Amish hauler

I drive about 70,000+ miles a year. No towing period. On the highway on the back-roads and sometimes through the woods. I bought my truck to work and thats just what I do to it. Sometimes I spend 12-14 hrs. in it. It has just become natural for me to slip shift the six-speed through the gears (no-clutch) both up and down. Never no problems. At about
200,000 miles I had the clutch replaced. It wasn't slipping but I felt it was due..I also plow snow with this truck and didn't wan't any cold weather strandings. Now at 205,000 miles I started to notice a slight gear clash only between 5th-6th. It quickly (within a day or two) turned from happening Intermintently to every single shift. I can keep it from happening if I shift real slow. I figured that mabey the wrong fluid was used to top off the tranny so I drained it and replaced it with "SYNCROMESH" It still dose it. It's only 5th-6th and will always clash unless I use the clutch and slide her in real slow. All the other gears will still slide in just like normal. Could my clutch be out of adjustment? Or did I junk this thing slip shifting?

Monty

Sounds as though your 5-6 synchro is taking a turn for the worse. When you drained the oil, did you notice any brass or metal shavings?

The clutch in our trucks cannot be adjusted since they are hydraulic.

Amish hauler

I didn't notice any shavings although the oil did seem very dirty. I have had the fluid changed twice before along with all the other fluids by the dealer. I try to have this done annually. Do you think this was a result of the slip shifting. Is it possible to have this 5th-6th gear syncro changed easily? Any idea how much it should cost? Any idea on how much a rebuilt exchange may cost or where to get one. And last but not least what if I try to keep babying it along?? Will I just do further damage? Sorry for the thousands of Questions but I figure this is going to be thousands of dollars from my initial ignorance.
Again Thank you.

aaronisbad

When they installed your new clutch did they also put a new throw out bearing in? Floating gears is pretty rough on those bearings. I could almost swear when my clutch died at 150K they didnt bother to replace the throw out. Seems like its harder to shift now than it ever was before, very sticky. Wanna trade that 6-speed for my wimpy 5? Anybody ever had the gears undercut in these trannys?

Aaron

aaronisbad

OOOps that was supposed to be S H I F T

edited

dodgediesel4x4

Well "shift" happens.

aaronisbad

Man that sounded bad after I re-read it LMAOOOO!!!! very sticky

army_guy

I have a six speed and its OK. In town with alot of traffic its a real pain but put a trailer on behind it and you forget all about it and the love affair starts.

roadranger

BAD idea slip shifting a syncro equipped truck tranny. Puts a LOT of wear on the synros, as you found out. These 6 spd trannys have HUGE gearsets that the syncros have a hard enough time slowing down with the clutch in, nevermind with the drivetrain still engaged.

Now you've got to slip shift 5-6 for REAL, like in a big rig--get the engine speed matched EXACTLY with the road speed to get into gear without clashing, each and every shift.

OR, get the tranny rebuilt....

bigern24

I'm with everyone else, sounds like a toasted synchro. It's a big job to drop this tranny, and it probably won't be cheap. I would have it rebuilt, because odds are after a few more miles something else with go wrong. I'd just ride it out until it's reall hammered then rebuild it.

You could have a pilot bearing problem, but if that was so I think you'd see in other areas besides the 5-6th shift. Generally they get very hard to get into gear when stopped, the bearing drags and spins the input shaft, couple that with a bad synchro and makes it stubborn to get into gear.

I recommend against shifting without the clutch, in a non synchro transmission its ok, but with the huge gearsets in the NV5600 this can be devastating to the already loaded up synchro gears.

Mexstan

I agree with the above that you have cooked yuor own syncros. Once the tranni is dismantled be prepared to find other problems.

RCW

Do not panic. The syncros are inexpensive, and if you are halfway mechanical you can change them yourself. Just go to www.sixstates.com and chat with the transmission guy about the parts, and if you have not worked on this unit, pick up the book too.

By the way, I never use the clutch and run 250,000 miles without any trouble. This syncro issue is inherent in both the NV4500HD and NV5600 transmissions. They use kevlar syncro brakes, and when they get worn at all, they simply will no longer hold the gear from spinning. The same thing can happen from running moly in the transmission.

Rattletrap1

I believe I saw 5600's on Ebay for < $2K

thumper 549

mY VOTE IS IF YOU SHIFT like a semi trans. its ezer on it cause you are waiting for things to line up (the dogs) so you are doing what the syns. are soposed to be doing.BUT if you are forceing it thats very differant story.............my whole life I have been pretty much clutchles except stop lights and stuff.