power to the output shaft.



Those little dogs slip into "slots" (I don't know the correct term for them) in the gear, locking it to the output shaft. When you pull the shift lever, all you're doing is sliding those friction cones along the output shaft to engage and disengage the gears from the shaft.



Here's a link to a decent drawing of how the shift process works in a constant-mesh transmission.



That's why I can't understand why Steve has gear clash, unless he's missing parts of some of the teeth.



Ryan

 

[betterthanstock]

It's not gear clash, it's those numerous tiny teeth that grind when you "beat the synchro".



The synchro cone, which is labeled "1", helps to slow down, or speed up when downshifting, the shaft and the clutch disc, to match the speed in the new gear so it can slide in without grinding.

That surface labeled 1 jams unto the cone on the gear face, by the guy's thumb (drawing on previous page), and those tiny channels wring out the oil from the cone to generate some friction. If the cone is worn out, or the oil is too thin, it slides unto the cone too easily, and the tiny teeth clash with matching teeth on the sleeve moved by the shift fork. That sleeve rides in grooves on the shaft, and transfers torque.

The synchro is brass and cannot transfer torque, it just transfers enough torque to slow down/speed up the shaft.



Ok, some NV5600 pics. Big heavy parts.

 

[steved]

I cannot understand this. How do you explain this in a constant-mesh transmission? Are you thinking you've lost some teeth on 2nd gear? (Remember what Cattletrkr found in his transmission!)



Ryan

Sorry Ryan, I can't explain why it does it... I have never found anything in the trans, and only ever a slight fuzz on the magnets.



steved

 

[steved]

It's not gear clash, it's those numerous tiny teeth that grind when you "beat the synchro".

If that's the case, then the synchronizers are tougher than we are lead to believe...



The other thing is that I would expect to find metal flaked fluid, either steel or brass. I only ever find nice clear/clean fluid.



steved

 

[MCummings]

It's not gear clash, it's those numerous tiny teeth that grind when you "beat the synchro".

Wow. They are strong. That's what my trans does then. The little teeth, scurrlrlrl-klunk when a gear is pushed firmly. or, scurr-flunk when trying to really scoot.



Merrick

 

[Cattletrkr]

betterthanstock,

Where are all the little pieces like the ones I found in mine??

 

[steved]

Where are all the little pieces like the ones I found in mine??

Operator error? :-laf



steved

 

[JasonCzerak]

I hate this trans... it shifts poorly, it eats fluid, it is a PITA to change fluid... but at least it is supposedly stout?



Just got done replacing the fluid in the NV5600 last night... got almost 20k out of the Redline MTL/MT-90 blend, which is by far the longest I've gotten out of any fill of synchromesh-type fluid. Starting about two weeks ago, shifting started to drastically fall off... almost impossible to hit 2nd in the morning... had to baby every shift in order to not get a little bump (gear clash). It was mainly 2nd that was the problem... but there was no normal shifting of the trans (it was bad enough I almost got rear-ended by a Stratus... the pause between shifts isn't something the other drivers are anticipating). Not to mention the fact the trans was starting to run warm... it was heating up quicker, and a little higher than it should normally do. A UOA last year of another synchromesh indicated the fluid shears in this trans... that causes my increased shifting difficulty.



Ordered 7 quarts of MTL from Summit Racing on Monday, got it last night. The bottles of MTL now read that it is a synchromesh fluid... which is new. Decided that since it was winter, I'd just use straight MTL, and leave the MTL/MT-90 blend for summer.



Did a quickie drain and fill, didn't pull the side covers (this leaves around 0. 75 quarts of old fluid in my trans). The fluid drained absolutely clear and red, just like when I installed it. And the magnet was completely clean. Refilled with straight MTL (short what was still in the trans) and got around 6. 5 quarts in the trans (it has Fast Coolers). This was the first time I actually didn't end up wearing half my fluid change...



Take off this AM... I can hit 2nd fine, but now its cranky going into 3rd... Overall it does shift better... and it rolls a ton easier (I feel this might be where some of my mileage has been lost as of late).



I'm starting to drive it like a 3-speed... 2-4-6 shifts instead of the typical row through the gears. This doesn't seem to lug the engine at all and no clutch slipping is needed, and is a lot easier on the flats to gain speed... it is one of those things, there are only certain places you can get away with it, you got to know when...



Its hard to believe, but I've actually change the fluid in this trans more than I have changed the oil in the engine...



steved

Steve. In the morning before you go. Put the T-case in Neutral, put the transmission in 1st. let the clutch out, rev to 1600, shift to 2nd, rev to 1600, repeat until you get to 6th. put the shifter in N, pause 10 seconds, put the T-case back in gear and drive off. You'll notice drastically how much less grumpy the transmission is.



In the AM when it's rather cold I just leave it in 4th while on high-idle to put not only a little more load on the motor but to spin the transmission to get the fluid moving.

 

[steved]

Steve. In the morning before you go. Put the T-case in Neutral, put the transmission in 1st. let the clutch out, rev to 1600, shift to 2nd, rev to 1600, repeat until you get to 6th. put the shifter in N, pause 10 seconds, put the T-case back in gear and drive off. You'll notice drastically how much less grumpy the transmission is.



In the AM when it's rather cold I just leave it in 4th while on high-idle to put not only a little more load on the motor but to spin the transmission to get the fluid moving.

I've read your other posts about doing this, but unfortunately where I live, the neighbors might get grumpy...



I'll try this tonight, when I get ready to leave work.



steved

 

[JasonCzerak]

I've read your other posts about doing this, but unfortunately where I live, the neighbors might get grumpy...



I'll try this tonight, when I get ready to leave work.



steved

screw the neighbors..... I'm sure plenty have already done stuff to annoy you.



Tho, how my truck is parked, the tail pipe does not directly point at anything other then my front yard and then over about 100 feet across the street and to nothing. If you had to parked between houses, I can see this.



At least, at least run it thought he gears just off idle.

 

[steved]

screw the neighbors..... I'm sure plenty have already done stuff to annoy you.

Now that's no way to be... but I like your line of thinking! I could probably get away with it... besides, I'm hoping to move in under a year!



I'll try it tomorrow AM... it was pretty good this AM, considering the fact it was 0*F outside. (Maybe I was more worried about the fuel so I didn't notice it as much?)



steved