Bad98SS

The other night i was out cruising in my car and i went to down shift from 3rd to 2nd and it sounded like a bolt may have hit the ground but im not 100% sure, it could have been a rock or something of that sort in the wheel well, anyways after that the car started to vibrate bad. It runs good it doesn't miss and it shifts good, and holds good oil pressure. It does it at idle so i know its not in the drive train. I thought it might be that a weight fell off the fly wheel and put it out of balance so i took the pressure plate fly and clutch to a local shop and they said everything was in balance. So then i thought maybe it could be the harmonic balancer. I have a ProSport underdrive pully and i checked it all out and it seems to be tight and fine and doesn't wobble. I haven't pulled it off the car, would i have to, to find out if it was bad? I really have no idea where to look if its not that. Does anybody have any ideas? Also while i have my ls7 clutch out i was going to upgrade it since it was starting to slip, i have 490 to the wheels and i will be spraying a 150 next spring. Any suggestions on a clutch setup? I have a strange 60 rear end and drive shaft and a tic stage 2 with a tic master cylinder. Thanks

chrisfrost

iTrader: (8)

Have You checked or had checked the wheel balance ,,,,,,maybe a wheel weight popped off or possibly the driveshaft weight came off . Alot of possibilities like a shock bolt loose or missing ,,,,,a sway bar bolt ,,,,,,just about anything to do with suspension bushings or ball joints can cause an out of balance situation .

chrisfrost

iTrader: (8)

Oh it does it at idle ,,,,,it would almost have to be either the flex-plate , torque convertor/pressure-plate bolt missing or the balancer

kenp

iTrader: (9)

Hate to say it, and I sure hope not, but maybe a balancing weight in the crankshaft let loose.

chrisfrost

iTrader: (8)

He definately would have noticed that as the engine would have blown into a few different pieces going different directions ,,,,,,,,,,it's highly unlikely as the crankshaft is all 1 casting ,,,,,,normally

Bad98SS

I have a callies compstar c series crank and eagle h beam rods. I sure hope thats not what it is. All the pressure plate bolts were in and tight. How would i be able to tell if it was the balancer?

chrisfrost

iTrader: (8)

Well if there are no chunks missing and it's not wobbling then prob not balancer ,,,,,,,,so You must have dropped a valve or a push-rod popped out or ,,,,????? what were the rpm's when You were downshifting to 2nd and after d-shifting ? You have forged bottom end then 80-90% that it's valve-train related . Sure hope nothing serious or expensive .

Bad98SS

Had a problem with broken roller rockers manufacture defect they took care of it with no problems.The motor runs fine no misfiring, no codes are on scanner, good oil pressure no engine noise,you can kinda here in exhaust but runs good just has a vibration all the time.Going to put new clutch in it this week and take it for a test drive and see if we can figure it out.Change oil every 2000 miles with valvoline vr1 20/50 race oil it.When the rocker broke you could tell immediately something went bad. I just can not figure it out.

remauto1187

iTrader: (1)

Torque convertor on a manual transmission car?

Since flywheel bolts all checked good it sounds as if its isolated to the engine itself. Look that harmonic balancer over real good. Make sure the outer metal ring hasnt slipped on the rubber inertia belt. You can tell this by looking in from the front AND the rear of the balancer. If the rubber belt isnt completely flat in the space between outer metal ring and the inner hub or if its sticking out further in one area than the rest then it is junk and WILL destroy your bottom end. If that all checks out then its time to pull your valve covers and do a thorough inspection. Lastly but not least....pull the oil pan if valvetrain checks good.

I had a harmonic balancer back in 1997 decide to slip the inertia belt on a 2.8 v6. This resulted in the crank becoming a 3 piece crankshaft. Lots of fun.....on the interstate on my way from Norfolk, Va. to Pensacola, FL. on Thanksgiving. What a day!

k_stewart_21

iTrader: (2)

what was the final result in this? im having the same problem.

chrisfrost

iTrader: (8)

The "Rear" of the balancer ??? Yes I was just naming possibilities ,,,,,,,if You notice I said flexplate/flywheel ,,,,,,,,You had a bad day or something ?

chrisfrost

iTrader: (8)

Being that a rocker arm broke when the vibration started ,,,,,chances are pretty good that also maybe a valve bent or a p-rod or it somehow changed the shape of the 1 spring or could possibly have messed up 1 lobe on the cam and/or a lifter . To break a rocker would have taken a great amount of force ,,,,enough that something else either was messed up at the same time or something else messed up and broke the rocker !