Hello,
         I don't know if I should be posting this here or in the old time stunt section, but here goes. A couple of my old Atwood Champions felt a bit gritty when turned over by hand. Stripped them down to find that the thrust races had oval ball bearings in them and missing the two thrust washers completely!!! Pays to strip down new "old" acquisitions, before you do anything else! I wondered why there was a lot of end float on the crankshaft.
  To cut a long story short, I managed to reface the damaged "grooved" case and even obtained a couple of new crank shafts. New ball bearings and suitably sized thrust washers, completed the restoration. I then got to thinking that the brass cages were original and probably had oversize holes in them where the balls sit. There was no way I could find new cages, so I let the matter lie.
  Sometime ago, I read of a catastrophic failure of the thrust race assembly, on I believe a Super Cyke. This had me wondering what the rest of my antique collection was like! Sure enough there were signs of thrust race wear on several of my prized collection. Mainly grooved thrust washers and slackness in the bearing cages. Now I use my engines, they are not collectors pieces, so what to do? No one seems to make the old fashioned thrust assemblies anymore, so is there a modern substitute that I can buy? I realise that the chances of getting the correct fit may be unlikely, but I can live with that and modify accordingly.
  So far I have found nothing remotely like the type of thing I want. Has anyone else solved this problem? Maybe one could machine up a bushing to replace the thrust race, but it would need some work boring the casing.
  I can't be the only one to have this problem, suggestions?

Regards,

Andrew Tinsley

Andrew - I agree with Jim. I see no need for a rolling thrust bearing in our applications. When I machine new bushing for any engine, I always make a flange at the crankshaft face area. There is so much oil swirling around in there that the bearing should never run dry. Were it to be of concern, just make a radial oil groove on the flange. Also, you must insure that there are no burrs or galling on the crankshaft face. That would chew up a thrust bushing in record time.

I have recently heard from other people who have used the ALFA Romeo valve guides, with excellent results.

Bob Z.

Hi Bob,
          Your reply came in as I was typing my reply to Jim. Hope you don't mind me singing your praise! You have pointed me in the right direction to do the job.

Many Thanks,

Andrew.

Hi Jim,
          Think I may have misunderstood what you mean by a thrust bushing. I was thinking that it was simply an extension of the crankshaft main bearing bush, but enlarged in diameter. It has just occurred to me that you mean a thick "washer" machined from the valve guide material. Thickness determined by the correct endfloat required. If that is the case, it is even simpler and I can now understand that this could be made just using a drill press!
  Its amazing just how wrong you can be when you have some preconceived ideas!

Thanks,

Andrew.

I would not recommend this procedure.   
If you use a thrust washer, there is nothing to prevent it from rotating relative to the case. Should this happen, it might damage either the thrust washer, the case or both. 
You want all relative motion between the crankshaft face and the bushing - the bushing must not turn relative to the case.

Make sense?

                          Bob Z.

No problem - that was just my though on the subject.
Bob Z.

Just another thought,

Now, I'm worried!  I have three O&R 60 sideports, several O&R 23s, a Super Cyke and an Anderson Spitfire.  I think all have ball thrust bearings (but I haven't looked inside the Cyke).
So how much run time does it take to wear out the thrust bearings?  I've never heard of problems in this area.

Floyd