Hi all, newb here.

Ok, so first, I'm not trying to freeload. I've been trying to find a shop with a PicoScope NVH in my area, but haven't been able to locate one.

OK, I actually did locate one, but it was at the biggest Chevy dealer in the area, and the service manager told me they'd had it for over two years, and not only did no one there know how to use it, they'd never even unboxed it.

I moved on.

I called Pico to see if they could refer me to a shop in my area that had one, but they said they couldn't give out customer information.

I'm in Tulsa, OK. If anyone has a PicoScope within a couple of hundred miles of me, I will GLADLY pay you for your services.

OK, 300 miles.

OK, 400 miles.

So I have a 1989 Pontiac Firebird Formula.

111,000 miles

305 V8

T5 manual transmission

I bought the car new, and have never (overly) abused it. It has always driven smoothly.

It is stock, with four exceptions.

It came with a 3.08 open differential. About 25,000 miles ago, I had a 3.42 gear and a Zexel-Torsen limited slip installed. There were no problems with the installation, and there were no vibration problems at all.

About 20,000 miles ago, the original, factory clutch began to slip. I replaced it with a Centerforce clutch kit. The flywheel was resurfaced. Everything was fine afterwards; no vibrations.

At around the same time, I installed a custom, mandrel-bent exhaust system. Again, no vibration(s).

At around the same time, I also installed Lakewood tubular control arms, KYB shocks and struts, and a complete Energy Suspension Polyurethane bushing kit, front and rear. No vibrations.

Around 10,000 miles ago, the car suddenly began vibrating at around 70mph. Beyond that, the faster you went, the worse the vibration got. I hadn't changed anything on the car for more than 10,000 miles.

I had the tires checked for true and balanced; no change.

I took it to a driveline shop. He said the universal joints were bad, so I had him install new Spicer front and rear u-joints. No change.

Took it back. He said the driveshaft was twisted. I bought an aluminum driveshaft out of a 2001 LS1 Camaro (they interchange), took it to a local driveshaft shop, had it checked for true and balanced, had new Spicer U-joints installed, and installed it. The vibration was unchanged.

Had the driveshaft balance checked by another driveshaft shop. It was dead on. The vibration was unchanged.

One day, I was sitting parked in the driveway with the transmission in neutral, and slowly revved the engine up. Starting at around 1,800 rpm, until about 2,400 rpm, it vibrated pretty significantly.

This was puzzling. In 5th gear, at 70 mph, the car is doing right at 2,200 rpm, so it makes sense that the engine vibration is causing it. What doesn't make sense is, the faster you go, the worse the vibration gets. When the engine vibrates while sitting still, with the transmission in neutral, the vibration tapers off after 2,500 rpm. What's more, when driving down the road at 70 mph, with the car vibrating, I can throw it up into neutral, and it still vibrates until the speed drops down to below 65, or so ... the engine is idling! I can run it up till it starts vibrating at 70 mph, throw it in neutral, and shut the engine completely off, and it still vibrates. The vibration actually gets worse at first, as soon as you put it in neutral, then it tapers off as you slow down.

I came to the conclusion that I had two separate vibrations. I decided to focus on the engine vibration.

I took the fan belt off of it . With them not turning, it would eliminate the alternator, power steering pump, water pump, air pump, etc as causal. The vibration was unchanged.

I put a new harmonic balancer on it. The vibration was unchanged.

Every time I'd talk to someone new about the problem, they'd tell me I had to start back at square-one, so I'd have the tires re-balanced, and the driveshaft re-balanced. It was utterly demoralizing, and expensive.

I got disgusted, and decided to park the car; the vibration was getting progressively worse, and I'd already thrown over a grand at the problem, with no resolution in sight.

Well, that turned into seven years with the car parked in my garage.

Last fall, I put the car back on the road, and got back to lighting money on fire trying to find the vibration(s). The tires had dry rotted and separated, so I replaced them with new ones. I had the wheels checked for true when they were being balanced. They were fine. The vibrations were unchanged.

At the insistence of my mechanic, I had the driveshaft balanced again; this time up to 150 mph, not 80. No change in the vibration(s)

My mechanic put the car up on the rack, and we disconnected the control arms, torque arm, panhard bar and rear shocks and checked the bushings. They were all good. We ran the car on the rack until it vibrated (I know, I know). We could hear a bearing in the transmission squealing intermittently. Loudly. You couldn't hear it in the car, but listening to it up on the rack, it was alarming. The transmission shifted perfectly, but a squealing bearing probably eventually turns into a seized bearing, and I wanted to get it fixed before that happened, and did real damage.

We asked around for the best transmission shop in the area. One guy's name kept coming up. I took the car to him and let him check it out. He said he had a piece of diagnostic equipment called "Chassis Ears" which would allow him to isolate the causes of the vibrations. He said he'd put the Chassis Ears on it, then pull the transmission, tear it down, and call me.

He called me the next day, telling me the transmission just needed a refresh; new bearings, seals and synchros, and the Chassis Ears had indicated the clutch was bad. He said he'd pulled the clutch off the car, and he could see where the balancing weights were out of whack. We agreed he'd replace the clutch, have the flywheel balanced and turned, and then have the new clutch balanced on the flywheel.

I went to pick the car up, and the vibrations were exactly as before.

I'm not going to go into detail over all the problems with the shop. I'm still battling with them, lawyers are involved, and it'll probably be a couple of months before it's resolved. There are two key elements, though:

1) I sent my old clutch back to Centerforce. Their engineer said there was nothing wrong with it. More importantly, he said there were signs the release bearing had been coming into contact with the balancing weights, which suggested an out-of-balance condition. Since the balance on the clutch had checked out perfectly, he said I should look at the flywheel.

