| car speed and tire size and with stock size rear tires (245/45 x 16) with about a 12" loaded tire radius the DS is turning about 2600 rpm at 50 mph and 3100 rpm at 60mph. Because they balance the DS at a single rpm, what happens at other rpms? Ask what rpm they balanced your DS at. The reason the factory put a 2 piece DS in the Z car is because they wanted to reduce DS harmonic vibrations and not drone out the driver (they would have liked to reduce cost and use a 1 piece). The 1 piece can't do this as well as the 2 piece. Some here have had better luck than others with the 1 piece. I tried one and had no luck with what ever I tried to reduce the harmonics. In your case try clocking the DS in different positions at the reaf differential flange. That could change the harmonics? Tire balance might clear it up if they are mounted and balanced correctly. Ask the shop to: 1. Check the lateral and radial runout of the rims at the tire bead (if they know what that means and how to do it and what is acceptable spec). Here is how to check: [ http://300zx-twinturbo.com/cgi-bin/manual.cgi?list=ra&dir=&config=&refresh=&slide=6&cycle=off&scale=0&design=default&total=35 ] 2. Match mount the tires (tire shop response usually - HUH!. The side wall on performance tires has a colored dot that the factory took great pains to locate (how and what is it is another story) and needs to be placed at the average low point on the rim determined by measurement unless the OEM dot on the rim is still there for aligning the dot on the tire to it. These shops usually place the dot at the valve stem -NOT CORRECT! That is there easy way out.
3. After mounting while still on the balance machine check the tire for tread lateral and radial runout that results from poor tire construction. 4. For correct dynamic balance weights need to be placed on both sides of the rim as needed. If the tire/rim takes 4 oz or more of weight reject the tire. 5. Make sure they torque the lugs in proper sequence at the proper torque. I do a 3 step torque sequence. 6. Do a road test. If poor results get right back to the shop to fix it. Remember a cube can be dynamically balanced on any axis but it will not give a smooth ride on a road. Good luck! ZUL8TR in Orlando,FL
ZUL8TR in Orlando,FL |
07:21:46 12/17/13
