C1 Rear Axle Bearings

written by Tom Parsons and submitted by John Costales, #4F

 
   
 
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C1 Rear Wheel Bearing and Axle Info……….By Tom Parsons
(edited for publication by John Costales, #4F)
 
Frequently the subject of rear axle bearing replacement arises for 56-62 Corvettes.  It should be pointed out that “some” differences do exist when replacing the outer rear wheel bearings between the 56, 57 and 58-62 Corvettes.  Primarily you should first determine the bearings you currently have prior to purchasing new bearings.  Without checking you never know what rear differential is installed in your car.
Over the years there have been a total of 4 (actually 5) axle bearings for C1’s.
1) The replacement bearing for a 56 Corvette (55-56 Chevy pass car) is the RW507EN or RW507ER (507 series).  The RW507ER has a slightly thicker inner race.
2) The replacement bearing for a 57 Corvette (57 pass car) is RW307R (307 series).
3) The replacement bearing for 58-62 Corvettes is RW607NR (607 series).
All of the above 3 bearings are ball bearings.
4)JNR1542 was a roller bearing for 58-62 Corvettes with positraction as well as 58-64 passenger cars with positraction and also taxicabs and police cars (which may or may not have had posi). The JNR1542 (roller bearing) has been long discontinued and is replaced by (3) above ball bearing RW607NR that shares the same dimensions.
5) Many years ago, GM listed a roller bearing for the 55-56 pass car. I have never seen an aftermarket replacement part number for that bearing, but the GM part number was 7451414 (it has LONG since been discontinued). 
Last year, a customer brought me a pair of (what appeared to be) original axles from his 55 Nomad for me to replace the bearings. They had the roller bearings and the RW507EN or RW507ER was a direct replacement (first time for me to actually ever see 55-6 roller axle bearings).
The 507and 307 series are the same thickness, but the 507 has a smaller outer diameter.
The RW507EN or RW507ER are the only bearing that will fit A 56 Corvette and 55-56 pass car.
 
C1 bearing diameter comparison
The RW307R is the ONLY bearing for a 57 Corvette and pass car.
The 307 (57) series and the 607 (58-62) series bearings have the same outer diameter, but the 307 bearing is about .120” thinner. Note that the wider 607 (58-62) bearing has two “O” rings.
The inside diameter of all 3 bearings, and the bearing surface on the axle shafts 56-62 Corvette and 55-64 pass are the same, and they all 3 use the same lock ring.
Note: 56 Corvette bearings, axles and rear housings are unique to 56 only! Only the entire assembly can be used on other year Corvettes.
The original bearings used in these cars were usually NDH (New Departure-Hyatt) or Hyatt. If you pull an axle and the Bearing is NDH or Hyatt, it most likely is the original bearing installed in the car.
Shown below are the width differences between the 3 replacement bearings
Before installing new bearings on their axles:
As shown in the pictures below, measure the housing bore and depth dimension and compare it to the thickness and outside diameter of the new bearing to be used. When installed, the outer
race of the bearing should be nearly even with the outer edge of the housing.
If the bearing is recessed or protrudes in the end of the housing by about .100 -.120” you have the wrong bearing for that rear axle housing.
C1 bearing width
C1 axle housing bearing depth
C1 axle hub differences
Axles
REGARDLESS of year model, the Left axle is ALWAYS shorter than the Right axle.
The 57 Corvette axle housing is 100% identical to a 57 pass car axle housing, EXCEPT the position where the spring pads are welded to the housing.
The 56 Corvette and 55-56 pass car axles are the same and totally interchangeable.
If your car is a 56, and has a 56 axle housing, ONLY the 55-6 axles and axle bearings will fit PERIOD!  I point this out because a 57-62 Corvette axle housing is a 100% bolt-in swap.
When searching for a new axle:
The 56 axles are unique to 56 Corvettes only.
Although the bearings might be different, the 57-62 Corvette and 57-58 pass car axles are the same.
Shown to the above is a comparison of a 57-62 Corvette (57-58 pass car) and 59-64 pass car axles.
The splined end of the axle to the shoulder where the bearing seats are the same dimension. The difference is the distance from the bearing seat area to the outer side of the flange. When you look up the axles in the parts book, it shows different lengths for 57-58 and 59-64 pass car axles. As you can see in the previous picture, the additional ½” in length for the 59-64 pass car axles is between the shoulder for the bearing and the wheel flange. If a 59-64 pass car axle were to be installed in a 57-62 Corvette axle housing, the overall tread width would become 1” wider. This was once a method of increasing rear tread width on early Corvette race cars. 
Gaskets
The gaskets for the bearing retainer and for the rear end center section are still available from most parts stores (Fel-Pro 5188 or equiv).
I hope this will be helpful to a few who like to work on their own cars.
 
Tom Parsons
405-745-8383
tparsons6@cox.net
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Southern California Solid Axle Corvette Club