Re: 1924 Sport 136

Posted by Karl On 2024/5/24 11:23:54

In order to concretize my results of the synchronization measurement,...
First of all... yes, all relevant components for holding the rims on the balancing machine are perfect. The adapters I made that had to be made to mount these rims on the balancing machine have a vertical runout of 1/100 mm and a side runout of 1.2/100 mm. Also negligibly low. The adapters are manufactured in such a way that the rim is forcibly centered. The stop area of the rims, which lies against the brake drums, was metallically clean during the measurement. I measured the runout at the relevant point right next to the bead area of the rim, where the tire first rests on the rim and also at the end of the tire pad, 1 cm before the start of the snap ring connection.
I measured the side runout in the area of the tire bead, where the curve ends at the rising rim flange... also approx. 6-8 mm above the tire contact patch. Basically, it should be noted that the entire tire contact area around the rim was so irregular, even in the area of the greatest runout, that a measurement with the micrometer screw was not possible. And this despite the fact that I sanded the entire surrounding surface cleanly with the eccentric sander (180 grit) and filled the remaining shallows with spray filler and then sanded them flat again, so that only (!) the depressions and holes were filled and the rest of the metal surface closed see is. The rim was visible (..as shown in the pictures...) However, it was clearly visible that the rim ring was pulled deeper where the rivets were set. It can be seen very clearly on page 8, ... picture ... 439. For me, the external indication was that the inner diameter of the rim ring did not perfectly match the outer diameter of the inner rim disc. This was clearly visible as an undulating movement on the surface as the tire was rotated under the dipstick. The observed impact was not only visible in one location, but in various locations around the entire contact patch of the tire. The 3 mm mentioned was just the largest height difference measured. The same applies to the determined lateral runout. To me this suggested that this may have been a question of production output/capacity at the time. That's why I'd be interested to know if anyone knows that the heights and lateral runout for the same rims or rims with the same design agree with my results.
As far as side runout is concerned... I would have liked to have tried to have the rims optimized as much as possible by a specialist company. Unfortunately, the last company in my area that could repair steel disc rims closed 25 years ago. Everything only works on aluminum rims. So... if it turns out that the condition of the rims is due to production, I would forget the whole thing and drive the wheels as they are.

Karl