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drive train vibration.HELP

Posted By: dynamite

drive train vibration.HELP - 02/15/10 02:41 AM

I have a bad drive train vibration from about 2800 rpm up..Heres what i've done..it's a 440 with t-flight,8 3/4rear..motor is smooth in neutral. I have 2 converters.stock and 3000 stall.no change..stock drive shaft,and 3 + inch shaft custom made and both balanced as I had to have them stortened for my install.I have 2 center sections for the rear, one has 3:91 gear the other 2:76 open for road trips..that was the original 741 chunk that came with the rear housing, the other is a 489 with posi.Vibration with any combo is at 2800,tires balanced a few times plus another set,plus the Hoosiers.I'm out of things to try..feels like drive shaft type of vibration.I have gone from down 2 dg to o dg to up 2 dg on the pinion angle.Any ideas ???PLEASE READ MY LAST POST FOR THE RESULTS ..VIBRATION IS ALMOST GONE,THANKS EVERYONE FOR YOUR HELP.

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Posted By: OzHemi

Re: drive train vibration.HELP - 02/15/10 02:46 AM

How is pinion angle ?
Posted By: OzHemi

Re: drive train vibration.HELP - 02/15/10 02:48 AM

Oh, you must have added that bit..
Posted By: MoparforLife

Re: drive train vibration.HELP - 02/15/10 02:49 AM

Quote:

How is pinion angle ?

Read his Original post.
Posted By: 1hot68

Re: drive train vibration.HELP - 02/15/10 02:53 AM

Is the exhaust mounted ridged or with good rubber hangers? Is it hitting anywhere?
Posted By: FurryStump

Re: drive train vibration.HELP - 02/15/10 02:59 AM

tail shaft bushing?
Posted By: dynamite

Re: drive train vibration.HELP - 02/15/10 03:01 AM

Sorry OZ did edit that in.. with exhaust or just the headers ,,still there
Posted By: Paul

Re: drive train vibration.HELP - 02/15/10 03:02 AM

Possibly a bad bushing in tail shaft?
Posted By: 1hot68

Re: drive train vibration.HELP - 02/15/10 03:03 AM

engine mounts arent sagging? The headrs have any contact with the block? even just a little contact will be felt in a unibody car. What car is it?
Posted By: BigTerry

Re: drive train vibration.HELP - 02/15/10 03:09 AM

cracks in the flywheel?
Posted By: DoctorDiff

Re: drive train vibration.HELP - 02/15/10 03:10 AM

Many things can cause a driveline vibration:

Too much downward pinion angle will cause a vibration on deceleration.

Too much upward pinion angle will cause a vibration on acceleration.

Driveshaft run out

More than 1" slip yoke (internal) stand out

Less than 3/4" slip yoke (internal) stand out

Sloppy fitting slip yoke bushing

Sloppy fitting slip yoke splines

Sloppy fitting U-joint saddles/missing clips

Solid motor mounts

Poly transmission mount

Loose pinion yoke

Engine/bellhousing alignment

Torque converter/vibration damper balance

Exhaust grounding out on body

etc...
Posted By: dynamite

Re: drive train vibration.HELP - 02/15/10 03:11 AM

Not an exhaust problem..headers don't touch anything..vibration is there with the rest of the exhaust system off,for a 1/4 mile run..and yes it runs faster with the exhaust on.Car is my 1956 Plymouth you have seen here a lot.

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Posted By: OzHemi

Re: drive train vibration.HELP - 02/15/10 03:11 AM

Quote:

Quote:

How is pinion angle ?

Read his Original post.



He changed it, was not there originally...that is the first thing that came to mind with his going over other issues he has checked on..
Posted By: dynamite

Re: drive train vibration.HELP - 02/15/10 03:16 AM

DR Diff ...the vibration is there at a constant speed.. not only on accel or decell.just crusing at a steady 3000 rpm or so.

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Posted By: OzHemi

Re: drive train vibration.HELP - 02/15/10 03:20 AM

Does it change if you put the car in nuetral at that speed ?

Maybe it's an issue in the engine or trans ? (if it does it at 3000 rpm in any gear lets say)
Posted By: DoctorDiff

Re: drive train vibration.HELP - 02/15/10 03:22 AM

What angle is your pinion centerline at rest?

What angle is your transmission centerline at rest?

