Archived Hard gear shifting G56

[SquareDave]

It's the tip at the end of the rod on slave cylinder. They removed it to slide the rod through the wall and didn't make sure the tip was securely put back.

What seems weird is that the truck could be driven 10 or 15 miles without any shifting issue. All bets were off after everything warmed up. Pushing the pedal hard to the floor barely disengaged the clutch all because the rubber (plastic?) tip was not in place.

 

[GCroyle]

It's the tip at the end of the rod on slave cylinder.

SquareDave,

That is the part that I expected.

On the end of the slave cyl pushrod is a piece pf plastic that serves as a bearing surface to minimize wear on the pushrod tip and release fork. It also has retaining straps that hold the push rod in slightly for shipping and as an installation aid.

Dave, I will allow you to remove the plastic cap from my truck and it WILL NOT change the release or engagement points of my truck. It will accelerate the wear of the now metal to metal contact surfaces, that's all.

The distance that the slave cylinder push rod travels is determined by the area of the master cyl piston bore and the actual effective stroke as the pedal is pushed this creates displaced fluid looking for somewhere to go. It goes into the slave cyl. The distance the slave cyl piston travels is now determined by the fluid displaced by the master and the area of the slave cyl piston.

Any small change to the pushrod length (cap on / cap off) will not change the distance that the slave cylinder or release bearing travels. Period. A large change in length can cause the piston to bottom out and not allow for full system operating range or even push the cylinder out enough to cause fork to cover contact. But I've never experimented with these lengths to see what the damage would be. The piston area, stroke length, fork and bearing travel were well engineered to create a release system that gives the clutch and truck its correct operational functions.

I believe that the cap off / cap on and relationship to a correctly (?) functioning clutch release system is purely coincidental. The real culprit by my armchair diagnosis was an air bubble finally accidentally escaped and you now have a full release stoke or at least enough that you can shift better.

I feel that if the slave cylinder test with the steering wheel puller was executed and correctly administered and measured this might have been long over.

I'm currently at my office working at a clutch company. I seem to have in the last 10 years or so accidentally become our clutch hydraulic system bleeding specialist. I get to take these systems apart, work with them make cutaways and post YouTube videos about how to bleed these and many many other types of clutch release systems.

Thanks for the follow up rest of the story moment.

Gary

 

[SquareDave]

GCroyle

Thanks for the feedback. The implications are that I may or may not yet be out of the woods on this. Currently, it's like moving the gearshift through butter. At this point I'm just going to drive the truck until something rears its ugly head, which is always the case anyway. Perhaps, it's the 210000-mile-itus as much as anything else.

 

[GCroyle]

SquareDave,

My comments are solely based on what you were told. And one reason for the approach is how mis-understood, incorrectly diagnosed, incompletely bled and in general lack of a little bit of understanding about these simple but potentially troublesome clutch hydraulic release systems.

Let me cite one example from actual clutch tech calls.

Caller says he replaced the slave cylinder because the clutch was not releasing.

OK, question, did you pull the dust boot off and was there any fluid in the dust boot or on the exposed piston or pushrod?

Nope, dry as a bone.

Then why did you replace a non leaking part who's simplest job is to NOT LEAK? IF it ain't leaking, I don't think you've found the root cause.

Yeah, but it was the easiest part to R&R.

Gary

 

[NIsaacs]

It's the tip at the end of the rod on slave cylinder. They removed it to slide the rod through the wall

I wonder what "wall" they are talking about, it almost sounds like they were working on the master cylinder? It would also be interesting to know if both hydraulic systems that were changed were both sealed units, or separate units, or even one or the other.

Whatever happened, at least it is now working smooth.

Nick