So i'm still chasing down a vibration that won't go away. I'll start from the beginning and try and keep it short. stock 82 TA. gutted the whole drivetrain. Installed 350 crate engine, 2004r tranny, 12 bolt moser rearend with trutrac posi. spohn crossmember and torque arm. new driveshaft. all BRAND NEW, nothing was used. new motor mounts, transmission mounts. Tires have been balanced twice as has the brand new driveshaft.

now I get this vibration around 3000, this is when you really start to feel it, it pulses, like a whoooshing noise/vibration, almost harmonic. as I accelerate harder it gets faster and faster, if I shift into overdrive the vibration flattens out and over 70 mph it all out shakes the **** out of the car. So from third to overdrive as the rpm drops the pulse is not as intense under the same throttle position.

what I"ve done. since all this work, june 07, and chasing this vibration down i've changed motors, now a 383 (brand new) and had the torque converter double checked for balance. NOTHING, I still get the same vibrations. any ideas throw them out, I'm listening. so it definitly is RPM based and not speed. I'm at a loss.

 

If it's related to the engine RPMs and not the vehicle speed, sounds a lot like a torque converter problem.

 

Will it do it even in Park or Neutral sitting still? If so you know it's not the driveshaft, rear axle or anything at the back of the car.

Unbolt the torque converter from the flexplate and fire it up. Spin it up into the rev range where you normally get the vibration. If the problem goes away you know it's aft of the engine.

 

I'd say it was the torque converter. I had a "new" one on my car last year and that damned thing caused some ungodly vibrations depending on speed. Once it was replaced, no more vibrations.

Also, for what its worth... I had a different set of vibrations earlier in the year. I found these to be coming from the tires. I had always used whatever Tire Kingdom had in stock, usually the low end junk and this vibration remained through new sets of those low end tires and didn't care if they were new or had been on the car for a while. I finally got tired of that and got a set of Firestone Firehawk Wide Ovals. The nasty vibration I got around 60mph to about 70-80mph completely disappeared. This is likely not your problem, but figured I'd toss it out as it was also a nasty vibration that needed fixing.

 

it's the second engine with the same vibration so I know it's not the engine. when in park i rev it and I get some vibrations but not the harmoic pulsing, just stuff vibrates (plastic and such). I had the converter double checked for balance. It's a PDQ out of cali. and have heard they make decent converters, could it just be the converter is bad? I hate to spend 600 bucks or more on something and it not take care of the problem ya know. tires and rims were on the car when it was stock and I had no problems then so I can't imagine it's those (had them balanced again just to make sure), they are BF goodrich which is a decent tire too. so you guys all seem to think converter? If i get a good mechanic to take a ride think they would be able to narrow it down? it just really kills the pleasure of driving the dam thing. thanks for the imput guys, dan

 

Basically what you want to do or have done, while you watch, because I don't trust most mechanics if they aren't in my line of sight, is this. Unbolt the torque converter from the engine and run the engine up to speed, preferrably on a lift. If there is no vibration, problem solved. Well, at least you know then that it's either the converter or something attached to it.

I don't know what happened to the quality of mechanics lately, but generally if I do what you want to do(and should be able to do with confidence) and tell a mechanic, "Hey, my car is making this noise/vibration/etc" and let them have the car, they will do one of the following...

1. Replace part having nothing to do with the issue I explained to them. Their reasoning being they couldn't reproduce the problem so replaced the most likely item that could cause such a problem because it was x years old, plain old, dirty, looked at them funny or insulted a family member of theirs.

2. Return the car to me untouched, usually with a "diagnostic charge" or computer charge(meaning they connected it to a useless computer to find the problem.

3. Actually repair the car. This is rare, extremely rare, especially if it isn't something VERY simple like a bad water pump, power steering pump, alternator, etc.

Usually when I find that extremely rare mechanic who not only has a clue, but knows how to use that clue, I stick with em.

So, getting back to your issue. Unless you have a mechanic who you know is an Honest Abe and rock solid on his diagnosis of problems, just tell him you want the converter disconnected and the engine run up to speed. (That is, if you can't do this yourself). Also, before you do this, take said mechanic for a ride, with you driving and reproduce the problem. Make sure the mechanic sees/feels/hears and understands that there is something wrong. The converter could be out of balance. That was the issue with my new/old one before I took the whole thing to the dealer to replace everything.

About the tires, I really don't think that they could be the issue, but I will say that BF Goodrich tires should be solid. However, wear and tear, poor alignment, worn out components etc can easily and quickly cause tires to do bad things, regardless of them being balanced or not. The final straw in me replacing my set of "whatever was new in stock" tires was that one of them, with PERFECT alignment and all new parts had developed a bad problem. This being that it pulled hard to the right or the left depending on which side of the car you mounted it on. They rebalanced it, fiddled with the alignment, and that tire just caused me to have to fight with the steering wheel to keep the car from veering hard to the right. The tire looked fine too, no weird wear patterns or anything. On top of the horrible vibrations starting at 60mph they ALL gave me. The new set of Firestones cured every problem. It was like one of those snake oils from the 1800's. Cured all my ills, lol. Oh, and those problems never came back.

I only recently replaced the set due to damaging one of the rims, destroying one of the tires and partially damaging one on the damaged rim. So I wound up fouling up the 2 tires on the opposite side before the replacement rim and tires arrived.

 

yeah, I can try that, I did try that last year which seemed like there was no difference. hopefully there will be a noticeable difference and now I have a little more to go on. I do know a mechanic or two I would trust, but I would only have them ride with me, make sure they feel the problem and hear their suggestions and go from there.

is there any way it could be the transmission? I got it from BTO (bowtie overdrives) out of cali. I had nothing but problems with it blowing out the overflow last year and I had to send it back. they put a new pump in it and now it is fine, but I just don't trust the work they do. just a gut feeling. thanks guys, any other suggestions let me know, and I will update sooon. dna

 

I have had three PDQ convertors in mine. Including the one I replaced 2 weeks ago. Now I'm paranoid to drive it to see it if it is fixed.But atleast I have gotten really good at dropping the tranny.But my wife is getting tired of the cussing so I have to turn the stereo up in the garage.

 

are you saying you have had the same problem I'm describing? after 2 converters why are you going with them again? are they not great converteres? dan

 

You say its an '82.... did you reuse the mechanical fan when you installed the new 350? Its very possible thats your problem if its RPM related, especially as high as 3000 rpm. Dodge 5.2/5.9 trucks are notorious for vibration issues due to the cooling fan, same with the GM 4.3L trucks/S10/Blazer.

I'd suggest pull off the fan, fan clutch, etc... leave only the pulley on the water pump and take if for a quick drive (not too long, as you have no cooling fan) and see what happens.

 

mine did the same thing when i had a 2.8 took out and a 350 dropped it and we thaught it was in the driveshaft and everything but it ended up being the rearend the whole time so you might want to check that.

 

Hey Dan,
I was having a vibration when I would get on it hard,and after doing the wheels,driveshaft,etc, I took it out and had a machine shop check it for balance and it was off.The second one I paid for and it did it again. The third one I got free after raising some serious concerns with them. Now I have it in and it is smooth as glass. I definitely wouldn't recommend them to anyone though.