94 512TR 66,000 mile major

The Hill engineering throw-out (thrust) bearing appears to be infinitely better engineered and built than the original Ferrari part and much easier to install. The original part has a number of seals that have to be inserted into the bearing just so or they will leak and fail. If this turns out to be the problem I will still buy another Hill Engineering thrust bearing.
That being said, I think it is most likely the pressure plate that has failed. First I must determine that the noise is indeed coming from the clutch and not something else like the AC compressor, although this is not likely, given the loss of the clutch pedal temporarily. We shall see.

 

So here I am at 3PM on Friday at the intersection of Lorraine Road and Dog Kennel Road in eastern Sarasota County. Not exactly the center of anywhere. The first driver, Martin, came with his roll back truck but someone had removed the 2 pieces of 2x12 from his truck, so he could not help. I had told the dispatcher that we would need wood to clear the front spoiler on the bed of the truck. That took 1 hour. The next driver, Enrique, had the required small pieces of lumber, so away we went. Of course it took another 1.5 hours to get him on scene.
If you have never done it, make sure the tow hook in your tool kit has the right size threads for your car. I understand there were several variants and tool kits and parts get switched. My original tow hook did not fit. Thankfully I bothered to get the correct one 15 years ago.
Finally she was back home, but I was too depressed to do anything last evening.
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This morning was cool and glorious, perfect weather for golf. I shot 78 (good for me) and won $40, so I felt like things were going well. I started deconstructing.
First the airboxes were removed, then the rear valance, then the asbestos shield and then the exhaust. You can keep the pre-cats and the test pipes (or cats) together, just to make things simpler. After that, remove the pins that hold the Tubi on the spring mounts and lower her to the ground. The O2 sensors can be left attached, just disconnect them from the harness. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login

 

The air cleaner assembly comes off with 8 mm allen bolts. I may have said 6 mm in another post. The valance brackets also have to be removed. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login

 

Now first drain the gearbox oil (it's a tiny amount), disconnect and plug the clutch hydraulic line, then remove the nine 13 mm bellhousing bolts (don't forget the hidden ones on the bottom) and the three 13 mm starter bolts. Also remember to use your battery disconnect switch just to be safe.
A few taps with a rubber hammer and the bellhousing came off easily.
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With the bellhousing off, all looked unremarkable, but the culprit was the Hill Engineering thrust (throw out) bearing which was frozen solid. It's job is to spin with the rotating pressure plate (hence the name bearing). When the clutch is depressed, hydraulic (brake) fluid moves through the lines and causes a sleeve in the bell housing to push forward. This sleeve pushes the throw out bearing forward where it depresses the pressure plate fingers and releases pressure on the clutch disc so it is no longer pressed against the flywheel and you can shift (the motor is disconnected from the transmission at that point). The throw out bearing is always in contact with the pressure plate and spinning all the time. There are two springs in the housing that keep it lightly pressed to the pressure plate. The screeching noise I heard was caused by the motor trying to force the frozen bearing to turn (or maybe the frozen bearing rubbing against the pressure plate fingers). There is a press pin in the bearing housing that rides in a groove in the small bracket in the bell housing, I suppose to keep the bearing housing from spinning as it moves forward? There are multiple blue seals on the inside of the bearing that ride on the gearbox shaft. Again I am guessing they are to prevent any oil from getting to the clutch discs?
On an original Ferrari throw out bearing, each seal must be carefully pressed into its recess in the bearing and then the assembly gently slid onto the gearbox shaft. It is difficult to slide the bearing in place without knocking one of the seals out of its groove. No such problem with the Hill unit, which is why I like them.
Anyone with more knowledge on the workings of the throw out bearing please feel free to correct any incorrect and ignorant statements above.
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So this is definitely the problem and a new bearing must be ordered. I will contact Hill Engineering in England on Monday to see if there are any updated versions or if this batch has had any problems.
The clutch pressure plate and disc were replaced with new units 36,000 miles ago. They looked great when I took it all apart a few months ago, and I was careful to maintain the same relationship with the flywheel on re-assembly. The clutch was working great before the bearing froze. So, my questions to you ferraristi is:
Do I leave the clutch alone or should I replace everything (this is a $2000+ question).
Also, could I have done something in the scenario above that caused the bearing to fail? It did function perfectly for 70 miles after the major.

 

I agree, turbo-Joe, the loss of the clutch pedal is a mystery. I will look into having the pressure plate rebuilt (maybe locally). I did not clean the bearing. I just took the clutch apart, inspected it and put it back together.

 

Vincenzo, the Hill Engineering part is CRB 456/550
Batch #50997
On the Hill Engineering website, they state they have found that the original ferrari flange that the throw out bearing rides on has a rough surface and can lead to premature failure of the seals. They have remanufactured a new flange that is much smoother. Just another $995 and it can be yours. I am still unsure of the exact purpose of the seals.

 

In retrospect, I should have checked the bearing for smooth rotation. Maybe I could have felt it was not turning freely.
It seems like gearbox oil coats the flange and the gearbox shaft, keeping the bearing riding smoothly on the shaft. The seals keep the oil from getting to the clutch. Is that right?

