I have a bunch of old Hyatt rear axle bearings and I need to find 2 of the best to use on my Roadster. What is the usable OD of the rollers??
The axle book says .499" or .498" (.001" to 2.00" wear).
.001"-.002" wear... not 2.00" ! Got your back Steve. lol
My worst ones show .495 - I posed the question of what is acceptable and no-one told me not to use them as long as the rest of their condition is acceptable. I am installing new sleeves, however.
I believe the original spec is .498 +/- .002. Many posters report never having seen even a NOS roller at .500. Check this post for a good discussion on the subject.
As long as the OD of the rollers and axle match up to the ID of the installed sleeve it should all work, no? I seem to recall some people shimming between the sleeve and axle tube to take up play, and maybe even slightly thicker sleeves being available to go with worn rollers. I suppose you could also machine the bearing surface on the axle to be a little larger too, but that's probably the hardest way to solve this problem.
I've used them with quite a bit of wear, you can doctor the cages well if you need to. I'm surprised at how little people actually try to revive them.
And yes, if you have some worn down to .490 you can put 8-10 thou' shim behind the sleeve.
It's not the actual dimension that is the killer of Hyatts in the outer position on the rear axle, it's the uneven wear that causes more wear on the outside of the rollers, just as on the axle shaft - they tend to get conical and thus there will be bending strain on the cage, causing it to be loose at some point. When the cage eventually gets loose, wear will accelerate even more on the rollers.
Eventually the wear will cause flaking on the surface of the rollers, giving them a pitted look.
I don't mind using Hyatts with any reasonable dimension that can be shimmed to fit, but they shouldn't have loose cages, conical or pitted rollers. Welding or riveting a loose cage stiff may not last long if the rollers are worn conical?
Maybe it's a good idea to turn the outer bearings around each year when doing a cleanup / check of wear and grease, to distribute wear on the rollers?
The little I've learned about Model T Ford Hyatt rear axle roller bearings is mainly what knowledge I've gained from years of "association" with this forum. Accordingly, I have formed an "opinion" about rear axle roller bearings for a Model T Ford. Here's what I've learned, in no particular order:
The original Hyatts seem to work better in the long run than the solid roller replacement type available from major T parts suppliers.
Every Model T had four sets of Hyatt roller bearings in every rear end, and it's the "outer" bearings that wear the most by far. They support the weight of the car and wear accordingly, while the "inner" bearings seem to wear much, much less. As has been mentioned above, there are still a lot of used bearings available that show very little wear, and it seems that where the information is known, it will be found that these "good ones" are almost always one of the "inner" bearings.
It is my "opinion" that the original Hyatts with "spiral-wound" rollers work best because they will "flex" to a very slight degree which allows them to "survive" within the inherently imperfect sleeves and accordingly, they work much better than the modern solid rollers.
Besides the fact that the spiral-wound rollers will "flex" a bit, I have one other opinion about this design that again, is strictly "opinion" on my part. And that is that while the spiral grooves in the wound rollers in the original Hyatts were not particularly designed to distribute lubrication (grease) within the bearing sleeve, I believe that there is a certain amount of grease distribution within the Hyatt spiral-wound rollers due to the fact that the spiral grooves alternate in direction and accordingly, do in fact serve to distribute grease within the bearing more evenly. Again, merely "opinion" on my part here. Just one more reason why I think they offer a real advantage over the modern solid roller type bearings.
It is also my opinion that while loose cages can be somewhat "tightened' by peening, this repair will not last very long, and because there are many good, useable original Hyatts available, original Hyatts are a much better choice than the modern solid roller bearings.
Anyway, just my thoughts from years of following this great forum, for what it's worth,.....harold
I forgot to say that I agree with everything Roger Karlsson just said, and what I just wrote was merely in addition to his good advice,.....harold
FWIW, Ford specified the rollers' finish grind to be 0.4985" to 0.5005".