G56 not shifting when Hot

[Randomrunner12]

So for those of you that have seen all my not so glorious postings on the G56, I wanted to present you with another update on to what I am experiencing with my truck.

A few weeks ago I was checking fluid levels, Found that the fluid in my valair hydro reserve was almost black. Bought a suction tube and removed as much fluid as I could, Cleaned reservoir and replaced the fluid with Dot 4 synthetic brake fluid as you can mix DOT 3,4 and 5.1 together but cannot mix DOT5 and since I couldn't readily get 5.1 I just used the DOT4 from Walmart.

My issue with my G56 I am referring to is that when I have been driving the truck for a length of time everything gets hot and it then gets hard, almost impossible to shift into 2nd at a stop without feeling like the shifter is going to snap. Highway driving, holding power and shifting when moving not an issue. I have spoken with Valair and they have deducted it could be 1 of 3 things.

#1.. Bad or blown seal in Hydro causing shifting issues. (most likely the issue)
#2... warped clutch disk from transmission overheating at some point? not Sure how and when.
#3... recommend ordering the new clutch kit for my new power levels and to avoid a lot of R&R to change out different parts at a time.

Any Ideas from anyone out there?

 

[RVTRKN]

Your going to need new hydraulics any way when you change the clutch. Why not just replace the hydraulics first and see if it solves your problem. The black color may well be the rubber seal to the piston that has worn out, being cooler in temperature, it is less pliable and helps seal with a worn cold seal.

 

[Randomrunner12]

Rvtrkn,

I believe that is where I am going to start. I next day air ordered new hydros from valair since they haven't done me wrong and I have really good prior experience with them. I will hopefully have it installed Friday afternoon and I'll be able to tell right away if I need more.

 

[RT395]

“My issue with my G56 I am referring to is that when I have been driving the truck for a length of time everything gets hot and it then gets hard, almost impossible to shift into 2nd at a stop without feeling like the shifter is going to snap. Highway driving, holding power and shifting when moving not an issue.”

Having these same EXACT symtoms. Stock truck, 45k, Driving like an old guy all of the time. Towing a 8k bumper trailer some of the time.

Never seems to slip but the pedal gets softer and it becomes difficult to shift. Check for visual clues of leaks and found nothing. Fluid level is good...

Seems like it’s too early for the clutch to wear out...

 

[RVTRKN]

Are you running the ATF4+ or did you go with a better Trans fluid? The brass synchro's are suspect with the G56 and ATF4+ (too thin of oil in my opinion).

For the reasons quoted and your statement on getting hot is why I installed a true transmission cooler, which allows me to run a heavier weight oil (Mobil 1 Synthectic 50wt trans fluid) and keep it within 180*.

 

[Randomrunner12]

I am using the Mobil 1 Synthectic 50wt trans fluid you and I texted about long ago and it ended up being that 1 of the disc's developed a hair line crack in it that when hot would expand and warp the disc. I ended going to a dual disc ceramic setup since i don't tow very often or heavy anymore and the wife loves the truck so she wont let me sell it lol.

all has been good except for my odd clicking and popping that can be heard from the pedal master cylinder assembly inside the cab truck running or not. Ive greased everything that I can and still does it so im learning to coup with it. I even changed the hdyros out and after about a week of adjusting to find the right spot it started all over again. truck shifts and drives just fine hot or cold so its not in the trans or the clutch just something in the truck.

 

[RT395]

I'm running stock fluid and cooling. Since posting here I've realized that in my case it has something to do with elevation which is really weird. Only happens at higher elevations (hot or cool)

 

[Kettelhut]

So for those of you that have seen all my not so glorious postings on the G56, I wanted to present you with another update on to what I am experiencing with my truck.

A few weeks ago I was checking fluid levels, Found that the fluid in my valair hydro reserve was almost black. Bought a suction tube and removed as much fluid as I could, Cleaned reservoir and replaced the fluid with Dot 4 synthetic brake fluid as you can mix DOT 3,4 and 5.1 together but cannot mix DOT5 and since I couldn't readily get 5.1 I just used the DOT4 from Walmart.

My issue with my G56 I am referring to is that when I have been driving the truck for a length of time everything gets hot and it then gets hard, almost impossible to shift into 2nd at a stop without feeling like the shifter is going to snap. Highway driving, holding power and shifting when moving not an issue. I have spoken with Valair and they have deducted it could be 1 of 3 things.

#1.. Bad or blown seal in Hydro causing shifting issues. (most likely the issue)
#2... warped clutch disk from transmission overheating at some point? not Sure how and when.
#3... recommend ordering the new clutch kit for my new power levels and to avoid a lot of R&R to change out different parts at a time.

Any Ideas from anyone out there?

I highly recommend you contact Mike at http://www.lazarsmith.com/Transmission.html
I’m at his facility now with my G56. Nobody knows this transmission better than he does. Nobody! I was referred to him by Southbend Clutch. He will solve all your G56 problems.

 

[Randomrunner12]

KettelHut,

Way ahead of you sir. I am already saving up for when this trans starts to give me more issues I will drive it out to him and have him do his thing to it. I want it to hold 700-800hp even though i will never reach those numbers.

My first issue was the clutch disk warped on me. the second was the shop that installed the new clutch didnt locktite the pivot ball or torque it so over a couple years it backed itself out and eventually pulled the threads and fell into the bottom of the clutch housing. retapped and installed new ball with locktite torque to spec and good to go.

Next thing I need is a better clutch. Saving up for that as I have plenty of life left in this unit and still grabs perfectly.

 

[NIsaacs]

He may be a good transmission builder but I would do my homework on some of the Gorilla Juice oils offered before you use it.

 

[Randomrunner12]

I ran his g juice and wasn't happy with it at all. I pulled it out after 3000 miles and went back to the mobile delvac 50 from Grainger.

Not bashing his stuff or work but just wasn't for me. Seemed to cause notchier shifts and way stiffer shifting.

As far as his trans goes I've seen his work in other trucks and they hold up. Anything will break overtime no matter who or what it is.

 

[RVTRKN]

A lot of complaints of smell, but it’s too heavy of an oil, most comments were the about the heavy golden color, that’s from your synchronizer’s. I called him just after my SMF conversion, I didn’t like what he had to say about the oil. Been using Mobil Delvac 50 trans fluid, that I’ve got 30K+ miles on, that I’ll changing it soon.

 

[Randomrunner12]

Same here. I only had it in for 3000 miles and got rid of it. Went back to the MD 50 and havent looked back. Have about 25k on mine just ready to change it again at 180K. I feel like there might be a better fluid out there but I haven't read around to much on it because I like the MD50

 

[Regcabguy]

I highly recommend you contact Mike at http://www.lazarsmith.com/Transmission.html
I’m at his facility now with my G56. Nobody knows this transmission better than he does. Nobody! I was referred to him by Southbend Clutch. He will solve all your G56 problems.

I filled my G-56 with his trans fluid. I had to struggle to shift it. Drained the fluid and it was filled

He may be a good transmission builder but I would do my homework on some of the Gorilla Juice oils offered before you use it.

45 miles the truck and I lasted with GJ. Drained it through a black t-shirt and it was loaded with brass particles.
I now use Amsoil MTG. Shifts great.