Clutch Pedal Sinking
 

For the second time in my 2014 ZL1, I have a clutch pedal that has sunk to the floor. Over the course of a couple days the pedal begins to get spongy at the top of the travel and gets progressively worse. It eventually does not return to the top position and the engagement point is right at the bottom of travel.

The last time this happened, the dealer replaced the clutch pedal and reservoir cap. That was the solution from GM for a pressure differential that develops in the system. That solution worked for 2000 km.

This is not the same high rpm shift clutch pedal sticking. This is normal daily driving when this develops.

Has anyone else had this issue? Any thoughts before I take it into the dealer and they throw another $700 pedal at it?

did the dealership also replace the throwout bearing? if not that's something i'd say have done next, along with a Monster Clutch sleeve for the bearing

No. Neither the master cylinder or the slave cylinder (throw out bearing) were replaced. The car only has 15000 km on it.

are you noticing any clutch/brake fluid leaks while the car is parked? this sounds like something is failing, like the throwout bearing. The car should have the full powertrain warranty still, is this something that Chevy is covering?

No fluid leaking anywhere. Powertrain warranty outside of the 3/36 bumper to bumper does not cover clutch or clutch hydraulics (but does cover the slave cylinder as it is bolted to trans.

The first clutch pedal was covered under good will warranty (it was 2 days outside of 3 years).

I would bleed slave cyl and see if that fixes it. it may be getting air in system
correction: not fix it but makes work again then you know its in the hydraulic system of clutch slave is most likely culprit

They will stay down to the floor if you have been slipping the clutch as you over heat the fluid in the slave cylinder and loose the pressure. Its a shared master cylinder with the brakes so take a look in MC and see if you see brown slag floating on top. If its from an over heat you can pump the pedal around 25 - 40 pumps and that might change the pressure.

If the dealer never blead the clutch pedal after you reported soft pedal they are num chucks. It's not easy to do with out a Speed bleeder which should be installed if you take the trans out..

Turkey baster, MOTUL RBF 600, suck out as much old fluid as you can from the reservoir and replace with new fluid. Pump clutch 25-30 times. Repeat this process for about 8 times.

You should also perform a brake bleed as well.

Should solve your issue.

I had the same problem on my Z/28 and tried everything others are suggesting.
I pulled off the master cylinder and it had been leaking out the back seal.
I never had fluid drops on the garage floor!
The booster and the area below and behind the booster were heavily corroded.
I replaced the master cylinder, the booster (what a pain the booster is to remove) and stripped/repainted the corroded areas.
There have been some other members who have had the same problem.
Good luck!

Did you install a separate clutch reservoir ?

Clutch is not slipped. Fluid is clean and clear.

Dealer replaced the pedal assembly, which actually comes with the clutch master cylinder. Assembly replaced and system bled, pedal is great again.

Was it the brake master or the clutch master that was leaking?

I don’t understand, what do you mean the pedal is great again.

It has proper resistance throughout the pedal stroke instead of nothing until the last inch off the floor.

It also returns normally. Before the repair, it would stay an inch off the floor when released and would need to be pulled back up.