I was curious about the differences in design between the URD fix-U Hydro and the Clutch Master and found the video below discusses the air gap setting.
Some other differences:
- Not reversable (cut off your quill)
- No air gap adjustment needed
- Single hard line cable
- Solution if quill has been destroyed
- Not available
Hyrdraulic Throwout Bearing Air Gap Setting - Mantic Clutch USA
- Need to measure and calculate air gap during install
- Dual braided lines - more opportunity for leakage
Well I think with either the URD fix-u hydro kit or the Clutch Master kit, you're never going to go back to the OEM setup, but I do think cutting the quill off of the bell housing would be rather tricky without damaging the input shaft. I haven't really been able to find any thorough instructions on how the URD kit was setup, but they haven't offered it for quite some time now as far as I understand, sooo that basically only leaves the Clutch Master's option as the only available solution. I did also see people were having issues with properly bleeding the URD kit but again no idea how they setup the bleeder to work with that system so I can't say if they were performing the job correctly or if it was just a tricky setup.
If your "snout" or "quill" has been destroyed, well that really sucks, but from my research that is a very rare issue. It is by far nowhere near as common as the premature wearing and squeaking of the throwout bearing, which is the main goal the kit from Clutch Masters has set out to solve (as well as improve on the overall driving experience with the manual transmission). When I took my throwout bearing and clutch fork off I noticed that my snout had a slight mushroomed end to it from the throwout bearing wiggling around while it's spinning with the clutch. The Clutch Masters kit uses a spacer that is a very tight fit and at first it would not fit over the end of my snout, but I was able to tap it on there. If the snout is damaged and if you have at least I'd say 2" of good material left then the Clutch Masters kit could probably still be used because the main thing that is centering the slave cylinder around the snout is that spacer that slides all the way to the inner face of the bell housing and registers nice and tight on there. Then the actually slave cylinder is just held in place by the bracket. Pic below stolen from Clutch Masters website, but you can see the spacer and how that fits inside the slave cylinder.
Unlike the PDM press on snout and new throwout bearing update which I have seen people have issues with still breaking off their snout, I feel this could never happen with the Clutch Masters kit due to the physics at play. Unlike the clutch fork that is pushing the throwout bearing at what I can only say is an awkward angle, the Clutch Masters slave cylinder is pushing forward only.
Measuring and calculating the air gap is 3 very easy measurements. that any one with a caliper and a straight edge can obtain. Also by setting up the throwout bearing with an air gap you will never run into the issue that is causing these bearings to prematurely wear in the first place. Of course as I mentioned that is the bearing having preload applied to it and being constantly pressed up against the clutch diaphragm which is also how the URD kit would work. The pedal feel would most likely be improved with the URD internal hydraulic slave cylinder but you'd still have issues with the throwout bearing down the road.
Here are the instructions to installing any of the internal slave cylinders and getting the air gap correct: HYDRO BEARING INSTALL - Clutch Masters
As far as the stainless braided lines leaking, I see that as a mute point and something that would never be an issue. Because Clutch Master's makes a ton of these internal hydraulic slave cylinders, I know that they have a DOT certified hose manufacturing setup, they aren't just throwing these stainless lines together and sending them out the door. Each line and slave cylinder is bench tested to ensure there are zero leaks when the end user gets them. If you were to have a leak it would be because of improper installation and that would probably be as simple as the line not being tightened down.
Hopefully that clears up any thoughts/questions you might have had but I definitely appreciated the pros and cons list you came up with.