C3 differential strength
Thread Starter
AMP Racing
Joined: Aug 2006
Posts: 10,754
Likes: 589
From: Washington TWP NJ
2023 C5 of the Year Finalist - Modified
2017 C5 of Year Finalist
St. Jude Donor '09-'10-'11-'12
C3 differential strength
So, I'm planning my build for the 2012 drag race season and it's looking like a C3 is in my future.
My plan is to install an LS1 with about 520 shaft hp. (it's already built)
My plan includes a built 4L60 trans with a cooler and a 4000 rpm stall. I know most would say use a glide, but I'm going to drive it to the track. Don't bother trying to change my mind...
I'm not set on a particular rear gear ratio yet. Likley 3.73 or so.
What are the stock gear ratio options for the various year C3s? Are the stock rears strong enough for regular track duty? on an 11 second car?
Did GM install different diffs from year to year? In other words, is there a particular year range I should look for when finding a roller?
If I find a roller that's too good to pass up, but doesn't have a strong enough rear, what are my options for replacement?
Thank you for your help.
My plan is to install an LS1 with about 520 shaft hp. (it's already built)
My plan includes a built 4L60 trans with a cooler and a 4000 rpm stall. I know most would say use a glide, but I'm going to drive it to the track. Don't bother trying to change my mind...
I'm not set on a particular rear gear ratio yet. Likley 3.73 or so.
What are the stock gear ratio options for the various year C3s? Are the stock rears strong enough for regular track duty? on an 11 second car?
Did GM install different diffs from year to year? In other words, is there a particular year range I should look for when finding a roller?
If I find a roller that's too good to pass up, but doesn't have a strong enough rear, what are my options for replacement?
Thank you for your help.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Do a search on this and this has come up many times. The diffs from 65-79 are all pretty much the same. Terrible for drag race duty. You will explode it running slicks with that kind of power. A properly built one may last behind an automatic car for a while. Most here are going to a 12 bolt stuffed inside the Vette housing. It is not cheap but it pretty much bullit proof. You then have to install bigger ujoints and half shafts along with inner and outer axle stubs. It get expensive in a hurry. Most dedicated drag racers go to a straight axle. Cheaper and more durable.
Pro
Joined: Apr 2005
Posts: 591
Likes: 7
From: Batavia IL
3.73 gears, 28 inch slick and a th400 is a good strong combo that drives fine on the streets. I would recommend that over the 4l60 trans.
I currently have a 3.73 ratio spooled rear end converted to 12 bolt for sale right now. check the classified section in the c3 vette forum.
I currently have a 3.73 ratio spooled rear end converted to 12 bolt for sale right now. check the classified section in the c3 vette forum.
Instructor
Joined: Jan 2006
Posts: 228
Likes: 1
From: Warwick New York
79 is the last year for cast iron diff. 80 they went to aluminum housing and some say there weak. I don't speak from experiance just hear say. Since your not going stock why don't you go 9 in. with a four link unless that is not allowed in your class. Gear ratio depends on your motor power range, most drag racers go with high number gears 3.90s, 4.10s, 4.56s, and higher.
Thread Starter
AMP Racing
Joined: Aug 2006
Posts: 10,754
Likes: 589
From: Washington TWP NJ
2023 C5 of the Year Finalist - Modified
2017 C5 of Year Finalist
St. Jude Donor '09-'10-'11-'12
The motor makes peak hp at about 6200 rpm and it stays there until about 7100. I'm planning this car to run 11.50 index. I've got way too much power, so I'll scale it back a bit. The beauty of a computer controlled engine.
I'm not sure the tire size I'll be using, but, it will be a drag radial, as opposed to a slick.
I can't use a 4 link set-up. I really like the 9" conversion. That's something I'm going to really contemplate. I need to do more research. as in just how bolt-in friendly it really is. I'm sure it'll last forever - even if I do run it all out a few times...
I like the overdrive component of the 4L60, otherwise, I'd use a glide.
I stil have a lot of research to do. I thank you guys for your help. I just am sick of racing my C5 and want to put it back to a comfortable driver, so I need a race car to feed my addiction.
I'm not sure the tire size I'll be using, but, it will be a drag radial, as opposed to a slick.
I can't use a 4 link set-up. I really like the 9" conversion. That's something I'm going to really contemplate. I need to do more research. as in just how bolt-in friendly it really is. I'm sure it'll last forever - even if I do run it all out a few times...
I like the overdrive component of the 4L60, otherwise, I'd use a glide.
I stil have a lot of research to do. I thank you guys for your help. I just am sick of racing my C5 and want to put it back to a comfortable driver, so I need a race car to feed my addiction.
Pro
Joined: Apr 2005
Posts: 591
Likes: 7
From: Batavia IL
again, why are you fixated on a glide or 4l60e? a th400 is a good compromise of both and in many ways better for your street car/ weekend racer. your going from a 2 speed to a 4 speed without even looking at the 3 speeds. 4l60s cost alot of money to live behind 600 hp and they dont last long even with the full upgrades. its not a very good transmission for a high hp application. 4l80e is better suited but heavy and large for high hp overdrives. like I said my th400 / 3.73 gear combo was a very comfortable street combo and still kicked *** at the track.
