Rear end. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MSL · 04-01-2003, 04:10 AM

Ok the thing i have on my mind is how do you find out what gear ratio is in the rear end. in my truck it will not burn or chirp the tires it just goes. so what do i need to do to find out what im running. it seems its like it was geared more for hauling.

79BIG10 · 04-01-2003, 04:39 AM

Best way is to take the rear cover off and count the teeth of the ring and the pinion. Divide the smaller into the larger to get your rear axle ratio. This is a good time to clean out the old fluid and replace the gasket. You need to also make sure of no shavings in the grease. More than likely if the engine and tranny are in good shape then the rear axle may be a high gear ratio like mine 3.07. This is more for highway driving and not the get off the line fast ratio.

MSL · 04-01-2003, 05:01 AM

Hey thanks im pretty sure im running that same ratio. my engine and tranny seem in really good shape it will launch when i hammer it but it doesnt break loose i guess thats a good thing somewhat.lol But ya i will get the cover off and find out what i got and replace and clean things.

Ol' Grey · 04-01-2003, 06:58 PM

Check the RPO sheet in the glove box. Mine is GU4, but I swapped in a 12-bolt rear. I identified it as a 3.08 as well by the metal tag on the housing.

Code:

RPO    1st yr    lst yr      desc.
GU1      76          87       AXLE,RR 2.41 RATIO  
GU2      76          88       AXLE,RR 2.73 RATIO  
GU3      82          85       AXLE.AR 2.93 RATIO  
GU4      76          88       AXLE,RR 3.08 RATIO  
GU5      76          88       AXLE,RR 3.23 RATIO  
GU6      76          88       AXLE,RR 3.42 RATIO  
GV4       82         87       AXLE,RR 3.36 RATIO  
GV8       82         85       AXLE,RR 2.72 RATIO  
GW4      84         85       AXLE,RR 3.31 RATIO  
GW6      85         88       AXLE,RR 3.27 RATIO  
GW9      76         88       AXLE,RR 2.93 RATIO  
GX3       82         88       AXLE,FRT 3.33 RATIO  
GX4       76         83       AXLE,RR 3.75 RATIO  
GX5       76         83       AXLE,RR 4.09 RATIO  
GY5       76         87       AXLE,FRT 3.65 RATIO  
G44       85         87       AXLE,RR 3.07 RATIO

MSL · 04-01-2003, 07:51 PM

I dont have that in my glove box i have something that shows codes but nothing about the rear end.

apstguy · 04-01-2003, 10:21 PM

Most likely if it doesn't have the code, it is 2.75 or whatever the common stock one was. I have the 3.08 and my truck does the same thing. Doesn't break loose unless there is water or corner.

Mike76251 · 04-01-2003, 10:23 PM

Anyone know what a 1GQ1 rear ratio might be for a '84 Silverado 10 bolt?
Thanks

Ol' Grey · 04-01-2003, 10:58 PM

Quote:

Originally posted by Mike76251
Anyone know what a 1GQ1 rear ratio might be for a '84 Silverado 10 bolt?
Thanks

GQ1 is standard ratio, open carrier. Most likely 2.73

*1FaastC10* · 04-01-2003, 11:06 PM

heh, my C10 had 3.08s in it, and i couldnt keep the tires from spinning. wierd...

Mike76251 · 04-01-2003, 11:30 PM

Quote:

Originally posted by Ol' Grey

GQ1 is standard ratio, open carrier. Most likely 2.73

Ol' Grey,
Thank you very much.
That explains why this thing only does 1700rpm at 55mph.

*1FaastC10* · 04-02-2003, 01:32 AM

oh yeah, that's a 2.73 allright!

Lil Greg · 04-02-2003, 02:37 AM

If you don"t feel like counting teeth www.nastyz28.com has gear ratios just by looking on the staped numbers on the gear teeth for example 41-11 = a 3.73 rear end.

MSL · 04-02-2003, 02:38 AM

Quote:

Originally posted by Lil Greg
If you don"t feel like counting teeth www.nastyz28.com has gear ratios just by looking on the staped numbers on the gear teeth for example 41-11 = a 3.73 rear end.

Thanks for the site.

04-01-2003, 04:10 AM	#1
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	Rear end. Ok the thing i have on my mind is how do you find out what gear ratio is in the rear end. in my truck it will not burn or chirp the tires it just goes. so what do i need to do to find out what im running. it seems its like it was geared more for hauling.

04-01-2003, 04:39 AM	#2
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,774	Best way is to take the rear cover off and count the teeth of the ring and the pinion. Divide the smaller into the larger to get your rear axle ratio. This is a good time to clean out the old fluid and replace the gasket. You need to also make sure of no shavings in the grease. More than likely if the engine and tranny are in good shape then the rear axle may be a high gear ratio like mine 3.07. This is more for highway driving and not the get off the line fast ratio. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

04-01-2003, 10:21 PM	#6
apstguy LED King Join Date: Jan 2003 Location: Sacramento, CA Posts: 2,087	Most likely if it doesn't have the code, it is 2.75 or whatever the common stock one was. I have the 3.08 and my truck does the same thing. Doesn't break loose unless there is water or corner. __________________ Tyler 1985 C10 305 w/ Bowtie OD TH700R4 3.42 LSD 202,000 miles 2006 Ford Focus ZX3 5-speed Stick 2016 Chevy Spark EV Gone: 2002.5 VW GTI 24v VR6 Gone: 2008 VW R32

04-01-2003, 10:23 PM	#7
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,499	1GQ1 RPO Anyone know what a 1GQ1 rear ratio might be for a '84 Silverado 10 bolt? Thanks

04-01-2003, 05:01 AM	#3
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	Hey thanks im pretty sure im running that same ratio. my engine and tranny seem in really good shape it will launch when i hammer it but it doesnt break loose i guess thats a good thing somewhat.lol But ya i will get the cover off and find out what i got and replace and clean things.

04-01-2003, 07:51 PM	#5
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	I dont have that in my glove box i have something that shows codes but nothing about the rear end.

04-01-2003, 11:06 PM	#9
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	heh, my C10 had 3.08s in it, and i couldnt keep the tires from spinning. wierd...

04-02-2003, 01:32 AM	#11
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	oh yeah, that's a 2.73 allright!

04-02-2003, 02:37 AM	#12
Lil Greg Registered User Join Date: Feb 2003 Location: Mansfield,Tx Posts: 54	If you don"t feel like counting teeth www.nastyz28.com has gear ratios just by looking on the staped numbers on the gear teeth for example 41-11 = a 3.73 rear end.



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