overhauling a 550 clutch slave cylinder

Daniel- I do not see any service parts for the slave cylinder in the parts catalogs. Can anybody else help on that?

Taz
Terry Phillips

 

Daniel- Read this thread and it looks like it is probably the clutch throw-out bearing seals that have gone bad. Part 21 is just the flange that holds in the T/O bearing and allows the hydraulic pressure to reach the bearing. Best idea if that is the problem is to replace the T/O bearing and seals with a unit from Hill Engineering. While you have the transmission removed and the clutch pulled, you might think about replacing the clutch, too. They are not that expensive and you may have gotten some hydraulic fluid on the pressure plate from the leaks.

You can look at the clutch drawing and see the T/O bearing and seals, which are available separately. If you think it is just the seals, you can replace those on your current T/O bearing and reuse the old parts. Cheaper that way, but once ripped apart new parts are good insurance.

http://www.ferrarichat.com/forum/showthread.php?t=292759&highlight=clutch+slave+cylinder

Removing the clutch housing involves removing the exhaust system including the catalysts back. Brian Crall recommends removing the transmission rather than sliding it back like it says in the WSM. Unfortunately, the 575M WSM, which is normally very well illustrated, does not have good images.

Taz
Terry Phillips

 

That seal was damaged at installation. And the clutch was worn out anyway.

 

Brian- Is there a trick to installing without damage? I have always thought buying the T/O bearing with pre-installed seals was the way to go for amateurs, but not sure for you pros.

Also, do you recommend turning the flywheel or not?

Daniel- The wear limit on the plate is only 1.5 mm. If Brian says it is shot, it is.

Taz
Terry Phillips

 

Installing the seals is a real PIA. The come flat. Arcing them to fit properly in the ID is a little time consuming and if not done well it will catch on the edge installing it the way that one did. A real advantage to buying Hill TO bearings, they are pre installed.

Resurface all flywheels. Not doing it can often cause problems with good smooth engagement. Too much work to do it twice if there is a problem.


By the time it is losing the dust grooves in the friction material it is done. It was getting close to slipping. He got his monies worth.

 

Brian- Thanks. At least I did not lead Daniel down the garden path. To paraphrase you, sometimes even a blind pig finds an acorn. I will remember the dust groove indicator trick.

Taz
Terry Phillips

 

The wear on the outside of the disc indicates that the pressure plate is no longer flat. Neither will the flywheel - as Brian said it needs machining. This looks a bit like the clutch from my 456 (except for the seals which weren't leaking. Boy what a difference a fresh clutch makes - much nicer shift and 2nd gear synchro now works....even cold.

My clutch lasted 40 000ks - got my moneys worth.

 

Dave- Are the grooves the same depth across the face of the plate? It looks like they are deeper towards the middle, but maybe not. I have not ripped apart a clutch in a long time.

Taz
Terry Phillips

 

Taz, I believe that the grooves are supposed to be constant depth (well, they are on any other clutch I've replaced) - Brian can give the definitive answer. My pressure plate was dished (or coned) about 30 thou, which means that the first contact, on engagement, between the pressure plate and the disc is at the outer edge, hence the wear. It also means that the clutch doesn't clear properly, leading to a notchy shift feel - and eventually damaging the synchros, I guess. Sharpens up your double declutching skills though....

The clutch had also been grossly overheated by the PO - who was one of those people for whom slushboxes were invented - can't tell the difference between a clutch and a torque converter. With something like a 456 (or 550/575) it really isn't necessary to slip the clutch much - with Italian clutches, I've always thought it best not to boot the throttle until the clutch is fully engaged.

 

The grooves are even new. The steel parts tend to get cereal bowl shaped from heat. Also I suppose there is more wear at the outer edges because of higher speed further from the axis.

 

Brian- Makes sense, thanks.

Taz
Terry Phillips

 

What, are we bashing the Italians for the clutches as well now ?!

 

Alfredo- No, just trying to understand them. The clutches on the V12s are actually pretty good, with nearly twice the wear limit of the 360 clutch (1.5 mm vs 0.8 mm). The follow-on dual plate clutch for the 599 and 612 OTO is way better, though. I wish there were some way to adapt one to the earlier cars, but I do not think it is possible. The 599 got a new transmission case, which was also adapted to the 612 OTO, so I do not know if the clutch comes anywhere near matching the earlier cars.

Taz
Terry Phillips

 

Taz, FYI, I have a triple disc OS Giken in my 550, installed by Josh @ ECS, and it came with a new Giken flywheel, and a new HE release bearing. The whole assembly is about 1/3 lighter than the OEM setup.

