7.5 Gear Swap Question

[Killerdave8813]

Hey there rear end (drive axle) experts,
I need some opinions and or confirmation of the following:
Bratly51 has a set of 4:30 to 1 gears for a 7.5 from a late model Camaro for sale and I have a 7.5 with a limited slip & 2:73 gears,he thinks all I need to make the gear change work is a spacer,I think I need to change gear carriers as I believe what I have would be a series 2 and what I need would be a series 3, as I don't want to tie up a bunch of money in a 7.5 for a daily driver the only other choice would be a
4:10 gear from Jegs that is made for a series 2 carrier,unless someone out there has a 7.5 series 3 that they'll let go reasonable,anyway that's what I'm after for now,
Thanks,KillerDave

 

[grizwald]

maybe useless info for me right now, but i'd like to know the answer to this. i thought that a carrier origionally equipped with a 2.73 or numerically higher gear ratio was a 3 series carrier.

 

[DOUG213XRJ]

The 7.5 inch 2 series carrier is for 3.08 and down, And a 3 series is for 3.23 and up.
So a thicker spacer is needed to install 3.23s and up gears on a 2 series carrier.

 

[grizwald]

The 7.5 inch 2 series carrier is for 3.08 and down, And a 3 series is for 3.23 and up.
So a thicker spacer is needed to install 3.23s and up gears on a 2 series carrier.

is this true with 8.5" rearends as well?

 

[Killerdave8813]

So that means the ring gear mounting flange on the carrier is further away from the center line of the pinion gear on the series 2 than the series 3 ? That would mean the 4:30 gears Bratly has will fit my 7.5 with the proper ring gear spacer? I guess that would allow for a larger diameter (more teeth) pinion gear for a higher numerical ratio? Let me know as it sounds like I'm going to be buying some 4:30s,Thanks

 

[DOUG213XRJ]

Yes ,thats right. When a 3 series gear is needed on a 2 seriers carrier the gear is thicker or a spacer is needed.
Heres a 2 series with a 3 series gear. See the ring gear is thicker.

Heres a 3 series carrier and a 3 series gear , thiner gear.

 

[Killerdave8813]

Hey Doug,
Thanks for the help but I'm still a bit confused,the first pic has a thick flange that the ring is bolted to,even though it has a thick gear the flange will be closer to the pinion center line,series 3,the second pic clearly shows the ring gear mounting flange to be quite a bit thinner than the 1st pic making it further away from center of the pinion making it a series 2 where your pic says it's a series 3 as well,I think maybe you meant it was a series 2 carrier?

 

[DOUG213XRJ]

The first photo is a 8.5'' 2 series posi with 3.73 gears. The second photo is a 12 bolt posi 3 series with 3.08 gears. I wanted you to see a thicker gear (3.73 gears) on a 2 series carrier.

 

[Killerdave8813]

That's cool,the bottom line though is Brattlys 4:30's will work in my series 2 rear end with a spacer?

 

[lurchsmalibu]

I have this from an 7.625 open 3.73 ratio. It will need new bearings and such as seen in pic. It is clean and ready to ship, make offer and I can check on shipping cost if needed.

I took the Auburn LS out of an 7.5 rear with 4.56 ratio and threw the 3.73 ring gear on it and put it directly into the 7.625 rear and works like a charm, so I won't need the open carrier any more.