matthewb
New member
Many thanks all, especially Maurice and Felix on the subject of problems with balancing refurbished hollow-spoke turbo wheels. I'm afraid I can't remember the names of the others who answered my call, and unfortunately the forum doesn't go back more than a month (why is there almost no forum history? Any ideas?)
Well anyway, I finally got around to taking the car into my usual tyre and balance people (Thames View Tyres, Henley on Thames - nice folk). I explained the history and problem to a rather sceptical audience (hollow rims and spokes - pah - next you'll be telling me etc etc) but to give them their due they did let me have my way, i.e. a series of wheel balancing and rubber-hammer bashing exercises.
The problem wheel/tyre initially seemed to be sort of balance-able and didn't make any noise when spun, but I wasn't going to give up and, not wanting to appear a looney, I gave it one last serious rubber-hammer bashing, after which the balance reading was noted to be wildly out. Duly convinced, the lads removed the tyre and valve and, lo and behold, some grey dust fell out immediately the valve was removed.
I repeated Felix's (?) technique a half-dozen or so times, and about 70g of fine, dry, dense grey powder was eventually extracted. Jaws dropped!
The wheel was checked for run-out, appeared fine, and was out of balance by only 5g (without tyre or weights).
It took about 90 mins and the efforts of most of the staff (it was lunchtime and I think they were intrigued). Thank God the handling is finally sorted! I think the £10 I was charged was a bargain.
Once again, here are the instructions ...
1. Remove wheel and put on balance machine as-is to see how far out of whack it is. Give it a few bangs with a rubber hammer and then a good spin. Compare readings. Repeat several times. If the readings aren't consistent, there's something wrong!
2. Remove tyre and valve.
3. Place two empty tyres on top of each other, and place your wheel on top at a 45 deg angle with the spokes facing up. With a rubber hammer, tap all around while turning the wheel.
4. Settle the wheel with the valve opening at the bottom of the wheel. By shaking the wheel, the sand will fall out from the valve opening, FROM THE BACK. Do not try to let sand out from the front. If inspected closely, you should see that the opening from the back has grooves to let anything inside to flow out. The material used for blasting flows easily.
5. After doing the tapping and emptying proceedure several times so no more dust falls out, place the wheel on the balancing machine without the tyre, and test.
NB - The material is heavy, so a small quantity is a lot of weight inside.
NB - When using the rubber hammer, only tap the back of the wheel to avoid scratching the front.
