g56 hard shift question

[nukegm]

comrades! my 18 2500 today would not shift out of reverse with engine off and engine on ( idle ) in my driveway. yes - clutch to the floor. the only way i could get truck out of reverse was to begin reversing then shift out of reverse. i have 9 vehicles - most with manual transmissions, and have never had this problem in any other vehicle. seems to shift ok while driving. fluid in reservoir is full. temp was 26 f outside. keep in mind truck was at dealer 29 days for 3 hydraulic units for clutch. thanks in advance for replies. cheers!

 

[GCroyle]

Engine running, truck STATIONARY, push pedal down any issues selecting any gear other than REV? Clutch system has no feedback as to what gear you are selecting.

Engine running, clutch pedal to floor, count to two, select 1st, now slowly bring the clutch pedal up. How far off of the floor before the truck starts to move?

These hydro's and clutch do not have any noticeable free play. You push pedal master cyl push rod moves in about 1/8" to 3/16" and you are in pressure creation mode.

I don't know the whole story but 3 complete hydraulic systems? Really?

 

[nukegm]

Engine running, truck STATIONARY, push pedal down any issues selecting any gear other than REV? Clutch system has no feedback as to what gear you are selecting.

Engine running, clutch pedal to floor, count to two, select 1st, now slowly bring the clutch pedal up. How far off of the floor before the truck starts to move?

These hydro's and clutch do not have any noticeable free play. You push pedal master cyl push rod moves in about 1/8" to 3/16" and you are in pressure creation mode.

I don't know the whole story but 3 complete hydraulic systems? Really?

comrade - if i leave truck in any other gear but reverse after work, all seems normal. if i turn off truck while in reverse, i cannot get out of reverse next morning without difficulty...they also replaced the pressure plate, clutch, and flywheel when the truck had 6000 miles on it while it was at dealer for 29 days. i appreciate your input very much. thanks! cheers.

 

[MarkEagleUSA]

if i leave truck in any other gear but reverse after work, all seems normal. if i turn off truck while in reverse, i cannot get out of reverse next morning without difficulty...

Sounds like something binding in the transmission instead of a clutch issue... like an automatic stuck in park if on a slight incline.

 

[Flinty]

Considering what you've been through here's my theory: The input shaft is bent and it's destroying the pilot bearing -or- they never replaced the pilot bearing to begin with and screwed it up when they reassembled it -or- a variant of one of those possibilities involving the pilot bearing. As I'm sure you're aware; if the pilot bearing is bad the transmission won't quit spinning when you press the clutch allowing the user to smoothly change gears from a standstill. It won't come out of gear when the truck is turned off because there's weight against the gears locking them together. You can pop it out of gear in motion because the motion of the truck releases the preload i.e. - the slop in the gears releases the bite of the dogs in the transmission. I do this all the time when I'm backing my trucks up without pressing the clutch, I just feel for the transmission to unload and slip it out of gear at the correct moment. The forward gears work because the synchros are allowing you to get it in gear.

I have found reverse in my G56 to be very, very, tight, not at all like the NV4500's I have. Also with my truck, it will not come out of reverse in motion with the clutch pressed. If I stop, it will come out with the clutch pressed. It will also come out of reverse with the truck off and the clutch pressed and it is reluctant to come out of reverse with the truck off with out pressing the clutch but I can get it. And like I said, I can pop it out while in motion with out the clutch. Take that info for what it's worth, it's a mouthful.

I have a feeling your truck is destined for the dealer again. How many miles are on it? Is it difficult to put it in first or second gear from a stop or does it slip right in? If it takes a second and you have to push on the gear shift then I would definitely look at the pilot bearing.

 

[nukegm]

Considering what you've been through here's my theory: The input shaft is bent and it's destroying the pilot bearing -or- they never replaced the pilot bearing to begin with and screwed it up when they reassembled it -or- a variant of one of those possibilities involving the pilot bearing. As I'm sure you're aware; if the pilot bearing is bad the transmission won't quit spinning when you press the clutch allowing the user to smoothly change gears from a standstill. It won't come out of gear when the truck is turned off because there's weight against the gears locking them together. You can pop it out of gear in motion because the motion of the truck releases the preload i.e. - the slop in the gears releases the bite of the dogs in the transmission. I do this all the time when I'm backing my trucks up without pressing the clutch, I just feel for the transmission to unload and slip it out of gear at the correct moment. The forward gears work because the synchros are allowing you to get it in gear.

I have found reverse in my G56 to be very, very, tight, not at all like the NV4500's I have. Also with my truck, it will not come out of reverse in motion with the clutch pressed. If I stop, it will come out with the clutch pressed. It will also come out of reverse with the truck off and the clutch pressed and it is reluctant to come out of reverse with the truck off with out pressing the clutch but I can get it. And like I said, I can pop it out while in motion with out the clutch. Take that info for what it's worth, it's a mouthful.

I have a feeling your truck is destined for the dealer again. How many miles are on it? Is it difficult to put it in first or second gear from a stop or does it slip right in? If it takes a second and you have to push on the gear shift then I would definitely look at the pilot bearing.

comrade flinty - thank you for the info. very informative. 19,000 miles. it drives ok from a stop. sometimes, slight resistance engaging into first . seemed strange to me, with significant effort, i could not get the truck out of reverse in my driveway unless i started moving. and i pushed hard enough to lift me out of drivers seat a bit. im 6 foot and 200 lbs, so i was pushing pretty good. thanks again for your thoughts. cheers.