G50 Clutch Issues

pjd131 · 05-07-2015, 06:06 AM

Hi Guys, Need some suggestions. I have an 89 911. I have the G50 clutch fork update. I replaced the rubber centered clutch over the winter as well as the clutch slave and clutch master (just did the master). I have bleeded the hydraulic system many times. I have a very soft clutch pedal and the slave will not move the clutch fork more than 1/2 inch. I fired the car up today and cannot get into gear. So, before I drop the engine and trans again to make sure I assembled everything correctly , does anyone have any suggestions or other diagnostics before I take that major step. I was thinking about removing the slave cylinder and building a mount to make sure it is working properly. Any suggestions (anything) would be appreciated. I'm going for a drink now... Thanks

Quicksilver · 05-07-2015, 09:37 AM

I assume you have looked to see that the fork is moving correctly and doesn't have an issue like one of the forks bent or cracked...

I've had a couple instances where the system didn't want to bleed correctly. A pressure bleeder is your friend as the speed of flow is important. A couple things can help.
- First is to pre-bleed the cylinder. Fill the cylinder with brake fluid and make sure it has no bubbles before you connect it.
- Second is to bleed it while it isn't connected to the trans. Instead let it hang down with the bleeder at the top. Then you can't lose a bubble in it. Mounting it back is a test of patience but if you know it is bled it makes up for the effort.

BTW - Did the master get disconnected at any point in your rebuild?

john walker's workshop · 05-07-2015, 10:03 AM

You need to pressure bleed it. Leave it attached, hang a real short 7mm box end wrench on it and attach a hose to the nipple into a grain pan.

aston@ultrasw.c · aston@ultrasw.c's Garage

Check the pedal assy.

You might find the clutch pedal turning on the cross shaft.

A common failure is the spirol pin that connects the two.

pjd131 · 05-07-2015, 12:42 PM

Thanks will try removing slave. I have the Motive bleeder. Have also looked at pedal cluster.

pjd131 · 05-08-2015, 03:04 PM

Hey. Took clutch slave cylinder off and wanted some thoughts on this. See the pic. Looks to me that the bore for the hydraulic line may not be all the way through to the cylinder. Does this look right. Could this explain the lack of pressure. Anyone have a g50 slave cylinder they could take a pic of and post. Thanks guys.

shrtshck · 05-08-2015, 03:28 PM

Pictures of the slave cylinder removed a few years back.

Looking down the bleeder

And another down the hydraulic line port

Had no issues bleeding the system after replacement using a vacuum style bleeder

RedCoupe · 05-08-2015, 04:52 PM

How's the condition of the flexible rubber hose? I've had them get soft with age so they swell when you push on the clutch pedal and take energy away from disengaging the clutch. Also they can swell internally causing lack of proper brake fluid flow.

pjd131 · 05-08-2015, 05:47 PM

Hey Shrtshck, can you email me that pic of the hydraulic line port. I'd like to blow it up a bit and have a better look. Thanks for posting that.

And Redcoupe, that is a good suggestion. I will follow up with that it the slave gets a pass.

Thanks guys.

pjd131 · 05-08-2015, 06:07 PM

Here's a better pic - a closeup
Here's a closeup. Hopefully you can see my concern - that the bore is not all the way through. The dark is open intone cylinder. The medal is not.

shrtshck · 05-09-2015, 08:31 AM

Appears I can't attach a picture in a PM, here is another shot
Unfortunately my current camera doesn't have a good closeup mode.
Hope this helps

pjd131 · 05-09-2015, 10:44 AM

Hey Shrtshck, do you have a slave you can look at. Is the bore for the hydraulic line cut all the way through to the cylinder. You can see how mine is only cut 1/2 way. What does your look like.

shrtshck · 05-09-2015, 12:36 PM

The small bore is cut clean into the cylinder below. The under cut you show isn't normal but it may not effect the performance. As long as the opening has a larger area than the inside diameter of the fitting then it should not impede the flow of fluid.

When you had the new slave installed, did you confirm the rod was correctly seated in the small divot on the fork?

RedCoupe · 05-09-2015, 01:13 PM

Hey PJD, I'm thinking that your slave cylinder may be defective where the fitting enters the casting. I'm used to the machining looking like shrtshck's salve cylinder. I can't see how a fitting wouldn't leak when screwed into yours. You mentioned that you just replaced it, so I would show your picture to your parts vendor and have them compare it to one on the shelf.

pjd131 · 05-09-2015, 01:29 PM

Thanks guys. I have tried everything. I put the new clutch in myself and seating this new slave cylinder properly. I disconnected the slave yesterday and built a mount and a fulcrum for the slave. I blead the hydraulic system again and again and I still have very little hydraulic pressure. I have an email into FTE so I'll let you know what they say. Really puzzling me.

pjd131 · 05-18-2015, 04:33 PM

Hello everyone. I replaced the slave and the flexible hydraulic line and pressure bleeded and the new clutch and hydraulics are working very well now. Thanks for the ideas/suggestions. Paul