Bad Vibration @ 85 MPH

[Badasp5.0]

So I got my car back on the road and it has a very bad vibration @ 85 on acceleration and also on deceleration. It happened with 2 different set of wheels, new U-joints, new clutch, pilot bearing, bearing retainer, 2 different driveshafts. I did check my motor and trans mounts they look good and are newish ploy mounts. Its weird because its smooth before that mph.

Any ideas?

 

[Oceanside78]

Brake rotors good? I had similar issue when I towed a trailer with my Titan and warped the rotors. Had no vibes until 70. Then it vibrated the car slightly and the steering wheel. New rotors cured the issue

 

[Bad03gt]

I'm having the same problem but at 80 mph. Someone told me its my driveshaft out of balance. We will find out this weekend.

 

[mr-proper]

did you changed the stock gears? if you did , you need a aluminium driveshaft to get rid of the vibration,

 

[NickF1011]

did you changed the stock gears? if you did , you need a aluminium driveshaft to get rid of the vibration,

:??:

I ran a stock driveshaft on mine for years after swapping gears with no vibrations.

 

[SVTurbo]

If you're using aftermarket or adjustable rear control arms, check the pinion angle with respect to the driveshaft. If the angle is off at rest then it will be even worse under load leading to vibration.

 

[Badasp5.0]

did you changed the stock gears? if you did , you need a aluminium driveshaft to get rid of the vibration,

Its had 3:73s in it for about 10 years with the stock drive shaft. I did recently put aftermarket control arms. I may have to swap to stocks and see what happens.

I was also thinking it might be wheel bearings.

 

[bornatiger]

How do I check pinion angle? I just installed MM LCA's and had 4:10 installed. I've had a vibration for a long time but now its more pronounced.

 

[mustangsvt281]

How do I check pinion angle? I just installed MM LCA's and had 4:10 installed. I've had a vibration for a long time but now its more pronounced.

i have an alm driveshaft with 4.10s and i still have bad vibrations. I am replacing my control arms this weekend and putting in rear coilovers to adjust height. hopefully this will correct my pinion angle problem.

 

[D2Fresh16]

Most def pinion angle. It's a total pain in the ass to get it right. I'm still trying to dial mine in perfectly.

 

[bornatiger]

Most def pinion angle. It's a total pain in the ass to get it right. I'm still trying to dial mine in perfectly.

How do you check and adjust your pinion angle?

 

[Bad03gt]

My pinion angle is spot on but there is a ring cut into my driveshaft near the trans

 

[Badasp5.0]

I have been noticing a bad squeal/squeak coming from the rear end so I am assuming its wheel bearings. They have never been replaced.

 

[tistan]

OP you need to ditch the urethane trans mount, and put a stock rubber mount back in. They are notorious for causing vibrations. Second you need to fix the runout on your driveshaft. You need to mount a dial indicator with a magnetic base so that the indicator is on your driveshaft and then spin it. Mark the high spot and write down the measurement. Then take the bolts out of the pinion flange. Keep the pinion flange where it is and turn the drive shaft a quarter turn. Install bolts and remeasure then do it a total of four times. Leave it in the position with the least amount of runout, and make a mark on the drive shaft and the flange for future reference.

 

[GotJuice96]

Mine does the same when I'm at about 85-95 ish it sucks It vibrates terrible :/
Badasp5.0 let me know what it is when you figure it out =]

 

[Badasp5.0]

OP you need to ditch the urethane trans mount, and put a stock rubber mount back in. They are notorious for causing vibrations. Second you need to fix the runout on your driveshaft. You need to mount a dial indicator with a magnetic base so that the indicator is on your driveshaft and then spin it. Mark the high spot and write down the measurement. Then take the bolts out of the pinion flange. Keep the pinion flange where it is and turn the drive shaft a quarter turn. Install bolts and remeasure then do it a total of four times. Leave it in the position with the least amount of runout, and make a mark on the drive shaft and the flange for future reference.

Interesting. I really don't think its the Trans mount since that has been on the car for years with out a vibration. The runout is something I havent heard about before.

 

[Bad03gt]

Got my problem fix..... I had to replace my clutch cable cause it broke.... I have no more vibration... And I'm not lieing!

 

[nckissfan]

my car gets a slight vibration around 80, not less that that, and when you get past that, it goes away. It is not a bad one, just something I feel in the gas pedal.

 

[YellowSVTCobra]

Has any one figured out the issue. Mine just developed this issue. at 80 feel a vibration in the gas peddle.

 

[Twisted2]

Has any one figured out the issue. Mine just developed this issue. at 80 feel a vibration in the gas peddle.

My old five liter did the same thing. Anything faster or slower was fine. Kind of had this rhythmic gyration kind of vibration. It was that way before and after a gear swap, motor mounts, and flywheel resurfacing. Never figured it out...just tended to drive faster to shut it up.