Clarifying the SC Failure Phenomenon

[Jarrett]

It seems like the whole SC failure thing is snowballing into some overgeneralizations about the RXP reliability as a whole. I was hoping we could address them before it gets out of hand. People seem to lump all SC failures into a single category, but there are at least two that I've heard of. I'd like us to discuss them and find out what's really happening. It seems like right off the bat there are two different categories with multiple subcategories:

1. Stock Clutch

- Improper (synthetic) oil used to cause premature slipping point/wear. 5-15 hours

- Expected wear items causing premature slipping point. 15-??? hours depending on water/riding conditions.

Repair: None
Fixes: Replace improper oil if used and wear items


2. Aftermarket mods (adding shims, Rotax Racing HD components, Riva BOV)

- Too few pounds on slipping point causing premature slipping moment. 0 hours.

Repair: None
Fixes: Add shim to increase slipping moment or live with it?

- Improper installation of clutch assembly causing fractured ceramic washers. 0-5 hours

- Too many pounds on clutch assembly slipping point causing fractured ceramic washers. 0-10 hours

Repair: Pull oil screens (engine) and change oil and filter. Possible replace oil pumps
Fixes: Ensure proper installation and reduce slipping moment to point where ceramic washers aren't crushed


Rare exceptions that don't seem to fall into those categories:

- Vortech impeller improperly installed

Repair: Possibly replace SC housing. Possible wear on clutch?
Fixes: Ensure proper fit and installation

- Lack of oil flow caused SC clutch and other engine parts to seize (Bullit)

Repair: Replace all damaged engine parts
Fixes: Unknown


Recommendations:

Leave stock clutch alone until it begins to slip, then replace wear items?
Only use one shim on stock clutch setup?
Don't use the Rotax Racing HD clutch assemblies?


Unanswered Questions:

Has anyone seen a fractured ceramic washer come from a unit that was not using a shim?
has anyone seen a premature SC failure when using a BOV?
Has anyone seen a RXP stop running completely from a SC failure of any kind?
Can a RR ECU'ed, Vortech SC'ed, aftermarket IC'ed RXP run to its full potential with the stock slipping point in place or must the point be raised?

[Jarrett]

Does this sound right? Anyone seeing anything that falls outside of these ideas?

[Green Hulk]

Another cause for failure was some of the Riva/Vortech SC Impellers were rubbing the housing. When this happens the clutch slips and causes failure. These were very isolated cases though.

[Jarrett]

That's a good one. I added it in there.

[bankyf]

More unanswered questions:
Has anyone seen the RR unit with no shims(about 7-8 ft/lbs on mine) fail?
Is the RR unit just getting a bad name from improper installation( too tight)?
Wouldn't we most likely see an increased amount of stock clutch failure if we shimmed them up to 10-12 ft/lbs? Cermaic washers are ceramic washers, I am not aware of different grades of ceramic that might be more heavy duty.
The RR with no shims is not much tighter than stock. With that being the case, why are we upgrading? The parts don't really look more "Heavy Duty" to me.

I am at 2-3 hours on a RR clutch with no shims (approx 85 in/lbs). I do have the rr ecu / intercooler / vortech SC setup and I still see about 8lbs of boost with this low slip moment, so I believe the answer to that question is yes, it can perform to it's full potential with the stock clutch. I would like to believe that the bearings, shaft, etc. are better on the rr clutch and that is why I spent the money for it but I have my doubts.

[Green Hulk]

My opinion is the Rotax Racing unit is getting a bad name from improper installation.

[Water4fire]

For someone that needs a new clutch. And doesn't have the tools to do it.
Who do ya'll recommend to repair the SC clutch?

Has anyone come up with a no issue clutch install?

Just want to know, as I am approching 50 hours. So I might be close.

Thanks

[Jarrett]

bankyf, those are all valid points.

Has anyone seen the RR unit with no shims(about 7-8 ft/lbs on mine) fail?

I am running this setup with about 12 hours on it and its still working. To clarify, this is the $385 HD clutch assembly plus shaft. It was installed by Race Tech and said to be set at a starting slipping point of 10lbs. And that after breaking in it should be around the 8-9lbs. point. There are no shims in my setup and it appears to be working. I don't know if its the lack of shims or the 8-9lb slipping point that is making it reliable so far. I have seen this setup bump the rev limiter at 8500 RPM in cooler air and run consitantly 8300+ RPM in near 100 degree weather.

Is the RR unit just getting a bad name from improper installation( too tight)?

In my case, yeah. Improper installation was my fault. But initially, people were being told that 12lbs was the correct slip point on the RR setup, which now seems to be too much for the washers.

Wouldn't we most likely see an increased amount of stock clutch failure if we shimmed them up to 10-12 ft/lbs?

No idea, but my guess is yes.

Thanks for adding a positive note to my shim theory.

[bankyf]

Jarrett or anyone else that knows,
Since you mentioned hitting the rev limiter, do you know if hitting the limiter lights up the warning light on the gauges with the rr ecu. I noticed out of the corner of my eye while riding hard in rough water the other day that the red light was coming on occasionaly. Not flashing on a regular basis, just blinking occasionaly as if I was overreving or hitting a limiter. It was to rough to feel a limiter, but I am sure I was hitting it.

[Green Hulk]

My red light flashes when i hit the limiter.