"Road-force balancing"

[Roadster]

Originally Posted by efnfast

We used to have a guy that would shave the tires on the car to balance them. Like said earlier, this would balance all the rotating parts. i heard this worked wonders, but the company no longer exists.

If I remember correctly that was called "tire truing" or getting your tires "trued". Same principal as getting your rotors or drums cut. Did this with my first car, a 66 Impala. Had constant problems with vibration, that's when the alignment shop "trued" my tires, vibration eliminated. It did cost a few $$ though. The machine was kind of neat that did the job, as you watched some of your tire tread drop to the floor when shaved.....

[Hib Halverson]

Keep in mind that "road force" balancing is a band-aid for other problems. Yes, it's a capable band-aid, but still...a band-aid.

If you are putting high-quality tires–meaning minimally out of balance, nor out-of-round–on nor with any mass distribution problems–on wheels which are not out-of-round nor have runout and if the tires have been properly mounted, you don't need "road force" balancing.

Bottom line: it all starts with good tires and wheels.

If you're putting POS Summitomos on wheels which are out-of-balance, out-of-round or have run-out and they're mounted by some grease monkey using a tire machine which was new in 1960, well, yeah...you may need "road-force" balancing.

In 20 years of owning a ZR-1, I never had a significant balance problem because I used nothing but Goodyear tires–either GS-Cs, F1GS-D3s or F1 Supercars–ran them on one of two sets of stock A-Molds and had the tires mounted/balanced by the same tire serivice which used premium mounting equipment.

[Paul Workman]

Originally Posted by Hib Halverson

Keep in mind that "road force" balancing is a band-aid for other problems. Yes, it's a capable band-aid, but still...a band-aid.

If you are putting high-quality tires–meaning minimally out of balance, nor out-of-round–on nor with any mass distribution problems–on wheels which are not out-of-round nor have runout and if the tires have been properly mounted, you don't need "road force" balancing.

Bottom line: it all starts with good tires and wheels.

If you're putting POS Summitomos on wheels which are out-of-balance, out-of-round or have run-out and they're mounted by some grease monkey using a tire machine which was new in 1960, well, yeah...you may need "road-force" balancing.

In 20 years of owning a ZR-1, I never had a significant balance problem because I used nothing but Goodyear tires–either GS-Cs, F1GS-D3s or F1 Supercars–ran them on one of two sets of stock A-Molds and had the tires mounted/balanced by the same tire serivice which used premium mounting equipment.

Was this ^^ a "shot across the bow", Hib?

You'll get no argument against everything being 'perfect' - road force tests and basic balancing too would be moot, in a perfect world. But, they use wheel weights, even on "quality" manufactured tires, yes?

No "significant" balance problem... Hmmm.... Well, that's very subjective. And, it depends on the application/driving style and the speeds driven.

The only point I was trying to make was, road-force balancing is another test in addition to "traditional" spin balancing that can further evaluate tires/wheels and could shine a light on a flawed tire that may otherwise have gone undetected.

[WARP TEN]

You are right, Hib--nothing is better than starting with a good set of tires and hopefully reasonably true and well balanced rims. But without the guys doing the Road Force balance on the Sumis I had, I would not have known that two tires needed to be spun on the rims, as they were out of position to facilitate easy balancing. No one else noticed that. And I would not have known that one of the tires was so far out of whack that it could never be properly balanced. As you also note, professional experienced experts with top of the line equipment can resolve a lot of issues. Just simpler to start with good tires. I switched to Michelin Pilot Sports which were great--no balance problems. --Bob

[Racinfan83]

Update on my earlier post: I finally took the car for a longer romp on some smoother roads. I was mistaken before. Vibration is still there. One of these days I will be somewhere with one of you guys where I can swap a set of known non-vibrating wheels and tires on it and see what happens. Until then I guess I will live with it...

[Hib Halverson]

Or maybe...the vibration problem is not tires at all.

[Racinfan83]

Therein why I need a set of known good ones to eliminate the tires and wheels. Because as of right now I have little other way to determine that..

[Paul Workman]

Originally Posted by Racinfan83

Therein why I need a set of known good ones to eliminate the tires and wheels. Because as of right now I have little other way to determine that..

Well, like Hib said, the vibration may not be wheel/tire related. Good point.

However, substituting another set of wheels/tires could very well introduce a new/different set of problems. And, more than that, the very point and purpose of RFB is to evaluate the tires AND the wheels together as a unit, beyond simply using weights to compensate for balance. If the RFB isn't in spec before the wheel is verified, it danged well should be before doing anything else.

Bushings, alignment, etc. need to be considered next, especially if the wheels/tires check out.

Out in the countryside and nobody to share the road with, I nudged her well into triple digits and checked for vibration. There was none. She's a sweetheart!

[WVZR-1]

Originally Posted by Racinfan83

Update on my earlier post: I finally took the car for a longer romp on some smoother roads. I was mistaken before. Vibration is still there. One of these days I will be somewhere with one of you guys where I can swap a set of known non-vibrating wheels and tires on it and see what happens. Until then I guess I will live with it...

Two years ago I suggested this:

http://www.zr1.net/forum/showpost.ph...8&postcount=17

You need a car that satisfies your desired "driveability" before even considering the wheel/tire swap. If the car doesn't satisfy you the swap is a wasted effort. You need to duplicate the MPH/RPM where you "feel" yours to the same MPH/RPM in the "other car".

Since you've chased this at great length maybe you should consider contacting one of the GM dealers you developed a relationship with and use a Kent-Moore EVA2 to try and locate your source of vibration. Is there newer than the EVA2? Maybe!

A short discussion a few years old regarding the EVA2:

http://www.searchautoparts.com/motor...tomotive-vibes

[Racinfan83]

Yes I know. I don't drive the car much and haven't had time or funds to work on chasing it down. I have to get it inspected here soon for new plates so will see if they can do something with it then. Or one of these days I need to drive 5 hrs and get with the FBI crew... I was hoping it went away when I did the pilot bushing but I guess that was wishful thinking...

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