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06-17-2007, 06:39 PM
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#1 |
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Registered User
Join Date: Oct 2005
Location: Pittsburgh, Pa
Posts: 106
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axle ratio 80 GMC
I've been trying to fiond out which speedo gear I need to get my speedometer working. I've found some info on the i-net, but I have to determine what is my axle ratio. With my left back wheel jacked up, and the truck in gear(automatic trans)I had my wife turn the left rear wheel 10 revolutions, my drive shaft turned about 13.9 revolutions. does anyone know
what my axle ratio is??? your help would be appreciated very much. Thanks marvxyz1 |
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06-17-2007, 06:46 PM
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#2 |
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Gentleman Jim Driver
Join Date: Nov 2002
Location: Poulsbo, WA
Posts: 1,550
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Re: axle ratio 80 GMC
If you really want to know, take the cover off and read the numbers stamped on the ring gear.
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Joe '75 GMC Gentleman Jim '84 Chev C10 Short Wide - Super duper plain (manual steering, manual brakes, no dome light, no cig lighter) '85 Chev C10 Short Wide - Super plain Vortec 4.8 4L60E trans also: '81 K30, '83 C30 Crew Dually, '84 M1028 CUCV, '85 M1009 CUCV, another '85 C10 SWB, '89 R3500 Flatbed |
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06-17-2007, 06:47 PM
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#3 |
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Registered User
Join Date: Oct 2006
Location: Wisconsin
Posts: 174
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Re: axle ratio 80 GMC
it should say on the option code sticker in the glove box
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 1985 C10 SWB- *Project*
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06-17-2007, 07:12 PM
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#4 |
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Registered User
Join Date: Oct 2005
Location: Pittsburgh, Pa
Posts: 106
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Re: axle ratio 80 GMC
The axle is listed as rear axle- standard code is GQ1. Is anyone familiar with this????? Thanks Marvxyz1
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06-17-2007, 07:22 PM
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#5 |
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Gentleman Jim Driver
Join Date: Nov 2002
Location: Poulsbo, WA
Posts: 1,550
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Re: axle ratio 80 GMC
Do a search. It's been discussed many times. Same with figuring axle ratio.
__________________
Joe '75 GMC Gentleman Jim '84 Chev C10 Short Wide - Super duper plain (manual steering, manual brakes, no dome light, no cig lighter) '85 Chev C10 Short Wide - Super plain Vortec 4.8 4L60E trans also: '81 K30, '83 C30 Crew Dually, '84 M1028 CUCV, '85 M1009 CUCV, another '85 C10 SWB, '89 R3500 Flatbed |
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06-17-2007, 07:42 PM
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#6 |
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Registered User
Join Date: Oct 2005
Location: Pittsburgh, Pa
Posts: 106
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Re: axle ratio 80 GMC
I found the ratio!! With the code no. GC1 I was able to find the ratio on the i-net. I found it !!! found it!!! Thanks loads everyone - thanks a lot!!! marvxyz1
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06-17-2007, 07:56 PM
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#7 |
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Registered User
Join Date: Oct 2006
Location: Wisconsin
Posts: 174
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Re: axle ratio 80 GMC
no problem
in my glove box it says straight out 3.08 axle ratio
__________________
1985 C10 SWB- *Project*
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06-17-2007, 11:20 PM
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#8 |
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Registered User
Join Date: May 2003
Location: Shreveport LA
Posts: 3,170
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Re: axle ratio 80 GMC
I wouldn't trust a code or a glove box ratio on a 27-year-old truck.
13.9 turns to 10 turns = 1.39 turns per turn Multiply x 2 since one wheel was on the ground, and you get 2.78. The closest factory ratio to that was 2.73, so that's probably what you have. To be absolutely sure, pop the cover off and look at the edge of the ring gear. There should be a 7-digit part number, and four 2-digit numbers, two of which are a date code, and two of which are the tooth counts of the ring & pinion gears. Divide the big one by the little one and that's your ratio. |
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06-19-2007, 01:14 AM
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#9 |
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Senior Member
Join Date: Dec 1999
Location: Knightstown, in, usa
Posts: 2,525
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Re: axle ratio 80 GMC
Marvxyz1, please post the link to the site that you found. I wanna see it, too!
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1970 long fleet, 355 4 speed, primer, walnut goodies |
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