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:


http://www.youtube.com/watch?v=ZWrqEjBCO2c&sns=em

[Jstarr427]

Update:

Got in the new shaft from PST. installed it, drove the car, much better. still makes ringing noises at 45-50 (I contribute this to some other noise resonating in the driveshaft), and still shakes at 75, although it shakes less. Finally got to talk to Mark at PST, and he was much better to talk to then the other people I've spoken to there. He suggested that I try rotating the shaft 180* on the rear diff. Did that, made vibration slightly WORSE. So now I'm ready to either A. Sell the car or B. Fork over $1300 for a new OEM shaft. :-(

[green-lantern]

I wouldn't give up just yet. I'm surprised you are having this much trouble. Check your install again and the diff bushings. I hear people that have trouble out of the one piece carbon fiber drive shafts usually have bad rear diff bushings. If the U joints are stiff they might loosen up a bit over time. Also make sure you lined up the two pieces correctly. I don't want to offend you by asking you to double check that but I've been sure I've done something right to only find out later that I was supposed to do it a different way.

Might want to read through this. It might give you an idea of what could be wrong.
1995 3000GT VR-4: PST 2-Piece Carbon Fiber Driveshaft (CFDS) Installation (http://www.supercar-engineering.com/rubberducky/3S/Mods/TT/CFDS/)


Good luck and sorry about your troubles.

[Jstarr427]

No offense taken, so don't worry. Diff bushings are new. After a long back and forth with mark at PST they determined that the ujoints were the cause of the vibration. They sent a call tag but ups didnt get it until a week later after I called pst to see what the deal was. Meanwhile I keep driving the car, vibrations are now so bad that I can't take the car much over 50mph. Put the car up on the lift and find that the joint at the diff is loose enough that I can grab the driveshaft anf watch it move around. Holy shit! I then decided to put the old stock shot carriers shot resr ujoint shaft back in the car and more vibration. Apparently I will have ANOTHER shaft coming from PST the end of this week. Ill give em one more chance, and if the shaft still vibrates I'm getting my money back. They have been good sorting out the issues with me but I can't say I would recommend them to anyone else nor would I buy another driveshaft from them.

[green-lantern]

That sucks you are having so much trouble. I hope this new one does the trick.

[J. Fast]

I have this same drive shaft, a PST two piece carbon fiber, and an ACPT one piece carbon fiber. All of them show signs of sagging and/or preload, however, they all balance true. Its certainly possible something is defective with the shaft but it seems odd to me that a premier driveshaft company wouldn't be able to to build or balance a propshaft properly on multiple attempts. Do you have a balancing company near where you reside? Is it possible to have the balance checked before you reinstall again? If the prop shaft is balanced the problem lies somewhere else.Maybe try and put a jack underneath the rear differential when you have the rear chassis posted and lift it and examine if it moves. Take a prybar put it in between the spokes of your rims and move them towards the front and rear. Do that test with both rear tires off the ground and one tire on the ground. It really sounds like something in the rear end is loose and its sending a shimi forward. What about utilizing a chassis ear? I have a 4-channel Wireless Steelman Chassi Ear for this type of issue. I might clamp to everything except rotating parts to try and isolate the noise to a specific region and then reclamp to pinpoint.

[J. Fast]

t ( it's a hell of a lot cheaper now than it was when I bought mine) Steelman (STE97202) Wireless Chassis Ear:Amazon:Home Improvement (http://www.amazon.com/gp/aw/d/B00123J79O)

This gem is a huge problem solver!

[Jstarr427]

I have this same drive shaft, a PST two piece carbon fiber, and an ACPT one piece carbon fiber. All of them show signs of sagging and/or preload, however, they all balance true. Its certainly possible something is defective with the shaft but it seems odd to me that a premier driveshaft company wouldn't be able to to build or balance a propshaft properly on multiple attempts. Do you have a balancing company near where you reside? Is it possible to have the balance checked before you reinstall again? If the prop shaft is balanced the problem lies somewhere else.Maybe try and put a jack underneath the rear differential when you have the rear chassis posted and lift it and examine if it moves. Take a prybar put it in between the spokes of your rims and move them towards the front and rear. Do that test with both rear tires off the ground and one tire on the ground. It really sounds like something in the rear end is loose and its sending a shimi forward. What about utilizing a chassis ear? I have a 4-channel Wireless Steelman Chassi Ear for this type of issue. I might clamp to everything except rotating parts to try and isolate the noise to a specific region and then reclamp to pinpoint.

