stangtrader

iTrader: (2)

Hey guys took my ls6/th400 swapped 93 mustang for about a 40 mile cruise last night.after I get above 45mph the car gets a drivetrain vibration thats obnoxious. It almost seems like its caused by the motor because the vibration pulsates at 55 and goes away when off the throttle.never experianced this in a car with solid mounts so I dont know why it would with the aje kmember and poly bushings.
driveline is also brand new and balanced.your guys thoughts would be great
thanks

HioSSilver

iTrader: (8)

I think the poly mounts do it.

stangtrader

iTrader: (2)

It seems way to harsh to be poly mounts.its not a light vibration. Its pretty heavy I know there will be vibration but its almost unbarible to drive at freeway speeds for more than 10 minutes.im wondering if my pinion angle was off enough it could cause it.

Docked Wage

Sounds like you are on the right path by considering the pinion angle as the root cause.

stangtrader

iTrader: (2)

that's what im thinking.im gonna go buy a angle gauge here shortly and check it.probly need to buy some adjustable uppers

BayArea ws6

Probably not the poly motor mounts . I run them with no issues , they only were an improvement over the worn out stockers .After I threw a moser 9 " all hell broke loose cause of my drive shaft and pinion angle being off .Bad vibrations that get worse at highway speeds .

stangtrader

iTrader: (2)

Out of curiosity did they go away in neutral and when you let off the gas? Under a hard pull its fine but cruising at 55 is a little brutal

ijimmy

yes it does , unfortunately i have expedience the same , when you let off gas it stops , with the car on the groung measure your pinoin angle and tailshaft angle , and see how they compare , sould be equal , and opposite

JetMech442

iTrader: (1)

I agree, the throttle required to maintain 55 might be just enough to make the pinion climb out of range and hit a vibration sweet spot.

I also made sure my engine was pointed 2* down to help facilitate, and then my adjustable uppers helped set the pinion the opposite amount.

stangtrader

iTrader: (2)

Measured pinion angle just now.measured with the driveline in but measured from the yoke and balancer due to them being on the same centerline.both measured to 5 negitive then I measured at the driveshaft flange on the dif and got 1 degree positive.im gonna step out here on a limb and say the 4deg is the problem.im going to recheck at work on my alignment rack and start by shiming the trans up

gofastwclass

iTrader: (2)

Some helpful information on driveline angles.

stangtrader

iTrader: (2)

Awesome thank you.im gonna shoot for 1 degree negitive on the trans and that I think should work great.now if only my tuning cable didnt eff up tonight