rjdavis2001

iTrader: (1)

I recently rebuilt my rear susp. on a 1991 Firebird Convert, with all new Energy Suspen. Bushings, Including the Torque Arm and new bolts, shocks and springs, LCA bushings and Rod, Now before the rebuild the 9 bolt posi with 3.27 gears ran fine, no whines or howls, but after the Susp. rebuild the rear-end howls on hard acceleration only, but regular acceleration and coast its fine, now the torque arm bushing was toast So I replaced it with a new engery susp. bushing, and the trans mount was replace with a stock rubber one for now. Any Advice as to what went wrong?

PS at 60MPH the car now shakes untill I get to a lower speed, Is it possible I F%*ed up the driveshaft somehow, I never took it out?

Any Help?

Drew

iTrader: (58)

More likely you had the problem before you changed the bushings, and it only became more evident after stiffening the mounts.

big gear head

Harder bushings will transfer a lot more noise into the car. The noise was probably there before but you couldn't hear it untill you installed the harder bushings.

rjdavis2001

iTrader: (1)

Thanks guys for the advice. But will this also make the car shake at 60 and above? I just overhauled the front susp. With the same engety susp and HD it aligned. Is it possibe that I need to have the car realigned again?
To get the shakes to go away. Or is it possible I need new u. Joints to compinsate for the new rear susp?

Drew

iTrader: (58)

Changing the bushings won't cause an imbalance. It'll just make it more obvious inside the car. I'd start by having the wheels balanced. While you're at it inspect the tires for unusual wear patterns. If the vibes continue, take a look at your driveshaft. If it's steel, you may want to get it balanced and install new U-joints, or get an aluminum driveshaft and have it overhauled in the same way.

TZFBird

Your pinion angle is incorrect. Do a search here or on google for checking pinion angle and there are diagrams for what angles you need where. I have the same problem and am waiting until it's above 15* in the garage to get something done about it. It's amazing how sensetive it is. Not sure about the whine, I suppose if the U-joint is going bad it may make some noise. I'm about 3* off and the car is very skiddish above 60mph.

You can pick up an angle finder for about $20 most places. There is not really any room for change where the arm bolts to the rearend, but the bushing you replaced maybe moved the arm up or down from where it was before. I'd start by looking at that.

**EDIT** I just read another thread about the Energy Suspension transmission mount. Something about a plate that goes under the mount that ends up raising the tail of the trans? I'd try taking that out first to see if it makes a difference.

JamesC

iTrader: (5)

Many members have complained about vibration and the ES mount. How severe that vibration is, I'm unsure. The mount would be an cheap/easy first check. At the very least, checking would eliminate the mount as a possibility.

JamesC

rjdavis2001

iTrader: (1)

Agian thanks for the input, Maybe im not explaining right, here are the facts:

1. Rebulit rear LCA's and back Tie-rod end or bracebar with Energy Susp. Bushings, Pressed in and greased really well.

2. Old Torque Arm Bushing was original and shot, drilled out the old rivits and plate and installed and Energy Susp. Bushing and torqued to proper specs.

3. When replaceing the Torque arm Bushing, I noticed the Trans Mount was starting to Crack, Replaced it with a STOCK RUBBER MOUNT.

4. New Coil Springs, (correct Hieght), Along with Coil Spring upper Mounts, from the dealer, and correct hieght, and new shocks.

5. The car had no noise or vibration before the rebuild. now only on hard acceleration, the backend seems to groan from the rear-end.

6. On normal accel. and cruise/coast, is quite as a mouse, no noise.

7. Vibration at 60 mph and above.

have reviewed replies so far and some great advice, so from what im hearing, could be wheels out of balance, Had checked this morning and are balance correctly.

Possible out of balanced drive shaft? need to pull and have inspected.

Or Pinion Angle bad? Have no idea on how to fix, Im very Mech. inclined but seams like a mess if you ask me, maybe I should have left it alone, (not lol) anything ele I can check as the factory service repair book has no advice??

Thanks again for all the input....

rjdavis2001

iTrader: (1)

any new reply guys?

Drew

iTrader: (58)

Well, your pinion angle in the stock suspension isn't adjustable. If you haven't changed the position of the transmission or the rear axle, that diagnosis doesn't apply.

If you've balanced the tires and it's still there, I'd be looking at the driveshaft.

PV9685

Which transmission mount did you use? The "stock" ones they sell at Autozone are cheap and at least a 1/4" thicker than STOCK. They Definitely mess with the angle - perhaps they figure the springs have sagged by the time the mount is replaced lol! I put an autozone one in mine but I filled the cavities with Polyurethane just to help stiffen it - I like the idea of a rubber mount for the engine/trans but believe they should be solid rubber with no gaps. So I fill gaps with poly.

rjdavis2001

iTrader: (1)

ya, im having the ujoints installed tomoroow, they have never been replaced. I would do it, but have no idea on how to remove them LOL, once there replaced im also haveing the driveshaft balanced, then will see what happens