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timtechcorvairwiki:06c_rear_axle:early_cars_and_trucks_rear_axle

Early Cars and Trucks Rear Axle(Part of the series: "More than you ever wanted to know")

By Tim Palmer and Gary Baxter

The purposes of this article are:

  1. To document what we think we know. Much of what is in this is either not in any of the recent books or not in much detail.
  2. To provide interchangeability information.
  3. To provide some tips on maintenance and wear.

The information comes from GM parts books and our personal Corvair parts collections.

The Part names are names given in the GM parts books and shop manuals. The Group X.XXX is GM’s method of grouping part(s) in their parts books. The Part numbers are GM part numbers. | The upper axle in this picture is for trucks (also known as forward controls or FC’s for short). The lower axle is for cars. The upper axle in this picture is for trucks (also known as forward controls or FC’s for short). The lower axle is for cars.

Axle Shaft (Group 5.420)

Application Part Number Notes Interchangeability
1960 Car 6257874 Shallow wheel pilot with flat face. Reduced diameter on spline end. 1960-1964 Car with proper bearing assembly.
1960-61 Car 3777803 Shallow wheel pilot with flat face. 1960-1964 Car with proper bearing assembly.
1962-64 Car 3813321 Deep wheel pilot with hollowed face.
(This was also the general replacement part in later years.)
1960-1964 Car with proper bearing assembly.
1961-62 FC 3771921 Shallow wheel pilot with flat face. 1961-65 FC only.
1963-65 FC  Deep wheel pilot with hollowed face.
(Apparently the part changed without the part number changing.)

Notes:

  1. This part was painted chassis black we believe.
  2. The FC axle is longer, is larger in diameter and has five wheel lug studs.
  3. Look for wear and signs of corrosion on the splines. The splines should be square looking. If they are rounded or pointy, look for another axle. Put your best one on the right side since it takes most of the load.
  4. The bearing assembly is pressed on and requires either a press with a proper fixture or special puller to remove. Clark’s has the proper tools.
  5. Contrary to rumors spread by some, the axles are NOT right and left.

Wheel Hub Stud (Group 5.812)

Application Part Number Notes Interchangeability
1960 Car 1st Design 3705752
(375696)
7/16“-20 x 1-15/32”. 9/16“ diameter serrated shoulder. 3/4” head diameter. 1960 Car 1st Design only.
1960-62 Car
1961-62 FC
3775682 7/16“-20 x 1-19/64”. 15/32“ diameter serrated shoulder. 19/32 “head diameter. All except 1960 Car 1st Design.
1963-64 Car
1961-65 FC
3784976 7/16”-20 x 1- 7/16”
1960-64 Car
1961-65 FC
3775683 7/16“-20 x 1-3/8”
Became a general replacement sometime before 1969.

Notes:

  1. Ordered List ItemLook for wear and signs of corrosion on the threads. You can find replacement studs at a good auto parts store or from the Corvair vendors.

Parts that didn’t change through the years

Description Part Number Notes Group
U bolt 2118319 5.426
U-bolt nut 5/16“-24 8.915
U-bolt lock washer 5/16” 8.931
Axle Bolt   3/8“-16 x 7/8”. Appears to be a special bolt. 8.900
Axle Lock Washer 3/8“ 8.931
Axle Washer 6255782 1-3/16” O.D. x 13/32“ I.D. x 9/64” thick. Special. 5.426
Wheel Lug Nut 358501 7/16“-20. Probably not special to Corvair. 5.813

Trunnion (U-joint) (Group 5.428)

Application Part Number Notes Interchangeability
1960-62 Car
1961-62 FC
3713926
replaced by 3830580
1960-1964 Car and
1961-65 FC
1962-69 Car
1962-65 FC
3828469
replaced by 3849500
1960-1964 Car and
1961-65 FC

Notes:

  1. The two different part numbers are curious. We have not been able to determine the difference. The flange and the yokes didn’t change.
  2. This is a common part used on many GM vehicles. It’s available at most any part store.

Flange (Group 5.425)

Application Part Number Notes Interchangeability
1960-64 Car
1961-65 FC
6255781   1960-1964 Car and
1961-65 FC

Notes:

  1. This part wasn’t painted.
  2. The splines on the flange are the weakest part of the rear axle system. Look for wear and signs of corrosion on the splines. Red dust as shown below is a bad sign. The splines should be square looking. If they are rounded or pointy, look for another flange. Put your best one on the right side since it takes most of the load. If the splines fail there will be a loud awful grinding noise and you will not be going anywhere!
  3. The flange is fairly tight fit and should require a puller to remove. If it falls off when you remove the axle bolt, you should look at the flange and the axle to see which one or if both are worn and/or corroded to point you need replace them.
  4. When the axle is installed in the vehicle you should be able to pull on the axle as hard as you want and not see any movement between the flange and axle. When the flange is on the axle there should not be any movement at all! If you see a little puff of red dust when you pull on the axle you should check and replace parts as needed. You are on borrowed time before the spline fails. It’s usually the flange that fails.

