Oddball clutch issue (I searched!)

Rickysa · 11:03 AM

New owner!

I pose this question after trying a search of this forum with no luck (I'm not very net savvy, but gave it my best shot

)

The clutch works very nicely, shifting is smooth...but...if I press the pedal all the way to the floor, I get a horrible grinding noise. The previous owner just lived with it, as it didn't affect driving the car. I thought I'd try the braintrust here, as the mechanic I bought the car through did not have a good guess, other than tearing into the assembly.

Many thanks,

Rick

oops...'88 targa, 108k, full repair history (no past clutch work)

chiroracer · 04-27-2011, 11:03 AM

probably the fork is hitting the spinning pressure plate.the floor plate at the pedal should adjust up just short of this. S

Grady Clay · 02:42 PM

Rick,
Welcome to the Pelican 911 Forum

You will find a lot of help here.

In fact, I see the correct answer within 3 minutes.

As Pelican chiroracer points out, you can adjust the stop on the floorboard.
Ease the clutch out in neutral just touching the edge of the (non-syncro) reverse. EDIT, G50 has syncro reverse. Don’t do this.
The light ‘grinding’ will tell you where (clutch position) the clutch starts to spin the disc.
Ideally, adjust the stop half-way between this point and the beginning of your noise.
Exact ½ is not critical.
What is critical is the clutch completely releases when you shift.

Again, WELCOME.
How about a picture of your 911?

Best,
Grady

gregwils · gregwils's Garage

Congrats and welcome Rick,. You will probably want to buy a Bentley manual and Wayne's 101 book is cheap and worth it.

I assume you know that starting in '87 the clutch was switched from cable to hydraulic. Also, a new transmission known by the code name G50 was added. Prior cars have a 915 style transmission.

I have a 915, so don't know as much as others about the G50. You can limit the travel in a 915 by a simple adjustment on the floor board. Lift the carpet around the clutch pedal and you will see two allens on the floor board above the pedal. It seems odd that the prior owner would have never addressed such a simple fix, so it may not exist on a G50. Hopefully, others will chime in.

There was a clutch fork update for the G50. Do you know if it was ever done to your car?

Rickysa · 04-27-2011, 11:38 AM

Hi folks, and thanks for the kind welcome!!

Not to mention the lightning quick excellent info! Wow, what a great place ya got here...

First thing I did before I even got the car home was to buy the Bentley, Wayne's 101, and his engine rebuild (also bought the Haynes just for giggles....lol), but I appreciate the recommendation. I just got a bunch of new cleaning stuff from Griots, so I want to get her all nice and shiny before I introduce her to you folks (sadly, her previous (only) owner had been fighting illness, and hadn't been able to keep her tidy...all is in great shape, just needs some TLC)

Grady, I'll give that a try as soon as I get home.

Thanks again folks!

Rick

Grady Clay · 04-27-2011, 11:51 AM

G50, G50….
Doesn’t a G50 have a synchronized reverse?
Am I thinking of a G64?

Best,
Grady

Quicksilver · 04-27-2011, 01:49 PM

Quote:

Originally Posted by Grady Clay

G50, G50….
Doesn’t a G50 have a synchronized reverse?
Am I thinking of a G64?

Best,
Grady

Yeah the G50 is synchronized in all gears.

One suggestion I would add on your adjustment procedure when applied to a hydraulic clutch is to adjust the clutch stop farther down because the hydraulics have a much higher chance of partial disengagement because of leakage, air bubbles, etc...
You might need the extra pedal throw someday to get the car home.

----
Also as a general comment regarding clutch use: Don't push a clutch WAY past the engagement point. There just isn't any need and there is a chance you can make something grind needlessly.

Quicksilver · 04-27-2011, 01:52 PM

(Man, it just makes me feel weird to suggest any modification to any suggestion Grady makes...)

"Just shake it off and keep moving."

gamin · 04-27-2011, 02:17 PM

Rick - PM sent.
Gary

Grady Clay · 04-27-2011, 02:37 PM

Quote:

Originally Posted by Quicksilver

(Man, it just makes me feel weird to suggest any modification to any suggestion Grady makes...)

"Just shake it off and keep moving."

Hopefully I’m permitted an occasional faux pas when I correct it.

This is the wonderful part of the Pelican Forum – it is ‘peer reviewed’ and can be corrected (with the EDIT function).
I think the Pelican 911 Technical Forum may be the ‘most likely to be correct’ public forum on the entire internet.

Best,
Grady

Wavey · 04-27-2011, 03:01 PM

Here's a pic of the clutch stop. The rubber pad contacts the clutch arm, limiting travel. The farther down it is adjusted, the less the clutch arm can travel and the less the clutch releases. Loosen the 2 allens to let it slide up/down.

My Carrera was doing the same thing and I had to bend the metal part a bit to get the stop low enough.

dentist90 · dentist90's Garage

The other possibility is a dry/rusting throw out bearing. The classic presentation is grinding when clutch is depressed and stops when released. The thing is it would make the noise whether the clutch is pushed in halfway or all the way, unlike your description.

So the G50 hydraulic clutch has the same rubber stops as the cable 915? Learn something every day!

Rickysa · 08:07 AM

Thanks again guys...

I checked the clutch stop, and it was at the maximum down position (tried to force it lower...no luck). It doesn't grind until I'm about 1/4-1/2 from the stop...

So off to research other ways to adjust the throw? (Or I could just wrap duct tape around the clutch lever to close the gap

)

Just kiddin'!

Rick

Wavey · 04-28-2011, 07:07 AM

That is exactly what my clutch was doing. It functions perfectly otherwise.

3 things you can do to limit the travel beyond what the sliding adjustment allows. I did all 3, and I still get the noise if I really push down on the clutch.

- Bend the metal tab that holds the rubber bumper downwards a bit.

- Add material to the clutch lever - you can see a piece of fuel hose zip-tied to my clutch lever in the photo.

- Space the entire floorboard up at the bottom by adding washers under the retaining stud at the bottom. Not a lot to be gained there but it's something.

You may also be able to adjust the pushrod between the clutch lever and the clutch master cylinder - not sure if that's adjustable or not. If it is, you'd want to shorten it a bit.

I'd really like to know what's going on within the clutch or the hydraulic system to cause this.

Rickysa · 04-28-2011, 07:22 AM

Quote:

I'd really like to know what's going on within the clutch or the hydraulic system to cause this

Yep, me too (obviously

), but I've not found anything specifically mentioned in the manuals...time to check again

Wavey · 04-28-2011, 08:04 AM

Mine started at a track event. No other problem with the clutch at all - it's fully engaging, smooth, no slipping or anything, just over-disengages. Our area independent guy was there (Reid Vann, totally knows these cars) and had no clue as to why it would do this. If there was a hydraulic problem you'd expect it to NOT fully DISENGAGE, or if it was a clutch wear problem you'd expect it to not fully engage, and slip. All I can think of is that maybe the disk is worn enough that it still grips fine, but the slave cylinder has extended out further than it ever has, and is binding on the return, so that it's base position is farther out. But the disengagement/engagement point at the lever is perfectly fine, hasn't changed. Very odd. Once you get the stop adjusted it's not really a problem though.