New PST Hybrid Steel/Alum installed.. Issues :(

[Jstarr427]

Hey guys, I just finally got my car back on the road after blowing an AWS line, dropping the subframe, deleting AWS, etc.. In doing this found out I needed a driveshaft. Went with the PST 2pc Steel/Alum. shaft from 3sx.

I'm getting a weird ringing around 45-50 mph, only does it at cruise, doesn't do it of throttle or when accelerating. Haven't taken the car above 60 yes so I don't know if I've got more issues. The mating marks on the shaft are aligned, and I greased everything prior to driving the car (needed needle adapters to get to a few of the fittings). I have double checked, everything is tight, nothing is hitting or rubbing on the shaft.

I called PST and got some guy basically said "No that doesn't sound right, but I dont know what to tell you, you need to talk to the boss man who won't be back until next monday." Needless to say I'm VERY disappointed in this response when EVERYTHING I've read about PST has pointed to outstanding customer service.

What's interesting is I think I might hear the same noise revving the engine and holding at 2000 RPM, but cant be sure. I'm almost thinking it's the exhaust resonating in the driveshaft (?) Any ideas from anybody?

[NOMIEZVR4]

Put it on a lift and drive it...report back

[green-lantern]

It seems like mine did that also. It wasn’t very loud at all so I just assumed it was normal. Over time it quit doing it. I did notice the U joint that bolts to the rear diff was a bit stiff when I got the shaft. I contacted Steve about it an he said if I had any issues with it on the car let him know. I think the sound might have been that U joint resonating through the aluminum until it got loosened up a bit.

[Jstarr427]

It seems like mine did that also. It wasn’t very loud at all so I just assumed it was normal. Over time it quit doing it. I did notice the U joint that bolts to the rear diff was a bit stiff when I got the shaft. I contacted Steve about it an he said if I had any issues with it on the car let him know. I think the sound might have been that U joint resonating through the aluminum until it got loosened up a bit.

That's what I was thinking was it was resonating. I would have been fine with that, except I hopped on the highway on the way to work today, and the whole car vibrates at 75MPH. it's not like a tire, brake vibration, it's a whole car, seat-of-your pants vibration. I don't see this being caused by anything other than the shaft. I did swap subframes and delete AWS, but my alignment is good, It's got new wheel bearings, new diff bushings, and I'm using the same diff, axles, brake rotors/pads/calipers and wheels that were on the car before. Motor mounts were also replaced ~15k ago so I don't think that's the problem either

The one good thing is I did email PST about it, and then called 3sx to ask them the same questions. Jeff told me he had just talked to PST and they were going to make me a new driveshaft. I checked my email and there it was, an email back from PST saying the same thing. so hopefully it's just the shaft, and the new one will have zero issues.

[green-lantern]

I was going to say swap it out 180 with the rear diff and see if that helps but if it's that bad I don't think rotating it will help. That's cool they are sending a new shaft.

[Jstarr427]

I was going to say swap it out 180 with the rear diff and see if that helps but if it's that bad I don't think rotating it will help. That's cool they are sending a new shaft.

Yeah, I'm just hoping it solves the problem, I'm not going to be happy if I have to go chasing a mystery vibration...

[green-lantern]

When you take the shaft out check and see if the U joints are stiff just for shits and giggles

[Jstarr427]

When you take the shaft out check and see if the U joints are stiff just for shits and giggles

Ironically I did that today. After work I threw my car up on the lift, pulled the rear flange off to check the surface on the diff, and check the rear joint. I knew they were a little stiff before, but after driving the car for the 2 days I have, the joint in the steel flange is smooth as can be, while the one in the aluminum is still stiff, but not as stiff as it was before I put the shaft on the car. I'm thinking that they must buy the yokes and weld them to the tubes, and if weld shrinkage is not accounted for, the part could shrink, and that would make the holes for the joint not concentric anymore...
None of this really matters as I'm getting a new shaft on Monday, but I also put the car in 5th, at idle it's around 40mph. underneath the car, you can see the aluminum section shaking a bit. running a pen in until it BARELY touches the shaft, you can see where it marks maybe a third of the shaft. It's worse farther forward towards the carrier bearing. so the tube is not centered on the yoke. Damn, no wonder this thing shakes at 70. I can just imagine what it looks like.

[green-lantern]

Ironically I did that today. After work I threw my car up on the lift, pulled the rear flange off to check the surface on the diff, and check the rear joint. I knew they were a little stiff before, but after driving the car for the 2 days I have, the joint in the steel flange is smooth as can be, while the one in the aluminum is still stiff, but not as stiff as it was before I put the shaft on the car. I'm thinking that they must buy the yokes and weld them to the tubes, and if weld shrinkage is not accounted for, the part could shrink, and that would make the holes for the joint not concentric anymore...
None of this really matters as I'm getting a new shaft on Monday, but I also put the car in 5th, at idle it's around 40mph. underneath the car, you can see the aluminum section shaking a bit. running a pen in until it BARELY touches the shaft, you can see where it marks maybe a third of the shaft. It's worse farther forward towards the carrier bearing. so the tube is not centered on the yoke. Damn, no wonder this thing shakes at 70. I can just imagine what it looks like.

You think the balance is just way off?

[Jstarr427]

You think the balance is just way off?

I guess it could be, but I suppose I didn't drive the car slow enough on the lift to see that. I uploaded a video of me spinning the shaft, you can see the dark marks where the pen hit the shaft, and none where it didn't. So either the shaft isn't welded straight, or balance sooooo far out that its making the shaft move that much at only 40mph.
Here's the vid: