Chevrolet C60s - Front Wheel "shimmy"

[cordenj]

Excellent video Phil.

All seems very familiar to me!

I jacked up each axle and set up a pointer and ran each axle static. I had found one of my wheels to have a significant variation at the rim edge. changed that wheel with a spare I managed to obtain.

In the first two years of ownership, I had these split rims apart and together more times than I like to think about (good exercise I suppose). I made sure the mating faces of the two halves were clean and that they were bolting together correctly as I appreciate that a small error here will cause the rim movement we are seeing.

All 4 wheels are now reasonably straight in that there is only slightly movement at the rim on each one, certainly less than on you truck.

Tyres do have some "out of round" movement when run static, but am not sure how much of that is from sitting for a month between giving them some exercise.

Still, As I said at 25mph the truck runs well, and that is not a problem in the areas in tend to use it.

[Lynn Eades]

Phil, the wheels are forged and I think that "eccentric" extra bit, is commonplace. The military Dodge rim was factory balanced. (welded on steel weight) I assume CMP wheels were as well.
I noticed the brake drum is not running exactly true. An out of round drum can be a culprit.

[Andy Beevers]

John,
such a small world at times.
Somebody else reccomended Jones, called them this morning, in the post now, should be here tomorrow.
I have already got a bush puller and replacer so good on that thank you.
I have ordered an H10 adjustable reamer which should allow for what I need.

Phil, excellent video, however once you start on you tube difficult to stop, liked the HUP going out in the snow too.
Once those wheels start to go shimmy, it takes everything with it.
I did notice a little movement on the pitman arm draglink, (tighten screw all the way in, then back off half turn, fill with grease, sorry sucking eggs etc.) but from that view the temptation is to say the wheels start the shimmy and it just gets bigger till centrifugal force wins and pulls the shimmy back out like a gyroscope.

I will still follow the engineering principal of 1 item at a time, then I will know.
So, will get the springs done, then balance the wheels, and try to post a video like you have done, might take longer for me to do that than strip the truck!

Should be out for a roadtest this coming weekend, if all goes as promised.

[Andy Beevers]

Phil,
Some other points,
truck sounds real good, accelerates well, gear changes, wow, so smooth and quiet.

The following are random thoughts that may get me somewhere, or not.
I am tempted to try something a bit different.
What if a weight was placed, of a significant size, on the wheel and then run again. If the shimmy was worse or better, then wheel/drum imbalance is the cause. It is a theory, if it can be made worse, then the opposite should make it better.

I have a box of stick on weights, will try, 100g strips, a couple should do something.
Then using the logic of the on car balancer, using the tyre valve as a starting point, should be able to do on road balancing. Problem though, is one wheel at a time is the best way, some more thought perhaps.
Not overly keen on testing one wheel at a time on axle stands, the way it shakes could be a bit more excitement than I need.

[motto]

Originally Posted by Lynn Eades

Phil, the wheels are forged and I think that "eccentric" extra bit, is commonplace. The military Dodge rim was factory balanced. (welded on steel weight) I assume CMP wheels were as well.

The welded steel weights on the 3/4 ton Dodge wheels (I think supplied by Budd) seem to be a standard weight in a standard position to compensate for the valve stem cutout. I suspect they were not individually balanced though I have not compared wheels to confirm this. It would be an oddity if they were as I don't know of ex factory weights on Jeep or GMC/Stude wheels etc.

David

[Lang]

These balance beads work absolutely wonderfully. They take into account any unbalance caused by bearings, drum weight, wheel weight and tyre weight and even slightly out of round.

The physics behind them is very complex but they are very widely used, even on 200mph race cars. They are relatively cheap and many brands.

[Tony Smith]

Do they work with inner tubes? I understood them to used by putting a handful inside tubeless tyres when fitting to the rim. Would you have to remove the valve from the inner tube stem and feed in each bead one by one through the stem?

[Lang]

Tony

You can get small size balls to feed into a tube stem.

I saw a set of tyres (tires) fitted in USA for a Dodge WC and the kit came with the balls and a little funnel arrangement. Took some time and a little jiggling but the result was perfect.

You are right about the tubeless tyres, just throw in the bag, which quickly disintegrates to release the balls when fitting the tyre to the rim.

There is also heavy liquid to do the same job on the market which I presume would be easier for tubes. Motorcycles use this a lot.

Antique and Classic Car owners have discovered Dyna Beads®!
Classic Car and Antique Automobile tires, whether tube or tubeless, need Dyna Beads®. This long era of automobiles and the styles of tires that were used back then lend themselves perfectly to using Dyna Beads for tire balancing.

If you look at this video at around 2.25 minutes you will see a valve stem filling system.

https://www.youtube.com/watch?v=z4h0H7ycIBg

Lang

[Phil Waterman]

Hi

Simple caution about using Dyna Beads, be sure to use good metal value stem caps. Reason I say this is that years ago had a version of the beads put in the tires of my C60S tires by a heavy truck tire shop. No problem airing up the tires but later after adjusting air pressure down the the stem valves would not always seal complete. Blow a little air in problem would go away. Replaced the stem valves, same issue bleed air out valves would slow leak, quick blast of air in they sealed again. As a precaution replaced all the plastic value caps with good metal ones.

Now as to did the beads balance the tires no. These were used 11:00x20 military tires probably 50% tread cronic out of balance in the end replacement was the only fix.

Cheers