98sub2500leg Posted May 31, 2009 Share Posted May 31, 2009 I know there is a lot of info here on clutches, but haven't found all this yet. What is the real scoop on how much disc material should there be for re-use of the clutch disc to the higher rivets on the disc? I read to replace the disc if the measured disc material to the higher level of rivets measures .062". Mine measures .052". I just paid to have the clutch done 8k mile ago. The guy who did it got parts from Napa (not OEM). The 1st clutch lasted 78miles. I usually get well over 100k on clutches. I will onlly buy OEM parts. In clutches I have done myself in the past I have always changed the disc, and pressure plate and re-surface the flywheel. The dealer says that Subaru recommends in a service bulletin to replace the flywheel as well as you can get clutch chatter. They do not recommend resurfacing, not sure what to think. I would tend to believe after reading other threads/posts that chatter comes from oil leaking onto the flywheel and disc. (either a rear main or front trans seal). A new clutch disc measures .072", which should give me (approx) 52,000 left assuming I got the same mileage as the old one. The last guy who I paid to have it done resurfaced the flywheel if I remember right and it has worked fine. I thought the dealer said the parts they supply go together as a set with flywheel. Link to comment Share on other sites More sharing options...
MorganM Posted June 2, 2009 Share Posted June 2, 2009 I would only replace the clutch disc. You just did flywheel and pressure plate 8,000 miles ago so they should be fine. Sounds like you are going through clutch discs too quickly. 78k miles out of the last one and this one is already down to .052 of .072 after 8,000 miles ? Something doesn't seem right here... Link to comment Share on other sites More sharing options...
lostinthe202 Posted June 2, 2009 Share Posted June 2, 2009 Chatter can come from there being heat affected zones on the flywheel. When I changed my clutch I had both chatter (before the swap) and these heat affected zones. It took the removal of about .045 to get rid of it. I don't remember what the run-out spec was for the flywheel, but I got mine to be under .001 and I have had no chatter in the 24k I've put on the clutch so far. Assuming your flywheel surface and PP surface both look good, then I second replacing the disc only. If they show signs of heat (discoloration) then you might want to replace or resurface the flywheel. Did you take it easy on the clutch for the first few hundred miles? I've heard that can shorten the clutch life considerably. Will- Link to comment Share on other sites More sharing options...
98sub2500leg Posted June 2, 2009 Author Share Posted June 2, 2009 Chatter can come from there being heat affected zones on the flywheel. When I changed my clutch I had both chatter (before the swap) and these heat affected zones. It took the removal of about .045 to get rid of it. I don't remember what the run-out spec was for the flywheel, but I got mine to be under .001 and I have had no chatter in the 24k I've put on the clutch so far. Assuming your flywheel surface and PP surface both look good, then I second replacing the disc only. If they show signs of heat (discoloration) then you might want to replace or resurface the flywheel. Did you take it easy on the clutch for the first few hundred miles? I've heard that can shorten the clutch life considerably. Will- Well, this is the deal. Bought the car new, it had warrenty issues at 24k miles. The dealer said they had a mismatched set of gears in the tranny and while they were doing the job, they changed the clutch & flywheel. That clutch lasted until 98K+ miles, which is when I had the last one done. That is 74k miles on the last clutch. I dive it consistently the same. I now has 107k miles on it, which is 9k miles on the newer clutch. The manual says if there is less than 1/16" to the rivets, change it out. So apparently the spec. is .062" to the rivets, and I measured .052". On this overhaul I decided to change nearly seals everywhere except on the rear main which I figure it might be worth taking it into the dealer to have done. I asked the parts guy about the clutch, he said if you get a new clutch disc, Subaru specs you buy the plate. Any past clutch job I have done I have always bought the disc, plate & bearing together and had the flywheel surfaced. In this case, I asked if I could just get a new disc and possibly the bearing then reuse the plate. The flywheel was just resurfaced. The mechanic who did the work bought the parts from Napa (not OEM). Not that that makes a difference, but I prefer OEM as you should have more assurance the parts are to exact spec. (I say should be). He said there was a bulletin that Subaru recommended that the flywheel not be resurfaced due to clutch chatter problems. From reading a ton of posts, it is my belief that those problems are most likely caused from leaky seals. Heck there is the tranny front seal, the crank rear main, the pressure plate, and the small 2 screw baffle plate. One guy had a complete HG job done after finding major leaks, got the car back after the service and paid many $$$ to find all 4 tires locked up shortly after getting it back. Had it towed back to the dealer who then said his tranny was dry (no oil). It was apparently the front tranny seal. Since I didn't know the spec. thickness of the disc-rivets when new and Subaru doesn't list it, I decided to be safe and redo it all again. Too late now already bought the parts. By the way, the new disc measures .063" from the higher rivets which means I have used .010" of material which equates to just over 9k+ miles. That would mean I should have close to 62K miles left on the old clutch (62K miles + 9k Miles= 71k miles for the clutch disc I just pulled out-just about calculates out right within a few thousand miles which are in the wash). Link to comment Share on other sites More sharing options...
lostinthe202 Posted June 2, 2009 Share Posted June 2, 2009 I'm sure that a bad leak by either the trans front seal or the rear main seal could wipe out a clutch, but the evidence of that should be pretty apparent (ie an oil trail). If you don't see that, then you need to look at other causes for your premature clutch failure. Before I go further, from what I've read on this site, the rear main seals rarely fail when left alone, but often fail when installed because they are easy to mess up. So the lesson is, let sleeping dogs lie... What does leak however is the plate between the bell-housing area and the back of the engine. The updated one is metal the leak-prone one is plastic. If you have a plastic one, that's worth the update. You mentioned that you were changing all the seals, if that means you did the cam and crank seals in front, which means you did the T-belt (and hopefully the water pump and pulleys/idlers), you should also pull the oil pump and check the screws on the back plate. They like to back out and should be loctited and the oil pump reinstalled using an anaerobic liquid gasket. Back to the clutch: What caused you to think your clutch needed work? What kind of car/engine is this? Do you have a hydraulic clutch or cable clutch? How do the flywheel and pressure plate look? By the sound of your measurements, it doesn't seem like you've used that much material. I don't know if you could quantify the life of the clutch too accurately based on the amount of material used so far since there are a lot of factors that govern how long a clutch will last. Link to comment Share on other sites More sharing options...
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