1985 GMC Jimmy gear ratio? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mrmojo32 · 05-30-2009, 10:19 PM

Does anyone know what rear axle gear ratios were offered in 1985 GMC Jimmy K5 - 12 bolt?

I have tried to do some looking on the old brochure sites but the fine print is too fine to read.

Thanks in advance.

b454rat · 05-31-2009, 09:08 AM

Not that it matters, but will be 10 bolts front and rear. And gears could be anything from 2.73s up to 4.10s. Check in the glove box for the RPO codes, or could be under the hood on the inner fender. Starts with a "G".

mrmojo32 · 05-31-2009, 09:00 PM

Well I thought 10 bolt too but the guy who has the truck says that the rear is 12 bolt.

silvereagle07 · 05-31-2009, 09:17 PM

Take the covers off of the diffs and count the number of teeth on the ring gear and divide it by the teeth on the pinion.

piecesparts · 05-31-2009, 10:03 PM

My truck has a 12 bolt rear end and it is an 84 Sierra classic. The gearing could be 3.08, 3.42, 3.73, or 4.10. In those days you could STILL order what you wanted in a truck.

mrmojo32 · 05-31-2009, 10:35 PM

Right on about counting teeth or sometimes there is a number stamped on the ring gear that you can devide to get the ratio. I was asking because I do not have the Jimmy in my possession. I am going to pick up the front and rear axles tomorrow without know what ratio they are. I am just hoping that they are not 3.08.

05-30-2009, 10:19 PM	#1
mrmojo32 Registered User Join Date: Jan 2007 Location: Louisiana Posts: 216	1985 GMC Jimmy gear ratio? Does anyone know what rear axle gear ratios were offered in 1985 GMC Jimmy K5 - 12 bolt? I have tried to do some looking on the old brochure sites but the fine print is too fine to read. Thanks in advance. __________________ 1972 LWB 1969 4x4 Suburban 1989 4x4 Jimmy

05-31-2009, 09:08 AM	#2
b454rat Senior Member Join Date: May 2004 Location: Binghamton, NY Posts: 3,469	Re: 1985 GMC Jimmy gear ratio? Not that it matters, but will be 10 bolts front and rear. And gears could be anything from 2.73s up to 4.10s. Check in the glove box for the RPO codes, or could be under the hood on the inner fender. Starts with a "G". __________________ 2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 4” SAS 1999 GMC Yukon 350/4L60 6" SAS Last edited by b454rat; 05-31-2009 at 09:09 AM.

05-31-2009, 09:00 PM	#3
mrmojo32 Registered User Join Date: Jan 2007 Location: Louisiana Posts: 216	Re: 1985 GMC Jimmy gear ratio? Well I thought 10 bolt too but the guy who has the truck says that the rear is 12 bolt. __________________ 1972 LWB 1969 4x4 Suburban 1989 4x4 Jimmy

05-31-2009, 09:17 PM	#4
silvereagle07 Registered User Join Date: Sep 2008 Location: Bailey, NC Posts: 2,462	Re: 1985 GMC Jimmy gear ratio? Take the covers off of the diffs and count the number of teeth on the ring gear and divide it by the teeth on the pinion. __________________ Jeramy '84 GMC project truck '85 Chevy 4X4 SOLD '07 Chevy Trailblazer SS 5th Annual SHPHC Car/Truck Show Pics http://67-72chevytrucks.com/vboard/s...d.php?t=543605 UPDATED PICS! CHECK 'EM OUT

05-31-2009, 10:03 PM	#5
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: 1985 GMC Jimmy gear ratio? My truck has a 12 bolt rear end and it is an 84 Sierra classic. The gearing could be 3.08, 3.42, 3.73, or 4.10. In those days you could STILL order what you wanted in a truck.

05-31-2009, 10:35 PM	#6
mrmojo32 Registered User Join Date: Jan 2007 Location: Louisiana Posts: 216	Re: 1985 GMC Jimmy gear ratio? Right on about counting teeth or sometimes there is a number stamped on the ring gear that you can devide to get the ratio. I was asking because I do not have the Jimmy in my possession. I am going to pick up the front and rear axles tomorrow without know what ratio they are. I am just hoping that they are not 3.08. __________________ 1972 LWB 1969 4x4 Suburban 1989 4x4 Jimmy



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