MTFCA Forum

Can anyone give me the dia. of the roller in the rear axle roller bearings when they were new?
Thank you in advance Craig

.499 I believe

.500" Measured from nos.

John when you measure are you doing both ends & the middle? Just curious. I need a better caliper, ha.

JTT3 wrote: ↑

Tue Jan 24, 2023 3:44 pm

John when you measure are you doing both ends & the middle? Just curious

The new one measures .500 the whole length. The rollers were ground the same the whole length.

Used bearings - both ends & middle. They typically wear in a cigar shape if the cages were loose.

I measure each end. I do not like tapered ones, (more than a few thousandths anyway).

I'd go with a micrometer instead of a caliper. More accurate.

More than once I have had an apprentice come to me with an undersize part clamped between his calipers. I would ask to see the calipers, whereby I would send them flying into a dark back corner of the shop. I would then calmly ask him to bring me his 0-1” mic with calibration standard. I would take whatever time was needed to show him how to properly calibrate the mic…to the tenth, in most cases. They never forgot the lesson. A caliper has NO place in precision measurement. Fine for roughing work, sorting drill bits or selecting shim stock, but not in the toolroom.

The rollers were segmented in size classes. Each class was within .0002 inch. No need to measure these brgs to the nearest .0002 inch today. Just be glad there are still serviceable brgs. Eventually they will be used up.

Properly installed and maintained they should last for another century. But will they with current practices, I doubt it.

Art Mirtes

Bush Mike send me those old calipers. I’ve got micrometers but it takes too long when it’s raining and you moving from one vendor to another ha.

Realizing that this is pretty much "common knowledge" but in case there is someone that is not aware of this, there are four identical rear axle bearings (two inner and two outer) and the outer rear axle bearings, because they support the entire weight of the rear of the car, tend to wear much more than the two inner bearings, which wear very little as they do not support any weight at all. Typically, a car with very worn outer bearings will have inner bearings that usually show no wear at all. It's those INNER bearings that we are looking for at swap meets and the only to find them is with an accurate micrometer! FWIW,....harold

Harold,
Logical and interesting data. Thanx!

John,
You need to attend the Spring Jefferson Swap Meet. Every couple of years is snowing. I always felt bad for the vendors wives that were there bundled up in garbage bags and tarps to keep dry. Some looked absolutely miserable.