Horrible Vibration need help

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nasty69

nasty69

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just wondering if you guys have ever come across this problem before.. got the car broken in and most of the bugs worked out. but everytime i get around ..4000 rpms and up which would be 60 plus.. there is a mad vibration coming out of , it seems to be the front end..not really sure though. a friend of my has a 73 4 dr granny green nova with a 355 lingenfelter and says he has the same problem.. hes not sure either, thinks it maybe suspension.. i have no clue but i would like to hear if this has happend to you guys and help would be very much appreciated:clock:
 
Do you get it at 4000 in any other gears/ speed. If you only
get it over 60 mph. I would say it might be tires out of balance.
If you get it at slower speeds, but same rpm's, it could be
drivetrain related.
 
nasty69

Most of the time if the vibration is in the front end (front tires or suspension) the steering wheel will "rock" side to side.

If the vibration is rear tires or a driveline problem, you will feel it in the seat, rear view mirror, console, floorboard, sometimes a "roughness" thru the steering wheel, but not side to side rocking.

Also, does the vibration go away at higher rpm's or speed?
 
to answer you both.. its in 3rd gear all the time i've tried it at same rpm in 2nd gear and no problem it does feel like a roughness through the steering wheel. i assume it was the front end but the wheel does not rock side to side. Also had the tires and wheels mounted and balanced roughly a year ago . the assistant manager mounted and balanced the wheels right there in front of me and " kinda acted like he knew what he was doing" lol ...
 
Does it vibrate at 4000 in neutral? Take it up there and 3rd, hold the revs and push the clutch in and see what happens.
 
Is this an automatic or manual tranny? I missed that part.

Also, when you tried it in 2nd gear did you reach 4000 rpm or 60 mph?
 
sorry guys i didn't fully inform you..my fault here is my setup ..
360magnum crate motor
390hp, 425tq.
8.5 comp.
m1 intake
750 holley vs, as per suggested by mopar
tti headers
727 with shift kit
shortened aluminum driveshaft by houston driveline
dana 60 with 3.55
spintech mufflers.
spring reloc. kit
subframe connectors
built with the help of body men from out shop
G&G Collision , Rosenberg, Tx

i haven't not yet tried to throw it in neutral at that rpm yet . that would be kinda half *** smart lol. i just got out of the hospital due to extensive follow up surgeries due to a bad bike wreck that totalled my sportster and myself back in 06. we have had the valiant for roughly 10 years and after the wreck i needed somthing to keep me busy . and my dad wants me to stay off motorcycles so out comes the valiant lol. surgeons will do a major hip sugery in a month or so . but im back on crutches and on pain killers.. doc says to stay away from the wheel of a car.. although i do get my dad to drive it and see what he thinks.almost forgot. speedo cable not hooked up . 3900 rpms is a tad over 60 mph. i appreciate all the help guys.. really
 
Spin balancers run a set rpm that equals 50 to 70 mph depending on tire diameter. I thought it had tossed a wheel weight which happens all the time. Turns out I have 2 bent steel wheels. Placed both on the rear to keep the vibration out of the steering wheel. Shakes pretty bad from 65 on up.
 
What kind of flex plate and converter are you running? Did you use the B&M balanced flexplate with a unweighted coverter?
 
I believe the magnum crate motors are balanced the same as an LA 360 but it is certainly worth checking. If you are using a flex plate or torque converter that is balanced for a magnum engine that may be the issue.

Also, when I first put my Barracuda back on the road I had a terrable vibration during right turns that I couldn't track down until one day I was pulling on the shifter to reposition my but and I made the vibration. Pulling and pushing side to side made the vibration come and go regardless of whether I was turning or going straight. I am using a long tail shaft A833OD in the car and it turns out that one of the bosses for the front shifter mount only had a 1/16" or so of clearance to the torsion bar cross member and when making a right turn the engine would move in the mounts just enough to touch the crossmember, couple bangs on the cross member with a BFH and all was cured.

What I was getting at look real close for any part of the engine or tranny being close to any part of the body, if they touch it will send a vibration through the car like you wouldn't believe.
 
