456 manual clutch adjustment or clutch replacement?

Hi V12ers,

I have a 2001 456M GT manual. 16K miles.

Last few days while driving the manual shifter progressively became much more difficult to move through gears with clutch depressed; well past normal warm up time.

* Noted that the clutch depresses almost 1/2 the travel distance before I can feel the clutch beginning to engage.

* When at a stop (and while engine running) and shifter is in neutral, shifting to any gear is very difficult with clutch depressed

* 456 was driving last couple of weeks fine. Then just suddenly last two days this situation occurred.

* All fluids changed last November.

* No leaks on garage floor.

* Did not notice any clutch slippage prior to this situation.


Any clues to what might be going on?

Thanks.

-stu

 

Sounds like you have air in the clutch line. Get a trusted tech to rebleed the system and check for leaks while he's at it.

The rubber hose that feeds fluid to the clutch master cylinder from the reservoir, and the plastic nipple on top of the clutch master can get brittle with heat & time and crack.

Also check the clutch master for leaks. It has a rubber bellows wiper on its actuating rod, so you may not see a small leak, but if you can get up under the dash with a flashlight and have a look at that rod, and feel it to see if it's wet, that may tell you something.

It's either the master or the slave, and the master is a LOT easier to change. The slave requires the bell housing to come off.

 

Thanks John.

I am going to do a little exploration/splunking this weekend.

If this were a Chevelle or a muscle car, I would know where to begin and not do something stupid (or do less self inflicted damage, which I have a history because of curiosity).

-stu

 

Stu- You can download a workshop manual for free from ferraridatabase.com.

 

Thank you Taz...funny I just thought of you and your previous recommendations re. the shop manual.

Reading RIGHT now!

 

Well, the curiosity engine started....read shop manual...open garage...get shop light...

* verify master fluid reservoir next to max level.
** reads about a 1/4 in from the top of max level....this should be ok but may revisit possible leak issue later and fill to top.

* inspect all rubber lines running in/out of master cylinder.
** no leaks around rubber tubes or surroundings or possible drip landing spots. check.
** rubber tubing looks almost new and "rubbery". check.

* inspect plastic nipple on top of the clutch master to ensure not brittle like John stated.
** looks pretty good and new. check.

* inspect clutch piston actuator and rubber skirt under dash like John stated.
** no oil leaking around actuator. check.
** no oil leaking around rubber skirt. looks still rubbery and new. check.
** no oil leaking down onto possible drip landing spots. check.

* well, looks like I need to lift car and attempt air bleeding this weekend.
* looks fairly simple given where the picture shows the air bleed nipple is located on the clutch housing picture. that's usually where i start encountering issues and getting distracted into problems...hey, that manual picture isn't where the nipple is....i wonder if it is this....

 

drinking a beer and thinking about the last time I did a complete front disk brake replacement on hot rod 10 years ago....

plan a

* pump, bleed, inspect for air bubbles...repeat.
* hmm, i think i had wife pump the clutch inside the hot rod while i was holding bleed tube and old brake fluid container...schedule time with wife to go into garage this weekend. check.

plan b

if plan a fails, then

* recall having to do a "bench bleed" on the master cylinder.
* hmm, i think i have a hand vacuum pump somewhere in the garage to bench bleed; may need to splunk for that in old storage boxes

 

There are some handy one man bleeding tools around now. Motive Products makes the one that I like & use, but be sure to get their 1109 "Black Label European Adapter" so it'll mate up with your master cylinder.

You might want to have the 2nd person there to keep an eye on the fluid in the Motive Product jug as you're bleeding. You don't want the pickup tube in the jug to pick up any air at all, else you'll be compounding your problem.


There are also Speed Bleeder nipples, which require you to change the OEM bleed nipples out for their special ones with built in check valves. I have used them on other cars and liked them a lot, but haven't heard/read much about them being used in the FCar community.

 

I had similar effects on my 550 and at the same time observed slowly lowering clutch fluid level. By occasion of a large service with a main dealer I indicated to the workshop guys to check the clutch system for leaks. They returned the car to me with the comment that no leaks had been found.

I then looked by myself and found out in minutes that the clutch hose heat shield material was soaked with clutch/brake fluid. It obviously leaked a little, but enough to result in the effect.

I exchanged it myself, actually an apparently simple and quick job, just two hose ends to unscrew and fitting of the new hose. It however turned out to be a mayor job, since the lower end of the hose ends on top of the clutch bell and the only way to get there is to remove at least one cat (and the related probe). An initial try through the wheel arch made me see the joint, even reach there with the end of the wrench, but no chance to apply the necessary torque for removal. I hope that this is somewhat more easy in the 456, in case that the hose is indeed faulty.

 

Bernhard, that's interesting; did you locate where exactly the clutch hose was leaking? Was it from one or the other fitting, or had the line itself simply fatigued and failed?

 

Sorry, I did not take a really close look at it and simply discarded it. But I was surprised how much fluid was taken up by the heat insulation material. As I recall, it was wet right from the top, so that it might be that the upper fitting went bad. But this may also be a result of capillary forces in case that the line itself had failed.

 

I replaced the cluch on my 456. If your clutch is not worn out,if the shifter is properly adjusted,if the combined slave cylinder/throw out bearing is functioning,bleeding this sistem can be a PITA. I eventually bled mine with positive pressure thru the bleed opening from the bottom of the clutch. Why did ferrari put the bleed nipple on the bottom of the housing when air rises? got me.

