Still having vibration issues..

[GodAmGT00]

I guess I'm bringing this one back from a few months ago.. I need answers, hopefully someone can help..

I have a long story that goes along, that has a lot of insight, so please bear w/ me..

All started 2-3 years ago... I had to get the rear diff rebuilt since the whirring was terrible. Turned out to be an axle seal went bad, and I lost all the fluid over the course of a few months..

Well, shop rebuilds the rear-diff, but incorrectly. It slightly damages my 3.73's but as long as my Eaton LSD is fine, I don't mind a little gear noise.. Problem is, ever since then, I've had the vibration coming from what seems to be the middle of the car..

Fast forward to last Fall. Since I was sick of the noise, and it seemed to get slightly worse, I brought it to a good friend who took a look.. He recommended U-Joints. initially, since he didn't really get dirty that day.. After swapping them, I notice the vibration is a little worse.. He gets back under the car w/ me, and sees the tranny mount is trash..

I replace it. Most of the vibration is gone, but it's still pretty bad from 50-85mph, then it goes away. Gear noise is still present, so I re-shimmed my rear-diff. Noise is still there...

So.... Recently, I got a bunch of money, and decided to do the right thing.. Replace my entire suspension. Well.. No dice.. STILL have vibration, and I think it's causing the pinion seal to separate from the housing, and I'm getting a little oil spray right about the diff..

I replaced the U/LCA's, Shocks/Struts, Rims/Tires, Tie-rod ends, brakes, wheel bearings, hardware etc.. I mean, the only things original about my car are the engine itself, driveshaft and the paint on the rear of the car...

So I searched for rear-axle alignment, to see if maybe that is off. How does one go about aligning a solid rear axle?? Is it all toe-in/caster adjustments??


Any help would be huge!!!



JT

 

[COramprat]

Did you ever do anything with the driveshaft other than u-joints? May help to have it balanced. Also if you lowered your car the pinion angle could be off and cause a vibration but that generally happens if the car is lowered 2 inches or more. I'd lean more to an out of whack driveshaft.

 

[GodAmGT00]

Gotcha.. I'm still debating whether I should install my aluminum one yet, since I'm parking the car soon, for the winter...

I keep thinking the pinion angle is messed up, whether the angle is off, or if the rear axle is crooked, causing the pinion angle to be off laterally...

It sort of rumbles when I accelerate hard, almost like the rear gears are getting beaten as well.. I still have to throw the Diff. Girdle on, so I may check the gears out while I'm in there..


Thanks for the info..



JT

 

[Bolt on 5.0]

same sugestion here with the drive shaft. Try to loosen the shaft and rotate it 180% and see if the vibration changes better or worse. If so theres your problem. Also if it is noisy could be you pinion bearing expecially if your pinion seal became loose.

 

[Bolt on 5.0]

oh and you cannot adjust toe or camber on the rear of your car

 

[GodAmGT00]

Gotcha... Thanks for all the help... I just took the car out for a spin, and I'm definitely leaning towards the gears now, since there's a ton of howling. I just haven't driven it much lately.. Needless to say, I'm going the 4.10 or 4.30 route..



JT

 

[Denny55]

Driveshaft

When the U-Joints are replaced it is possible that the balance is out. If you have another d/s try it. If you are working on the old d/s be sure the cups are in place(and the snap rings are seated). You can try adding weight(about the weight of 2 nickels) to the rear of the d/s. You have to use try various weights and positions at the rear. Attach the nickels with reinforced packing tape--do not let it get hot or the tape will slip off. A hose clamp is the easiest piece to use but the screw weighs more that the nickels and may be too much imbalance..

 

[GodAmGT00]

While I was sitting around this morning, I thought of a few other things, and wanted to get a feeler for my thoughts..

Since I've gone w/ 315's out back, how much more of a beating are the gears going to take?? I also have a shiftkit, and do drive somewhat hard on the car sometimes...

I've noticed that since the wheel/tire/suspension install that the gear whine has gotten slightly louder.. I am going to be installed the Diff. Girdle today, to not just see about stiffening things up, but part of me thinks that the Driver's side axle seal has blown out again. I did notice some gear oil on the back of the hub, and a little on the wheel, but the seal looked in tact..

Without feeler gauges, what's another way to visually check for wear on the gears?? I'm assuming pitting, burrs, etc, but I also have the Eaton which makes it really hard to see all the way back into the diff..


Thanks for all the help guys, you've been huge!!


JT

 

[GodAmGT00]

Is anyone still following along??


So yesterday I installed the Rear Diff. Girdle, and between getting Permatex in my hair, and about an accidental 2qts of Gear oil on the street, it wasn't such a bad day after all..

I switched to 80-145w Gear oil, just regular Petro, and it quieted down a lot of the gear whine. It's funny though, I thought I wasn't going to feel a difference, but when the car shifts, and launches now, it feels so much more firm...

Anyway, after inspecting the gears, there isn't much crowning, or any burrs, however, there was quite a bit of metal "dust," floating around in the old oil...


So, either I'll roll the car off a cliff, after I set it on fire, or I'll have to wait until the Spring to rebuild it..


4.30's or bust..



JT