Is there supposed to be any end float to a Goldie crank, and if so, does anyone have a spec for it? I'm getting about .01".
As I view the assembly diagram, I can't see how the crank would be drawn to the drive side. Everything tightens down on the inner races. I could shim the end float out, but I'm wondering if it is necessary.
Joined: Sep 2002 Posts: 7,812Alex
BritBike Forum member
BritBike Forum member
Joined: Sep 2002
Now, I'm no expert on Goldies, but I've recently been spending a lot of time looking at the B/M series bottom end but I believe that the drive side ball bearing (held in by a spring ring) should be controlling endplay. If the bearing itself has .010" of endplay (most deep-groove ball bearings have around .001"), I would think that something is wrong and check either the bearing itself or that the bearing has pounded out the case...or that the spring ring that holds it in either came loose or has wallowed out its groove. Hopefully some of the Godie experts will chime in and fill in the gaps.
A smattering: '53 Gold Flash '67 Royal Star '71 Rickman Metisse '40 Silver Star '37 Rudge Special sixtyseventy Lightboltrocket road racer...and many more.
There should be No perceptible crank end play in any pre unit BSA big single. When the drive side crank nut is tightened, the crank assembly is snugged up against the outer ball bearing which is secured in the case.
It's Very Important to insure the shaft nut is never allowed to come loose. If this happens the crank will bang side to side and there is a danger the timing side roller bearing will break the case web. And natch the large nut will scoure away at the inside of the primary case.
Insure the thin steel shim is fitted in the case behind the outer ball bearing and the snap ring securing the bearing is in place. BTW, many of us have upgraded to a sealed one side ball bearing. We also use a 'true arc' internal snap ring vs that #$%^ OEM snap ring.
Insure the drive side spacers are in place. There's a large stepped spacer between the drive side roller bearing and the outer ball bearing. There's also a spacer ring that fits on the drive axle between the outer ball bearing and the cush drive splined collar.
Not to cause any confusion .. When a non OEM crank is fitted like a Pearson, ABSAF, NEB, etc. it's important to insure the ends of the rollers of the timing side main bearing are running clear of the lip on the outer race. This is checked by insuring there is ~ 20 thou crank end play before the crank is moved snug against the outer drive side ball bearing with the crank sprocket nut. Make sense?
By coincidence I'm reassembling a Goldie engine as we speak.
Thanks for the helpful information (thanks too, Alex).
I'm assembling this engine with an NEB crank, but didn't check for timing side play. I'm not exactly what the issue is yet, so back in we go. At least I now know that what I'm observing isn't right. Any other tips and suggestions are greatly appreciated.
Alex and Dave have covered the salient points. I am not familiar with the detailed setup of a GS crankshaft, but many folks get "endplay", "float" and "clearance" terms mixed up or use them interchangeably. "Endplay or endfloat" is measured when a crankshaft actually moves back and forth relative to the case of block. This is seen on almost every plain bearing motor and is generally a thousandth or two from one thrust surface to the other. When a ball bearing is employed, often with a roller on the heavier loaded side, the movement of the crank is virtually imperceptible with a good bearing. The only movement should be the "running clearance" of the balls in a deep groove ball bearing which is a few ten thousandths. Now, with the crank fixed as in unit singles, you still have to be sure there is some end clearance so that differential rates of expansion of the crank relative to the cases does not bind the crank.....or because of different machining tolerances from one case or crank to another may require some shims. If at final assembly there is any perceptible bind, you must disassemble ane remedy the problem. I hope I am not just making things confusing.