Hello everybody Just after 1000 km of being rebuild my tob was leaking again !! First a few drops of brake oil under the clutch but now the reservoir is empty after only 2 weeks ! No clutch pedal of course. Took the clutch apart and the tob but very strange nothing damaged to see on the engine axle or both the seals ?? The seals are as new. Very strange. In the brand new tob bearing itself all the grease was toasted with the brake oil penetrating. So cleaned and re-greased the bearing. Because it did not drive the car the bearing ( balls and surface) itself was as new after close investigation. After greasing it worked as new. No sound or vibrations. I can't understand for now how this could leak this heavy ?? Only thing i noticed was a very very minor scratch on the inside of the metal housing where the seal go's.(foto 3 ) But then why it leaked only after 1000 km ? Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Luckily this leak is "before" the pressure plate so the clutch disk is not affected. Was also a new one.
I have to find a way to "hone" the inside of the grooves where the seals go. I assume here is the problem.
Here a photo from the leak and the clutch. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
No The seal was installed ok. The oil pressure needs to "open" the seal lips. I assume it was the 4 quadrant seal that leaked not the lip seal. Not 100% sure of course. I have read there were some problems with these seals from SP. "Christof " had the same problem after 1000km.
I checked both the seals with a magnifying glass. Nothing bad, as new ! Strange. Why leak only after 1000 km and 4 months ??? And i mean LEAKING not dripping ! Reservoir empty after 2 wks standing stil.
For the trouble of having to open it up again and change out new seals as well as being stuck someplace, you could have bought and replaced with Hill Engineering one. The factory TOB is well known to go bad. HE one is really not that expensive, either. This is the reason why I no longer use rebuilt clutches or pressure plate and always use new TOB from Hill when I do any 348/355 clutch work. That, or I don't do it.
I agree with mitch. I used to reman my clutch discs etc but the skill of those doing those jobs is getting very poor. Lots gets lost when people think a 12mm wrench is the same as 1/2 SAE
After doing a bit of research this looks promising.Especially the ZBR profile. Going to consult hydraulic specialist next week. The system with the "normal" cast iron housing should work perfectly. No need for a adapted housing in my point of view. I don't think the tob reaches 400 bar. lol Image Unavailable, Please Login
TPU will be "eaten" by the brake fluid rather quickly, not suitable at all. The correct material for brake/clutch cylinder seals is EPDM rubber. You may be able to use Viton but, generally, it will swell excessively in brake fluid unless you can find a specific Viton formulation for use in brake/clutch (dynamic) seals. Some other materials are also suitable for use with brake fluid but only as static seals like O-rings, fluid reservoir seals or hoses.
Thx M Indeed TPU is not suited at all ! I told also "looks promising". In the meanwhile i also found out EPDM (or in fact most Ethyleen-Propyleen materials) is the way to go. https://en.wikipedia.org/wiki/EPDM_rubber Looking into "rod" seals made from EP.. now.
This is the best I found. Strange but on the drawing Ferraris uses for both seals a 4 quadrant model ?? In my TOB the one closest to the engine was a U cup seal. Somebody knows why ? Image Unavailable, Please Login
Here a little drawing i made very fast. I am not a CAD drawer I have been to a specialist today and apparently there is something wrong with the seal sizes and type from SP. Don't know exactly what. Keep you informed. Image Unavailable, Please Login
As the inside of the U groove looked a bit used i wanted to clean / hone the sealing surface off the groove. How to get in there and stay square? I draw and 3D printed 2 little tools with the exact dimensions ( diameter and width) of the U groove's. This way the tool stays very square in the groove. As it should. Then i glued to the bottom surface some 1200 grid sanding paper and cut it to fit very precise. Image Unavailable, Please Login Put some oil on the sanding paper and i could manually hone the bottom of the groove by rotating the little tool. This is where the sealing takes place here. Image Unavailable, Please Login As you can see already in the background the sealing surface on the bottom of the U groove starts to shine again. Clean and smooth. Image Unavailable, Please Login Grts Patrick
You must be doing this because you like a challenge. In that case, continue. I would just get a Hill Engineering unit by now.
Indeed i do and like to get to the bottom of things, not take the easy way. It is called learning. Unless there is no other option of course. I am also not stupid. Grts Patrick
One of the clutch slave cylinder seals comes in two sizes, depending on whether it is early or later type. The part numbers are: 151822 is 58.5 mm (later), 139436 is 60.5 mm (early). Which one of these have you installed?
I assume you mean OD of the U cup seal (closest to the engine)? It was the 151822 I used. The TOB worked leak proof for 5 months!! Image Unavailable, Please Login As far as i can judge now afterwards it was the x ring seal (139438) that leaked.The oil went in the bearing. But 100% sure I am not. Image Unavailable, Please Login The oil went in the TO bearing itself and destroyed the grease. Did not find brake oil at the U cup seal/engine side. Image Unavailable, Please Login
You have used correct seals for your clutch slave. My car has the same type of TOB as yours and I replaced the seals using 151822 & 139438 (bought from Superformance) about 4 years ago and have had no leaks (still, I keep a Hill Eng slave as spare). I thought I read somewhere that there was a problem with a batch of X seals (139438) but I am not sure.
