Hey guys....here's the dilema of the week: I just got my C4 auto transmission rebuilt last week and since then I'm experiencing some fairly strong vibrations between around 1500-3000 RPM. I thought I had a vacuum leak somewhere on my stock 302, so I checked with my gauge...nope...it's pulling a steady 18.5, which is about as good as it's ever done. Plugs, distributor, rotor all look ok and not seeing any crossfiring at night. It vibrates like it's a vacuum leak but everything seems ok. No misfiring, popping, sputtering, etc. I started looking into this some and it seems possible that maybe the mechanic could have put the wrong flexplate onto my car, because I've read that this can cause a bad vibration like I'm experiencing. What flywheel is supposed to go on my car? It needs a 157 tooth, 28oz flexplate, correct? If that's wrong, then of course I'll have him fix it. If it's not the flexplate, what else could be causing this vibration?
If it vibrates with the car setting still, not a driveline problem... Vac leaks generally cause a high idle and possibly late shifting if it's being lost near the trans modulator... I'd check the front balancer to be sure it hasn't slipped, otherwise you may be looking at a flexplate issue, especially if it was replaced...
Yeah, it vibrates sitting still. The modulator was replaced in the rebuild. The balancer...no idea if it slipped. Is there an easy way to tell?
exactly if you didnt have that problem before they worked on it its something they either didnt do or did wrong
I had this problem. Was a bad flexplate. It was the correct part number but the balance was off and it shook like crazy. Shake from misfire dimishes at higher RPMs Shake from imbalance gets worse. Why was the flexplate replaced? If you didn't change the engine or harmonic balancer, either the flexplate or torque converter is out of balance.
it could be the torque converter also. i would definitely take the car back to the trans shop to have it fixed
My flywheel was all chewed up and wasn't replaced when the motor was rebuilt and I didn't know about it until the torque converter almost came off of it and I took it somewhere that told me about it. This new shop that did the transmission rebuild replaced the torque converter (the old one was damaged) and replaced the flexplate/flywheel too. They haven't touched anything else on the motor, from what they told me. It's back at their shop right now. Last I heard today, after the mechanic drove the car, he put a strobe on the rear wheels and found my driver rear to be bent. He said all driveline parts look really good and properly aligned, mounts look good, etc. He said his guy that ordered the parts will be in tomorrow to double check what was ordered and put in with the rebuild, but so far he says it seems like something with the motor. Got any more ideas? Slipped balancer, vacuum leaks, misfires have been mentioned. Can you think of anything else that would give me bad vibrations (while sitting still) between 1500-3000RPM with the worst of it being around 2000-2500? If the harmonic balancer is bad, will one of these work? My 302 is stock so I don't need a racing balancer. Can you think of anything wrong with these? http://www.summitracing.com/search/...mmit-racing-oem-harmonic-dampers?autoview=SKU http://www.oreillyauto.com/site/c/d...lancer_1132119_1913&keyword=harmonic+balancer http://www.autozone.com/autozone/pa...ick/_/N-iq4ocZ93y2h?itemIdentifier=155381_0_0_
The suspense is killing me. No word yet about the problem from that shop. Any advise for getting a new balancer if mine is indeed shot? Are those that I listed above ok or do you have other suggestions? Thanks for all your help!
odds are they put the wrong flex plate on the motor. its an easy mistake to make and would cause your problem.
Got the car back on Friday night. The mechanic did confirm that the right parts were used and that everything looked good. He said that he thinks the carb is running too rich and that it might be the power valve or some junk plugging a passage or something along those lines. Sound right? Would these problems cause my car to run really rough between 2000-2500 RPM without giving me misfires, popping, sputtering,etc.? Could it be the plug wires? I'm wondering if maybe they didn't pull a plug terminal loose when removing the exhaust manifold to get the tranny out. Could a bad wire give me this problem?
