Hunter GSP9700 balancing - how much $$?

Messages
74
Location
Colorado
How much have you paid to have a GSP9700 balancing done? My local Audi dealer says $45 for the whole car. I am confused. I thought they usually charged $80+. He said it included the load force analysis and everything you would expect. I know he is competent because he was recommended by the local Hunter service tech.
 
Messages
943
Location
Central Valley, CA
You do not "have" to unmount and remount the tire to line up the roadforce matches between the tire and rim/wheel. All you have to do is break the bead, and then rotate the tire to the spot. Lower profile tires will be much harder, light truck tires are easiest. I've done so in my Auto 53 class, we have a slightly older GSP9700 machine and a (somewhat crappy) snap-on tire changer; we really need one of those new tire changers, something like a Hunter TC3500. What I'd do is thoroughly clean the hub of the wheel, and as much of the stuff off the wheel. Then I'd remove all weights. Of course I'd have air pressure setup. I'd mount the wheel on the spindle. Then I'd use the "dataset arms" on the 9700 to measure the rim dimensions. Then I'd measure rim runout using the dataset arms (the posistions you'd use for dimensions and runout are NOT the same; anyone who reads the manual would know this). Then I'd exit to balance, then close the "autostart" hood, and it'd do the roadforce measurement and balance spin. Everyonce in a while, i'd do a balance calibration, its completely guided onscreen. There are three different settings for the system, P, P/SUV, and LT as far as roadforce variations. Each setting has a different tolerance, with P being the most sensitive, and LT being the least. You can manually change the margins for the tolerances. You can do static or dynamic balancing on the machine. You can also select between clip on weights, clipon/sticky, only sticky, or internal tire patch weights.
 

chuck wood

Thread starter
Messages
74
Location
Colorado
Wow thanks for the reply Chris, I have no clue when it comes to working with tires and everything you explained is something a mechanic isn't going to try to rattle off while you're standing there. My tires are 225/60/15 so they are in between truck tire & low profile, which should make the rotation after bead break easier than a low profile I would guess. Will the machine also tell you if the tire/wheel combo isn't going to ever be balanced enough to meet its tolereances? When they originally balanced them I remember they needed 3oz on one of them, isn't that a lot for a 15" passenger car wheel?
 
Messages
943
Location
Central Valley, CA
Yes, the 9700 machine can and does calculate whether or not the assembly (tire and wheel) will come within roadforce limits after matching the tires and wheel. It will tell you if the tire is excessive or if the wheel is excessive. It shows you exactly where to mark the wheel and tire, and has a "preview" option to show you what the assembly would be if it were to be roadforce matched. Getting a good mounting on the 9700 is critical and key to having the machine perform its duties well; in class I was doing some LT tires on a mazda pickup, and it showed 5.25oz! for just one flange of the wheel. I remounted the wheel to the spindle shaft on the 9700, and the weight was a lot more tolerable at 1.75oz. Thats why I make sure to clean the spindle threads after everytime I use it (not so sure about others in the class), and if I have time, i'll usually calibrate the balancer using a quick calibrate; takes about 5 minutes. The 9700 is a great machine...I'm glad our auto 53 class has use of one. I just wish it was a little less expensive so I could buy one for home/personal use; i'd balance tires all day long just for fun. I think the 9700 costs about $10,000 brand new. The TC3500 tire changer is about $5500.
 
Messages
943
Location
Central Valley, CA
Oh, imo, 3oz is a lot for one flange of one rim. (For total weight, not too bad) for a 15" passanger tire. I've only seen it that high on truck tires for a Toyota 4Runner using the 9700. Hopefully the 9700 would be able to lower that weight significantly. If you don't care so much about the appearence of weights on the outside rim, then by all means get the tires dynamically balanced, or use stickies. Static [usually] only puts weight on the inside flange/rim.
 

chuck wood

Thread starter
Messages
74
Location
Colorado
This is for balancing a set that is already on the rims. I am thinking they will charge extra if they have to unmount & remount any of them. I was under the impression that to fully utilize the load force analysis feature, you first run and measure, mark the high spot on the tire, remount according to the analysis, then run again. I'm dealing with a set of BFG Traction T/A V rated tires and according to the original installers they came without being marked for a high spot, so they just kind of put them on as best they could, I guess... I'm seeing a small vibration that starts in the rear once I hit 75+ cruising speed on the interstate. I had to get them rebalanced while on a trip after an initial 800 miles and that fixed most problems except this very small annoyance. [ March 16, 2005, 12:27 PM: Message edited by: chuck wood ]
 
Messages
3,933
Location
Somewhere in the US
Chris, Have you noticed the GSP9700 has the same tolerance for the wheels as for the tires (and for the entire assembly)? I take this to mean that an uninformed tech would say if the assembly is over the tolerance, but the wheel is in tolerance, then the tire is bad. BTW, I'm trying to reprogram the tolerance for the wheels to about 1/3 of what the presets are, but I can't seem to find enough time to wade through the book to find out how to do that. Luckily, everyone who uses our machine already knows what the OE tolerances for wheels are and can recognize they have a bad wheel.
 
