Wheel balancing machine - educate me a bit here!!!
 

So, some time back I picked up a tyre changing machine and a wheel balancing machine from a garage that was closing down. I figured that with the racing etc, I would make back the money quite quickly :)

Here is what I picked up.

http://forums.pelicanparts.com/uploa...1331726879.jpg

I know this is really low end stuff and not anything that a professional shop would use - but for me it is perfect :)

I managed to use the changing machine to replace the tyres on the racing car and on the family car - but the balancing machine has me confused (easy I know).

I balanced all the wheels last night and did manage to get it so that the machine told me all the wheels were balanced perfectly - but now I am having second thoughts and wondering if I have done it correctly. For me it felt like more work than I see done when I have the wheel balanced professionally.

Here is the process I went threw and the results I was getting - is there something strange here, or is this how it should be?

I would put on a wheel and start up the machine - it would indicate what weights to put on the inside and outside and where. I would put on the indicated weights in the indicated locations and then spin up the machine again.

At this point I would expect it to say "congratulations your wheel is balanced" but this was never the case. It would indicate additional weights to be put on in new locations.

I would go threw this process anything between three to six times for each wheel. And by the time it indicated that the wheel was balanced I would have weights all over the inside of the wheel :eek:

On one wheel I tried to do so that I would put on the weights on the inside as indicated but not on the outside as indicated and spin the wheel again - expecting the machine to indicate the same weight and location as before, but it would give me a different result :mad:

I must be doing something wrong, or is this correct operation, and I should just put the wheels on the car and go racing?!?

Thank you for any help and advice :)

First thing you need to do is calibrate the machine. Usually a set size steel wheel and tire is used. Google and try to find the PDF manual to the machine. Once calibrated it will tell you to put the weights on the same place each time.

Also when you mounted the tires did you match mount them using the dot and the valve stem?

Thank you for the info. I did calibrate the machine using the supplied instructions. I used an old Boxster wheel with no tire to do the calibration.

In the instructions it said i could use any wheel, so that was the best option I had. the process was to run it once and then again with a 100g weight on it...


Hmmm - what is this dot aligned to valve thing? Where do I find this special dot on the tire?

OK - google was my friend :)

I found some info on the dot to valve alignment thing, and according to this article it is not a done thing any more? Tire Tech Information - Match Mounting to Enhance Tire & Wheel Uniformity

It is still practiced and due to simple physics it helps. Now if you have a wheel without a low spot that's a different story. The tire will have a high spot. Your problem seems bigger though; are you sure the wheels are true and the tires are definitely good?

All tires don't have the dot (at least not motorcycle tires, haven't done car tires in 25 years).
But your machine shouldn't take more than 2 spins/weight adding to balance a tire.
And the machine shouldn't care if the tire has a high spot, it should be able to balance a brick (though it won't ride very well).
Jim

Thank you for that Jim.

As I am new to this it might be that I am not getting the weights in the correct location or something which is making it take more than two spins. I was assuming that as the machine finally told me the wheels were balanced after a number of spins, that I must have got things correct in the end.

It is just that some of the wheels ended up with weights a bit splattered all over the place. i.e. on wheel at the moment has weights on two locations on the outside and on three locations on the inside - but the machine repeatedly told me at the end that the wheel was balanced...

I think I will either just mount the wheels and see how they feel when driving. Or a suggestion I have had is to balance one wheel, take a picture of the weight locations. remove the weights and then take the wheel to be balanced professional and see how close they do it to the picture from my DIY effort.

But according to the instructions that came with the machine - if I balance a wheel and remove it from the machine and put it back on again it will not necessarily give the same results. This statement is something that confuses me, as I thought a wheel that is balanced is balanced whatever the case!?!

1) Better picture of the balancing machine would be helpful.
2) Make sure that the cone or cuff that you use seats the wheel properly on the balancing machine.
3) There should be adjustments for the rim width, diameter and offset. Be sure those are correct for your wheel.
4) Generally, when you rotate the wheel it to the point where it needs the weight, put it a 12 o'clock. Your machine may be different. RTFM
5) As the wheel spins, watch it to make sure it's not wobbling. If it's wobbling, you're doing something wrong.
6) I generally try to have tires inflated to correct pressure when balancing. YMMV

Hope that helps. Good luck. Report back.

Maybe I should have been more detailed in my descriptions :)

I did calibrate the machine again as per the instructions (which are not very user friendly - they are English translated from some ching-chong language, and assumes you are not a complete beginner!)

The instructions state to put a wheel (any wheel) on the machine and calibrate it with a 100g weight. I followed the instructions and used an old (crash damaged) Porsche wheel I have in the garage.

For each of the wheels that I balanced, I did input the measurements as required before spinning it to balance.

The machine looks to be the same as this one that is available to you in America - UnitedProducts Wheel Balancers Model WB-1100 Just mine is blue and not red :)

As the only instructions I have are what was supplied with the machine and what I have found on YouTube, I have no idea if I am missing some details.

Based on the fact that the machine does eventually indicate that I have managed to balance the wheel - even if it might take 3 or more spins, makes me think that maybe it is me not putting the stick-on weights in the correct location and as such the wheel gets put out of balance again - if this makes sense?

I will just have to put the wheels on the car and give them a go - all it will cost me is my time and the price for more stick-on weights! And I will be pleased once I manage to get it all sorted out ;)

Do you have a better wheel to calibrate with? If that wheel isn't true, it could mess up your calibration, no?

Also, how did you input the offset?

make sure that the machine is secured to the floor!!

Hah!

We had to do a (single plane) rotor balance in a vibrations lab I had. The theory was it would take two spins. The first one you spun it up to find the original imbalance, and corrected it for slow roll. We were using transducers that measured the distance betweeen the shaft surface and the fixed transducer. The slow roll correction was done at slow speed and by subtracting that signal from the total at any speed you could see the dynamic imbalance, ignoring the vibration due to any bends in the shaft. So if your wheels are not true that can screw things up if you are not spinning the wheels very fast.

After that we did some stuff that would be way boring for here. We basically added a weight in a spot close to the heavy side (which we determined looking at the graphs from the initial run), then spun it again, saw the effect of that weight, and based on that effect calculated where to put the next weight. We had fixed spots and fixed weights so it was not really possible to get the rotor balanced without a lot of weights. If you want less weight you need to calc the vector sum, yada yada yada.

Basically, you should have a true and balanced wheel to calibrate I would imagine, and do the balancing at high speed. You may need several weights since you have fixed amounts of weight to choose from and you may not put them in the exactly right place.

And yeah, our machine was bolted to a lab bench but if you set your arm down on the table too hard you could see the effect. Especially at slow speed. The machine needs to be rigidly bolted to a concrete floor.

Kroggers is probably adding grams while the machine is set in ounces. ;):D

Based on how bad the manual is written and how stupid the user interface is, this could be true :)

I think I might have found my problem - it is most probably me not taking enough care to make sure the wheel is centered properly on the cone which is creating the problem. And also the fact that I am trying to do something I have never done before, with very little knowledge and experience :rolleyes:

We calibrate our Hunter with a special calibration weight. Interesting you can use any wheel to do that.

Does your machine offer different weight placemnet options? Can you measure and tell the machine exactly where you will be placing the weights, in terms of offset?

At any rate, a grease pencil is your friend. Use it, of a felt, to accuratly make the wheel. Be precise in where you place the weight strip. Put them right where the machine wants them and you should be fine.