Distributor Shake Rattle Roll

[guzzul]

One of the beauties of electronic ignition is that there is no side load on the rotating parts and therefore the mechanical bits are supposed to last much longer.

Good point Doug. It didn't occur to me that the centrifugal mechanisms should indeed be balanced. I wonder in practice whether they stay that way over time, or if spring tensions, friction and dirt play their part in creating some imbalances.

Maybe the electronic dizzys do, in fact, last longer than the mechanical points models. I don't know. The fact is that the electronic dizzys do wear. I replaced mine in the Spit last year for this very reason (i.e. wobbly dizzy). I had quite a bit of play in the shaft, to the point where I could physically close the pickup gap by moving the shaft.

So back to your question of what causes the wear? Again, I'm just assuming that if you spin a shaft in a bushing for long enough it will wear on the bushing, lubrication notwithstanding. There has to be some dirt in that oil causing wear. I would think too that over time the advance mechanisms will not work perfectly.

 

[dklawson]

The bob weights in Lucas distributors are identical to each other. I'll grant you that the springs are different, but whichever spring moves the most... controls how far out both bob weights move. The weights do not spin out different amounts from each other. The only imbalance will be introduced by the actual weight difference of the two springs and any manufacturing related tolerance variations of the rotating components.

The dizzy runs at 1/2 engine speed. For most of us that means our dizzy may be turning say 1800 RPM most of the time. That's a pretty low speed for relatively unloaded bushings.

The force introduced on the dizzy spindle bearings from such an imbalance will be insignificant (AND will move around the entire perimeter of the bushings) when compared to the uni-directional high load from the contact points always pushing to one side. Simply put, there are not significant enough demands placed on the bushings of electronic ignition distributors to explain 1-2mm of movement as was reported earlier.

The last time I put oil on my dizzy bushings? Two years ago. However, in the Mini I replaced my Lucas with a 25 year old Hitachi electronic unit which shows no bushing wear. Even when I was running points I made it a routine practice to pull the breaker plate and oil the bob weight pivots ever other time I'd replaced the points. Any time I went in the dizzy I'd make sure there was at least evidence of oil on the center screw and I'd typically put a thin film of grease on the point's four lobe cam.

 

[vettedog72]

ITs not just in the rotor. It looks like the entire unit.

Sounds like nothing is wrong with the dizzy except it is not fastened correctly to the block (the clamp is not holding the dizzy to the block). Check to see if the hold down clamp is installed correctly and tighten it down. Then there should be NO EXTERNAL MOVEMENT of the dizzy; not even 2 mm.

 

[guzzul]

Simply put, there are not significant enough demands placed on the bushings of electronic ignition distributors to explain 1-2mm of movement as was reported earlier.

I think you're right on this, Doug. 2mm is close to .080". I think the earlier post must have been referring to external movement, and as vettedog posts, maybe due to a loose clamp.

The electronic pickup gap is set at .015", or about .4mm, not even close to 1mm, let alone 2mm. If you start to get wobble in the shaft of more that .015" at the top, the timing rotor/reluctor will start to bang into the pickup and make it impossible to set a proper air gap. My old dizzy was at this point, where I could see the scrape marks on the reluctor.