Ok, so I have asked this question before and have tried all of the recommended fixes. Now I am back with more information, but the same question....What is causing this bad vibration in my engine??? I bought a 72 Grabbber with original untouched 302 that had been sitting in a garage for over 13 yrs without being started and moved around. I have done the usual..points,plugs,cap,rotor and wires. I have removed all of the belts and front pulley and that didn't do anything. I pulled the trans after someone thought a bad converter and just installed the freshly rebuilt trans and re-man converter, but the vibration is still there. I checked the flexplate for stress cracks and looked it over real good. The motor has never been pulled out of this car, and it has run like a top from the day I hauled it home. I didn't have to rebuild the carb, or nothin. I just cleaned and sealed the tank, put fresh gas in and it has been runnin great ever since. Could it be a problem still with the firing? Bad coil? or should I just pull the trans back out and replace the flexplate, balancer,distributor, coil, rebuild the carb, and overhaul the motor too??? I am about to go crazy!!! I just want to be able to drive this thing.
Is it an engine vibration or a vibration in the car while you are driving down the road??? Have you checked the original harmonic balancer. Its possible the outer ring has slipped on the hub due to failure of the rubber ring that bonds em together. This will cause a vibration you feel all the time and pretty much at any RPM...Good luck!!!
Will it do it in Park or only driving. What RPM or all the time. Need to narrow it down to what type of vibration or misfire.
I had an engine vibe, and these are what I fixed in the process. Never fixed it, and found it to be exhaust drone. New motor mounts, new trans mount, new trans tailshaft bushing, new u-joints (make sure you get the right ones, one needs bigger caps on two ends), straighten and balance drive shaft, new transmission, new flexplate, new engine (302 to 5.0), new Professional Products harmonic balancer. Verified rear bearings were good, had differential redone to verify no slack or play there. Those are typical places where you "might" get noise and vibes. Mine ended up being the dual flowmaster mufflers droning, and I verified this by putting in an H-pipe last week, which caused the drone to move from 60 mph to 40 mph, but still droning. Hope that helps. Chasing down vibes can be a major pain, and expensive.
When doesn't it happen Ok, I forgot to mention when the vibration occurs.It starts to happen just above idle, and gets worse until about 65 mph, well that is the RPM range anyway. I don't have a Tach in the car. It will do it with the car in any gear and in neutral. When I pulled the transmission out,I bolted the bellhousing and starter back on and started the car up and reved the sh*t out of it and I didn't really notice the vibration, but I did have open manifolds and it was hard to tell anything. That is when I was sure it was the torque converter. It does seem to be a litle worse now that I had re-man trans and torque converter in and i drove it. The driveshaft and u-joints are fine, I checked them over before and after I pulled the trans. No it isn't exhaust "drone" because it is all bone stock with the single pipe with round muffler. I bought this car off of the original owner and they said that the motor had never been out of the car, and other than tune-ups, and a maybe the usual, starter or leaking water pump, it hadn't had anything major done to it.
The neutral part cancels out most of what I was suggesting... Is that neutral while in motion? Could be tires out of balance if so. If neutral while sitting still, then cancel that out as well. I hate engine vibes...
You should be able to distinguish a shake caused by mis-fire from a shake caused by imbalance. If the engine is misfiring, you can hear it out the tailpipe. That should narrow the possible problems for you. I had an imbalance because of a flexplate that didn't have the correct imbalance. Part number indicated a 50 oz imbalance, which was what I needed, but imbalance wasn't right. Replaced the flexplate and problem was cured. Hope that's not your problem.
I had the same problem a few years back...had a vibration which felt like a imbalance which ended up taking out my front seal about 4 or 5 months later. I still had the flexplate from my 250cid behind my 302..had it there for about 5 years with no problems but as soon as I put a new trans and converter in..it started to vibrate...odd! Replaced it and it was gone!
Problem solved!!!!! Thanks everyone for your input. I decided to go ahead with the mount idea and change all of them out since that is the easiest and cheapest fix. I changed the trans mount first and that fixed it. Seems that the mount was bad after all. not only was it the original mount with a Ford part number on it, but it was also bout 1/2" lower than the replacement one because the rubber was so weak.
A short story on weird vibrations. My friend bought a 67 Fairlane that had sat in a barn for at least 15yrs! It was in good original condition,with a 289 automatic. There was nothing wrong with the car when it was stored. My friend went over the car quite thoroughly and it had this vibration,whether being driven or not. It drove him nuts! It was finally determined to be a wasp nest back in behind the harmonic balancer,where you couldn't see it. This was discovered after pulling it off to replace the seal. How this hunk of mud stayed there for well over 6 months boggles me! Strange,but true!
