Engine/Transmission (1998.5 - 2002) NV5600 & Synchro's

[Silver_Ram]

My truck still shifts great. As the weather gets warmer it seems to help even more...

 

[Hohn]

Well, it's safe to say I will NOT be using the RP synchromax again.

When I first put it in, shifting was the best it's ever been.

Then it started degrading. By 2 weeks or so, it was down to "merely average".

2 Months after install, shifting was just BAD. Like VERY difficult to get into gear from a stop.

Not wanting to ditch some somewhat new fluid, I decided to try a stopgap measure.



I added a little bit (. 5pt or so) of Lucas Automatic Transmission additive. Yes, it's for auto trannies. But I wasn't getting enough synchro action, so I thought that this would 1) make the synchros have higher effectiveness, and 2) increase the overall viscosity of the fluid.


I'm very please with the improvement the LUCAS transmission stuff made. It's still stiffer than when I first put in the RP, but at least now it's liveable and the truck is fun to drive again.


I'm thinking I may try more Lucas next change, and add it to Torco or MTL or whatever I use next.

FYI: this is not related at all to the installation of the new Con FE clutch, as the shifting was terrible before, with the old clutch. The new clutch didn't change shifting for better or worse.

jh

 

[NVR FNSH]

Hohn,

When you installed the new clutch did you check the pilot bearing-input shaft clearances and slave cylinder stroke?



Brian

 

[Hohn]

Yes-- as I stated-- this shifting was the same before and after the clutch install.

When the clutch went in, I had a new Super HD pilot bearing from www.quad4x4.com put it (the TK75).

Slave cylinder holds pressure just fine-- no leaks internal or external.

I'm satisfied that the only contributing factor to shifting difficulties is lube-related in my case...

Heck, the stiff shifting started on the way down th FL from WY, when I had some high-mileage MTL in there. Thus the change to the Synchromax, which caused a huge improvement that soon disappeared only to go back to acting the same as the previous high-mileage MTL.

Confused yet?

 

[steved]

Y

I'm satisfied that the only contributing factor to shifting difficulties is lube-related in my case...



Heck, the stiff shifting started on the way down th FL from WY, when I had some high-mileage MTL in there. Thus the change to the Synchromax, which caused a huge improvement that soon disappeared only to go back to acting the same as the previous high-mileage MTL.



Confused yet?

After reading this, I'm doubting I'm going to switch from the Pennzoil syncromesh I have in my 5600 to the RP synchromax I have sitting there waiting to go in... at least the pennzoil is consistant... even with 25k plus on it...



steved

 

[Hohn]

Well, YMMV, but my experience with the RP was disappointing.

Lots of guys on TDR love the stuff

Maybe you should try it yourself and see if you like it.....

jh

 

[steved]

Well, YMMV, but my experience with the RP was disappointing.



Lots of guys on TDR love the stuff



Maybe you should try it yourself and see if you like it.....



jh

I might try it... I got to install a temperature sending unit into one of the PTO covers... might refill with the synchromax and see... I just hope it doesn't damage the syncro's.



steved

 

[nps]

8 months and 10,000 miles later the Redline MTL and Lube Gard are still holding up in my transmission. But it's never been in temps below freezing either. Wonder if that may make a difference in the stability - the heat cycle range the lube is subjected to?

 

[steved]

8 months and 10,000 miles later the Redline MTL and Lube Gard are still holding up in my transmission. But it's never been in temps below freezing either. Wonder if that may make a difference in the stability - the heat cycle range the lube is subjected to?

When it gets below 40*s here, I can tell a difference. At -10*, you're either double clutching or shifting without the clutch.



Mine shifts (and has always shifted the best) after about 500 miles of driving (must get the transmission pretty warm by then).



What Lube Guard did you use??





steved

 

[rivercat]

How do you like your FE hohn? Mine is still grabby I think I got the pressure plate bolts to like 50lbs instead of the 29#s(i think) they recomend. I have slipped it a coulple of times too, prolly need to go pull a sled to fully break it in right.

 

[nps]

What Lube Guard did you use??



steved

One 9oz bottle of Lube Gard Gear Fluid Supplement-NAPA carries it. Read about it here. Hohn initially tried it but said it didn't last. As I said, so far so good.

 

[Texas Diesel]

I believe Pennzoil Synchromesh is the factory fill IIRC. I agree, I changed mine at 50k and it only made a slight improvement for a short time... I used PZ synchromesh.



