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03-17-2012, 10:47 PM
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#1 |
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Senior Member
Join Date: Jul 2010
Location: South Dakota
Posts: 4,093
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rear end gear ratio
Hey guys, i have a rear end off a 71 Chevy 350/350 combo that I'm about to put up on the for sale section and I'm tryin to figure out the ratio. The pinion spins around 15.6 times every 10 tire spins. Any help would be appreciate it!
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1969 Chevy c20(Miss Hackjob) |
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03-17-2012, 11:01 PM
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#2 |
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Senior Member
 
Join Date: Oct 2009
Location: Godley, TX
Posts: 17,940
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Re: rear end gear ratio
assuming you have no posi - need to drop one tire on the ground and count pinion vs elevated tire. If you have both tires in the air, then one spins opposite direciton, cutting your revs in half.
So, if this was the case, I'd say you have about a 3.08-ish, but if you didn't do the above, recommend trying that. Only way to know for sure is count ring and pinion teeth and divide. Since you're sellin it, might be worth poppin the cover off and making sure. If it's already off the donor vehicle, then you won't be able to do all the stuff i mentioned above about locking one tire. Brake drum on ground to eliminate other side wheel spin might work though. |
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03-18-2012, 12:45 AM
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#3 |
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18 Till I Die
Join Date: Mar 2005
Location: Alberta, Canada
Posts: 1,522
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Re: rear end gear ratio
I was told this works...Mark the tire and count how many times the driveshaft turns for one revolution of the tire. 3 3/4 turns =3:73 ...just over 4 = 4:11 etc...
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2011 GMC Acadia 1969 GMC BBC LS7 2007 GMC Crew Duramax 1987 Camaro Iroc 350 Tuned Port Injection 42000Km 1987 Chevrolet Silverado 350 TBI 1987 Chevrolet Silverado 350 TBI(yes 2) Take me drunk, I'm too home... 
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03-18-2012, 02:24 AM
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#4 |
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Still plays with trucks
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,556
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Re: rear end gear ratio
Does the SPID say anything about your gearing?
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miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E 79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars |
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03-18-2012, 08:07 AM
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#5 |
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Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: rear end gear ratio
to get the most $$$ from selling it it is best to remove cover drain old gunk out and clean it up so buyer can see what he is buyin// at the same time it makes it real easy to see gears and say accurarly what rotio it is
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71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY |
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03-18-2012, 02:57 PM
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#6 |
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Senior Member
Join Date: Jul 2010
Location: South Dakota
Posts: 4,093
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Re: rear end gear ratio
Hey guys thanks for the help, ill have to remove the cover an see, I was gona last night but got busy trying to get other stuff done. I checked the options list but got nothing from it.
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1969 Chevy c20(Miss Hackjob) |
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03-18-2012, 02:59 PM
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#7 |
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Senior Member
Join Date: Jul 2010
Location: South Dakota
Posts: 4,093
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Re: rear end gear ratio
So for my truck I jack it up an then count the drive shaft spins/the tire spins? I've been trying to see what rear end I have for a while now.
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1969 Chevy c20(Miss Hackjob) |
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03-18-2012, 04:33 PM
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#8 | |
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bbadfred
Join Date: Mar 2008
Location: rantoul Il
Posts: 461
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Re: rear end gear ratio
Quote:
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03-18-2012, 07:49 PM
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#9 | |
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Senior Member
Join Date: Jul 2010
Location: South Dakota
Posts: 4,093
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Re: rear end gear ratio
Quote:
Posted via Mobile Device
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1969 Chevy c20(Miss Hackjob) |
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03-18-2012, 09:19 PM
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#10 |
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Senior Member
Join Date: Jul 2010
Location: South Dakota
Posts: 4,093
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Re: rear end gear ratio
Ok I spun the thing with one wheel on the ground. The tires ten times around and driveshaft is 20.4. This is a 69c20 I didn't think they made rear ends this high? Could it be after market or am I missing something?
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1969 Chevy c20(Miss Hackjob) |
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03-24-2012, 12:47 AM
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#11 | |
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Still plays with trucks
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,556
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Re: rear end gear ratio
Quote:
I agree with above and say just pull the cover and read the numbers off the ring gear. Reseal the thing and fill it with synthetic gear oil. It will be a selling point and increase the rear wheel HP & fuel efficiency too.
__________________
miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E 79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars |
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03-24-2012, 07:17 PM
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#12 | |
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Senior Member
Join Date: Jul 2010
Location: South Dakota
Posts: 4,093
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Re: rear end gear ratio
Quote:
 Posted via Mobile Device
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1969 Chevy c20(Miss Hackjob) |
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03-24-2012, 09:56 PM
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#13 |
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Registered User
Join Date: May 2000
Location: Storm Lake, Ia
Posts: 1,449
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Re: rear end gear ratio
Try with a good steel brush in the circle area the factory numbers are there
get us those and we can tell what factory gears are. gotta clean real good as numbers are sunk not raised
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