 

When removing the hose to the slave cylinder,get a proper line wrench on it. The fitting strips easily.

 

John,

Did you completely remove the master or were you able to master cyl bleed without removing from firewall? Those pesky air pockets in there....

Andrew,

That is what I was thinking re. putting the bleed nipple down there. I need to positive pressure bleed.

Thanks for the tip re. the line wrench....I have those in "standard" ....no metrics...another tool purchase.

Andrew/John,

Silly question....can you positive bleed the system by slowly pumping clutch while dumping fluid out the bleed nipple and concurrently adding fluid to master cyl? My thinking is that is how we would do it with old "american" car brake systems...i am probably missing something here.

 

The last clutch bleed that I did, was initially done with the master on the car, however, it was a custom sleeved master that was poorly done, so no amount of bleeding would help it.

I trashed it for an aftermarket master in the bore diameter that I wanted, which I initially bench bled, then I mounted it and finished bleeding the system after that.

On the procedure, yes if you choose to do the 2 man operation, it's still the same as it's always been. Don't forget to put the 2x4 to limit the pedal travel

 

I ran positive pressure up thru the master by attaching a pressurized syringe to the bleed nipple at the bottom of the slave.. It takes a little time,one below pushing on the syringe and one above seeing when the bubbles stopped. Worked first time we tried it after endless tries to bleed from below. No brake pumping needed with this method. Still holding hard clutch 1 year later.

 

Every car manufacturer in the world does it that way. Brake systems are really no different. Master at the top and bleeders at the bottom. It does work but some systems are more trouble than others. It requires a method that insures high fluid velocity.


Unlike brake systems, clutch systems are so simple I bleed many by just pumping the pedal. The movement of fluid makes the air rise back to the master.


There is actually a method shown in old Mercedes manuals. Hook a hose between a brake nipple and the clutch bleeder nipple and pump the brake pedal until the clutch system is full.

 

Thank you John and Andrew.

Going to partner with wife to help perform the 2 man operation; she helped me last time on the hot rod bleed project.

If that doesn't do it, then will buy the Motive Product to positive feed from the top and dump out the bottom.

Looks like my favorite online hot rod shops (Summit Racing and Jegs) stock Motive Products with the European "1109" 44m screw on cap for about $70.

 

Thank you for the background info Brian.

I never had a Chevy manual tranny cyl to bleed; only had automatic trannys.

Brakes...open nipple at each corner, pump brake, add fluid, watch for fluid with no bubbles..repeat...I like simple.

 

Well, success (or at least for now).

* Wife pumped the clutch
* Watched the bubbles dump into bleed bottle
* Refill master cyl
* Repeat for about 15 pumps till no more air
* Drove for about 5 miles running through the gears without issue

------

Thank you guys.

I am remain curiously suspicious, despite the success. The sudden deterioration and not seeing fluid leaks has me nervously thinking about the other reservoir in the transmission, which John mentioned.

Cyl reservoir filled to the max line so I have a visual baseline.

 

There is only one reservior. If the clutch feel suddenly changes and bleeding the clutch fixes it you have addressed a symptom but fixed nothing. In my experience slave cylinders only leak externally so if that was an issue fluid would be comming out of the bell housing. If the master cylinder is bad it will usually leak where the push rod enters, usually under the dash. Air can also enter there. It is a really simple system so should be easy to figure out. There are some more exotic systems with magnesium cylinders and standard fluid will create gas in the fluid but a 456 is not one.

 

Roger that Brian.

I need to explore more around the bell despite not seeing fluid on the garage floor. Is just doesn't add up.

 

Stu, is it possible that you let the fluid in the reservoir drop close to the level where the clutch hose picks up?

If you did, then if you happened to do some fairly high-G driving, the fluid could have sloshed around in that reservoir and introduced some air into that line. Doubtful, but possible.

Your system will bear some watching now. Leaks rarely get better and fix themselves

p.s. Where did I mention a 2nd reservoir in the transmission? AFAIK, there's only the one reservoir that feeds both the brake & clutch systems. I'm not a big fan of this system as I've seen that hose and plastic nipple fail on several cars, and plus, it doesn't take much of a fluid drop in the reservoir for air to get into the clutch circuit.

When my car goes back together, I'm going to investigate using an Alfa clutch master cylinder, which will have its own fluid reservoir.

 

Hi John,

My bad. You wrote slave cyl.

I never inspected the reservoir level before this issue arose, and upon observing the level this past week it was a quarter inch down from the max fill line. The min line is pretty far down the reservoir tank, and I would assume that level or just below (for added security margin) is the point at which air could get introduced into the system, but I could be wrong. The Delco master cyl, if I recall correctly, do it this way and that was 1960 eng design.

I don't track, and I rarely and bordering on never get to do spirited driving....( that's a different, work too much day job problem).

Agreed this will not fix itself, and the reason I am curiously chasing down this issue.

Given Brian's experience and observations re. second cyl leaking out bell housing, I am going to lift car again and carefully observe the bell housing.

 

I have yet to see a hose failure and the only plastic nipples I have seen fail were damaged from people trying to remove them.

It is one part of these cars we have never needed to fix.