Messages
943
Location
Central Valley, CA
From what i've gathered reading the manual and using the machine, yes, the wheel can be good (the measured runout will be ok) but the tire can be bad, or vice versa, but the machine cannot get a very accurate reading of the roadforce on the tire if the wheel has too much variation (though i think it does take this into account when doing the matching process). The machine can and does tell you whether the tire or the wheel is causing the assembly to be out of tolerance, or at least the way our is setup it does. If after the balance the machine detects excessive variation, it will ask you to re-measure the rim runout using the dataset arms; using the correct location of the arms against the wheels is crucial to obtaining correct data. Some rims cannot be measured on both sides very well, and it's not very convinient to dismount the tire to measure a bare rim. I belive the machine does take into account rim runout and tire roadforce variation when calculating the assembly's total variation in pounds. However, rim runout (which the machine converts to pounds through some formula) i think has different tolerances than tires. There are three settings for tires, P, P/SUV, LT/SUV and you can make you own as well, and modify the tolernaces for the presets. I am pretty sure I remember there is a way to change the rim runout tolerance for the wheel as well. I remeber when using the roadforce measurement screen, when you make the marks, it can tell you in pounds, how much force is at the point you marked either on the tire or on the wheel. When you are on the balance screen, it tells you the pounds on the total assembly. As far as changing the tolerances, the manual gives pretty good instructions on how to do so. if you can find what "K" button it is, i think the onscreen prompts are good too. I've never changed the default tolerances. When I measure the rim runout using the dataset arms, the machine tells you either pass, fail, marginal from what i recall. You can also hit one of the "K" buttons to show the actual readings on the runout. Same goes for the roadforce variation on the tire; there is a "K" button you can push to show a graph and numbers of the roadforce on the tire, and also the assembly as a whole.
 
Messages
3,933
Location
Somewhere in the US
I think you missed my point. Set the machine up to look at the tolerances. For the "P" setting the tolerances are: Assembly = 26 pounds, Tire = 26 pounds, Wheel = 0.026" (which is 26 pounds) So if you have a 28 pound assembly, the machine will say this is out of tolerance. If you were to measure the wheel, and it said 0.024" (which is twice the allowable OE limit), the machine would say the wheel is good. So even if the tire is only 10 pounds (on a tolerance of 26 pounds), it's possible for a tech to conclude (incorrectly) that the tire is the problem. Hope this helps.
 

chuck wood

Thread starter
Messages
74
Location
Colorado
I got mine balanced today. One had to be turned, it started out as .027 and once turned it was .012 So in the end there were two @ .012 and two @ .010. The techs said one required 3oz & .75 oz to balance it. They didn't think it was a problem as long as the final balance showed up 0's These are BFG Traction T/A V rated 225/60/15 on original 1988 Mercedes Benz rims. However... there is about 8" of new snow on the ground so I couldn't really take them for a 75mph+ cruise test... [SPAZ!]
 
Messages
943
Location
Central Valley, CA
Ahh...i see what you're saying. The machine does tell you whether the tire is good/bad or if the wheel is good/bad. I've never encountered that particular situation you describe myself; all the wheels i've checked have always measured "pass" (or sometime marginal) so if there were excessive roadforce variation, then the machine would say its the tire. I had one tire/wheel assmebly that the machine intially said the wheel was no good, but, i remounted it , and then the wheel read fine, but the roadforce was out by only 1 lbs; i assume the tire caused this. It balanced out fine though. It's better to measure the wheel runout after it does the roadforce/balance because if it detects to much variation, it will ask you to do a wheel check anyhow. I guess its sorta a judgement call as to how much over the tolerance a tech would allow versus the machine. The machine does a pretty good job in my opinion of telling you; i've encountered where it will [strongly] suggest replacing a tire/wheel, or it will just let you know that the assembly is not within tolerance but it will/might balance ok. If you are getting a lot of variation, time to [fully] calibrate the machine in my opinion.
 
Messages
1,908
Location
Fort Worth, TX
Great info about the 9700! DISCOUNT TIRE (can't remember $) is where I buy tires and have this service done. It's nice to find the "worst" wheel (alloy, in this case) and have it mounted with the spare. All other benefits aside, the -9700 service is also peace of mind in isolating other problems (alignment, steering, etc) otherwise exacerbated by tire/wheel balance problems. BITOG likely has as many guys assiduously researching the "right" tires (at least, I hope so) as in searching out fluids, the use of, etc. The service of a knowledgeable tech on a -9700 is invaluable, IMO, in keeping the "right" tires alive and like-new for as long as possible. [ March 18, 2005, 12:44 PM: Message edited by: TheTanSedan ]
 

chuck wood

Thread starter
Messages
74
Location
Colorado
The test drive is a success. Up to 95 mph and absolutely solid. The .027 reading was obviously a big factor that would have been tough to nail down without the Hunter. Once the Traction T/A's get warmed up they are smooth with lots of road feedback so you have to be careful to not confuse that with vibration on poorly surfaced highway.
 
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