YAY! Another Vibration Question!

[MasterFrmMO88]

Let me take this moment to apologize beforehand for yet ANOTHER vibration question.

About two weeks ago my clutch started slipping. I figured this day would come because when my ACT 2600 popped a spring awhile back I only had enough money to put a stock clutch in it. So I got myself a new 6 puck and spent friday putting that in. For all intents and purposes, the engine was running great before that. It was rebuilt less than 1000 miles ago by yours truly and everything was changed including (the important part) the b/s belt and everything was properly timed.

The second I got everything bolted back up and was pulling out of the garage, I noticed a vibration seemed to have developed that definitely wasn't there before. It only happens between 2500-2800 and only under load. It wont vibrate on clutch in or in neutral. The best way I can describe said vibration is it feels like I'm running solid mounts.

Now I'm not car illiterate so I got the car back up on the lift and started shaking my exhaust around thinking maybe it was rubbing someplace but to no avail. Next, I double checked all the mounts and they seem to be good. The only other two possibilities I can think of would be the flywheel/pressure plate is out of balance or the b/s belt broke. The questions I have are has anyone heard of a new b/s belt breaking and what is the likelihood it would have done so when the engine wasn't even under much stress? Or what would be the chances that its the flywheel/pressure plate? When I got the old clutch off I noticed the ring on my fidanza has a groove in it so I pulled the ring off to resurface it and decided there wasn't enough material on it to try to grind it down. Would it be possible that putting the ring back on in a different orientation could cause enough of a balance problem to do this much vibration at lower rpm?

Again, sorry for yet another one of these but I wouldn't be asking it if I wasn't completely stumped on this one. I'm also looking for other suggestions that I might have overlooked.

Thanks.

 

[XiKeiyaZI]

To check on the BS belt you're going to have to go ahead and remove the crank pulley and remove the bottom bolts of the timing cover. Pull the timing cover back and bit and check it. Or, if you're cheap, drill you a view-hole in the side of the timing cover.

Another thing it might be : Did you have the flywheel resurfaced before the new clutch? Some people swear by this, some don't. It's something to consider, however, as you're experiencing this after installing a new clutch.

 

[MasterFrmMO88]

Well, I pulled the timing cover and the b/s belt is still okay. The other bs is run by the timing belt so that's obviously not the problem because the oil pump is about the last thing I would suspect of jumping timing, especially on a start.

On two other notes though... I did not have the flywheel resurfaced because I didnt have the time to. I live 200 miles away at college and I was only going to have the weekend to work on the car and didnt have the time to get the flywheel resurfaced. At the same time, I have changed the clutch before with the same flywheel without a resurface and it performed okay. There is the whole issue possibly with me removing and re-installing the ring at a (most likely) different orientation but given the nature of the components, I didnt think that would matter.

The second note would be, it does sound like my exhaust note has changes. On clutch in, my exhaust sounds a lot deeper and more hollow if you will. But I cant think of a single reason this would have changed. The only thing I did remotely relating to aspiration is I removed the J-Pipe for better access to the shift linkage and put a new gasket on it when I replaced it.

After looking through everything a little more, there does seem to be a decent chance that my front tranny mount may be shot. (Let me see if I can explain this so it makes sense.) If you take a line and draw it through the diameter of the mount that the bolt that goes through the center of the mount will travel when the engine flexes (for simplicity I'll say its straight up and down) The bolt rests at about 1/3 of the way up that line. Now given that this particular mount is meant for engine roll more-so than weight, it would seem to me it should be resting in about the center. The reason I point this out now is because it hadnt occurred to me at first, but I noticed a day ago that there is VERY little clearance between the tranny and the cross member that motor mount bolts to. So understanding that when the engine is under stress, it may torque enough to rub up against that cross member and vibrate the frame of the car. Now, after all that explanation, can anyone confirm or deny my suspicions in thinking that mount may be shot?