I got a case of Royal Purple Symchromax sitting waiting for me to get off my butt to change... anyone else running RP??





steved

Me, I've run Synchromax for 100,000 plus miles, actually ran it in two different 5600's. No problems, it's good stuff.

 

[steved]

One 9oz bottle of Lube Gard Gear Fluid Supplement-NAPA carries it. Read about it here. Hohn initially tried it but said it didn't last. As I said, so far so good.

I only knew they made the auto fluid additive... didn't know about the manual transmission stuff.



steved

 

[NVR FNSH]

Yes-- as I stated-- this shifting was the same before and after the clutch install.



When the clutch went in, I had a new Super HD pilot bearing from www.quad4x4.com put it (the TK75).



Slave cylinder holds pressure just fine-- no leaks internal or external.



I'm satisfied that the only contributing factor to shifting difficulties is lube-related in my case...



Heck, the stiff shifting started on the way down th FL from WY, when I had some high-mileage MTL in there. Thus the change to the Synchromax, which caused a huge improvement that soon disappeared only to go back to acting the same as the previous high-mileage MTL.



Confused yet?

Sorry, I sort of changed topics on you w/o any warning. I've always suspected a tight pilot bearing and/or marginal slave cylinder have been contributing factors to my poor shifting. I was just wondering if you had noticied any issues with those areas when you changed your clutch.



Brian

 

[Hohn]

How do you like your FE hohn? Mine is still grabby I think I got the pressure plate bolts to like 50lbs instead of the 29#s(i think) they recomend. I have slipped it a coulple of times too, prolly need to go pull a sled to fully break it in right.

The FE is a dream come true-- I love how direct it feels.

When combined with that mega pilot bearing, it makes the whole driveline feel a lot more solid.

It's just smooth enough to be a joy.

 

[Hohn]

UPDATE:

Shift quality continues to improve as the Lucas AT additive gets more distributed through the trans. The stuff is thicker than honey, so it probably take a while to get mixed into the lube.

It seems that the toughest shifts on my 5600 are always Neutral to First, Neutral to Reverse, and Fourth to Fifth. If THESE shifts improve (which they are) then all the rest of the trans fall right in line.

jh

 

[nps]

It seems that the toughest shifts on my 5600 are always Neutral to First, Neutral to Reverse, and Fourth to Fifth. If THESE shifts improve (which they are) then all the rest of the trans fall right in line.



jh

Hummm - 2 of your 3 poor shifts are usually executed from a stop thus don't even exercise your synchros. The other (4-5) is going into direct drive. Wonder if your mainshaft is hanging up somehow. When you go from N-1 or N-R do you spin the input with the clutch, or have you been holding the clutch disengaged at a light?

 

[Hohn]

I push the clutch in ONLY when I need to.

If I'm sitting at a light, I have it in neutral. I don't push the clutch in and put it in gear until the light changes or the car in front of me moves (whichever is later).

So the mainshaft should be spinning, right?


The other thing is that this new uber-pilot bearing has more rolling resistance. .


Again, it's worth repeating the shift quality is exactly the same before and after the clutch installation. That leads me to believe that everything was done right, or they somehow managed to perfectly reproduce the exact same mistake the OEM setup had.

It could be better, but shift quality if "good enough", and I don't mind it at all.

The fact that it keeps getting better is encouraging.

jh

 

[nps]

Actually the input shaft is spinning, along with the countershaft and all the gears on top of the mainshaft. The mainshaft itself is stationary, but the synchros are moving.



I'm thinking that there's something in your transmission/clutch setup causing the poor shifting that still hasn't been changed yet, even though you've already changed everything on the clutch side of the equation.



Guess I'm intrigued by the fact that you lost the MTL/LubeGard combo benefit early on, and I haven't (yet).

 

[steved]

I'm thinking that there's something in your transmission/clutch setup causing the poor shifting that still hasn't been changed yet, even though you've already changed everything on the clutch side of the equation.

Then it must be a NV5600 "thing" because mine has the same exact symptoms as Hohn's... "sticky" getting into 1st and reverse... I too sit in nuetral at a redlight (saves wear on the throwout bearing)... and it is usually hard to get into first.



Although I don't have the shifting issue between 4th and 5th... mine is simply "notchy" feeling... there is no quick shifting with this thing.



steved