Thing is, like i said in my previous post, putting the stock shaft in the car makes the vibration go away, and PST has said that the u-joints they used were loose. The fact that the BRAND NEW driveshaft's joints were shot in less than 1500 miles sure coroborates this story. I've seen chassis ears like those before and If the new shaft doesn't fix the entire problem (which the old shaft does) then that's the route I'll take.

[green-lantern]

I then decided to put the old stock shot carriers shot resr ujoint shaft back in the car and more vibration.

This is a bit confusing, I assume you mean no more vibration. lol

The stocker is pretty good about adsorbing vibration. There could still be something else that's causing the new drive shafts to wear out/vibrate. If this new one still vibrates I'd look into this a little further like something is wrong with the rear diff.

[Jstarr427]

This is a bit confusing, I assume you mean no more vibration. lolup

The stocker is pretty good about adsorbing vibration. There could still be something else that's causing the new drive shafts to wear out/vibrate. If this new one still vibrates I'd look into this a little further like something is wrong with the rear diff.

Yes I meant no more vibration lol. The stocker is better at absorbing vibration but it went from severe to GONE. PST did say the u joints they're using were 'loose' and that they were sourcing them from another manufacturer. So either that's the problem or PST is just blowing smoke. oh and this point they've had my driveshaft back for a week and I've heard nothing. Starting to get pissed...

[Checkered vr4]

I had a vibration issue with my one piece PST card fiber driveshaft and sent it to them. They changed both U joints and it is all better now. The shaft was probably five years old by the time I started getting vibration and I'm not easy on it either.

[Jstarr427]

So what's happened is PST sent shaft number 1 back with new u-joints... no more vibration, however it resonates at 45 and now at 70. I cant deal with it for a daily driver, so PST is refunding me, and I'm going with a rebuilt OEM shaft. Disappointing that this hasn't worked out, but I'm just PRAYING that a new stocker doesn't have the same problems.

[green-lantern]

I swear there has to be some other issue other than the shaft, like the stock one is masking the problem better or something. Anyway sorry it didn't work out, hopefully the stock one will work out for you though.

[vr4tune]

I also have a pst aluminum hybrid driveshaft. I have a small vibration at 65 and up

[Streamln1]

seems like a lot of aftermarket driveshafts have this problem at around the critical speed of 70mph or so, that's the point that has the most harmonic resonance, and from what I have heard our drivetrain is tough to design one for. I am wondering if running stiffer diff mounts will help or make the problem worse. Some food for thought, if the drivetrain components are loose I/e bad motor mounts, worn out diff / subframe mounts, would that not cause more movement in the driveshaft also?

Theres a local guy that has a PST CFDS for dirt cheap I am on the fence about picking up. He said he had the same problem but also running stock mounts

[J. Fast]

Have you guys considered the possibility of the rear section of your driveshafts to be damaged? The rear driveshaft section is dual core. The rear propshaft section is larger than the first two sections for a reason. Maybe you have an unbalanced rear section guys? The inner core is steel then theres a rubber harmonic damping core and another steel core shell. I'm willing to bet the issue is the entire shaft assembly is not being balanced just the upgraded sections.

[Alan92RTTT]

The rear section of the PST 2pc is aluminum

http://www.3sx.com/store/catalog/driveshaft-pst-alum-2pc-5spd-09-650l.jpg

[J. Fast]

Here's the TIM on the propshaft from stealth316. I had a recollection but needed confirmation on the rear driveshaft section design. It does infact have dampening built into it. Obviously the PST design depicted is missing that boundary layer.

http://www.stealth316.com/images/stim/tim_16-02.gif

[Alan92RTTT]

I would not say missing I'll say different.

I and others have the same shaft no vibration.

[CoopKill]

Have it, not vibrating.

[Keyan]

I had one years ago and it vibrated very badly.

but.

the splines of my tcase are worn.

So the fact that the driveshaft isn't perfectly angled means that every revolution the u-joints speed up and slow down (i forget what it's called, but it happens. the driveshaft varies in rpm depending on what position of 360degrees it is in),

MAY mean that the vibration may be coming from the slack in the transfer case splines, not the driveshaft itself.

Is there anyone who has a confirmed mint spline transfer case with vibrations?

[Streamln1]

That was my point, there could easily be other areas creating the vibration for some folks and not the others. The fact that the stock drive shaft doesn't do it merely could be its own damping characteristics cancelling out a vibration that is from some other area.