 

Mine is a late run 1994 with ABS and the 512M type diff. The Hill Engineering seals remain perfect. It was the bearing itself that failed. I will try to contact Hill tomorrow and see if there are any updates or suggestions. I'm not going to shell out $900+ for their "updated" flange.

 

I got a reply from Paul Hill himself. It appears that the first run of the Hill Engineering Clutch Release units used the same bearing as the Ferrari units up until 2011 when they were replaced by a better designed bearing (mine was installed in 2005). So it was the Ferrari portion of the Hill Engineering bearing that failed.
New assembly from Ferrari is almost $1100 before tax and shipping.
New Hill assembly from Ricambi will be at my door tomorrow for $430.20. I'll make a not to change the bearing as part of my next major in 15 years (or 40K miles).

From Paul Hill:
All the clutch release bearings that we produced before 2011 used the factory SKF clutch bearings. In the interest of continual improvement we asked RHP/NSK to develop the clutch bearing for us based on the SKF bearing but using our specifications (uprated seals, grease etc) These bearings have been used in every CRB clutch bearing since 2011.
The area where the clutch bearing sits is an extremely aggressive environment and these parts are intended to be service replacement items and unfortunately the longevity of the unit has many variables to exactly how long they will last. (We have no recorded problems / issues with that batch number)
Hope that helps.
Regards

Paul Hill

 

New Hill assembly from Ricambi will be at my door tomorrow for $430.20. I'll make a not to change the bearing as part of my next major in 15 years (or 40K mile

TYPO: the above should read: "I'll make a NOTE to change the bearing..."

 

Sunday was re-assembly day.
I cleaned up the fingers of the pressure plate with a 2" scotch brite pad on my cordless drill. There were no burrs before or after cleaning and the mating surface of the bearing was also smooth. I suspect the screeching noise was the seizing bearing being forced to move.
I took this opportunity to replace 3 of the bellhousing attachment studs that had some iffy threads. The old studs came out with a vice grip and the new ones put in with some loc-tite. All the other threads were cleaned up with a die (M6 x 1.25 I think)
The gearbox drain and fill holes were also cleaned up with a M22 x 1.5 tap and the hex head 22 mm plugs had their threads cleaned with the corresponding die. Both now thread smoothly with finger pressure. The drain was sealed with a bit of thread sealing compound.
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The new Hill Engineering Clutch Release Bearing assembly was lubricated with some brake fluid on the seals. The thrust assembly was inspected for any rough spots. None were found. The roll pin was removed from the old clutch release assembly and tapped into the new. The triangular bracket that guides the pin was cleaned and lubricated with a bit of lithium grease. The two clutch release bearing springs were set on their perches (they fit into corresponding recesses on the bottom of the bearing assembly) The bearing and thrust assemblies mated easily with minimal effort. Travel of the bearing on the thrust assembly was smooth. The triangular bracket was reattached with two 8 mm bolts and lock washers. Easy travel of the bearing was again confirmed.
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The driveshaft sealing O-rings were set in place and the drive shaft inserted into the transmission. The bell housing was then placed over the studs, but it did not slide easily into place. I removed it and rotated the splined shaft slightly and it all slid into place with a reassuring thud.
After that the bell housing nuts were applied and torqued, the starter bolts and starter re-attached, followed by the clutch hydraulic line, the exhaust, the O2 sensor harnesses, the rear valance and finally the air boxes. The gear oil that was drained from the gear box was replaced and the fill plug tightened down. The clutch was bled and the initial outflow of fluid was brownish, no doubt cooked by the excessive heat of the seized bearing. Once bleeding was complete and the pedal firm, the car was started and the clutch tested. It engaged smoothly with no rattles or noises. Time for a beer. That was actually not so bad, probably because I had just done the same thing a few weeks ago.

 

Earlier in the week I decided to replace the electrical junction boxes I had installed many years ago. I used pieces designed for car stereo which employ an allen head bolt to clamp the wires into place. Unfortunately, when dealing with fine multi-strand wires, the strands tend to separate around the bolts. It looks very cheap and amateurish now. I was ashamed, and over time the wires had become loose, which is a recipe for disaster. Tinning fine strand wires in a high vibration environment is frowned upon, as the strands tend to break. I needed to have a secure source of 12 volt power for my Dave Helms fuse box 8 gauge power wire, the stereo amp and the relays for my custom headlight harness.
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A search on Amazon found this automobile electrical junction/distribution block (much beefier than the previous piece of crap), and a trip to Harbor Freight got me this 16 ton hydraulic crimper. Not a high quality tool, but if I use it 20 times in my lifetime that will be a lot. I already had crimp-on ring terminals rated at 100 amps.
Before doing any of this, the battery disconnect switch was enabled, and the battery removed. The hold-down clamp takes a 13 mm socket. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login

 

A schematic was created, wires cut, stripped and crimped, heat shrink tubing heated, wires labeled and everything arranged in an orderly fashion. Much better and totally bullet proof. The new distribution block has four 5/16" studs for the larger circuits and 3 screws for smaller amperage needs. The 6 gauge black wire on the right side of the block goes to the positive battery terminal.
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