65 MPH Front End Vibration

[Hooligan]

Originally Posted by rScotty

Balancing tires starts with checking that the wheel is symmetrical on the balance machine. Confirming hat the center hole is in the center, and that the rim is equidistant from the center. Every tire balance machine - whether cone, hub, or axle mount type - allows for this type measurement , but not every shop does it.

You might want to search for a shop that knows how to set up their balance machine and are willing to do so. Be aware it will cost more to do it right. That will double or triple the balance time and is not the sort of time that a shop gives away just to sell a set of tires. But worth it, IMHO.

Ask if you can watch the technician work. As the machine spins up you can see for yourself good balance jobspins smoothly without jumping.
rScotty

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This was a process over more than a week. Major chain tire shop. Wheel set up, centered, measured, spun and weighs applied. Spin to confirm and gave new results. Even replaced the centering cone from Hunter. 2nd shop had brand new equipment, still unable. Mercedes shop right on the money first time. Mounted to a hub.

[rScotty]

Different brnds of struts feature a spring and damping rate that is different from the factory equipment. In fact, those differences are exactly what the after market suspension company is selling you.

To answer your question - Yes, changing the spring and damping rate will change the amplitude and frequency of any unbalanced shaking that is going on. Tires and suspension are the classic case. Changing struts can even cause a quiet system to become a shaker.

All the after-market suspension companies make their living by betting that their engineering dept. does a better job on designing a smooth ride than the Mercedes engineers do. They back this up with advertising, and it's up to you to decide if their argument has merit.
This whole subject is simple basic mechanical engineering of vibration systems and is common throughout the manufacturing industry. It used to be as much art as science because the calculations were so complex and one brilliant designer could start his own custom spring and damper company. But anymore the design part it is just pushing buttons on a computer program. Now it is advertising as much as performance that sells after market suspensions.

rScotty

[JPalmer]

So I thought I would close the loop on this thread or at least give an update. The weather finally broke I got the Sprinter out of winter storage and bought it some new Michelin Agelis tires, and I bought them from a shop that does the road force balancing. I am happy to report that my 65 mph vibration is gone, even up to 85 mph.

I also witnessed some interesting things during the balancing process. When I bought my Sprinter (Winnie Class B) it came with Alcoa aluminum wheels, and like with most alum. wheels the inside duals were steel. Now here is the interesting part, when the tire guy put the Alcoas on the balance machine they were really out of balance compared to the steel wheels. The alcoas required 2.25 - 2.75 ounces on the inside and 1.5 - 2.0 ounces on the outside. Now not having any experience with balancing tires this didn't mean anything to me until the steel wheels went on, each steel wheel only required .25 ounces on the inside and none on the outside.

All of you out there that are savvy to this kind of thing, is this normal, are steel wheels better than the aluminum ones, or just a coincidence?

By the way, thank you all a ton for the info on the tires and road force balancing thing! Not to mention the info on suspension!

[outlaw5067]

Originally Posted by JPalmer

The alcoas required 2.25 - 2.75 ounces on the inside and 1.5 - 2.0 ounces on the outside. Now not having any experience with balancing tires this didn't mean anything to me until the steel wheels went on, each steel wheel only required .25 ounces on the inside and none on the outside.

I'm glad you got it taken care of... That much weight is not too bad... it's more than desirable, but it is acceptable. My '08 2500 CCLB 4WD diesel PU has more than that on 2 of the factory rims... Your steel wheels combined with the tires are almost perfect... You don't see that too often even on the regular automotive side...