1970s 67-78 Eldorado wheel balancing

[TJ Hopland]

I have always had issues getting and keeping the wheels in balance on all the 67-78 Eldos I have owned including the one I have had for 30 years now.  Over those years in that car I have tried everything but the beads.  Different rims different tires roadforce balancing mixed and usually fairly short lived results.   Best results have always been using the proper CAX weights on the outside and inside seems to be fine with regular clip on weights.  Stick on weights have always been a complete failure. 

For those that don't know the earlier 70's cars the hubcaps grab right in the bead area where the weights normally go rather than in that first flat step.  Their workaround for that issue was to design a weight with an extended clip to leave a gap for the hubcap.  I think I read Lincoln also had the same thing going on some models in the same era. 

The RWD cars could have the same issues I am talking about here if they also use that style of hubcap but I don't think the RWD cars are as sensitive to out of balance as the Eldo's are so we don't seem to hear about as many issues with the RWD cars. The CAX weights are very hard to find these days.  Party because the cars that used them are in the 50 year old range now and many shops had or chose to get rid of the lead weights in favor of some non lead material and as far as I know no one ever bothered to make lead free in this style. 

Recently I bought my own used balance machine I keep at a friends home shop that already had a tire machine.  He kinda knows how to run one but is more used to heavy trucks which apparently is usually done differently.   I have no idea what I'm doing or if the machine is any good and on my first attempt got a way better balance on at least the front tires than I have ever got before.  If my back tires were not aged out and bald I would have done those too but was too lazy to take the skirts off since they just need to be replaced.

Anyways what got me wondering why most shops can't seem to be able to do this other than lazy unskilled or untrained people that just don't give a crap and are using abused equipment is many machines seem to have a steel and aluminum mode.  Steel mode assumes you are using clip on weights like as been used forever.  When you got to aluminum mode you have to use your judgement about where you are able to place the stick on weights and then select that position on the machine so it can do the math properly based on all the distances. 

From what I can tell in aluminum mode you can't actually measure where they are gonna go and they are making some assumptions on how thick the material is in the area you are placing the weights.  You just get maybe 5 options of the most common areas yo could put them on a typical aluminum rim and they must also have come up with an average thickness offset since all you program in is the diameter at the bead area.

So I'm wondering if the reason the tape weights have always been a failure is if you set the machine in steel mode its assuming they are right there in the bead area.  Even if you get them as close as you can to the bead you are a little further in diameter wise and width wise.  Maybe one of those isn't that big a deal but both maybe add up? 

If you go to aluminum mode the machines don't really have a position setting that is where you could put them on these steel wheels plus they are way thinner wall wise so again the calculations will be off a bit.  It doesn't seem like a lot but we are working in 1/4 ounce increments so being inches off in the calculations you are constantly missing the target and starting to balance the out of balance you have created using the wrong calcs.

Basically if you don't have the CAX weights the machine can't really accurately balance one of these wheels.  They should be saying they are out of balance so I assume they tech just keeps slapping weights on and failing so they just kinda give up and call it close is good enough which isn't with these cars. The CAX weights I have I think are slightly lighter (or maybe heavier I can't remember) by like a 1/4 oz than their labels say.  I suspect this is maybe to compensate for their extended clip changing the position slightly?   

When you put a tire on the machine there are several settings you have to set.  The machines have a built in measuring tool to measure from the side of the machine to the bead lip of the rim.  You then have a caliper tool to measure the width of the rim. Then it asks for the diameter which you can just take off the tire.  You have to enter all those numbers with a keypad.  Once you get all that in you have to select the mode steel or one of the various aluminum modes.  Screw up or miss any of those steps and you won't get good results.  With all the sizes of tires out there today I really wonder how often the average techs try very hard to get all that right?  The annoying thing is if you put the wrong numbers in that doesn't result in a perfect balance reading so these people likely know they didn't do a good job.       

[TJ Hopland]

Someone contacted me and said if you buy the like $20k latest and greatest machine those have some built in laser stuff that makes it less dependent on the operator to both measure and input all that size data.  Still seems like the average tech these days could screw that up like the time I was watching them do an alignment on one of my cars and they dropped the gizmo that hangs on the rim twice then apparently bent it back so it would sorta stay on the wheel and continued the alignment. 

The person also said I could be onto something with my theory about the placement in this case if you don't have the cax weights and did confirm that I am correct in screwing all that up should not result in a false 'perfect' balance, its gonna read that its not in balance.  They also said the more common place things go wrong is how much care is taken placing the wheel on the machine and how badly the machine is abused and out of calibration.  Those issues could result in a good balance reading that won't be anywhere close once its back on the car.  It seems like pretty much everything is against us with these old cars.

[bcroe]

Certainly the wheel absolutely must be centered right
on the balance machine.  I figure run it again after
the weights are added and it should be perfect, is
that always done? 

To compensate for weight increments, you could put
a pair of weights, each slightly over half needed
at the correct spot, then move them apart to
reduce the effect.  Bruce Roe