Harmonic balancer out of balance?

I have a suspicion that my new Pioneer harmonic balancer may be wrong. I have a vibration in my car that seems to be RPM related. My driveshaft has been balanced twice and I know my wheels are balanced and alignment is good. You can feel it most when you are at cruising speed and make very slight movements to the gas pedal, it feels more RPM specific than drive train specific. How can I tell? Can I change the balancer without changing the front seal?

Yes, you can change the balancer fairly easy if you have a puller. You'll probably have to pull the radiator.

If the vibration is engine related you should be able to reproduce it in a different gear at the same engine RPM. You should also be able to produce it with the car in neutral sitting still.

Note the speed and RPM and try to reproduce the speed at a different RPM and also the RPM at a different speed. That will help determine if the vibration is somewhere from the transmission forward to engine, or transmission backward.

Tracking a vibration like this can be very frustrating and difficult, not to mention a lengthy process. Any, and more than one, component from the balancer to the lug nuts may be involved. For instance, a ring gear that is out of round or has too much runout can cause the problem you describe and is called tip-in vibration. basstrix's suggestions are a good starting point. It will be a process of elimination, you'll need to make sure that your fan and pullies aren't the problem. You'll have to make sure it's not the flexplate or torque converter. A transmission that is not aligned to the crankshaft or has a chunk of debris between the bellhousing and block can cause this type of vibration. A u-joint with missing rollers in one of the cups will cause problems, as will a bent or improperly machined u-joint cross or yoke. Other possibilities include a bent axle or bad bearing or anything else that rotates.

Good luck.

Took it out again yesterday and did the RPM test stated above, the vibration is not consistent to one rpm range, and also, when I put the trans in neutral it goes away, so now I'm back to drive train somewhere. It is not a full time vibration, its kind of: ________............___________............__________, if this makes any sense, so to me it still feels like driveshaft, but I watched the tech balance it last time I took it in and he got it perfect. It's going to be tough figuring this one out I think. Thanks for the input gents!

Things that rotate at different rates, like axles and driveshaft can cause the come and go vibrations. For instance, if you have an axle shaft that is slightly bent and a u-joint that was improperly assembled, at one point in their cycle they will cancel out each other's vibrations and at other times will add together to make what would normally be a negligible vibration noticeable. A torque converter, because the differences in rotation rates vary before and after it due to power input, can make the vibrations disappear or reappear randomly if it is part of or between the vibration causing items.

Don't forget to check the tranny mount.

Yes, as mentioned, put the car in neutral.

Rev the engine to around 1500 for 10 seconds.

rev it to around 2000 for 10 seconds

rev it to around 2500 for 10 seconds

if it gets worse and pulses faster as the rpm increases, it is in the trans [torque converter or bent flex plate] etc, or the engine.

When an engine is balanced, it should be done with the damper and flywheel.

If the vibration is constant [not cyclic/pulsing] it is a dynamic imbalance . if it is cyclic/pulsing, it is a harmonic imbalance.

Even though an engine has been balanced, it does not mean it was done correctly.

Isn't this the big dollar Tim Meyer engine?

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It is the Tim Meyer engine, I did do a neutral rev test from 1000, to 3500 rpm, no vibration in neutral, but when I have it in gear, right around cruising rpm "45-60 mph", If I'm holding a consistent rpm, and increase or decrease a little bit there is an intermittent vibration. The trans mount is a new polyurethane, and yes it is tight. I did check. The flex plate is a B&M STI approved 164 tooth with welded ring gear and 28 0z. imbalance, I know there are no guarantee's with new parts but I want to exhaust all other possibilities. Thanks for the insight Gents!! I'll keep everybody posted.[/align]

Your polyurethane transmission mount may be too rigid. A rubber mount might reduce the vibrations.

Throwing this out there.

Possibly lean surging at cruise?

Your polyurethane transmission mount may be too rigid. A rubber mount might reduce the vibrations.

Click to expand...

Could be the above, I had a very similar issue and it was the poly engine and trans mounts. Try switching back to rubber. Shouldn't be too difficult or expensive.

I was kind of thinking that too, I do have a couple of the stock mounts, maybe I will try that! What is lean surging? I have never experienced that. Would it feel like a driveshaft out of whack?

ok, your engine is not out of balance so thats the important thing.

urethane engine mounts increase vibration also.

if you installed a t5 trans, it is possibly incorrect drive shaft angles.

if the front yoke on the driveshaft is fairly loose in the trans, that can cause probs.