986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - All "IMS failures" are not IMS failures! Carnage within!

jaykay · 10-20-2009, 05:40 PM

Well I hope having a 2000 3.2 with a steel rest pad rather than plastic will keep me a bit safer than most!

Nice idea with the rollers! One has to consider the chain shape produced with them especially the speeds we are talking about; I would guess flat would be better. Any bearing dia that small is going to be doing some wicked rpms assuming no skidding/wear; one will need to ensure strength/lubrication at these sites...increasing the bearing dia will weaken the the arm at points; all in a limited space.

From what I can see the LN arm has a greatly increased web area which would give increased strength. I am surprised the Porsche arm fails as it has. It must be a combination of poor castings or choosing to put a casting where one shouldn't and shock loading resulting from the rest pin failling......just a guess without seeing the set up of the engine

10-20-2009, 05:40 PM	#33
jaykay Registered User Join Date: Sep 2009 Location: toronto Posts: 2,668	Well I hope having a 2000 3.2 with a steel rest pad rather than plastic will keep me a bit safer than most! Nice idea with the rollers! One has to consider the chain shape produced with them especially the speeds we are talking about; I would guess flat would be better. Any bearing dia that small is going to be doing some wicked rpms assuming no skidding/wear; one will need to ensure strength/lubrication at these sites...increasing the bearing dia will weaken the the arm at points; all in a limited space. From what I can see the LN arm has a greatly increased web area which would give increased strength. I am surprised the Porsche arm fails as it has. It must be a combination of poor castings or choosing to put a casting where one shouldn't and shock loading resulting from the rest pin failling......just a guess without seeing the set up of the engine Last edited by jaykay; 10-20-2009 at 07:39 PM.