Jim Lane

I believe that I have found the source of my constant vibration.

I am going to turn the rotor 180* on the hub and see if it stops in the same place, hopefully it is just the cheap Chinese junk rotors from the auto parts.

I am looking for some place locally that can dynamically balance my hub separately and then the rotor as an assembly.

I know they balance the brakes on race cars this way, but just about everyone I have talked to hasn't a clue what I am talking about.



http://www.racingbrake.com/v/main/dynamic_balancing.asp

http://www.racingbrake.com/

This rotor has to be off by several ounces.

The other side is not as bad, but it is still out of balance.

So what do you think?

Jim

patdaly

I think you are way too detail orientated................

Seriously, I could see it for a race car, the wheel speeds are far higher, but it would take at least in my rough head calculations more than just a few ounces at the radius and wheel speeds of your truck. New rotors can't be much more expensive than balancing your old ones.

If you are serious, I had my local electric motor rebuilder balance a set of blower pulleys for my supercharger drive, I had to make the balancing mandrel to fit my pulleys, but they didn't charge me too awful much ( 25 bucks for the pair IIRC )

Thunderhog

All of my "older" cars and trucks had balanced drums and rotors (as evidenced by a portion machined off) from the factory. YES it makes a difference, those rotors are HEAVY!
The balancing costs money, and when you are selling rotors for 20 bucks, they probably cut that proceedure out. Pity.

93flatbed

Why not a set of the centramatic deals? Wouldn't that take the "shimmy" out of the entire rotating assembly?

DodgeFreak

or roughly find the heavy side and grind alittle off untill you can't tell its out of balance

torquefan

Yep, I definitely think you are on to something. Sounds like the right idea, to move the rotor on the hub 180 degrees to see if it will balance out better. The one possible problem I can see by doing that is that you might end up with some runout in the rotor requiring machining, then afterwards your balance might change. I think it's worth a try though.

NJTman

So what happened here ?


Did you get it balanced ? Was it out much ? did it make a difference ?


You holding out on us again, Jim ?

torquefan

Yeah, I'm curious too. If a rotor that big and heavy starts to turn by itself, it must be a pretty big imbalance. I would guarantee that would cause a vibration.

j_martin

It's Jim L. He'll have to "engineer" on it for about 3 weeks.

Pry-p

It's been 4 weeks now!

gadget.35-06

I used to get Canadian-made Aimco rotors at AutoZone that weren't too expensive...no problems...finished right out of the box; just wipe 'em down with acetone and throw 'em on. Never had one shimmy.

Totallyrad

One of the funny things about steel is an absolutely flat and true piece can be spun and usually is out of balance due to the density of the molecules in one area as a result of the rolling process. A brake rotor/drum is an even bigger challenge to keep balanced. Jim, when I was a kid my father would take his cars to a little garage in Scio, Ohio because that guy was the only one left in the area that balanced the tire on the car, thus balancing the entire rotating mass. It did produce the smoothest ride we could get at the time but it had one major drawback. Anytime you remove the wheel you need to mark the parts so you didn't lose the balance when you reassembled the assembly. Today, I would add a set of Centramatics or Balance Masters to the trucks resume'. They balance the entire rotating mass after about 22 mph. I've had mine now for a little over 5 years and still love them. I strongly recommend them.


http://centramatic.com/Home.aspx
http://www.balancemasters.com/