It worked OK as installed, but once I installed a sleeved down master cylinder (5/8" instead of 3/4") it made a big difference in the clutch pedal effort and drivability.

I'm very satisfied with it at this point and would recommend this combo to anyone seeking an alternative to the OEM clutch, and a much lighter pedal as well.

We'll see how its longevity fares in Houston traffic.

 

John- That sounds very interesting. They do not list any Ferrari applications, so which one did you use? A longer wearing clutch would be a great thing.

http://www.osgiken.net/index.html

Price appear to be about the same as OEM, but you do get a new flywheel, too.

Taz
Terry Phillips

 

Plus, don't forget a new Hill Engineering release bearing (worth around $800 IIRC)

I don't think this clutch is in their catalog yet - I was advised I was the first customer for it. It's their Type STR housing, so it has a lighter pressure plate than their race clutches, but shares some of the DNA. A friend who I have enormous respect for has driven only Giken clutches (and quad disc ones at that) on his Supras for years and swears by them, so with his recommendation and Josh standing behind it, I felt OK with the situation.

I wanted a clutch with a lighter pedal so that my wife could drive the 550 if she ever felt inclined, and not be intimidated by the heavy pedal. And frankly, I wasn't too enamored with the pedal myself. After looking at some kevlar clutches that a guy makes for the Lambo crowd, and some other alternatives, I felt this was the safest solution, since Giken have a very good reputation for quality.

I probably got a better deal than retail under the circumstances, but I'd recommend if anyone is interested to contact Josh ([email protected]) if they want to know more about it, and apologies to Daniel for the thread drift!

Here are some weight comparisons that Josh made:

OEM complete with flywheel: 45lbs
OSG complete with flywheel: 31lbs

OEM flywheel only: 20 lbs
OSG flywheel only: 16 lbs

OEM clutch only: 25 lbs
OSG clutch only: 15 lbs

And a few pics of it, including a couple side by side with the OEM setup. As you can see, quality is top notch:
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John- Very nice and we will be very interested in hearing how she wears. I would like to see some specs on the clutch, so probably worth contacting Josh. Some of those Supras were putting out a ton of hp and torque. That may be a better deal than trying to adapt the 599 clutch, especially with the dreaded "call" for price from Ricambi.

What was the issue with 3/4" vs 5/8" slave cylinder on your car? Longer stroke on the 5/8" cylinder for lower effort? Not an issue with F1 cars. 900 psi of hydraulic pressure makes a pretty good slave cylinder substitute.

The HE T/O bearings are only $575 from Ricambi, and, with seals already installed, are definitely the way to go based on Brian's description of the expertise (patience?) required to install the seals.

Might be difficult to adapt to the F1 system's clutch position sensor.

Taz
Terry Phillips

 

Taz, resleeving the cylinder had several positive results, and no real negatives that I've experienced, so far:

1) Due to the clutch being a triple design, its engagement/disengagement point prior to resleeving used very little of the master cylinder's stroke. In fact the engagement point was in the upper 1/3" of the pedal travel. This was a bit unnerving to me until I learned Ferrari's release bearing is a "no free play" design, meaning it's riding on the pressure plate fingers all the time.

Sleeving the cylinder moved the engagement point quite a bit closer to the floor, and used more of the master's stroke and pedal's travel to achieve engagement/disengagement.

Thinking of it another way, to move the same amount of fluid as before, now requires more stroke on the master because of its reduced bore.


2) The resulting greater pedal travel resulted in much lower pedal effort. It's now not too much of an exaggeration to compare it to a Honda Civic clutch.


3) It's now also easier to modulate in stop & go traffic, and is not so grabby.

It still completely disengages when the pedal is on the floor, and the transmission goes in & out of all gears with no problem, hot or cold. Downshifting is also not a problem and there's no crunching that I can detect, but then I also rev-match when downshifting.

The only thing is there's a bit of a shudder in the drivetrain when reversing, but the shudder was there before I sleeved the master cylinder, and IIRC, it may have been there with the OEM setup.

Note: Sleeving the master obviously changes the hydraulic ratio between the master & slave, and isn't something that people with OEM clutches should try. It worked well with this aftermarket clutch because a multiplate clutch does not require nearly as much travel on the slave/release bearing as the big single plate organic does. If this were tried with the stock clutch, it might not disengage fully, and the car could be difficult to get in/out of gear.