The Official 356Talk Forum

I had to have tires shipped into Bahrain. I got some All SEASON Classic Radial 165/80 R15s. Before I had a slight shimmy at around 55mph. But now it is very pronounced. Even after dynamic balancing. I bought a spacer a long time ago and this is the first time I've used it. Should I spin balance the spacer and see how close it is to balanced before using it with the tires? Not sure why it was ok before and now unacceptable. Thanks for any info.

James, jack the car up and spin the front tires in turn. Check and see if there is any out of round on the tires or if there is any wobble. If so try a rear tire and see if that is better. You can also check balance while doing that because the wheel should stop in a random position every time you spin it up as long as the brakes are not rubbing. It is also possible the shop did not get the tires balanced properly and also possible that they distorted the rim depending on how they changed the tires.

Most tires (other than Michelin) used to be out of round in the 60s and 70s but I haven't seen that for a long time. I had some Dunlaps "trued" (they cut them until they are round) and I lost half the brand new tire but it did make the car run smooth.

Chuck

1 Try it with out the spacer. 2 balance the tire mounted with the spacer and the wheel on .

As David said, turn the tire on the car just off the ground and see if there are high spots on the tire (with and without the spacer).

Chuck

It is surprising to me how often tires are a bit out of round but balance and work just fine. 3/16" is not a problem on a modern car, probably wouldn't bother a 356 either, as long as they are balanced correctly. Also check for a bent rim or bent rear axle. Were yours balanced on a modern machine, or spin-balanced on the car? The type for on the car usually spins too fast to do it right.

I do mine on a bubble balancer like the one pictured in this Ebay ad. I initially bought it to balance race tires on the F Vee and it paid for itself in one season. Balancing at the track was expensive unless you bought new tires then when you turned them to maximize wear it was at least $20 each time and that adds up over a season of racing.
https://www.ebay.com/i/332442739785?chn=ps&dispctrl=1
Mine is in somewhat better condition and gets used quite often but I also check the tires on the car for wobble and out of round as obviously one can only do a static balance using the bubble balancer. I believe the tires are not wide enough to need dynamic balance as the out of balance forces cannot be far enough apart to have much of an effect even with a 185 width. At least that has been my experience.
One should however endeavor to split the weights side to side even so to obviate dynamic unbalance.

My fiat 500 shimmied like crazy at 50mph with unbalanced 125 width tires. Shimmy gone after spinning them on balancer.

It seems like radial tires are more mysterious than bias-ply to balance properly. Bias-plys usually are fine on a static balancer, radials less often are. My Bridgestones are nice and smooth luckily as I have no way to balance them at all.

I used to balance mine with the balancer I made (balanced when circles are concentric). Very accurate and worked fine, but now I spin balance.

Chuck

I've just got back to country and thanks for your inputs. I'll try them all but not sure I understand the last set up. It looks like it hangs but is horizontal. Please explain if you are still in this line. Thanks again.

Let me tell you my best balancing story. I was at Leguna Seca with Ray Knight in the Sauter Roadster. He thought he wanted the tires balanced. I don't know why they were a million years old. So I went to the balancer guy who had an thick aluminum plate with studs for the large bolt pattern (pre 356C) wheels. Next to the plate was a Carrera alloy wheel with a racing tire and a ton of weight on it. That should not be! as it turned out the heads of the wheel studs encroached on the centering mandrel never letting it position itself correctly or repeatably. I convinced the vendor to have the studs modified and the situation was resolved.
in the very early 60's we used a Stewart and Warner strobe light spin balancer with a pick up that attached under the trailing arms on the front of the car. All 4 wheels were balanced on the right front so the customer could not accuse us of excessively driving his car. Fast forward 52 years. Lots of stuff happened inbetween1 We now us a Hunter spin balancer with a 356 modified rear brake drum as an adapter. Not only can this machine determine the high or low spots on the rim but can match them to the high or low spots on the tires. Every rim we sell is checked on the balancer to make sure it is round and concentric to the bolt pattern. If you have the same size tires and rims on all 4 corners of the car, our balancer can tell you where to put each tire to minimize the pull of the car. I have been a Michelin tire man, even for the cars that sit and the tires rot off them. It is a good value to pay for a premium quality part that your well being depends on. Call me if you have a question, 800.356.2964 al zim