Balance
 

You would be correct- I think I said that earlier on.

I think the main question should be is static balance alright, or do we need dynamic balance?[/QUOTE]

Hmm. I must confess I have never seen the distinction made above. Sumflow, did you make that up just to fool us dumb folk?

The "dynamic imbalance" you show in the image looks a lot like what I would call a bent wheel. If true then I probably don't accept dynamic imbalance. If the wheel doesn't run true I throw it out.

If it appears to run true but gives a little wobble in the steering wheel or shake in the car (apparently the output of static imbalance by the previous diagram) then I just live with it - I got plenty of other stuff to really worry about.

Laurie

I think the concept is this: If the tire has a "heavy" spot towards the outside edge, and you put the balance weight on the inside edge of the rim, it will balance in a static test, but not dynamically. The offset between the two masses causes a "wobble" , that axis is what the drawing is trying to represent.

Static imbalance is a up & down force

Dynamic imbalance is a side to side force

NASCAR balances all of its Goodyear racing tires....

Tire busters face balancing act throughout season - May 12, 2011 - NASCAR.COM

"Once finished at Darlington, mounters rolled their work to 18-year-old Devon Tucker, who in turn passed it along to one of eight people manning balancing machines under a tent just outside the mounting building. There, the balancing contraptions spin at 35 mph to give a weight readout on the front and back of the tire.

Depending on the results, clipped weights from a quarter of an ounce all the way up to a full ounce are hammered onto the rim. The tire is spun again, until the tire is perfectly counter-balanced. Each balancer initials the tire and marks it with his machine number, so that if there's a problem later, it can be properly traced."

When I worked for Shelby who is the western region authorized Goodyear Race tire distributor. I saw them load several tire balancing machines in the tractor trailers preparing for each race. I had them install my new tires a couple times too.

This is a very interesting discussion and almost like talking oil - everybody has their own opinions and recommendations :)

I have just over three weeks to the first race for the 2012 season, so still some time to think about it. I think I will try to run the first race with the wheels not balanced and see how it feels - I can always balance the wheels after the first race if I feel like it.

I will report back after the first race...

What (other than a bent wheel) would cause a side to side force? Seems to me that all forces on a unbent wheel (ie forces derived from rotation around a single fixed axis) would be "up and down".

Read post #24.

Balance them. Clean the wheels thoroughly prior to having them balanced. Remove ALL traces of tape/glue/rubber.

The first job given to team newbies for EVERY RACING team in the world.. is wheel cleaner. They are cleaned prior to every single dismount/mount.

Customers paying me to attend track events? I clean the wheels between every round and make sure the weights are taped on after they return from mount/balance.

It takes 5min per wheel. I set them partially into a trash barrel and scrape off the clag :)

Walk up to any of my cars on grid, and look into the wheels.. spotless..

Jitts:

your way way behind on the GT3 wheels... you have to scuff the area on the rims that the bead sits on. Then.. you have to instruct your mount balance guy to not utilize so much damn LUBE during install. Real race shops/track install guy's use a different lube that evaporates quickly and they know not to use a ton of the sh_t on Hoosiers/Kuhmo's/Toyo's/Slicks.

too many times I have seen people have wheels powder coated, then watch the tires slip big time on the rim throwing the balance off. They have to be scuffed.. all of them.. when generating the braking force of a GT3

I mark all of my wheels at the valve stem with an arrow.. for this exact purpose.. to see if my tire guy is using too much lube :)

BY the way.. this is personal preference. I have not met a diver yet that "likes" to have a unbalanced set of wheels running around the track.

The real issue is: if the wheels are unbalanced, how am I going to be able to tell if there is another issue with the car? Wheel bearings going bad can cause a imbalance, axles coming loose can cause a vibration, rear main bearing in the engine going bad can cause a vibration.. lots and lots of reason to balance the wheels to eliminate them from masking another problem.



B

I did steve but here is my problem: if I have a heavy spot on the outside edge of a wheel the compensating weight would be placed on the same edge 180degrees away. Wouldn't it? I am no expert so I'm looking to understand here.

Thanks Brad, as it is I no longer track the GT3 so not an issue anymore. When I did track it we tried all sorts of tricks and eventually I just gave up and stopped worrying about wheel balance. As I said at the start I have a very inexpensive guy so I do balance the Boxster's tires. Having said that, am I the only guy out there that finds that after a session or 2 between flat spots and built up junk etc. they are way out of balance anyway? Do other people balance tires between replacements?

Thank you Brad - good and helpful insight as usual :)

Jittsl, as I said at the start of this discussion. I had been told by two very experienced people (One is a professional driver and the other has been working crew and looking after cars for most of his working life including some big teams in Europe). And both told me not to bother balancing the wheels on my racing car...

The key is, if you're not dynamically balancing, you won't know if the imbalance is towards the inside or outside, so getting the weight in the exact right spot is a crap shoot.

They are out of balance.. but it is because of buildup!! Clean them out once a day during the weekend!!

Inside secret for keeping the clag off the inside of the rim??

PAM

Seriously. Clean the wheels with Simple Green thoroughly.. get all the Sh_t off of them. Have them balanced, tape the weights on with the silver tape.. then spray the inside of the wheels with PAM. NO JOKE. The rubber chunks/clag won't stick to the PAM (the large pieces won't) Re-PAM them prior to each weekend :)

I hate.. hate.. wheels out of balance on a race car.. and if need be I'll make a list of pro drivers that have complained over the radio about wheel vibrations that drove them nuts. The list is long...



B

Sorry to ask, but what is PAM?

We use it for cooking! It's an anti-stick spray we use in cooking pans! :)

I'm sure you have something on the shelf at your local grocery store/supermarket


http://thriftywifey.com/wp-content/u.../pam-spray.jpg

lateral runout in the wheel &/or tire or brake rotors

uneven tread wear

damage

heavy spots

nothing is perfect