Gears standard or thick? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

john0540 · 08-12-2004, 01:13 AM

I have an 84 1/2 ton 4x4 with a 12 bolt diff and I am looking to order a new ring and pinion set. How do I know if I have standard or thick gears?

79BIG10 · 08-12-2004, 02:56 AM

It depends on the carrier. If you have a series 3 carrier and want gears like a 3.73 or numerically higher then you need thicker gears to compensate for the difference. If you have a series 4 carrier then you probably can use standard gears. Contact the supplie with what gears you have and they can help you in your decision.

john0540 · 08-12-2004, 11:45 AM

I currently have 3.73 gears in it now but I don't know if that makes a differance. Is there any stampings or physical features that would tell me if it was a 3 or 4 series?

Destructo · 08-12-2004, 03:30 PM

If those 3.73 gears are factory then you have a series 4 carrier and can go up to 4.10, 4.56, etc. with standard gears.

Grim Reaper · 08-12-2004, 04:37 PM

That's a good rule for a 12 bolt rear. The factory "Carrier break" was 3.73.

The D44 front had a single carrier I believe. I think the same is true for a 10 bolt front.

NOW a 84 truck SHOULD have come with a 10 bolt rear not a 12 bolt. Go count the bolts on the cover and verify what you have.

If someobdy swapped the axle who is to say the gears are original to it as well? might want to pull the cover and get the numbers off the gears. A good gear supplier will probably be able to verify a thick or thin ring and make sure you get the right parts the first time.

john0540 · 08-12-2004, 10:22 PM

It does have 12 bolts in sort of a D shape cover (not oval) as far as the 84 vs. 12 bolt Grim reaper hit the nail on the head. A previous owner did change the rear end but I don't know where it came from or if the gears have been changed also.

I had to change an axel bearing a few years back, that is when i found out about the oem 10 bolt I gave the year make and model to the parts guy and received the incorrect diff gasket (the oval one)

It looks like I'm going to have to get my hands dirty and just open it up

Grim Reaper · 08-13-2004, 02:17 PM

Yeah that would be the best thing. Sucks to order the wrong parts and then have to wait a second time and the hassle to return worg parts. The ring gear will have a parts number and there will be something like 9 41 The 9 41 would tell you the teeth on the gears 9 pinion 41 ring and you would have a 4.56 gear.

08-12-2004, 01:13 AM	#1
john0540 Registered User Join Date: Aug 2004 Location: norcal Posts: 14	Gears standard or thick? I have an 84 1/2 ton 4x4 with a 12 bolt diff and I am looking to order a new ring and pinion set. How do I know if I have standard or thick gears?

08-12-2004, 02:56 AM	#2
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,774	It depends on the carrier. If you have a series 3 carrier and want gears like a 3.73 or numerically higher then you need thicker gears to compensate for the difference. If you have a series 4 carrier then you probably can use standard gears. Contact the supplie with what gears you have and they can help you in your decision. __________________ 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

08-12-2004, 03:30 PM	#4
Destructo Registered User Join Date: Sep 2003 Location: Lewisville, NC Posts: 1,836	If those 3.73 gears are factory then you have a series 4 carrier and can go up to 4.10, 4.56, etc. with standard gears. __________________ 1985 Scottsdale Shortbed 4x4 Stout 350 with some "upgrades"-700r4-33x12.5" Mud Tires, Warn 8274-50 winch. 2005 Chevrolet Colorado Regular Cab 2wd 4-banger, 5 speed, Street Pack with 3.73 axle.

08-12-2004, 04:37 PM	#5
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	That's a good rule for a 12 bolt rear. The factory "Carrier break" was 3.73. The D44 front had a single carrier I believe. I think the same is true for a 10 bolt front. NOW a 84 truck SHOULD have come with a 10 bolt rear not a 12 bolt. Go count the bolts on the cover and verify what you have. If someobdy swapped the axle who is to say the gears are original to it as well? might want to pull the cover and get the numbers off the gears. A good gear supplier will probably be able to verify a thick or thin ring and make sure you get the right parts the first time. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

08-13-2004, 02:17 PM	#7
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	Yeah that would be the best thing. Sucks to order the wrong parts and then have to wait a second time and the hassle to return worg parts. The ring gear will have a parts number and there will be something like 9 41 The 9 41 would tell you the teeth on the gears 9 pinion 41 ring and you would have a 4.56 gear. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

08-12-2004, 11:45 AM	#3
john0540 Registered User Join Date: Aug 2004 Location: norcal Posts: 14	I currently have 3.73 gears in it now but I don't know if that makes a differance. Is there any stampings or physical features that would tell me if it was a 3 or 4 series?

08-12-2004, 10:22 PM	#6
john0540 Registered User Join Date: Aug 2004 Location: norcal Posts: 14	It does have 12 bolts in sort of a D shape cover (not oval) as far as the 84 vs. 12 bolt Grim reaper hit the nail on the head. A previous owner did change the rear end but I don't know where it came from or if the gears have been changed also. I had to change an axel bearing a few years back, that is when i found out about the oem 10 bolt I gave the year make and model to the parts guy and received the incorrect diff gasket (the oval one) It looks like I'm going to have to get my hands dirty and just open it up



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