im sure im not the only one that has this problem. my 6 speed dosnt shift like it should. ive got it overfilled with the dealership "special" oil and lucas syn, and posi rear end additive. It helped a little, but i grind going into all gears. mostly 3rd and 6th. draining my oil and changing it is not going to help anything. its worse than that. ive rebuilt it once, but i didnt have the 40 ton press to take the bottom shaft apart. so i couldnt get to the 3rd and 6th gear syncros.

so basically im wanting to know if anybody knows a good trans rebuilder. Or should i buy an already rebuilt one, or should i go with a whole different trans. Need a stick, but cant run a nv-4500. Any opinions?

 

You have the '02 DEE version, which already has the 3-4 shifting fixes - what all was involved in the 'rebuild'?

1-2 are on the output shaft, 3-4 are the countershaft, and 5-6 are on the input and output shaft.

Sounds more like the oil is too thick, and DD clutch is not releasing quickly.

 

it wasnt a professional rebuild, just me and a buddy worked on it for a coupla nights. we replaced all but 2 stop clutches. all new seals and bearings.

what would the dd not releasing quickly have anything to do with grinding gears? i aint tryin to speed shift it, but it shifts better when i dont use the clutch anymore. (i WAS using the clutch to shift before, during, and after the syncros broke) oil isnt to thick, because it was worse with just the nv-5600 fluid.

reason for rebuild was that i broke 2 "teeth" off of the reverse stop clutch. then that got caught up in the gears and locked my tires up. Twice.

 

You must remember - that DD clutch is not meant for releasing, it is meant for tremendous hookup when pulling sleds and stuff.

It is meant to transmit much more continuous torque than is required for, say, drag-racing.

It cannot be used for speed-shifting, as in drag racing, unless your trans is setup for clutchless or semi-clutchless shifting.

And, the NV5600 is not meant for clutchless or speed-shifting.

Basically, imo, you seem to have mismatched application - you've clutched for pulling, yet you want quick shifting capability.

Far as the NV5600, the friction cones and the gears were modified between the DEA and the DEE versions to facilitate smoother shifting, a common complaint on those trans made before 2001.

The gears recd non-stepped, flat friction cone surfaces and closed clutch-dog holes, and the friction cones lost the stepped mating surfaces and recd six 1/8"dia holes each to increase lubrication, all meant to improve release when shifting.

And, I'm fairly certain that limited-slip additive isn't helping - it's meant for clutch-type units to reduce friction when going around curves and corners.

While you want to enhance the syncro release function, you don't want to decrease the syncro engage function - one way or the other, you're likely to get the grinding, particularly when attempting to shift quickly with that dual-disk clutch.

Not a fault of the clutch, just mis-application.

Imo, of course.

 

i clearly said that i WASN'T speed-shifting. go re-read the post.

the additive isnt hurting anything, and if its not being helpful, it was worth a shot

i dont know where you got the idea that i was trying to drag race my 4 ton flatbed dually truck, thats not why i bought it. Its a work truck. and i use it to pull trailers and haul loads. i just dont like the grinding when im trying to drive it.

anybody else have a shifting problem?

 

Sorry - didn't intend that impression - was just covering all the bases.

If the clutch doesn't release as quickly as you try to shift, even if you shift slowly, or doesn't release completely, the gears will clash, moreso if the trans also has issues.

The NV5600 has been noted as having that type shifting problems, particularly 3-4, particularly before warmup, with the oem clutch.

You might try double-clutching each shift, or try it with something other than that super hd clutch, or look into the '06 6-speed, which is not a New Venture Gear product.

 

its the g56. has anybody stuck one of these in a 2nd gen? will it bolt up to my transfer case? can my dd clutch be used?

 

I have a NV5600 in my truck and I still have the stock clutch, mine is difficult to shift sometimes but I contributed it to the clutch not releasing all the way, as my master and slave leaks a little and I have to add oil to it every once in a while, I noticed that after I add oil, and the master/slave is working properly it shifts real nice, but if I let it get low on oil, it will shift, but it shifts HARD, like, you pull it in gear and you feel the syncro and then if you don't jerk it in fast it will grind after it slips past the syncronizer, IMO you really need to check your clutch master/slave, especially if you have a dual clutch, those things push harder and that would put extra strain on your master/slave, I don't know if there are any aftermarket HD master/slaves out there but if I was you I'd check around, cuz I'm bettin' thats your problem.

 

i had a 99 dually with the 6spd and it grinded into 6th all the time,i learned to get it to the rite rpm and not use the clutch,maybe i shouldnt have sold it,i thought the tranny was going.