Harmonic balancer on driveshaft

[Blakers]

I’m getting a shake at about 47 mph, that lessons when I get over 50 mph. I found a bad CV joint on front driveshaft, so replaced that. Then had a tight cap on rear of rear driveshaft, so replaced both joints. Still have shake. Jacked up rear of truck and ran it and can feel shake.

So today I take it to tire shop where I bought my tires and they said both rear tires were out of balance. They balance them and say they are good. But now the shake is worse than before.

So, I’m wondering if the harmonic balancer on the driveshaft could be causing it? The rubber has been subjected to oil from a transfer case seal leak for years. Or do I have a tire going bad? Or is the tire shop incompetent?

Thanks.

 

[Wayne M.]

Since you describe a shake, and not a buzz, in other words, a low frequency vibration, not a high frequency vibration, I’m going to say it’s a tire/ wheel or something axle/ brake related.
It’s good that you found the bad U joints, and that damper is easy to check. I grab mine and try and twist it like a steering wheel. If that rubber had failed, like what happens on engine vibration dampers, I think it’d be obvious.

 

[JR]

Did you make sure your driveshaft was properly phased when you reinstalled it?

 

[Wayne M.]

Yes, Blakers, could you please establish a signature with your truck specifics so that we know what we’re referring to?
I thought the damper was only on one piece shafts.

 

[seafish]

In fact the rubber part of the driveshaft harmonic balancer one the rear driveshaft DOES tend to fail after number of years and can lead to a vehicle shaking. As does the center bearing/center bearing bushing.
That said, and as you are finding out, there are multiple possible causes to driveline (note I said driveline and not just driveshaft) balance, including tires and wheels and joints etc.

I believe that there are still oem replacement parts for your truck, but any reputable driveshaft shop in your area should be able to remove the HB and then rebalance the driveshaft without it. Another EXCELLENT though more costly option is to have them build you a new single piece aluminum driveshaft and install it after removing the center bearing and center bearing support assembly. The single piece driveshaft that I installed on the truck in my sig entirely stoped the startup vibrations I had and has been trouble freee for many years now (knockwood... LOL)

 

[Blakers]

Thanks guys! Sorry about the signature - I’ve been on here since 2000 and had a signature for years, but it’s not showing up. Truck is 03 2500 4x4 Quad cab short bed with 6 speed. One piece driveshaft.

The harmonic balancer has some movement in the rubber when forced, but does not rotate at all. The driveshaft can’t really get out of phase with the four bolt flange and splined ends.

Judging by the frequency, I think it’s the tires. It feels like a larger mass moving the shake than would be the higher speed and much less mass driveshaft.

This is the second set of tires I’ve had where the balance changes over time. Both name brand tires I bought new. Goodyear Wrangler studded mud tires, and these General Grabber ATX all terrains. Both in 315-70-17 on H2 rims. Both purchased at the same tire store several years apart.

I drive up and down some pretty good hills everyday to work and back. Could the torque being sent through the tires cause some kind of internal fatigue over time?

Blake

 

[Wayne M.]

Doubtful on the torque damage theory.
I’ve had the same truck since new, and that ring had always had some yield, but it won’t rotate much.

I’m sticking to a wheel speed balance issue.

 

[jhenderson]

How likely is it that after balancing the vibration gets worse and it’s not the balance job?

 

[Wayne M.]

How likely is it that after balancing the vibration gets worse and it’s not the balance job?

Not very, but if he’s got a tire with a failing cord or other defect, this is very likely.
Rotate the tires up front and then spin the wheels.

 

[seafish]

How likely is it that after balancing the vibration gets worse and it’s not the balance job?

EXCELLENT observation and point !!!

 

[Ozymandias]

Well they can be perfectly balanced, but that doesn't affect an out-of-round tire.
Did the tire shop check for this also?
I'd swap wheel front<>rear to see if something changes.

 

[jhenderson]

Anything is possible, but any competent tire jockey checks for out of round and runout while they’re tightening the wheel to the balancer.

 

[GCroyle]

Hunter Road Force Balancer

Finds out of balance and the road force the tire transfers back to the vehicle. Finds what isn't easily found. And its not a always a runout issue it sees the tires as a series of rotating springs, Hunter explanation not mine and reads the force applied finds hard and soft spots.

Not a tire guy.

 

[Blakers]

Today, after leaving for work, the shaking was hardly noticeable, but after driving about 30 miles, it was back. I’ve noticed this before too. I’m thinking it could be heat related; after they heat up, something changes in a tire.

 

[cerberusiam]

How likely is it that after balancing the vibration gets worse and it’s not the balance job?

VERY often if it is bad tire. 2 brand new Toyo Proxes 4+ tires on my challenger. Steering wheel shakes any time I exceed 70 mph and it comes and goes. Discount tire says they can find nothing wrong and re balances. Shake is now present under 70 mph and worse. This is after I TOLD them to spin the tire up and watch it, definite hop in both tires, one worse than other. Made them put 2 more tires and problem gone, they would not believe it could be the tires.

The OP's problem is more than likely the tires since it gets worse when they warm up.

 

[KATOOM]

Since you describe a shake, and not a buzz, in other words, a low frequency vibration, not a high frequency vibration, I’m going to say it’s a tire/ wheel or something axle/ brake related.

I'm not sure why more people dont point out what you just said...
Every time there's a "vibration" post its needs to be pointed out that there are two types of vibrations. Fast/harmonic (like a vibrator) and slow/wobbly (like a fan missing a blade). The fast/harmonic vibration is going to be driveline related because those are things that spin fast and dont weight a lot, like driveshafts, u-joints, clutch, crank harmonic balancer, transmission, etc...
The slow/wobbly vibration is tire/wheel related as they spin much slower and weigh a lot more than everything else.
If the vibration changed after re-balancing the tires then its obviously tire related.

 

[Blakers]

Resolution of the problem:
After three return trips back to the tire store where I bought the General Grabber ATx tires in April 2018, they found the balance on each tire had changed with each visit. Blaming everything from the rims to the weights falling off, they finally said they didn’t know what was wrong.

Each time I left the tire store, it was obvious within 30 miles that the tires were no better than before, and still shaking down the road.

I got mad enough after my next drive home from work that I decided to take it on myself and figure this out. Two of the tires were worn down to the wear bars, but one was worn more on one side than the other, so I suspected it could be the culprit. So I took it off and replaced it with one of my original Rugged Trail tires that came on my truck when new. Now I drove it a few miles and no shaking! So I figure it must have been that tire that was the culprit. Then I replaced all four General tires with the original Rugged Trails that came on the truck new in 2003. All is well and they ride as smooth as ever!

These tires are over 16 years old and have very little tread left, so they will need replaced soon. I need to talk with the tire store and see what they want to do about replacing the Generals, two of which are worn down to the wear bars after only 36,000 miles. They are warranted for either 50,000 miles or 60,000 miles. Hopefully they want to do something about the warranty; otherwise I will be looking elsewhere.

Thanks for all your help!