G50 clutch - how much play in pedal is normal?

[ejp]

My clutch pedal felt kind of spongy and would engage closer to the floor during hard braking w/multiple heel-and-toes. I figured that it was time for a bleed.

The bleed job was super fun, and I have the scratches and scrapes on the underside of my right forearm to prove it.

Initially after the bleed, the pedal felt firm. Maybe it's my faulty foot dyno, but halfway into my shakedown drive, the play in the pedal returned to what it was previously. It takes a few inches (almost 1/4 of the travel) before I can feel any resistance on the clutch pedal. The play does not change under hard braking, like it used to.

Before I start wondering if I have any bad hydraulics or should have flushed more fluid through the system, maybe the fine folks at Pelican can help me out. Is this normal? How much play do you have in your hydraulic clutches before you feel resistance on the pedal?

Thanks!

[Steve@Rennsport]

Ethan,

Without more information, its difficult to offer anything constructive,......One needs all the details for the "big picture" here,...

1) How many miles on the car?

2) How much fluid did you run though the system?

3) Original slave and master cylinder?

4) Has the release lever update inside the bellhousing ever been done (needle bearings to bushings)?


Hydraulic clutches generally run with zero freeplay at the pedal so a few inches is not normal.

[ejp]

Originally Posted by Steve@Rennsport

Ethan,

Without more information, its difficult to offer anything constructive,......One needs all the details for the "big picture" here,...

1) How many miles on the car?

2) How much fluid did you run though the system?

3) Original slave and master cylinder?

4) Has the release lever update inside the bellhousing ever been done (needle bearings to bushings)?


Hydraulic clutches generally run with zero freeplay at the pedal so a few inches is not normal.

Thanks, Steve, for the followup. Sorry for my lack of context/detail. I'll try to provide answers below in the same order that you posted:

1. The car has 168k miles and is an '88.
2. When I did the brakes, I accidentally ran the reservoir dry and the clutch took on air. There was clearly air in the system - the pedal was just barely engaging, and sank to an inch off of the floor. I ran an entire bottle of fluid through it (~16.9 oz/500ml). The pedal felt fine at first, but developed the problems I described today over a few weeks. I just ran approximately 4-8 oz of fluid through it today...just under half a bottle.
3. As far as I can tell from the service records, there is no indication that the master or slave cylinders have ever been replaced...and I have not replaced either since purchasing the car in the summer.
4. From the service records, there is not much to indicate that the needle bearings were done. The clutch was replaced with a spring centered unit at 69k miles, only the pilot and release bearings (and a machined flywheel) were indicated in the records. After doing some "needle bearing" searches, there is a cross shaft update kit, which may or may not be relevant (please excuse my ignorance on this - I'm still new to the 911 game). There is an item on the service records for "crosshaft kit" (sic) when the clutch was replaced.

If there is any additional information that I can provide, let me know. The fact that there should be no free play in the pedal indicates that something isn't right. Now, the question is where I should look? After the hurricane blows through, I can try bleeding additional fluid through the system...if it will help.

Thanks again,

[Steve@Rennsport]

Hokay,...thats MUCH better,...

One more thing,...did you bleed the system using a pressure bleeder or pump the pedal??

If you pumped the pedal to bleed, you likely finished off the slave cylinder and perhaps the master, too. These things, like brake MC's, do NOT like to be bottomed out as that drags the piston seals over a corroded/rusted area of the bores, ruining the seals in short order. These systems really should only be serviced using a pressure bleeder for that reason.

Indeed, I was referring to the cross-shaft upgrade kit which needs to be installed when the clutch is done. If the records indication this was done (along with part numbers), thats a good thing for you.

For now, I'd replace the slave & master (if they are the original ones) and re-bleed the system using a Motive bleeder (not expensive at all). Unless there are other resident issues, I think you'll find the clutch to be back to normal.

[shrtshck]

Your description matches what I had with my 87, immediately after bleeding it felt much better only have the symptoms come back after a couple of days.
A new slave fixed the problem, will be a PIA to put in as access is very awkward but you already know from the bleed. I use a vacuum bleeder, not as convenient as a pressure bleeder but it gets the job done.

[ejp]

Originally Posted by Steve@Rennsport

Hokay,...thats MUCH better,...

One more thing,...did you bleed the system using a pressure bleeder or pump the pedal??

If you pumped the pedal to bleed, you likely finished off the slave cylinder and perhaps the master, too. These things, like brake MC's, do NOT like to be bottomed out as that drags the piston seals over a corroded/rusted area of the bores, ruining the seals in short order. These systems really should only be serviced using a pressure bleeder for that reason.

Indeed, I was referring to the cross-shaft upgrade kit which needs to be installed when the clutch is done. If the records indication this was done (along with part numbers), thats a good thing for you.

For now, I'd replace the slave & master (if they are the original ones) and re-bleed the system using a Motive bleeder (not expensive at all). Unless there are other resident issues, I think you'll find the clutch to be back to normal.

When I bled the system dry, I had a friend pump the brakes (I hadn't figured out that I needed clamp off the overflow line on the reservoir for my powerbleeder to hold pressure). Afterward, when I bled the clutch, I used a Motive Powerbleeder.

Now the question is how to determine whether or not to R&R the master cylinder or slave? Just pull both?

Any tips for doing the slave while the tranny is still in the car?

Thanks again!

[Steve@Rennsport]

Originally Posted by ejp

When I bled the system dry, I had a friend pump the brakes (I hadn't figured out that I needed clamp off the overflow line on the reservoir for my powerbleeder to hold pressure). Afterward, when I bled the clutch, I used a Motive Powerbleeder.

Now the question is how to determine whether or not to R&R the master cylinder or slave? Just pull both?

Any tips for doing the slave while the tranny is still in the car?

Thanks again!

Whoops,...that's what likely did it in, considering its age. I would be replacing both, given your mileage as I hate doing the same tasks twice.

No tricks; its really tight in there, especially for those with oversized hands,...

Patience is rewarded.

[ejp]

Originally Posted by Steve@Rennsport

Whoops,...that's what likely did it in, considering its age. I would be replacing both, given your mileage as I hate doing the same tasks twice.

No tricks; its really tight in there, especially for those with oversized hands,...

Patience is rewarded.

Thanks, Steve.

I'll order the parts and post pictures of the job. It does kind of suck to even get at the slave cyl to bleed without a lift. Debating the merits of Rhino Ramps vs. using jack stands.

[dominicxu1]

Check that you dont have excess movement or wear at the clutch pedal assembly of the pedal box. Remove the floor board and using a torch, push down on the clutch pedal by hand and check for any wear and freeplay.
Regards...Dominic

[Quicksilver]

Originally Posted by ejp

Thanks, Steve.

I'll order the parts and post pictures of the job. It does kind of suck to even get at the slave cyl to bleed without a lift. Debating the merits of Rhino Ramps vs. using jack stands.

Jackstands all the way. Take off the left rear tire and it improves visibility and access greatly.

I've got a hate/hate relationship with the clutch release on the G50 cars. Hydraulics are a very straight forward and reliable setup. I've sheared multiple pins in the pedal assembly, had a spiral fracture of the clutch pedal shaft, wore out a set of the "upgrade" needle bearings, and when I initially got the car: Someone had put in the release fork shaft in backwards so you couldn't pull it!.

Why couldn't they put in a nice boring push release clutch with a nice boring pivot?


Next time I open it I'm going to see if they make a bushing setup to fit a case that has been bored out for the "upgrade" bearing setup.