Difference between 3 series and 4 series carriers? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71GMC 4x4 · 05-15-2002, 12:12 AM

I have a posi carrier for a 12 bolt. I need to know what series it is. How can I tell the difference between a 3 series and 4 series? I'm going to 4.56 gears, and I don't know if I need to buy thick gears or regular gears. Please help me out. Thanks, Albie

Wasted Income · 05-15-2002, 12:18 AM

What was the gear ratio originally installed on the carrier. A 3 series carrier is for up through 3.73. A 4 is for higher than 3.73. The difference is the thickness of the ring gear mounting surface.
I believe that you can use taller gears (ex. 3.07) on a 4 series carrier if you use a shim, but you can't go back the other way?
Am I correct?

------------------
-Jeff

-------------------------
"You might be a REDNECK if someone yells 'Hoedown' and your girlfriend hits the floor"
-Jeff Foxworthy

'69 C-10 LWB (hot rod)
'67 C-10 SWB (hot rod in progress)
'92 K1500 'Burban (daily driver/tow vehicle)

texnician01 · 05-15-2002, 12:42 AM

yes you are correct. the 3 series carrier is for 3.07 to 3.5? gears.(they only used 3.07's 3.73's and 4.11's in our trucks) the 4 series carrier is for 3.73 and up gears. here's the way to tell the difference. just take these measurements.

doesn't matter if they are open or posi.

------------------
1969 C-10 292 I-6 4 spd in the middle of a restoration. going to get a 327 and 3.07 gears but keeping all of the original parts so I can put it back to original later on down the road.
55 chevy 4 door 150
47 Willys CJ-2A

[This message has been edited by texnician01 (edited May 15, 2002).]

70c10 · 05-15-2002, 06:59 AM

Tex,
Excellent post!

71GMC 4x4 · 05-15-2002, 12:43 PM

Cool, Thanks Guys!!

bigvinnie · 05-15-2002, 01:05 PM

tex, looks like the 3.07 is open and the 3.73 is posi..?? I have an open 3.73 carrier that has a much smaller flange depth, like less than 1/2 inch, but has the tapered casting that you point out in your pic...

I assume the difference between mine and yours is based on whether it's posi or open...??

------------------
'72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA
http://www.ixpres.com/vlusardi/chevtrk.htm

texnician01 · 05-15-2002, 06:23 PM

yes one of these is an open carrier while the other is a posi. The place that you measure to is the face where the ring gear touches. these all have to be the same within the same series, open or posi.
I also noticed that some of the castings are a little different. I was unsure of what you were asking but I hope this helps. thanks

Nathan

bigvinnie · 05-15-2002, 08:13 PM

tex, where you show a measurement of 1 7/8 inches on the 3.73 carrier, my 3.73 open carrier measures less than 1/2 inch.... but my casting tapers toward the roller bearing just like the one you have pictured...

I'm thinking that some of your flange depth could actually be part of the ring gear casting, like 71GMC is talking about, thick vs. regular gears....??

texnician01 · 05-16-2002, 11:29 AM

bigvinnie you are measuring from the table top to the bottom of the ring gear correct? dont' measure the flange width that pic is kind of missleading. just measure from tabletop to ring gear mounting surface. the thick and regular gears he's talking about is to adapt gears between carriers. you can only do this on a series 3 carrier though. if you want to put 3.73 gears on a series 3 carrier you have to have a thicker gear because of the flange offset. you CANNOT put 3.07 gears on a series 4 carrier though. they would have to be paper thin in order to fit.

I'm still not catching on to the 1/2 inch thing though.

Nathan

bigvinnie · 05-16-2002, 11:44 AM

tex, you are correct, the pic is very misleading.... the red lines suggest that the 1 7/8 measurement is for flange thickness only, not from table top to bottom of ring gear... that clears things up, thanks.

texnician01 · 05-16-2002, 11:58 AM

ok, I get it now. sorry I was a little slow on the uptake myself. the pic was done a while back for another guy and I drew the flange lines in cause I didn't want him to think that the step on the 3.73 carrier was a spacer plate. this one should help a little.

sorry, my lightbulb just took awhile to warm up and turn on...LOL!!

Nathan

bigvinnie · 05-16-2002, 12:07 PM

yeah no problem, if I'd looked at the ruler instead of your lines I would have seen what you were talking about... learned something about carriers so it's all good...

05-15-2002, 12:12 AM	#1
71GMC 4x4 Registered User Join Date: Mar 2002 Location: Redway,Ca. U.S.A Posts: 37	Difference between 3 series and 4 series carriers? I have a posi carrier for a 12 bolt. I need to know what series it is. How can I tell the difference between a 3 series and 4 series? I'm going to 4.56 gears, and I don't know if I need to buy thick gears or regular gears. Please help me out. Thanks, Albie __________________ [IMG]http://mustangmods.com/publish/topless99/truck2.jpg[IMG]

05-15-2002, 12:18 AM	#2
Wasted Income Boosted Member Join Date: May 2002 Location: Mackinaw, IL Posts: 2,200	What was the gear ratio originally installed on the carrier. A 3 series carrier is for up through 3.73. A 4 is for higher than 3.73. The difference is the thickness of the ring gear mounting surface. I believe that you can use taller gears (ex. 3.07) on a 4 series carrier if you use a shim, but you can't go back the other way? Am I correct? ------------------ -Jeff ------------------------- "You might be a REDNECK if someone yells 'Hoedown' and your girlfriend hits the floor" -Jeff Foxworthy '69 C-10 LWB (hot rod) '67 C-10 SWB (hot rod in progress) '92 K1500 'Burban (daily driver/tow vehicle) __________________ 1972 2wd K/5 Blazer Turbocharged 370 LSx - 941 rwhp / 1093 rwtq 1969 Chevy K-10 L33 5.3 / 4L80E / NP241 / 4" lift 1964 Buick Skylark Twin TURBO 383 LS pro-touring project 2014 VW Passat TDI - Daily Driver Turbo diesel 2015 Sierra Denali HD Duramax Turbo diesel 2016 Ford Explorer Sport - Twin Turbskis 2017 Polaris RZR Turbo 2014 Nor-Tech Center Console - Twin Supercharged Outboards *TURBO ALL THE THINGS!!*

05-15-2002, 12:42 AM	#3
texnician01 Senior Member Join Date: Mar 2002 Location: 12 Miles South of Des Moines, Iowa Posts: 359	yes you are correct. the 3 series carrier is for 3.07 to 3.5? gears.(they only used 3.07's 3.73's and 4.11's in our trucks) the 4 series carrier is for 3.73 and up gears. here's the way to tell the difference. just take these measurements. doesn't matter if they are open or posi. ------------------ 1969 C-10 292 I-6 4 spd in the middle of a restoration. going to get a 327 and 3.07 gears but keeping all of the original parts so I can put it back to original later on down the road. 55 chevy 4 door 150 47 Willys CJ-2A [This message has been edited by texnician01 (edited May 15, 2002).] __________________ 69 C-10, 340HP 327 55 chevy 4 door 150 47 Willys CJ-2A 05 Harley Night Train 06 1200 Sportster (Wife's bike) 70 Honda CL350 OIF2 & OIF7 Veteran Nathan & Tiffany

05-15-2002, 06:59 AM	#4
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	Tex, Excellent post! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

05-15-2002, 12:43 PM	#5
71GMC 4x4 Registered User Join Date: Mar 2002 Location: Redway,Ca. U.S.A Posts: 37	Cool, Thanks Guys!! __________________ [IMG]http://mustangmods.com/publish/topless99/truck2.jpg[IMG]

05-15-2002, 01:05 PM	#6
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	tex, looks like the 3.07 is open and the 3.73 is posi..?? I have an open 3.73 carrier that has a much smaller flange depth, like less than 1/2 inch, but has the tapered casting that you point out in your pic... I assume the difference between mine and yours is based on whether it's posi or open...?? ------------------ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA http://www.ixpres.com/vlusardi/chevtrk.htm __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

05-15-2002, 06:23 PM	#7
texnician01 Senior Member Join Date: Mar 2002 Location: 12 Miles South of Des Moines, Iowa Posts: 359	yes one of these is an open carrier while the other is a posi. The place that you measure to is the face where the ring gear touches. these all have to be the same within the same series, open or posi. I also noticed that some of the castings are a little different. I was unsure of what you were asking but I hope this helps. thanks Nathan __________________ 69 C-10, 340HP 327 55 chevy 4 door 150 47 Willys CJ-2A 05 Harley Night Train 06 1200 Sportster (Wife's bike) 70 Honda CL350 OIF2 & OIF7 Veteran Nathan & Tiffany

05-15-2002, 08:13 PM	#8
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	tex, where you show a measurement of 1 7/8 inches on the 3.73 carrier, my 3.73 open carrier measures less than 1/2 inch.... but my casting tapers toward the roller bearing just like the one you have pictured... I'm thinking that some of your flange depth could actually be part of the ring gear casting, like 71GMC is talking about, thick vs. regular gears....?? __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

05-16-2002, 11:29 AM	#9
texnician01 Senior Member Join Date: Mar 2002 Location: 12 Miles South of Des Moines, Iowa Posts: 359	bigvinnie you are measuring from the table top to the bottom of the ring gear correct? dont' measure the flange width that pic is kind of missleading. just measure from tabletop to ring gear mounting surface. the thick and regular gears he's talking about is to adapt gears between carriers. you can only do this on a series 3 carrier though. if you want to put 3.73 gears on a series 3 carrier you have to have a thicker gear because of the flange offset. you CANNOT put 3.07 gears on a series 4 carrier though. they would have to be paper thin in order to fit. I'm still not catching on to the 1/2 inch thing though. Nathan __________________ 69 C-10, 340HP 327 55 chevy 4 door 150 47 Willys CJ-2A 05 Harley Night Train 06 1200 Sportster (Wife's bike) 70 Honda CL350 OIF2 & OIF7 Veteran Nathan & Tiffany

05-16-2002, 11:44 AM	#10
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	tex, you are correct, the pic is very misleading.... the red lines suggest that the 1 7/8 measurement is for flange thickness only, not from table top to bottom of ring gear... that clears things up, thanks. __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

05-16-2002, 11:58 AM	#11
texnician01 Senior Member Join Date: Mar 2002 Location: 12 Miles South of Des Moines, Iowa Posts: 359	ok, I get it now. sorry I was a little slow on the uptake myself. the pic was done a while back for another guy and I drew the flange lines in cause I didn't want him to think that the step on the 3.73 carrier was a spacer plate. this one should help a little. sorry, my lightbulb just took awhile to warm up and turn on...LOL!! Nathan __________________ 69 C-10, 340HP 327 55 chevy 4 door 150 47 Willys CJ-2A 05 Harley Night Train 06 1200 Sportster (Wife's bike) 70 Honda CL350 OIF2 & OIF7 Veteran Nathan & Tiffany

05-16-2002, 12:07 PM	#12
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	yeah no problem, if I'd looked at the ruler instead of your lines I would have seen what you were talking about... learned something about carriers so it's all good... __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project



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