Early signs of rust and possible failure.

Yoke (Group 5.425)

Application Part Number Notes Interchangeability
1960 Car 6255777   1960 Car.
1961-64 Car
1961-65 FC
3784936 Right stamped 34. (I couldn’t find it.)
Short one.
Replacement for 1960 both sides.
1961-65 all.
1961-64 Car
1961-65 FC
3784935 Left stamped 33. (I couldn’t find it.)
Long one.
1961-65 all.
1962-64 Car
1962-65 FC
?????? Right.
The sheet metal part isn’t as dished as the regular ones.
1962-64 Car & 1962-65 FC with positraction.

Notes:

  1. This part wasn’t painted.
  2. Check the splines for wear on this part also. The splines should be square not pointy!
  3. The positraction yoke does not show up in any of my parts books! It does sort of show up in the assembly manuals. If you use a regular yoke, it will rub on the positraction differential side adjuster.

Wheel Bearing (Group 5.855)

1960 Car 1st Design

Application Part Number Notes Interchangeability
1960 Car GM=7451114
(Hyatt AD-11034Z-15)
Housing riveted together. 1960-64 Car.
1960-62 Car GM=7451254
(Hyatt AD-11034Z-18)
Housing riveted together.
1963-64 Car GM=7451328
(Hyatt AD-11034Z-20)
Cast housing. 1963-64 Car.
1961-65 FC GM=7451321
(Hyatt AD-11154Z-17)
Housing riveted together.
Like the 1960-62 car but the axle shaft hole is larger than the cars.
With removing ring.
1961-65 FC.

Notes:

  1. The 1960-62 fit 1963-64 but 1963-64 do not fit 1960-62. This is because the axle hole in the A-arm got bigger in 1963.
  2. Car bearings also fit a few years of Pontiac Tempest.
  3. FC bearings fit nothing else!
  4. NOS bearings have been expensive for some time, especially FC’s, so it is a good idea to keep the bearings greased as has already been documented.
  5. While aftermarket bearings were available in the day, only recently have newly manufactured replacement bearings been made available in two types.
    1. The first type is a new bearing and aluminum housing. If you chose this type you should be aware that the aluminum housing is thicker than the original housing and only leaves 3 or 4 threads left on the stud for the lock washer and nut. The bearing comes with new self-locking grade 8 nuts (the self-locking nut eliminates the need for the lock washer and therefore the space for it), but I would strongly recommend installing longer studs because I don’t believe the original stud was grade 8. This is important because that nut and lock washer are all that keeps the axle from becoming detached from the rear a-arm when you are driving aggressively.
    2. The second type is a new bearing that fits in your old housing. This is so new I haven’t seen one yet. It sounds like a really good solution that fits just like the original and the price is competitive with NOS.

Wheel Bearing Puller Ring (Group 5.816)

Application Part Number Notes Interchangeability
1960 6257187 2-1/4” O.D. x 1-3/16“ I.D. x 3/16” thick 1960-64 Car
1961-62 3782154 2-5/64“ O.D. x 1-3/16” I.D. x 3/16“ thick
1963-64 Car 535883 2-1/2” O.D. x 1-3/16“ I.D.
1961 FC 1st Design3771923 2-1/4” O.D. x 1-3/8“ I.D. x 3/16” thick1961-65 FC.
1961-65 FC 2nd Design 3814314 2-1/8“ O.D. x 1-3/8” I.D.

Wheel Bearing Deflector & Shield (Group 5.815)

Application Deflector
Part Number
Shield
Part Number
Notes
1960 Car
1st Design
6257106 6257365
1961-62 Car 3779875 3780078 2-1/8“ O.D. x 11/16” thick
4-3/8“ wide w/six 7/16” holes
1963-64 Car 3779875 3780078 ??? The shield changed when the bearing changed but the part number did not in any parts book I have. This odd because you can’t interchange the two. 1961-65 FC 3771924 ??? The shield doesn’t show up in any of the parts books.

Notes:

  1. The 1960 has an arrangement completely different than the later years. The deflector is mounted backward from later ones. The shield is mounted to the A-arm instead of the bearing. (Sorry no picture of the shield).
    The 1960 and 1961 Shop Manuals show this arrangement even though it changed to the later arrangement in 1961 and maybe sooner.
  2. The Chevrolet Service News indicated there was a first design 1961 FC and 2nd design although the parts book doesn’t show anything.

timtechcorvairwiki/06c_rear_axle/early_cars_and_trucks_rear_axle.txt · Last modified: 2015/01/15 16:23 by tlpalmer