2) After much back-and-forth, the transmission guy finally admitted not only had he not had the flywheel balanced, he hadn't had it resurfaced, either. He'd never even taken it off the car.

This definitely leads me to suspect the flywheel is the culprit in the case of the engine vibration. The transmission isn't right, and it's going to have to come back out. When it does, I'm going to have the flywheel trued and balanced, and have my original Centerforce clutch balanced to the flywheel, and put back on the car.

That won't address the chassis vibration, though. When he'd rebuilt the transmission, the transmission guy had put a new transmission mount on the car, and told me the engine mounts were bad, too. After I got it back, I inspected them. Even though the driveline angles were dead-on, they did look a little sketchy, so I had them replaced. At the same time, I had the rearend gone through; all new bearings and seals, and the ring and pinion setup checked.

Something changed. The car still vibrates, but before, where it would start at around 70, and get worse as you went faster, now it starts to taper off at around 80mph, and remains constant as you go faster and faster. It's vibrating at a much less severe level than before at high speed.

"A-HA!" You say. New motor mounts and rebuilding the rearend resolved the driveline vibration!"

Well, not exactly. As before, when you get it up to 70, where it starts vibrating, throw it up in neutral and shut the engine off, and it vibrates until it gets down to about 60. That can't be an engine vibration.

Wait, there's more! Now, sometimes it starts vibrating at 60, instead of 70. Sometimes it doesn't. Sometimes it barely vibrates at all, even at 70. Sometimes it's almost as bad as before.

Maybe I have/had three vibrations.

Sigh .....

I'm totally, completely, absolutely, utterly exhausted, and out of things to replace.

Can anyone help?

Thanks.

Here's a youtube video of the vibration at about 1:23

https://www.youtube.com/watch?v=9ZsitDTG61U

Sean I will look at you stuff in more detail later. I will say I have taken plenty of centerforce pressure plates off to get rid of issues. We will not install them.

Care to come to Pa and we'll get ya figured out.

DLTWFC   

Maybe some Nerdz here has the Ford vibration test gear??

Or you could play with some wheel weights and clamp them with a hose clip on the drive shaft.

place some marks on the drive shaft and then keep moving the weight around to see if it gets better or worse

good luck

I can't be much help, I am in California.

But, the pico NVH software gets important information like engine speed and vehicle speed from the DLC, the obd2 port. Your vehicle is too old to be obd2 complain, that started in 1996. I am not sure if the NVH software is set up for alternate inputs...

JNelson wrote on Oct 5^th, 2016 at 7:44pm:


There is an option in the NVH software to select a square wave or tach signal for engine speed.  If the transmission information is entered, vehicle speed will also be displayed.

Wookie wrote on Oct 5^th, 2016 at 7:19pm:


Thanks for the response, Wookie.

Yes, running the car when the transmission is out is one of the things I've been trying to accomplish. When the transmission comes back out, that is definitely going to happen.

I had never considered a misfire or an engine problem as a potential cause of the engine vibration.  That is absolutely going to be looked into!

Thanks for the idea!

autosparky wrote on Oct 6^th, 2016 at 12:35am:


Autosparky, I have not yet done either.  I will take the car out tonight and try both.

Thanks for the ideas.

I have just looked at a series of videos you have posted with your list of complaints about your car.

https://www.youtube.com/channel/UCglJzIcP0WHjCngPa6WlueA

Sure is one sad dirty old neglected car.

Tell me, why would you come to this group of good people seeking to get vibration analysis when you have prepared a series of videos to assist your case on litigation and on that old thing.

I would suggest that you pay for your advice with someone who will go the mile with you....but that advise and the lawyers would cost you far more than the car is worth.

i think it is wrong for you to involve the good people who attend this group with the real agenda you have.

By the way I would not mount that rusty old clutch in any car, especially after you have dropped and damaged the disc

autosparky wrote on Oct 6^th, 2016 at 12:35am:


OK, so I waited till 4am, when the roads would be clear.  There's a 6-lane highway near me they just resurfaced with asphalt, so it is absolutely smooth.

I ran it up till it vibrated about a dozen times, applying varying amounts of brake pedal pressure, and handbrake pressure.  I never felt anything in the pedal, or the handbrake lever, and the application of the brakes had no effect on the vibration.

There has been two hopeful developments.  I'm on thirdgen.org, a forum for '82-'92 Camaros and Firebirds.  I started a thread on the vibration there.

One member attached a vibration analysis FAQ that was really illuminating, and gave me some more things to test.  I'm attaching it here.

Another member works for GM in Detroit, and contacted the Field Service Engineer for this area, and had him read the thread to see if he could recommend a tech in the area who was trained on the Picoscope NVH.  The Field Service Engineer recommended a tech, and linked him to the thread.  I'm supposed to contact him next week.

Paying dealership labor rates won't be cheap, but it can't be more expensive then almost randomly throwing parts at the problem, as I have for so long.

The odd thing is, in my initial post about this, I mentioned that I'd gone to the biggest GM dealership in the area, and the service manager had told me they'd had a Picoscope NVH for two years, but no one had been trained on it, and they'd never even opened the box.

Well, that's the dealership the tech I've had recommended to me works at.  I'm just going to hope that dealership is so big the service manager didn't know he had a technician trained on the equipment.

We shall see.

(fingers crossed)

I doubt any of the folk helping used anything like the EVA.