burnout8488 Posted October 11, 2010 Share Posted October 11, 2010 After replacing my clutch a month ago and bolting everything back up, nothing seems "right," or the way it used to be. The engine/trans seem to flop around a lot more now. When I'm in 3rd gear around 1200-2000rpm moderately accelerating out of a corner, there is a horrendous drone and it shakes the entire dashboard, and every plastic piece rattles inside the cabin! Here's the kicker - I've replaced the motor mounts and transmission mounts with brand new OEM parts, and they've made no difference. Driveline slop is WORSE somehow. It feels like I'm driving on solid polyurethane mounts the way the noise is transmitted into the cabin...but everything except the shifter bushing is stock. I know that the entire car isn't vibrating because of that, so I'm keen to rule that out. My possibilities, see if you agree with me, or suggest one. Cause of resonance = overtorqued transmission crossmember mount bolts? Cause of slop = bad pitch stop? I removed the pitch stop and went for a drive, and the slop was only slightly worse. When I reinstalled it, I barely noticed a difference. Could jacking the transmission up too high with the pitch stop installed have ruined it perhaps? It looks fine, but it does have 103,000mi on it. Hard for me to believe that this little piece could have changed so much to account for this much new slop though. Please help Link to comment Share on other sites More sharing options...
johnAWD Posted October 11, 2010 Share Posted October 11, 2010 Who did the clutch swap? Was everything torqued to spec? Did the vibration start immediately after the clutch work? Link to comment Share on other sites More sharing options...
burnout8488 Posted October 11, 2010 Author Share Posted October 11, 2010 I did. (Most) everything was torqued to spec. Everything regarding the clutch/FW definitely was. It was done over the course of 2 weeks, so I figured by taking my time everything would be done right. The vibration and slop started immediately after I got the car bolted back together, yes. It's an odd combination, because you usually wouldn't attribute harsh NVH to a powertrain on soft mounts. Link to comment Share on other sites More sharing options...
johnAWD Posted October 11, 2010 Share Posted October 11, 2010 In that light, you missed something. Exactly what it is - hard if not impossible to tell without being under the car/etc. Did you replace with OEM parts? Link to comment Share on other sites More sharing options...
burnout8488 Posted October 11, 2010 Author Share Posted October 11, 2010 Yup, clutch was OEM replacement Exedy and mounts are Subaru. I removed the transmission to do the job, so pretty much everything from the bellhousing back was removed. I not inclined to think the clutch portion of the job is causing this, but who knows. Later this evening I'll back off the crossmember mount bolts and see what happens... maybe the rubber is being "squished" too much. Sheesh. I'm going to bed. Link to comment Share on other sites More sharing options...
robbie_R Posted October 11, 2010 Share Posted October 11, 2010 Was that the kit with the new singlemass flywheel? Did you use shorter bolts? Link to comment Share on other sites More sharing options...
brum Posted October 11, 2010 Share Posted October 11, 2010 If its a single mass or lightened flywheel then it's just chatter that happens. The Stock dual mass flywheel does a great job of dampening drivetrain vibrations on the stock clutch. If I do any hard acceleration (nearing 1200-2000 rpm) with a stage 3 clutch and 15.5 lb flywheel it chatters like a mofo. Link to comment Share on other sites More sharing options...
burnout8488 Posted October 11, 2010 Author Share Posted October 11, 2010 The 2.5i has a single mass flywheel stock. I had it resurfaced at a machine shop and put it back in. The clutch is already 100% engaged before the noises start, leading me to believe its not the culprit...unless its somehow possible. Here's a better scenario... if I'm cruising at 3000rpm in 3rd, coast down to 1200rpm, then give it half throttle or more, my teeth get chattered out of my skull. I'm gonna go try to loosen the crossmember bolts and see if they give it a little more play. I'm sure those little cushions are probably designed to absorb some of this. I've never seen this problem documented online for anyone else, so maybe I can help someone. Link to comment Share on other sites More sharing options...
Boostin1657615274 Posted October 12, 2010 Share Posted October 12, 2010 One thing I noticed when I was installing a new clutch, was that the factory service manual stated that the balancing marks for the pressure plate and flywheel must be 120 degrees apart. Could this potentially be causing a problem? On the search for a new DD... Link to comment Share on other sites More sharing options...
robbie_R Posted October 13, 2010 Share Posted October 13, 2010 ^^ Good call, the dowl pins might keep you from doing this though and only allowing you from doing it one way only. You might notice some clutch drag with this. Link to comment Share on other sites More sharing options...
Ridgeracer Posted October 13, 2010 Share Posted October 13, 2010 Could it be a problem with the pilot shaft and or bearing? Think you are right about the PP. I think the dowel pins only allow you to install it one way.. Would it help to maybe get all four wheels off the ground, put it in gear and confirm its not something coming from the rear of the tranny or prop shaft for the rear diff. "Gimme mines Balboa...Gimme mines".....Clubber Lang - Mr. T Link to comment Share on other sites More sharing options...
burnout8488 Posted October 13, 2010 Author Share Posted October 13, 2010 Ugh you guys are scaring me Link to comment Share on other sites More sharing options...
robinlsb Posted October 13, 2010 Share Posted October 13, 2010 The 2.5i has a single mass flywheel stock. I had it resurfaced at a machine shop and put it back in. The clutch is already 100% engaged before the noises start, leading me to believe its not the culprit...unless its somehow possible. Here's a better scenario... if I'm cruising at 3000rpm in 3rd, coast down to 1200rpm, then give it half throttle or more, my teeth get chattered out of my skull. I'm gonna go try to loosen the crossmember bolts and see if they give it a little more play. I'm sure those little cushions are probably designed to absorb some of this. I've never seen this problem documented online for anyone else, so maybe I can help someone. The flywheel is out of balance. If the flywheel was improperly mounted before machining, then too much could have been taken off one side. "Belief does not make truth. Evidence makes truth. And belief does not make evidence." Link to comment Share on other sites More sharing options...
