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| | | | Joined: Dec 2013 Posts: 45 'Bolter | | 'Bolter Joined: Dec 2013 Posts: 45 | How do I tell what gear ratio is in my 51 3600? Were they all the same or did they offer different ones. Thanks , Gerry | | | | | Joined: Jul 2010 Posts: 592 Shop Shark | | Shop Shark Joined: Jul 2010 Posts: 592 | I think that your '51 3600 has a short enclosed torque tube in the front and an open driveshaft on the rear. If so, here is an easy way to tell which rear end you have without pulling the pumpkin to find the stampings on the ring gear.
Park your truck on a safe, level surface. Chock the left rear wheel (fronts, too, if you have enough chocks). Put the truck in neutral. Release the emergency brake. Jack up the right rear wheel just enough to allow you to easily turn it. Make a chalk mark on the drivesaft or u-joint yoke. Turn the tire and count the number of turns while watching the chalk mark. Using the ratios Tim gave you above, if it takes about 4.5 tire rotations to give the driveshaft one complete turn, it is a 4.57. It it takes just over 5 tire rotations, it is a 5.14.
This wouldn't work if you had a limited slip, but they weren't available until '59.
Matt
PS--There is also a possibility that you could find that you have a 4.10. They were available from '67 to '72 on the same rear end. Certainly not available back in '51, but a previous owner could have made the easy swap to get better top end. Only three possibilities if you have the original Eaton rear end---4.57 or 5.14 from the factory or 4.10 with a later change. | | | | | Joined: Jul 2010 Posts: 592 Shop Shark | | Shop Shark Joined: Jul 2010 Posts: 592 | I got myself confused and explained this backwards. It should be number of times required for the driveshaft to turn the tire once, not vice versa...sorry. | | | | | Joined: Aug 2006 Posts: 486 'Bolter | | 'Bolter Joined: Aug 2006 Posts: 486 | Actually it's the number of drive shaft turns required to turn the tire twice. Since one wheel is chocked the free wheel will have to turn twice.
'64 swb stepside (gone)
'57 1 ton
'53 phone truck
'59 swb
'46 1 1/2 ton
'68 swb gmc
| | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 | If you really need to know, the only way is to buy a gasket and some gear lube, pull the cover and read the stamp or count the pinion and ring teeth.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | | | | Joined: Aug 2004 Posts: 1,418 ODSS Lawman | | ODSS Lawman Joined: Aug 2004 Posts: 1,418 | I agree with Bartamos. Given the two options by Tim, it would be hard to distinguish 4.6 rotations versus 5.2.
SWEET Sergeant At Arms: Old Dominion Stovebolt Society BUNS?!?!?!Where we're going, we don't need no buns.....1950 GMC 450 1951 Chevy 1/2-TonThe GreenMachineIn the Stovebolt Gallery | | | | | Joined: Dec 2013 Posts: 45 'Bolter | | 'Bolter Joined: Dec 2013 Posts: 45 | Thank you for all the in put! I guess I'll open it up and look for the stamp. Thanks again, Gerry Lee | | |
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