Harmonic Balancer?

[OldGray]

For a while now it feels like I have an unbalanced front wheel at certain speeds.  Tires are new and have been balanced twice and they are good.  New bearings too.  Still feel a "bounce" in the front end, but pretty positive it isn't the wheels. 

Also, there appears to be a slight "hop" in the main pulley.

Since most of the parts on my truck are ages old, my next guess for a fix is to replace the Harmonic Balancer.

Yes?  Or other suggestions?

THANKS

[AZ4X4SQBDY]

An engine vibration is different than a wheel/tire issue. The engine vibration should be there when in park and you rev the engine. Harmonic balancers do fail and can cause a vibration although I have never seen one actually do that.

Any chance one of the front tires has a shifted belt in it? It would still balance and cause the issue your describing. I would rotate the tires front to back and see if it goes away. If that is too much work, you can try altering tire pressures and see if it changes how it drives.

I had a 85 K30 Silverado that I bought off a farmer in Texas, if I ran max pressure on the sidewall of the tires, 3 of the 6 tires had belts shifted and made the truck un-driveable. Dropped the tire pressure to 45psi and it drove nice.

[OldGray]

Yeah - motor does not shake when parked and revved, so I guess you're right and it's not the Harmonic Balancer.  Will check the tire pressure.  After having the wheels balanced twice, I added balancing beads to all four - since they work very well for me on my motorcycles.

Motor (and Trans) mounts are definitely in need of replacement, and my Buddy said might even check the U-Joints.

[Stewart G Griffin]

i am going to guess the trans and/or engine mounts.   i had a vibration problem---only when braking.   My trans mount was shot.  Replaced with Energy Suspension polyurethane (not saying you need to do specifically that) but the problem stopped.

[philo_beddoe]

I have had both engine and drivetrain vibrations. Nasty ones that were hard to pinpoint. VileZambonie figured out the engine one, bad crank and a not so good cam. I was fortunate to finally pinpoint the drivetrain vibe, front ujoint was a little sticky or tight. Either way, vibrations can drive one nuts.

But as AZ4X4SQBDY mentioned, at least its not so tough to isolate if its the engine or not.

[Rattler12]

Have you had the driveshaft off and maybe put it back 180 out ?

[OldGray]

Have you had the driveshaft off and maybe put it back 180 out ?

I have not removed it.

I will probably take the truck to my local repair guy and have him do all three mounts and check the u-joints while at it.  Thanks!