Help? Clutch vent pipe removal - add filter...
02-01-2011, 08:03 PM
#17
Rennlist Member
Thread Starter
Hi Alex.
That was then and this is now. You wont find that gear on later 911s. In part because they used a cheaper pre assembled Japanese gearbox on the production 996. The clutch vent kit wasnt present on th 964s either as far as I am led to believe. It was a clever idea like Varioram and early 4WD systems that has since eithe rbeen recognised by accountanst as over engineering or by engineers as over complicated and has been simplified The idea of the kit was a sound one but involved alot of pluming. They vented both sides of the cluch casing. You can see it if you look at the gearbox/clutch aseembly. Ive attached pictures of my own below both sides. The spinning of the clutch drew air in and dispelled it. The idea of creating some negative pressure via the airbox was partly due to the length of the tract they devised to dispell the air/particles (long and this needed some venturi help) and secondy to create a boost in pressure making sure particals were all dispelled from the housing. It worked well too as when we opened by 40,000 mile clutch case it was pretty clean.
The modification still allows the air and partciles to dispell using the centifugal velocity of air created by the inlet side and the rotation of the flywheel/clutch assembly. However my race mechanic noted there would be some increase in dust build up potentially inside the case but as he stated much less so than on 964s and earlier 911s and infact on 993 Cup cars they didnt exist (no need I guess when youd be replacing clutches on a frequent basis). The end synopsis was that with the plumbing removed build up still wouldnt be an issue that would affect the performance of the OT bearing or other within the life of the clutch - or indeed probably withing twice the life of the clutch.....Tipo boxes di not have the breather of course...
Time will tell but in terms of downside effects for a mod I think this one is well within the 95% safe limit...
Lastly - remember with a cut out factory airbox you are effectivelt reducing ant eeffective pressure on the clutch breather tube to Zero! Worse still 7 out or 10 tubes I have seen have deformed over the years from the heat and are not mated to the airbox in any case meaning there is no pressure being created.....
Pics of gearbox both sides before removal and pics stolen form anothe rmember showing brass mesh set up over the factory plastic fitting. Ive attached a picture of my finished engine bay without the tube - you will see I removed it in favour of adual cone filter....
Cheers
M
That was then and this is now. You wont find that gear on later 911s. In part because they used a cheaper pre assembled Japanese gearbox on the production 996. The clutch vent kit wasnt present on th 964s either as far as I am led to believe. It was a clever idea like Varioram and early 4WD systems that has since eithe rbeen recognised by accountanst as over engineering or by engineers as over complicated and has been simplified The idea of the kit was a sound one but involved alot of pluming. They vented both sides of the cluch casing. You can see it if you look at the gearbox/clutch aseembly. Ive attached pictures of my own below both sides. The spinning of the clutch drew air in and dispelled it. The idea of creating some negative pressure via the airbox was partly due to the length of the tract they devised to dispell the air/particles (long and this needed some venturi help) and secondy to create a boost in pressure making sure particals were all dispelled from the housing. It worked well too as when we opened by 40,000 mile clutch case it was pretty clean.
The modification still allows the air and partciles to dispell using the centifugal velocity of air created by the inlet side and the rotation of the flywheel/clutch assembly. However my race mechanic noted there would be some increase in dust build up potentially inside the case but as he stated much less so than on 964s and earlier 911s and infact on 993 Cup cars they didnt exist (no need I guess when youd be replacing clutches on a frequent basis). The end synopsis was that with the plumbing removed build up still wouldnt be an issue that would affect the performance of the OT bearing or other within the life of the clutch - or indeed probably withing twice the life of the clutch.....Tipo boxes di not have the breather of course...
Time will tell but in terms of downside effects for a mod I think this one is well within the 95% safe limit...
Lastly - remember with a cut out factory airbox you are effectivelt reducing ant eeffective pressure on the clutch breather tube to Zero! Worse still 7 out or 10 tubes I have seen have deformed over the years from the heat and are not mated to the airbox in any case meaning there is no pressure being created.....
Pics of gearbox both sides before removal and pics stolen form anothe rmember showing brass mesh set up over the factory plastic fitting. Ive attached a picture of my finished engine bay without the tube - you will see I removed it in favour of adual cone filter....
Cheers
M
02-01-2011, 08:08 PM
#18
Rennlist Member
Just did mine w/o incident. Pretty straight-forward. As mentioned above, most difficult part was accessing the rearmost bolt holding the tube to the sheet metal but found it easier to work from the top. Tight squeeze to get the tube to clear rear suspension near the swaybar mount but just yanked it out. To cover the hole in the engine tin rather than buy and install the tip version, fabbed a cover plate and painted it black. In all my years of wrenching, have never seen such a gizmo coming off a clutch bellhousing.
