C Rob 99Z

I got some bad vibrations at 50mph and up. I'm assuming it is a u-joint but I won't know until the first of the week. If so, would it be a good investment to go ahead and get an aluminum driveshaft? Is there anything else I should consider replacing while I'm into it? Car is 420hp n/a and has a built trans with a 3500 stall. I don't know if that matters or not but I am not familiar enough with the F-body's to identify the weak points.

Thanks,

C Rob

hlaalu

iTrader: (3)

does it vibrate on acceleration or deceleration? or just all the time after 50mph?

C Rob 99Z

Mainly at a steady RPM. When I accelerate it smooths out some but not much. Deceleration doesn't do anything.

C Rob

Wesmanw02

iTrader: (4)

An aluminum shaft would definitely be a nice upgrade, its amazing how much lighter they are than the steel ones.

I got a used one for $150 from a salvage yard, u-joints entact.

You can tell if the u-joints are original by looking at how they are secured in the yoke. The stock ones are "injected" with glue from the factory to hold them in, while replacements will be held in with snap rings.

Palomba

iTrader: (1)

I had a horrible vibration that never went away, and the faster i went the worse it got. Was my Driveshaft bent. Had a new one made and new U joints pressed in for 150

Wesmanw02

iTrader: (4)

Same here, took a while to figure out. I just picked up a used shaft with u-joints already installed to replace it.

C Rob 99Z

How can I tell??? I'm not much on diagnosis. I figured it either had to be converter, driveshaft, or rear end. And the rear end isn't making any noise.

C Rob

Wesmanw02

iTrader: (4)

Mine was bent badly enough that it was visible by eye. I put it up on jackstands, engaged first gear, and observed the driveshaft as it rotated. I could see the shaft was traveling in an ellipse instead of spinning straight. When I held a straight edge up to the shaft, it was also obvious that it was bent. Thats probably the best way to check.

C Rob 99Z

Gotcha. It's not horrible though so I doubt it would be easy to spot by the naked eye. It almost feels like when you have a flat spot in your tires. Ya know what I mean? It's enough to irritate me for sure. Is it still possible it is a rear end issue though? If so I don't wanna go 12 bolt really. I'd actually prefer fitting an 8.8 cause I know they are strong and don't rob a ton of power.

C Rob

Palomba

iTrader: (1)

Id try the drive shaft first, Take it to a driveshaft shop, they can tell you in a heartbeat for cheap, and if it turns out to be good, then at least you know that its not the issue.

C Rob 99Z

Yeah. I guess I just need to get it checked out before I jump the gun. I am just frustrated that I've only had it 2 weeks and I'm already having to shell out more money.

C Rob

95zpro

I had a few dents in my driveshaft and that threw off the balance. I had a new one made and so far so good. I'd definitely suggest taking it to a reputable driveshaft shop as they can diagnose it for you.

lavoy

iTrader: (2)

I just went threw this with my datsun, we assumed that since it was a hybrid that the pinion angles are probably not right and all that, so we messed with them for a few weeks and the vibration just didnt go away, i took the shaft to a machine shop and they said it was 12 grams out of balance and the run out wa soff a tad, they fixed it and now its smooth as silk. my vibration was also around 50 mph and up and only moderate at worse.