14 bolt gear ratio - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JohnyCash4x4 · 08-03-2004, 07:34 PM

Hello,
Recently bought a pieced together truck and am trying to find out what the gearing is on this beast.

The 14 bolt rear has RFZG3001 stamped on the axle tube. Is there any way to find out what the ratio was originally with this number. I have a very strong feeling it is the stock ratio for the chasis (either '76 or '79 K20).

I do know that it is the FF rear and the front is the D44 with a spool. I don't have a tach yet but the RPM's are up there travelling at highway speeds with the TH350 and 32" tires.

I'm about to build a new motor and install a new TQ converter but really need to know what I'm dealing with first.

If anyone could help it would be MUCH appreciated!

Russell · 08-03-2004, 08:26 PM

I'd guess either 3.73 or 4.10 if they are stock... My 80 has a 3.73 rear, and my 76 has a 4.10 year, but the 4.10 gears were an option on the build sheet for the truck.

JohnyCash4x4 · 08-04-2004, 12:51 PM

ttt

Grim Reaper · 08-04-2004, 01:16 PM

best thing to do is take a cover off an count the teeth. No tell whats in it if they swapped them under there. they may have swappped gears as well. Personally I always service the diffs on vehciles I buy so I can see wat sort of shape the gears are in and if it has a locker.

You could jack it up and have somebody spin the wheel same direction as you and then count the tire turns till you get one turn of the pinion.

JohnyCash4x4 · 08-04-2004, 06:12 PM

Yeah, I can pop the cover but really want to know what the original gearing was so I could have an idea as to what was actually modified on this truck. Plus it may help determine what the year this chasis is so I can buy the right parts etc.

Grim Reaper · 08-04-2004, 08:46 PM

Quote:

Originally Posted by JohnyCash4x4

Yeah, I can pop the cover but really want to know what the original gearing was so I could have an idea as to what was actually modified on this truck. Plus it may help determine what the year this chasis is so I can buy the right parts etc.

Well the orginal to the truck is going to be on he build sticker in the glove box. If it doesn't list a gear then it's the defaul ger and most cases that's 3.08 in the 70's and som 2.75 or something on some of the 80's on half tons. 3/4 tons usualy got a 3.73 as default

JohnyCash4x4 · 08-04-2004, 08:59 PM

lol
I don't even know what the chasis came from. All I know is it's a K20 chasis under a '72 C10 body.

Txstruck · 08-07-2004, 05:39 AM

My 14 bolt FF has 4.56 gears.

stan79chevy · 08-07-2004, 10:03 AM

from the factory in a 77 k20 with a straight 6 and 3 speed manual. i think the only gearing that came on teh ff 14 bolt was 3.73 4.10 and 4.56.

stan

JohnyCash4x4 · 08-07-2004, 04:46 PM

Yeah, I'm thinking it's at least 4.10's. I've had a few 3.73's and the RPM's this one turns at speed as far more than that even with the 32" tires.

08-03-2004, 07:34 PM	#1
JohnyCash4x4 Registered User Join Date: Aug 2004 Posts: 11	14 bolt gear ratio Hello, Recently bought a pieced together truck and am trying to find out what the gearing is on this beast. The 14 bolt rear has RFZG3001 stamped on the axle tube. Is there any way to find out what the ratio was originally with this number. I have a very strong feeling it is the stock ratio for the chasis (either '76 or '79 K20). I do know that it is the FF rear and the front is the D44 with a spool. I don't have a tach yet but the RPM's are up there travelling at highway speeds with the TH350 and 32" tires. I'm about to build a new motor and install a new TQ converter but really need to know what I'm dealing with first. If anyone could help it would be MUCH appreciated! __________________ Bill '72 C10 body on '76 or '79 K20 chasis 355/TH350/NP205/D44 with spool/14-bolt FF

08-03-2004, 08:26 PM	#2
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I'd guess either 3.73 or 4.10 if they are stock... My 80 has a 3.73 rear, and my 76 has a 4.10 year, but the 4.10 gears were an option on the build sheet for the truck. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-04-2004, 12:51 PM	#3
JohnyCash4x4 Registered User Join Date: Aug 2004 Posts: 11	ttt __________________ Bill '72 C10 body on '76 or '79 K20 chasis 355/TH350/NP205/D44 with spool/14-bolt FF

08-04-2004, 01:16 PM	#4
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	best thing to do is take a cover off an count the teeth. No tell whats in it if they swapped them under there. they may have swappped gears as well. Personally I always service the diffs on vehciles I buy so I can see wat sort of shape the gears are in and if it has a locker. You could jack it up and have somebody spin the wheel same direction as you and then count the tire turns till you get one turn of the pinion. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

08-04-2004, 06:12 PM	#5
JohnyCash4x4 Registered User Join Date: Aug 2004 Posts: 11	Yeah, I can pop the cover but really want to know what the original gearing was so I could have an idea as to what was actually modified on this truck. Plus it may help determine what the year this chasis is so I can buy the right parts etc. __________________ Bill '72 C10 body on '76 or '79 K20 chasis 355/TH350/NP205/D44 with spool/14-bolt FF Last edited by JohnyCash4x4; 08-04-2004 at 06:15 PM.

08-04-2004, 08:59 PM	#7
JohnyCash4x4 Registered User Join Date: Aug 2004 Posts: 11	lol I don't even know what the chasis came from. All I know is it's a K20 chasis under a '72 C10 body. __________________ Bill '72 C10 body on '76 or '79 K20 chasis 355/TH350/NP205/D44 with spool/14-bolt FF

08-07-2004, 05:39 AM	#8
Txstruck Registered User Join Date: Nov 2002 Location: Dallas Posts: 459	My 14 bolt FF has 4.56 gears. __________________ Steve 86 K30 4x4 6.2L Diesel\TH400\NP208 - 14bolt FF rear w/detroit locker and Dana60 front w/detroit locker- both with 4.56 gears "Runs on Mud"

08-07-2004, 10:03 AM	#9
stan79chevy Registered User Join Date: Sep 2003 Location: COVINGTON GEORGIA Posts: 477	mine came with 4.56 from the factory in a 77 k20 with a straight 6 and 3 speed manual. i think the only gearing that came on teh ff 14 bolt was 3.73 4.10 and 4.56. stan __________________ 79 chevy k20 350/350/205/D44/14bFF 4.56 gears rock LWB pimer black 01 S-10 ZR2 extended cab 4.3/4L60E/233 3.73 gear 31" DICK CEPEK CRUSHERS

08-07-2004, 04:46 PM	#10
JohnyCash4x4 Registered User Join Date: Aug 2004 Posts: 11	Yeah, I'm thinking it's at least 4.10's. I've had a few 3.73's and the RPM's this one turns at speed as far more than that even with the 32" tires. __________________ Bill '72 C10 body on '76 or '79 K20 chasis 355/TH350/NP205/D44 with spool/14-bolt FF



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