tire vibration and balancing

[Melbo]

Ok so I got the repower done and everything is going fine. I have this miserable vibration that I can feel in the steering wheel and some cupping on the front tires.

You can drive around town all you want but it's not the same as a good old road trip.

We took the coach up the mountain to a little restaurant and my girlfriend even drove it a bit a had a ball.

But at certain speeds the vibration would set in -- not all the time just at certain speeds.

My son wants to do a triathlon and there is one in Mexico ( 800 miles each way ) ( 240 a gallon diesel in mexico ) so that seems like a good road trip and off we go.

Everything goes as planned but the vibration at certain speeds kicks my butt.

The Mexican roads and the vibration at certain speeds -- I'm not happy but we press on.

Coming home on a lonely stretch of AZ highway a loud noise in the back of the coach tells me something is VERY wrong.

The fuel peddle does nothing and the engine sounds fine but we are coasting. I locate a wide spot in the road and pull to the side. -- Nothing like traveling in a motor home -- wherever you are at your home.

I have good sam ERS and give them a call they tell me they don't do buses I explain again it used to be a bus but it is now a motorhome and I asked that question before I sent them money and they need a trailer to haul me in. After a couple of minutes they tell me they will be sending  someone to haul me to a campground ( this is sunday about noon ) and then they will take me to a repair facility on Monday.

Once I have secured transportation I begin to investigate what has happened. I discover the drive line has dropped out. -- I feel like a fool --  I thought it was tire vibration and now I think it was the driveline.

Long story short I get the driveline balanced and replaced and when I go to pick the coach up I mention that the tires might also be vibrating -- the mechanic who worked on the bus tells me to be sure and have the tires spin balanced ON the coach. Friday when I begin the drive home I have a new balanced driveline and the vibration still is making me crazy.

So I get home and start the search for new steer tires. The tire man I talk to says yes they spin balance them but they do it off the coach and that way if you have any vibration when the wheels are installed it is from the coach and not the tires.

Makes sense to me but what the heck do I know I just dropped a drive line and didn't know it was coming and now still have this obnoxious vibration I still can't explain.

My question is do most people get the tires spin balanced on the bus or off and what are the pros and cons of each way and is it worth the effort to find someone who will do it the other way if you want them too.

Melbo

[Lin]

There are different things on the market to balance the wheel in motion.  I forget the names, but one is a powder that is put inside the tire.  Another is pellets.  The idea is that as the wheel spins, the stuff spreads out where it is needed to perfectly balance it in motion. Another is called a Centrmatic Wheel Balancer.  These are mounted outside the tire to do the same thing.  I think some on this board say they use them.

[TomC]

Take this from one who has driven 1.3 million miles and tried all ways to keep tires balanced.  Here's what I have found that works best. Put new quality tires on the steer (since they are cupping now, they'll only get worse-you can't stop it [actually you can by shaving the tires, but most tire shops have abandoned the practice because of insurance reasons]) and have them static balanced before mounting.  Before putting the freshly new and balanced tire on, put on the Centramatic balancing rings also.  When replacing the rears, do the same thing.  They make a Centramatic for mounting in between the duals.  Do not use golf balls, Equal powder, liquid-it doesn't work.   Do what I have said and you'll have a very smooth ride for the duration of the tire life.  Also make sure the front end is in alignment with the toe setting being the most important (usually 1/16-1/8" of toe in).  Good Luck, TomC

[JohnEd]

Yes!  What Tom said many times over.

To answer your question:  You can static balance and the tire will bounce you to hades.  If you spin the tire on the bus you are balancing ALL OF THE WHEEL....everything that spins.  The brake drum comes balanced but is often not true.  The rim is certainly not perfect AND the mating of the wheel to the drum is off center by thousandths and with the weight of these massive things those thousandths add up to some serious vibrations...sometimes.  The optimum sequence is to have the drums balanced, then the rims, then insure that the rims are rotating in a perfect circle and that the tire mating surface in the rim is turning true.  THEN mount the tire and static balance for the perfect balance....sure you do   I have done that with race cars and the final result was a vibrating tire/wheel/drum assembly.  You mount it up and spin it and cut it so it is running without any surface irregularities(oval)and add weights till it is running without vibration AND IT IS BALANCED as an assembly or system.  Not forever though.  Forever will take the FIX that Tom advocated.  Those little balls spinning in oil self correct for any changes to the tire as it ages.  Give the system a break though and have the tires static balanced before they are mounted.  Those balancers are not FREE though and the cost may give you pause.

