I got asked how to locate a vibration in a car that seems to not exist untill about 50mph then it gets worse with increased speed.
well the first thing you want to do is find if its related to the engine speed (RPMS)or the cars speed over pavement, simply keeping it in a lower gear and running the engine speed up a bit should allow you to determine that as a factor, if its engine speed related, your probably looking at a loose or unballanced damper (harmonic ballancer) or flywheel,(flexplate) or loose torque converter, etc, if its speed related its probably in the wheel ballance, wheel or tire concentracy, or drive shaft ballance, KEEP in mind driveshafts can get twisted or bent, throwing them significantly out of ballance.
it can also be bad wheel bearings, ball joints, tire rods etc. the first step mis to swap the rear tires to the front and vs versa, see if it changes anything, put the car up on 4 sturdy jack stands , and with the engine not in gear or running verify everything looks good in the suspension,u-joints, ball joints, tie rods etc, and spin the tires while holding a strait edge next to the wheel rim to see if it wobbles, if youve got doubts, visit a reputable chassis shop.
these bits of info might help
http://www.leemyles.com/articles/your-d ... ained.html
http://www.machineservice.com/technical.htm
http://www.indiacar.com/techqa/suspension.htm#2
http://www.aamco.com/troubleshooting/ma ... ssion.html
http://www.indiacar.com/techqa/suspension.htm#11
viewtopic.php?f=50&t=609&p=2370&hilit=+problems+throwing#p2370
think mback to ALL the little clues?????
when did the problem start? were there any other things, even seemingly u-related things going on with the car?
example When I was about 19 years old,I once had a high speed engine vibration, and I kept needing to adjust my fan belts on a 400 pontiac firebird I owned , after two days and several adjustments I finaly noticed the front damper was working its way loose moving forward on the crank snout, something I should have noticed faster but thru lack of experiance I didn,t know to check.
example
I had a neighbor who had a bad vibration from about 45mph that got worse as speed increased, only after questioning him did I look closely at the wheels (WHICK WERE BENT SLIGHTLY) after he mentioned running over an unseen speed bump on a private road at 70 mph that had surprised the $$%%^ out of him the week before.
example
had a freind stop by complaining about tire noise, on the lift I found bludging tire sidewall damage, only after pointing it out did he remembered getting drunk and backing the car over the sprinklers, in his yard
IF YOUR GOING TO PUT THE TIME AND EFFORT INT A DECENT ENGINE BUY AN SFI CERTIFIED FLEX-PLATE< STOCK ONES ARE SO THIN THEY CRACK CONSTANTLY IF SUBJECTED TO HIGHER STRESS
the next question that comes up,
("can I re-use my 350 damper and flexplate or flywheel ?")
OEM flex plates are far thinner and more flexible than the SFI certified flex-plates , so they are far more likely to crack and split over time, sometimes a small crack can make a constant banging noise thats hard to isolate , other times it rapidly causes a failure that fairly easy to locate :mrgreen: :roll:
well the first thing you want to do is find if its related to the engine speed (RPMS)or the cars speed over pavement, simply keeping it in a lower gear and running the engine speed up a bit should allow you to determine that as a factor, if its engine speed related, your probably looking at a loose or unballanced damper (harmonic ballancer) or flywheel,(flexplate) or loose torque converter, etc, if its speed related its probably in the wheel ballance, wheel or tire concentracy, or drive shaft ballance, KEEP in mind driveshafts can get twisted or bent, throwing them significantly out of ballance.
it can also be bad wheel bearings, ball joints, tire rods etc. the first step mis to swap the rear tires to the front and vs versa, see if it changes anything, put the car up on 4 sturdy jack stands , and with the engine not in gear or running verify everything looks good in the suspension,u-joints, ball joints, tie rods etc, and spin the tires while holding a strait edge next to the wheel rim to see if it wobbles, if youve got doubts, visit a reputable chassis shop.
these bits of info might help
http://www.leemyles.com/articles/your-d ... ained.html
http://www.machineservice.com/technical.htm
http://www.indiacar.com/techqa/suspension.htm#2
http://www.aamco.com/troubleshooting/ma ... ssion.html
http://www.indiacar.com/techqa/suspension.htm#11
viewtopic.php?f=50&t=609&p=2370&hilit=+problems+throwing#p2370
think mback to ALL the little clues?????
when did the problem start? were there any other things, even seemingly u-related things going on with the car?
example When I was about 19 years old,I once had a high speed engine vibration, and I kept needing to adjust my fan belts on a 400 pontiac firebird I owned , after two days and several adjustments I finaly noticed the front damper was working its way loose moving forward on the crank snout, something I should have noticed faster but thru lack of experiance I didn,t know to check.
example
I had a neighbor who had a bad vibration from about 45mph that got worse as speed increased, only after questioning him did I look closely at the wheels (WHICK WERE BENT SLIGHTLY) after he mentioned running over an unseen speed bump on a private road at 70 mph that had surprised the $$%%^ out of him the week before.
example
had a freind stop by complaining about tire noise, on the lift I found bludging tire sidewall damage, only after pointing it out did he remembered getting drunk and backing the car over the sprinklers, in his yard
IF YOUR GOING TO PUT THE TIME AND EFFORT INT A DECENT ENGINE BUY AN SFI CERTIFIED FLEX-PLATE< STOCK ONES ARE SO THIN THEY CRACK CONSTANTLY IF SUBJECTED TO HIGHER STRESS
the next question that comes up,
("can I re-use my 350 damper and flexplate or flywheel ?")
OEM flex plates are far thinner and more flexible than the SFI certified flex-plates , so they are far more likely to crack and split over time, sometimes a small crack can make a constant banging noise thats hard to isolate , other times it rapidly causes a failure that fairly easy to locate :mrgreen: :roll: