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Author Topic: how can you tell what gears are in the rear end  (Read 9435 times)

Offline keachers

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how can you tell what gears are in the rear end
« on: December 07, 2010, 08:48:54 pm »
looking to rebuild my front axle but need to know what gears the rear has, is their anyway to tell bc the guy i got it off of doesnt know and its not the factory gearing
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Offline Grim 82

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Re: how can you tell what gears are in the rear end
« Reply #1 on: December 07, 2010, 10:37:12 pm »
Remove the cover and on the ring gear there will be numbers stamped. Divide the small number into the big number and that is the ratio. Example      41:11   = 3.73:1 gears
You can also count the teeth but if the number stamping is visible that's the easiest way.



Chris, can we put something in the tech section about this?
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Offline Captkaos

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Re: how can you tell what gears are in the rear end
« Reply #2 on: December 07, 2010, 11:27:07 pm »
I took some pics on this just haven't added the article yet.
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Offline Yamaha74

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Re: how can you tell what gears are in the rear end
« Reply #3 on: December 08, 2010, 10:27:28 am »
Are you talking about the main cover on the back of the pumpkin?  Sorry for probably a stupid question, but I want to verify my gears to so I want to make sure I understand.
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Offline Grim 82

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Re: how can you tell what gears are in the rear end
« Reply #4 on: December 08, 2010, 10:44:16 am »
Yes. Remove the meatball cover to see the gears inside.
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Offline 1979C20

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Re: how can you tell what gears are in the rear end
« Reply #5 on: December 14, 2010, 11:51:39 am »
Is there a stamp anywhere on the axle that would say what ratio there is?
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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF

Offline Grim 82

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Re: how can you tell what gears are in the rear end
« Reply #6 on: December 14, 2010, 01:05:58 pm »
Quote from: 1979C20 on December 14, 2010, 11:51:39 am
Is there a stamp anywhere on the axle that would say what ratio there is?
Not that I know of. That still wouldn't positively ID the gears, as they may have been changed.
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Give a man a gun, and he might rob a bank. Give a man a bank, and he might rob the world.

Offline 1979C20

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Re: how can you tell what gears are in the rear end
« Reply #7 on: December 14, 2010, 03:11:07 pm »
Well, I know for a fact the truck is COMPLETELY stock except for the front suspension. I have every invoice and receipt from this truck in a folder in my closet. Its a 1979 C20. I can only assume it is 4.10 or 4.11. And it has some form of limited slip.
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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF

Offline Captkaos

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Re: how can you tell what gears are in the rear end
« Reply #8 on: December 14, 2010, 04:46:51 pm »
Yes there is a stamp on the axle, but most are rusted so bad you can't read it.  Generally on the front passenger side I believe.

MUCH easier to pull the cover and get the numbers off.  If the oils has never been changed its a good time to do it.
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Offline 1979C20

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Re: how can you tell what gears are in the rear end
« Reply #9 on: December 14, 2010, 05:09:29 pm »
Well, I really don't to pull the cover off again, I just did it 2 weeks ago and put new oil in it. :/  I took a picture of the carrier, But I cant really count the splines considering its only the front half of the ring and no pinion. My truck has like ZERO rust, Arizona truck so its only got slight surface rust. I crawl underneath her tonight and see if I can find a stamp. How do I know from what the stamp says?
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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF

Offline Captkaos

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Re: how can you tell what gears are in the rear end
« Reply #10 on: December 14, 2010, 05:23:20 pm »
Someone on here has posted the info...
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Offline 1979C20

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Re: how can you tell what gears are in the rear end
« Reply #11 on: December 14, 2010, 05:33:45 pm »
Okay, I see it. I looked for a tag on the diff cover, but there was none. So I'll check the pass. front of the axle and see if I can find the stamp.
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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF

Offline joesgarage71

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Re: how can you tell what gears are in the rear end
« Reply #12 on: December 15, 2010, 11:54:43 am »
 RPO numbers will tell ya the gearin, There is a sticker in the glove box
Or its on the inner front fender
« Last Edit: December 15, 2010, 11:56:21 am by joesgarage71 »
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78' K-20 355/SM465/twin stick 205 6" on 36's
14 bolt FF/big bearing Dana 44 4.56 gears
92' GMC C-1500 454/4L80E/14 bolt

Offline 1979C20

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Re: how can you tell what gears are in the rear end
« Reply #13 on: December 15, 2010, 02:41:20 pm »
No stamp on the front of my axle. ): and that sicker is gone from my glove box. It was loose in there and now I can't find it. It might be with my title, ill check when I get home.
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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF
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