How to check gears?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ChevBlazin, Mar 12, 2002.

1. ChevBlazin1/2 ton status

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Ok, heres the deal. I just got my new axles today which have 3.73 gears in them, so I'm told. He said he "spun" the axle to see what was in them. I thought I knew how to do this, but now i'm confused. If I spin the drum on one side one full turn the yoke almost makes a full turn, about 90-95% of the way around. And vice versa if I spin the yoke one full turn the drum goes just past one full turn. How do I figure my ratio from this? Does this mean I do have 3.73's, or are they something else? I know pulling the cover is the best way, but I'm away from home now and am wondering if the 3.73's are really what I have. Also if the gearing means 3.73 to 1, right?, what is it that is spinning 3.73 times for every 1 turn of something else? (if that makes any sense at all) Thanks for any help that can be given.

2. Thunder3/4 ton status

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3.73 to 1 = For 3.73 turns of the drive shaft(pinion gear) the Axles(ring gear) at the wheel make one complete turn.
To check it without removing the cover. Turn the pinion shaft (where the drive shaft connects) and count how mant turns it takes to make the drum/axel make 1 revolution.
EX: pinion shaft turns 3 3/4 times to 1 drum revolution = roughly 3.73 to 1 .
But its best to pull the cover. The ratio is stamped on the ring gear. Plus you can see if the axel is worn out or not.

3. StonerK51/2 ton status

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I agree with Thunder, it is best to pull the cover since you just bought them, you need to know what is going on inside there. I think that doing the rotation stuff is for when you are searching for axles in the junkyard and have like 30 to go through.
Look to see if the gear oil is burnt, or really brown. If it looks like chocolate milk then there is water in there and needs to be cleaned out and changed.
Get some brake cleaner and squirt it inside to clean everything off. Like Thunder said, the ratio is stamped on the ring gear. Out of all the numbers the ratio is near the end... should say 41:11 then the date the gears were made.
41 divided by 11 is 3.73 actually it's 3.7272727~

Chris

4. ChevBlazin1/2 ton status

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ok, sounds good guys. I am going to pull the covers when I get home this weekend, but was just curious about how people spin them to check, makes sense. Thanks

5. Chris_T1/2 ton status

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Remember, if it's an open carrier that only works if you have both wheels off the ground. To do it with one wheel off the ground you have to spin the tire twice.

C

6. 79Beast1/2 ton status

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I think everyone is on the money, but it surprises me that nobody pointed out the most precise way of all. Sometimes the gear ratio is on the ring gear, sometimes its stamped on a little tag. You can always count the number of teeth on the ring gear and divide it by the number of teeth on the pinion gear.

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