The cupping means YOU HAVE AN alignment or mechanical problem or both.  The tires will never wear smooth and will cup even more on a steer axle and start vibrating again even if you can get them balanced to their cupping condition now.  Have a partner sit in the bus and rock the wheel back and forth rapidly.  You lay under the coach and grasp each tie rod end and flex joint and feel for movement between the two pieces or clunking inside the joint.  Nothing should "slip" back and forth but rather smoothly rotate slightly in you hand.  Also look at all those massive steel mountings and make sure nothing is doing a "DANCE".

All of everything I have suggested has worked for me many times in the past.  Tom's advice is nearly foolproof.  Check out the joints and check the toe regardless of what else you do.

[tekebird]

I would say it is probably a ballance issue.

but also, tires are not always true round....and ballancing will not fix not round.

Ballancing products I can attest to working

Centrimatic
Dynabeads
Equal.

Equal is a pain because you need valve filtes and any moistur in supply air will make the stuf a solid

also if you can find someone to true the tire (shave it as Tom called it)  it is a lost art.....but maily because the tire quality controll is much higher than 50 years ago

Also I can attest to a rear ballance issue can also cause front end vibrations.......\

Those cupped tires are done for....you will not get them back......

Another possibility....the tires are not designed for that use.  Tires are designed for different applications.....and I have seen City/short haul designed tires cup from the start when put on a coach...these types of tires are designed for regular stops, not hours of highway speeds......thus the tire guts are different

Be sure your new tires are highway/long haul tires......and have the weight rating you need......also that they are properly inflated based on your coaches weight (per axle)

[TomC]

To further expand on what Tekebird said, I had a fleet order 10 trucks from us and the gal that was being the "salesman" at the time ordered the trucks with Michelin XZE tires.  While they are rated for 75mph, they are a regional tire with stiffer side walls and no decuppler groove on the sides of the tread.  They started cupping out around 60,000miles and were done at 80,000mile.  I have the XZE's on my bus, but knowing I would never get to that kind of mileage before the 10 year mark, it didn't matter.  Most over the road highway designed tires, like the steer tire XZA3 should last 120,000 mile.  The drive tire like the XDA3 should last close to 200,000 miles.  Good Luck,TomC

[edroelle]

TomC mentioned the decoupler groove on the outside edge of the tire.  I have found that this groove is a key element to preventing the edge cupping.  The tire apparently does not start "squirming" down the road, then cupping.

I had brand new Goodyear G159 tires (no decoupling groove), spun balance, and Centramatics at all wheel locations.  Suspension parts were tight.   The tires cupped on front AND rear of my MCI8.   I also looked at many other G159 tires of other's busses, with similar cupping.   Goodyear reps, at an FMCA rally, claimed ignorance !!   I now say, "Ed, why would you want to buy from ignorant people?"

Whenever possible, try to buy a tire with a decoupling groove.

Ed Roelle
Flint, MI

[tekebird]

yeah that grove will make the difference..........I was actually elightened to that my a goodyear leased tire rep when I inquired......

He asked what type of tire and what they were on.......plain and simple wrong application

[Kristinsgrandpa]

Some rims come from the factory ballanced. Accuride rims with a "C" suffix on their number designation are ballanced.
Produced for coach applications.


http://www.accuridewheels.com/Aluminum_wheels.asp

The number on mine is 27834 C.  8.25" X 22.5", hub piloted.

Ed

[TomC]

That's a good reason why Goodyear doesn't make the G159 anymore.  It is now a G169.  Good Luck, TomC

[Tony LEE]

Don't rule out diff-pinion bearing problems if the vibration appears to be coming from the back