Norman_E
Well-Known Member
This is a VDO Logic masthead unit in pieces. Other makes are similar in design so I hope this helps anyone with bearing problems in their unit.
Taking the unit apart is fairly simple. Firstly the upper cap unscrews complete with the bearings and rotor of the wind direction unit. I have not disassembled this because it is OK, but I have done so in the past. The shaft and rotor just pushes out from the top, after which the two ballraces can be pressed out, washed and replaced.
The next stage is trickier. First you pull out the cable protector from the mast end of the long shaft and release the cable from it. This allows the cable to be pulled into the unit a little. After that you insert a finger into the plastic cap on top of the printed circuit board, and gently pull it out.
Firm pressure on the end of the shaft will push the wind speed rotor into the body of the instrument, allowing it to be removed. In my case the inner bearing and the spacer came with it, and the outer bearing was then pushed out from the inside using a metal rod.
The bearings are S693zz (3mm bore, 8mm OD and 4mm thick), made of stainless steel, obtainable http://www.rcbearings.co.uk/index.php?route=product/product&product_id=841.
The rotor has a thin disc ceramic magnet on its inner end, and in my case this was actually broken into two halves, and fitted to the steel cone only by its own magnetism. I fixed it with a drop of superglue.
Re-assembly needs care and pushing the inner bearing into its plastic housing by pressing on the magnet risks shattering the fragile magnet. The way to do it is to get a length of steel rod about 5mm diameter and drill one end 2.5mm and tap the hole 3mm to match the thread on the end of the shaft. The shaft and bearing can the be pulled into place without risk of damage.
Taking the unit apart is fairly simple. Firstly the upper cap unscrews complete with the bearings and rotor of the wind direction unit. I have not disassembled this because it is OK, but I have done so in the past. The shaft and rotor just pushes out from the top, after which the two ballraces can be pressed out, washed and replaced.
The next stage is trickier. First you pull out the cable protector from the mast end of the long shaft and release the cable from it. This allows the cable to be pulled into the unit a little. After that you insert a finger into the plastic cap on top of the printed circuit board, and gently pull it out.
Firm pressure on the end of the shaft will push the wind speed rotor into the body of the instrument, allowing it to be removed. In my case the inner bearing and the spacer came with it, and the outer bearing was then pushed out from the inside using a metal rod.
The bearings are S693zz (3mm bore, 8mm OD and 4mm thick), made of stainless steel, obtainable http://www.rcbearings.co.uk/index.php?route=product/product&product_id=841.
The rotor has a thin disc ceramic magnet on its inner end, and in my case this was actually broken into two halves, and fitted to the steel cone only by its own magnetism. I fixed it with a drop of superglue.
Re-assembly needs care and pushing the inner bearing into its plastic housing by pressing on the magnet risks shattering the fragile magnet. The way to do it is to get a length of steel rod about 5mm diameter and drill one end 2.5mm and tap the hole 3mm to match the thread on the end of the shaft. The shaft and bearing can the be pulled into place without risk of damage.
