edusmc1

I have 77 c3 and want to know what gear was in car so jacked up marked tire and pion yoke and its 3 and 1/4 turns and from what I read it’s 3.08 ger.
My question now is will 3.55 gear fit in that rear housing?
Thanks for any help I can get.
Robert edwards USMC Retired

HeadsU.P.

Absolutely. I believe all the way up to a 4.33 maybe. 4:11s are common as well.

edusmc1

Thanks a lot I’m trying to improve my 1/8 and 1/4 times. Tryed it at track and 2004 Z06 got me twice by 1 car and want to change the out come next time. Lol

bence13_33

Numerically higher gears shouldn't have a problem fitting in the housing....it is the carrier that is different (series 3 and series 4 carriers). I can't remember exactly but I think series 3 carriers cover up to 3.70 gears, series 4 carriers cover 3.90s and up. Gears are interesting in that they are a mechanical advantage and need to be matched to your setup. A for instance would be I had 3.36s with my 468 with a bunch of 1/4 miles passes and then switched to 4.11s. The gear swap made no difference in my times. The only thing that changed was with the 3.36s I was going through the traps in 3rd gear at around 6800RPM or so and with the 4.11s I was going through the traps at about the same RPM only in 4th gear. The 4.11s did make around town driving much easier (I unknowingly started from a dead stop from a red light on more than one occasion by accident in 3rd gear without much of a problem). Just something to consider before you go changing rear ends.

GTR1999

You can get Tom's gears from 308-336-355-373-411, maybe he still has 433 and 456's all made to bolt onto your 3 series posi case. I suggest you do some more work to the diff beyond the gears if you are going to push it hard. A 77 diff isn't too bad, it has lousy axles and clutches but those can be replaced with better parts. Toms are the last gears still made in the USA for the c2 & c3's and who knows how long they will be around.