[SAJ]

I have had many problems with both Indian made drives and recently a Weldon USA one.
The problem is shown in the pics attached of two starters side by side with standard bendix and Weldon barrel drive in retracted and engaged positions.
The steel ruler shows how the bendix pinion comes about 1/8 inch past full engagement with the ring gear teeth, whereas the barrel pinion sits about 1/2 inch further back from this position when fully extended. It engages only about half the ring rear teeth and would need at least 3/16 of starter shims behind the starter to bring it forward and fully into mesh. This of course is impossible and the starter face locating spigot itself is only about 1/8 high. You can clearly see the partial-engagement wear pattern on the barrel drive photo.
The other factor is that, fully extended, the bendix pinion hits the front collar which in turn is abutted to the bush in the mating face of the starter. So there is a solid immovable stop as the pinion throws forward upon starting.
On the other hand the barrel pinion flies forward, with more gap to accelerate and gain velocity, until it is arrested by the thin cast collar on the root of the helix. It hits this hard enough in the case of the very thin casting on the Indian barrel drives to fracture it under tension. And in the case of the Weldon USA drive it jams in the forward engaged position and the engine then turns it at huge speed! Plus something happens to both Indian and Weldon at the rubber buffer end and the washer covering the grub screw becomes impossible to retract since the inside washer will not contract the rubber inside the dished cover,
Even a few tons on a press will not retract it, so the only redress is to saw the washer in half to get the grub screw out so the drive can be pushed forward on the shafts to get the woodruff key out. See the Weldon photo showing this.
Between David Mossman and I we have destroyed 4 Indian-made ones and 2 Weldons, all on 6 volt starters.
And the partial engagement and higher velocity of engagement does not do the ring gear teeth much good. And 3 of us, Terry Costello too, have jolted our ring gears forward on the flywheel. Possibly because they are made oversize and heat shrinking and loctite does not hold them in place tightly enough.
I do read others have broken or jammed them like we have. Terry Burtz a while ago wrote up an analysis showing the lack of full engagement.
I have just put back on a 5/16-bolts bendix and it starts quietly and gently, unlike the barrel drives which go in with quite a bang. Roadster and Tudor have high compression and static timing is set at 5 to 7 degrees after TDC, for more gentle starting. They are never started with the advance lever down from the stop.
Some say they have never broken a barrel drive, but irrespective of that the partial engagement that is engineered in because they were not designed for the Model A engine, but for tractors, is something I do not care to accept.
SAJ in NZ