Boostin1657615274 Posted October 13, 2010 Share Posted October 13, 2010 The flywheel is out of balance. If the flywheel was improperly mounted before machining, then too much could have been taken off one side. Most likely cause ^. But as far as the pressure plate and flywheel balance marks, there are 3 dowel pins of identical size. the pressure plate can be mounted three different ways, one of the ways would have the alignment marks almost matching. On the search for a new DD... Link to comment Share on other sites More sharing options...
burnout8488 Posted October 13, 2010 Author Share Posted October 13, 2010 :-| I'm not gonna say that doesn't make sense, because it does. My poor body can't afford to take the trans off again. I never noticed the alignment marks, but maybe I didn't look hard enough. Does that jive with the fact that it only happens at low rpm though? You would think that if it's out of balance, it would do horrific things at higher rpms. I was playing around near redline today for quite awhile and she purred like a kitten. Perhaps if its slightly out of balance it's creating a resonance through the drivetrain at precisely 1200-1500rpm? I torqued all the mounting bolts today, didn't change much. I still have an inkling the pitch stop might be f*cked; My friend has an STi one I can throw on to test. Link to comment Share on other sites More sharing options...
jagcars26 Posted October 14, 2010 Share Posted October 14, 2010 The flywheel is out of balance. If the flywheel was improperly mounted before machining, then too much could have been taken off one side. I tend to agree with this as well. Link to comment Share on other sites More sharing options...
burnout8488 Posted October 14, 2010 Author Share Posted October 14, 2010 Another thought: If the FW was out of balance wouldn't it vibrate regardless of throttle position? It doesn't happen unless the throttle is applied to try to accelerate... the engine is still spinning at the same rpm regardless of throttle position. Link to comment Share on other sites More sharing options...
robbie_R Posted October 15, 2010 Share Posted October 15, 2010 Most likely cause ^. But as far as the pressure plate and flywheel balance marks, there are 3 dowel pins of identical size. the pressure plate can be mounted three different ways, one of the ways would have the alignment marks almost matching. They are the same size but IIRC they are different distances apart to only be installed one way. Problem might be linked to load as well though hence why it does it sometimes. Link to comment Share on other sites More sharing options...
burnout8488 Posted October 18, 2010 Author Share Posted October 18, 2010 I flipped around the crossmember bushings in the rear and it seems to have quelled it a little better, still not gone though. http://i24.photobucket.com/albums/c20/burnout8488/damper.jpg Anyone know what that little rubber thing is on the crossmember? Possibly some sort of vibration dampener that went bad? Link to comment Share on other sites More sharing options...
robinlsb Posted October 18, 2010 Share Posted October 18, 2010 Another thought: If the FW was out of balance wouldn't it vibrate regardless of throttle position? It doesn't happen unless the throttle is applied to try to accelerate... the engine is still spinning at the same rpm regardless of throttle position. Umm, no:) "Belief does not make truth. Evidence makes truth. And belief does not make evidence." Link to comment Share on other sites More sharing options...
burnout8488 Posted October 19, 2010 Author Share Posted October 19, 2010 Please explain Link to comment Share on other sites More sharing options...
robinlsb Posted October 19, 2010 Share Posted October 19, 2010 Please explain This may do it better: http://www.hyundaiaftermarket.org/tech/DualMassFlywheel.pdf We are kinda using Ocam's Razor here. The only thing that is new is the flywheel refacing. Presuming that the FW was installed correctly, and all the springs meet the standards, and the clutch is good, then the only thing I can think of is the flywheel is out of balance. This is issue is the same as having disk brakes turned. Many shops just send them out, where they are turned by a CMC machine that has not been checked for accuracy for God knows how long. "Belief does not make truth. Evidence makes truth. And belief does not make evidence." Link to comment Share on other sites More sharing options...
burnout8488 Posted October 19, 2010 Author Share Posted October 19, 2010 Gotcha When torsional frequencies of the crankshaft match those of the transaxle an effect known as torsional resonance occurs, which may cause excessive wear on the drivetrain components. This looks like something I'm just going to have to live with for awhile then. Gahhhhhh. If my harmonic dampener was bad I'd be ecstatic, but that doesn't seem to be the case. Link to comment Share on other sites More sharing options...
burnout8488 Posted October 29, 2010 Author Share Posted October 29, 2010 I'm getting convinced something is definitely broken or installed wrong, I just can't figure out what. Yes, the vibration is still there. But, every mount has been replaced and there is still an awful lot of slop in the drivetrain, with a "clank" under the car at times. I've checked everything it it all appears solid and torqued down. Totally stumped. If there is a secret mount or method I should be doing, someone tell me before I go insane. This car is a chore to drive around, I have to baby it so the engine doesnt flop around and make terrible noises through the firewall. New pitch stop. New trans mount. New x-member bushings. New engine mounts. Link to comment Share on other sites More sharing options...
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