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

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)

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.
http://pic5.picturetrail.com/VOL83/5...66/9704538.jpg
http://pic5.picturetrail.com/VOL83/5...66/9704531.jpg
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).]

Tex,
Excellent post!

Cool, Thanks Guys!!

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

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

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....??

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

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.

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.
http://pic5.picturetrail.com/VOL83/5...66/9736344.jpg
sorry, my lightbulb just took awhile to warm up and turn on...LOL!!

Nathan

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...