A Hunter 9700 performs two primary functions. First it can be used to accomplish a static/dynamic balance - same as conventional wheel balancing machines.

The second function, and one that is unique to the 9700, is its ability to measure radial force variation and wheel runout. It will also analyse the data and recommend if excess radial force variation can be corrected by reindexing the tire on the wheel.

If you just have your tires "balanced" on a 9700 the result will be the same as any other modern balance machine. Having the tires "analysed" on a 9700 is what you need to do if you have a chronic vibration problem, and the shop will undoubtedly have an additional charge for this service.

A couple of years ago the Dunlop D40M2s on my 190E 2.6 developed a vibration that I eventually attributed to out-of-round. I sought out a shop on the www.gsp.9700 web site, and it turned out that the America's Tire Store where I bought the D40s had one. Though the tires were about three years old they still had enough tread for a Dunlop warranty adjustment. I could go ahead and autorize the 9700 analysis, and if the tires were out of spec, there would be no charge. If in spec, I would be charged the quoted rate for the work. I authorized the work, and they let me hang out with the tech as he did the test. I recorded the data. The radial force variation was beyond what is considered acceptable, and the machine's analysis indicated that it could not be brought into acceptable range by reindexing because wheel runout was minimal.

I ordered a set of Sport 8000s (The D40M2s were out of production with no remaining inventory.), and got an allowance on the price based on the remaining D40 tread depth. When the tires arrived the same tech match mark mounted them and balanced them on the 9700, I slipped him a tip and he ran the 9700 analysis. They were all in the range of 8-12 pounds radial force variation, which is very good. The D40s were in the range of 30-40.

Needless to say the car is now very smooth - what you expect for a Mercedes, and I was satisfied with the deal.

There are still a few shops around that have old on-the-car balancers that spin the tires on the car. These balancers only provide static balance, but can be effective in eliminating unbalance of the hub and drum or rotor, but this is rarely an issue. Also, since the entire rotating mass is balanced, you must index the wheel on the hub for future reference. If you remove the wheel/tire from the car and do not install it with the same radial indexing relative to the hub, you will lose the balance.

Duke