What's my ratio? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bw4sale · 04-28-2009, 08:25 PM

I marked a spot on the driveshaft and then turned my hub and counted the revolutions. My driveshaft only went around a little less that 2 turns to the hubs 1. So, what's my ratio?

Green Machine · 04-28-2009, 10:00 PM

Turn the wheel around twice, or if you have the time, turn it 20 times, that will get you a spot on answer. For instance, if you turn the wheel 20 times and the ds goes around exactly 41 times, you have a 4.10 rear.

**LockDoc** · 04-28-2009, 10:09 PM

-
You can look on the housing (for Location see the pics below) then go here and look up the code:

http://www.americanclassic.com/paint.htm

You just need the first two or three letters....

LockDoc

bw4sale · 05-09-2009, 08:10 PM

Ok, I tried it again and got this

Wheel/DS

10/18
20/37
30/56

I don't understand your math, but according to that would that make mine a 3.73??

ERASER5 · 05-09-2009, 08:23 PM

Yes. 3.73. Now put a posi in it, and your golden.

**special-K** · 05-09-2009, 08:44 PM

How do we come up with 3.73?
3.73 would aprox.3 3/4 driveshaft turns to 1 axle turn.You`re coming up with around 2:1.

**Hart_Rod** · 05-09-2009, 08:47 PM

Quote:

Originally Posted by special-K

How do we come up with 3.73?
3.73 would aprox.3 3/4 driveshaft turns to 1 axle turn.You`re coming up with around 2:1.

For a "one legger" I always multiply by 2......

hgs_notes · 05-10-2009, 07:55 AM

Quote:

Originally Posted by special-K

How do we come up with 3.73?
3.73 would aprox.3 3/4 driveshaft turns to 1 axle turn.You`re coming up with around 2:1.

Because of the spider gears, if you have one wheel down and not turning, the ratio is half. If you were to roll the axle, both wheels down, the pinion would turn twice as fast. I just did this myself friday and figured it out. I don't think it works this way for a posi axle, but I'm not positive of that.

bw4sale · 05-09-2009, 09:35 PM

I still don't understand the reasoning, but I would trust it to be a 3.73 long before 1.80.

DMARCUM123 · 05-09-2009, 10:21 PM

I had my check and it came up with a2-1 the friend checking it said was coming up right so i pulled the cover it was a 373

04-28-2009, 08:25 PM	#1
bw4sale Registered User Join Date: Sep 2006 Location: Hendersonville, TN Posts: 1,528	What's my ratio? I marked a spot on the driveshaft and then turned my hub and counted the revolutions. My driveshaft only went around a little less that 2 turns to the hubs 1. So, what's my ratio? __________________ BRENT -'68 Stepside Project -'98 Z71 Daily Driver -Enough extra parts to build another truck and a half

04-28-2009, 10:00 PM	#2
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: What's my ratio? Turn the wheel around twice, or if you have the time, turn it 20 times, that will get you a spot on answer. For instance, if you turn the wheel 20 times and the ds goes around exactly 41 times, you have a 4.10 rear. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

04-28-2009, 10:09 PM	#3
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,772	Re: What's my ratio? - You can look on the housing (for Location see the pics below) then go here and look up the code: http://www.americanclassic.com/paint.htm You just need the first two or three letters.... LockDoc Attached Images __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

05-09-2009, 08:10 PM	#4
bw4sale Registered User Join Date: Sep 2006 Location: Hendersonville, TN Posts: 1,528	Re: What's my ratio? Ok, I tried it again and got this Wheel/DS 10/18 20/37 30/56 I don't understand your math, but according to that would that make mine a 3.73?? __________________ BRENT -'68 Stepside Project -'98 Z71 Daily Driver -Enough extra parts to build another truck and a half

05-09-2009, 08:23 PM	#5
ERASER5 Registered User Join Date: Jun 2006 Location: Indiana Posts: 4,859	Re: What's my ratio? Yes. 3.73. Now put a posi in it, and your golden. __________________ '70 GMC C1500 LWB Power disc brakes. WooHoo! Posi 6 Lug Dana 60

05-09-2009, 08:44 PM	#6
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: What's my ratio? How do we come up with 3.73? 3.73 would aprox.3 3/4 driveshaft turns to 1 axle turn.You`re coming up with around 2:1. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

05-09-2009, 09:35 PM	#9
bw4sale Registered User Join Date: Sep 2006 Location: Hendersonville, TN Posts: 1,528	Re: What's my ratio? I still don't understand the reasoning, but I would trust it to be a 3.73 long before 1.80. __________________ BRENT -'68 Stepside Project -'98 Z71 Daily Driver -Enough extra parts to build another truck and a half

05-09-2009, 10:21 PM	#10
DMARCUM123 Registered User Join Date: Sep 2006 Location: WAYNE, WV. Posts: 675	Re: What's my ratio? I had my check and it came up with a2-1 the friend checking it said was coming up right so i pulled the cover it was a 373



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