These angles should be a couple degrees within parallel.
Posted By: dynamite

Re: drive train vibration.HELP - 02/15/10 03:31 AM

DR diff..righr now it is as close to zero as I can get it..Drive shaft when first made for me was a hair too long and was hard to get in, but once past the yolk it still had about a half inch play..I took it back and had it shortened another 3/4 inch..it had the vibration both ways..no change
Posted By: dynamite

Re: drive train vibration.HELP - 02/15/10 03:35 AM

OZ HEMI.. yes the vibration is there if I put it into neutral at that speed..trans bushing thing may be my next thing to check..Thanks Jeff
Posted By: OzHemi

Re: drive train vibration.HELP - 02/15/10 03:46 AM



Be interesting to get the car on a chassis dyno so you could look under it at speed and see if you can see anything moving, feel for vibration at different points,etc...

Aside from what Cass said about angles...are the u-joints in good shape too ?

Cracked flexplate maybe on a long shot ?
Posted By: RapidRobert

Re: drive train vibration.HELP - 02/15/10 06:24 AM

Not moving it is smooth @ 2800 in neutral right? I gotta go w driveshaft related as you originally mentioned. ujoint/shaft/yoke/angles
Posted By: Magnum

Re: drive train vibration.HELP - 02/15/10 09:41 PM

How about the front u joint angle and the centering of the entire drivetrain viewed from above?

Check the runout of the tires AT THE TREAD with a dial indicator.
Posted By: dynamite

Re: drive train vibration.HELP - 02/15/10 09:59 PM

I found a broken left motor mount..Guess the safty chain held it down, and I didn't know it broke,..but it wasn't broken when first installed,and it had the vibration..I'll get to it tomorrow..let ya'll know..

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Posted By: RapidRobert

Re: drive train vibration.HELP - 02/15/10 10:02 PM

Quote:

I found a broken left motor mount..Guess the safty chain held it down,

too much horsepower
Posted By: dynamite

Re: drive train vibration.HELP - 02/15/10 10:05 PM

No such thing as too much !!!!!!

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Posted By: Lefty

Re: drive train vibration.HELP - 02/16/10 01:59 AM

Quote:

but it wasn't broken when first installed,and it had the vibration



Here is some good info - go to page 4

http://www.reillymotorsports.com/ABAR20600.pdf
Posted By: dynamite

Re: drive train vibration.HELP - 02/16/10 01:32 PM

Thats some good info there, thanks Lefty
Posted By: MO_PA

Re: drive train vibration.HELP - 02/16/10 01:51 PM

The ball bearing, in the extension housing, that carries the tail shaft could be the culprit...ask me how I know. Another annoying vibration can be caused by an axle bearing. Other bearings that cause vibrations are the carrier bearings.
Posted By: dynamite

Re: drive train vibration.HELP - 02/20/10 05:22 PM

OK,a week has gone by and I have done everything mentioned and then some ..The vibration is definatly in the drive train..I replaced the broken motor mount.Nothing is touching or rubbing..the vibration gets worse when I get to 3000rpm and shift into neutral..worse than a normal decell in gear.Reving in neutral the motor is smooth as can be..even when decell in neutral and reving to 3k it does not effect the vibration..Now I am going to shim it up 2 dg to see if that helps..I have raised the rear trans mount for o dg coming out of the trans . I'm getting tired of this already..Just shoot me..

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Posted By: MY340

Re: drive train vibration.HELP - 02/20/10 05:33 PM

Sometimes you definitely have to play with pinion and transmission angles to rid of pesky vibrations.

On my 1973 Duster 340-4spd-4.10 gears I used 3 degree pinion shims in the rear and a 1/4" spacer up front to raise the tailend of the tranny.

Good luck!
Posted By: MI_Custumz

Re: drive train vibration.HELP - 02/20/10 11:29 PM

Revving in neutral the engine is as smooth as can be.........is that parked or rolling about 50mph?
Posted By: dynamite

Re: drive train vibration.HELP....UPDATE !!! - 02/22/10 12:55 AM

BOTH,parked or at 50 mph...But I'm zeroing in on the problem ...I'll keep you posted..THINK TRACTION BARS.. HERE's THE DEAL--THE TRACTION BARS I HAD ,HAVE THE SPRING PLATE AS PART OF IT..SO THE U-BOLTS BOLTED THRU THE TRACTION BAR ITS SELF..THUS TORQING THE REAR SPRINGS AND NOT LETTING THEM FLEX..I INSTALLED STOCK SPRING PLATES AND 75% OF THE VIBRATION WENT AWAY..NOW ALL I HAVE TO DO IS UNDO ALL THE SPACERS AND SHIMS AND GET EVERYTHING BACK TO WHERE THEY BELONG..DID SOME ALIGNMENT TODAY AND IMPROVED THE VIBRATION SOME MORE..GOTTA UNSPACE THE REAR TRANS MOUNT TOMORROW ...WILL KEEP YA'LL POSTED..Thanks for all the help guys..

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