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If the Luk pressure plate allows for a total throw out bearing travel of 0.5 in from fully extended fingers to the catch fingers and the throw out bearing has a total possible travel of 1 in then why would spec for free play be 0.1 in? After all when the clutch wears the fingers will extend out using up the free play that you've calculated and hot clutch pucks also extend out the clutch fingers. 0.2 inch seems much more sensible because 0.2-in of free play plus 0.5 in of max travel permitted is only 0.7 in and the throw out bearing can move a total of 1 in. Am I missing something here? (Red lines indicate the limiting fingers that limit throw up bearing half inch travel)
What's more is since the fulcrum of the pressure plate fingers is closer to the pressure plate than it is to the bearing We find a ratio of about 3 to 1 where .02in of clutch wear is going to result in .06in of lost free play at the bearing. Wouldn't it make more sense to have about .2 in of FreePlay minimum? Why not even more after all a new clutch only has .5 in of free travel at the finger end?
It's no wonder that if somewhat worn clutch slips. You ran out of free play in the throw out bearing is resisting full extension of the fingers...
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Last edited by douglasjre; Sep 20, 2023 at 12:18 AM.
Reason: Add photo
Can’t speak for anyone else, but I’m going to have to ponder on the questions you raise. Does Luk have some accessible documentation or did you take a dial caliper to a pressure plate? Fun questions, to be sure.
Can’t speak for anyone else, but I’m going to have to ponder on the questions you raise. Does Luk have some accessible documentation or did you take a dial caliper to a pressure plate? Fun questions, to be sure.
Veneer caliper measurements done by me
It's not just a fun question. It's a vital one because as the clutch just wear out the fingers will move further towards the throw bearing taking up that free play that we have and since it's about a 3:1 ratio that means 0.100 of wear of the clutch is going to result in 0.300 travel on the fingers and since we only have 0.100 free play you'll never get to use the whole clutch because you'll run out of free play in the clutch will slip because the throw bearing will be bottomed out
So if the total travel is limited by the bottom out fingers allowing a total of a half inch of travel and we know that the throw bearing allows for a full inch of travel why are we putting these in with only 0.100 of free play when we could put far more than that allowing for more use of a clutch in the future?
Take note that the travel limitation is at the end with the fingers where the throw bearing meets the fingers. So 0.500 travel of the fingers equals 0.500 travel up the throw bearing. But 0.100 where on the clutch would equal 0.300 travel of the fingers and since we've only allowed for 0.100 free play will never get to use the whole clutch. Am I the only one seeing this?
Why not start out with 0.500 free play which would allow us to use the whole clutch. After all the throw bearing will be auto adjusted out to that point
Last edited by douglasjre; Sep 23, 2023 at 06:20 AM.
C5 replacement clutch free play specification
