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| | | | Joined: Nov 2006 Posts: 27 New Guy | | New Guy Joined: Nov 2006 Posts: 27 | In 55 first series 1/2 ton GMC and Chevy went to an open drive shaft rear. What are the years they made that particular rear. I assume the Chevy and GMC are identical. Were there also different rear ratios as options. Did brake configuration on the rear also change in later years? | | | | | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | Bruce,
The 55.1 was a ony year only rear, as far as the springs and perches go. The same rear was used till about 57 in gmc, and 62 for chevy with different spring widths. This rear is known as the Eaton HO33. The possible ratios are 4.11, 3.90, and 3.38. These center sections will interchange with the earlier 1947-1954 closed drive axle housings, and may be backwards compatible to 1940. 3.90 will be the most common gears for the open HO33. 3.38 gears are available through some of the parts suppliers, but are often on backorder.
As for brake configuration, I believe 1953 is when the Hucks were replaced with Bendix brakes, but I may be off on the year. All 1955 1/2 ton rears would have had bendix brakes. | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Nice write-up, John. Regarding brakes: The change-over to Bendix brakes started in 1951 (at least in Chevrolet trucks). Front & Rear were Bendix in 1/2 tons in '51. And, by '52, I think front & rear were Bendix in all sizes of Chevrolet trucks. http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0502.htmBruce, What are you considering (a possible change for your Hydra-Matic)? | | | | | Joined: Nov 2006 Posts: 27 New Guy | | New Guy Joined: Nov 2006 Posts: 27 | Great Info.
Thanks.
Tim,
The hydramatic stays put in the 54 3/4 ton. Still shifts hard. I have a very rough 55 1st 1/2 ton that got towed out of the woods. Broke front shackles with floating front axle. That is fixed with new springs and shackles. Then I noticed it has 5 lug wheels on the rear which I know is incorrect. It has an open drive shafts to a 4 speed. So I am looking for a new rear to get it back to original. So assuming the springs are correct for now, I am looking for a Eaton HO33 found in 55 to 57 GMC or 55 to 62 Chevy. Brakes should all be Bendix. If springs are wrong then I should get 54/55 1st springs and shackles.
| | | | | Joined: May 2001 Posts: 7,438 Extreme Gabster | | Extreme Gabster Joined: May 2001 Posts: 7,438 | I'm nitpicking here but using "original" for "stock" needs to stop. They are only original once. You can get one back to stock but you can't get it back to original. | | | | | Joined: Nov 2006 Posts: 27 New Guy | | New Guy Joined: Nov 2006 Posts: 27 | Cletis,
Understood. I will try and correct my wording. | | |
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