Installing the new 3:55 set. Ordered what was supposed to be a crossover to the original Hyatt A11445 bearings. National kc 11445 y. not a crossover. the original Hyatt has a bearing cage measurement of .65, where the National measures .845. What bearings have you used to replace the original Hyatts? Were you able to find the original Hyatts, and if so where? Hyatt is now a product of General Bearing/SKF. Thanks in advance.
Ed
"it's only old if you can't find a use for it; otherwise it's cool and i'll use it."
Ed - According to the Bearing Chart in a 1954 Chevy Master Parts Book, your original Hyatt A11445 was listed as GM# 187434 and also Hyatt 11445Z. I came across a couple of NOS Hyatt 11445Z bearings offered on line from $95-$125 each, which seems excessive to me. Only one source listed a quantity of 2, and those were the $125 each priced ones -ouch!
The Filling Station offers a replacement differential carrier bearing as FS-343 for $79.95 each + shipping. Their description indicates theirs replaces both GM# 187434 and Hyatt KA-11445-Z (which is a later designation for Hyatt 11445Z).
I think you will find these will fill your need.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
I just started doing this conversion today myself. I’ll share a picture of the bearings numbers that are suggested, but that Hyatt number seems correct.
Last edited by klhansen; 11/03/202511:31 PM. Reason: removed unrelated question - already in another thread
I called several bearing companies. EZ Bearing (717 568 8800, ask for Daryl, owner) was able to track down a set of KA 11445z. That is the number for a complete set which includes bearing and race,, requires 2. They are from Hoover KA11445Z. My question is the original bearings (the ones I removed from my truck, I call them original) were tapered rollers. The new Hoover set are ball bearing. Any issues? I am not around to take pics or access my shop manuals. Were the bearings in '46 ball bearings to start? As someone mentioned in another post, you can tell if the pinion has been apart by the numbers of thread set marks on the bearing retainer ring. There are two sets of marks on mine, so someone has been inside before. Maybe they updated to the tapered rollers?
"it's only old if you can't find a use for it; otherwise it's cool and i'll use it."
I've never heard of ball bearings being use for differential side bearings (a picture in the 1947 shop manual Link) definitely shows tapered roller bearings. However, the front pinion bearing is a double ball bearing link with the rear pinion beairing being a roller type.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Ed - The Hyatt KA11445Z is a tapered roller bearing design, not ball bearing. The Chevy MPC reference I provided above notes that it has "18 rollers" under the earlier differential side bearing Hyatt Part Number HY 11445 Z. KA 11445 Z is a number used by multiple aftermarket manufacturers as a replacement for the original bearings.
Below is a picture from a Chevy Shop Manual showing the differential side gears being tapered rollers (Item 9). Next to this picture is one from The Filling Station of their offered replacement (also a tapered roller bearing and race set) for this bearing application, which also indicates theirs replaces "KA 11445 Z" in the linked description above.
I think your source needs to double check the information they have as these should not be roller bearings.
Edit: Kevin beat me to the post button.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
With the alternate part numbers on the Filling Station offering that Dan posted, I actually found one of them at O'Reilly KC11445Y which matches the dimension shown for Timken 17887 (cone) and 17831 (cup). A little spendy actually more than what the Filling Station wants. These numbers all come back as tapered roller bearings.
I think I'd be reluctant to use a ball bearing on a differential as they don't have near as much contact area as a tapered roller bearing.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Ball bearings can not carry the side loads a tapered bearing can. The adjustments for the differential require a side load being placed on the two bearings to keep the ring gear in the correct position. They had to be tapered rollers, if they are in fact ball bearings, post a picture of them in place.