63dartman said:
What kind of flex plate and converter are you running? Did you use the B&M balanced flexplate with a unweighted coverter?
Click to expand...
dartman ..if im not mistaken senor and will have to check my receipts but i believe he flexplate is b&m and the converter is horrible. i even feel bad for saying this to you guys please dont hurt me lol the stall is redonkulous something like 1900-2300 lol which will be changed pronto. and i think they are for the crate motor which comes prebalanced if im not mistaken..
 
dgc333 said:
I believe the magnum crate motors are balanced the same as an LA 360 but it is certainly worth checking. "If you are using a flex plate or torque converter that is balanced for a magnum engine that may be the issue"
Click to expand...
why would components for a magnum engine be the problem if it is a magnum engine??
 
Like was said in your previous post.Take the car out of gear when the vibration starts. This should eliminate the entire driveline.

I have had rough wheel bearings cause vibrations,but it was only in corners. And bad U joints are a source of vibration that can be hard to find.

I had a 76 Feather Duster that had a horrible vibration at 60 mph. Turns out the original ujoints had turned to powder!
 
It's amazing how bad u-joints will get and still keep going, vibration, noise and all.
 
alright guys i appreciate the help, im out the door now that the pain killers have worn off..:cheers:
 
Just curious what size tires put you at 3900rpm @ 60mph with 3.55 gears?
 
nasty69 said:
why would components for a magnum engine be the problem if it is a magnum engine??
Click to expand...


Because if I am not mistaken the MP catalog says they balanced the engine using the LA factors. I guess the reason is they are selling these engines to go into older cars and wanted the flywheel, flex plate/torque convertor that was balanced for a LA 360 to work.

I may be wrong about this but I would check.
 
mod5v said:
Just curious what size tires put you at 3900rpm @ 60mph with 3.55 gears?
Click to expand...
lol well i forgot to mention that earlier but they guy who put the take in for me as a favor that was owed..i guess they're is some type of adjustment b/c i know its not right ...is there some type of adjustment if you pull it apart or some pins somewhere.. but im runninb 225/45/17's in back and 245/45/17's in back
 
Your tach must be way off. I ran the numbers on the Moparts rpm calculator and you should only be running about 2900 rpm give or take a little. Most tachs do have a switch inside them to switch from 4, 6, or 8 cylinder. Maybe it's set wrong.

If you can get someone to jack up the back end and put it on jack stands and run it and you'll see if the vibration is in the drivetrain or steering. If it don't vibrate with the rearend off the ground running 60 plus mph it's definitely in the steering.
 
fishy68 said:
Your tach must be way off. I ran the numbers on the Moparts rpm calculator and you should only be running about 2900 rpm give or take a little. Most tachs do have a switch inside them to switch from 4, 6, or 8 cylinder. Maybe it's set wrong.

If you can get someone to jack up the back end and put it on jack stands and run it and you'll see if the vibration is in the drivetrain or steering. If it don't vibrate with the rearend off the ground running 60 plus mph it's definitely in the steering.
Click to expand...
yea thanks for the input, ****** must have hooked the tach up wrong. which makes me real uncomfortable when mash the loud pedal.ill probably get a few cups a joe in me this morning and run it up to the body shop if the guys aren't to busy and see what i can come up with.. thanks for the input i really appreciate it, and ill fill you guys in on whats goin on
 
hey fishy68 could you calculate a 65Dart w/323gears and225/70/14 rearswhat rpm@60???thanx
 
65DrtGT said:
hey fishy68 could you calculate a 65Dart w/323gears and225/70/14 rearswhat rpm@60???thanx
Click to expand...

The chart I have shows 2665 rpm at 60. That is for a car with an automatic and corrects for the torque converter slippage. I think it uses 8% correction which is pretty loose. Most stock converters don't slip that bad. Usually 5-6% is plently to account for it. If you have a manual trans. it will be 2467 rpm.

Here's a link to it. You can play with the parameters yourself. It even shows you what speedometer gear to use with different gears.

http://www.moparts.org/Tech/tech/img/AUTOMATICchart.xls
 
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