Best Rear end Ratios
Thread Starter
Drifting
Joined: Sep 2004
Posts: 1,638
Likes: 3
Best Rear end Ratios
OK guys,
Right now my brothers C-3 is making good horesepower and speed - built for running at Bonneville - 460 HP 2.73 rear end. Tremek 5 speed.
But now he wants to change the rear end and make it better for closed course road racing - places like Spring Mountain, Reno Fernley, the new track going in outside of Salt Lake etc.
What he really needs is to get out of the corners with a kick (mostly he's pissed because he has my C-4 top end by 40 MPH - but I kill him on the road course ( I go much slower aroung the corners than my C-4 can handle - because it puts him in to big of a hole for his HP to pull him out.
Any way any suggestions on rear ends - we would like to be able to just change out the 2.73 with the new one - so we can go back and forth.
Carl Johansson
Right now my brothers C-3 is making good horesepower and speed - built for running at Bonneville - 460 HP 2.73 rear end. Tremek 5 speed.
But now he wants to change the rear end and make it better for closed course road racing - places like Spring Mountain, Reno Fernley, the new track going in outside of Salt Lake etc.
What he really needs is to get out of the corners with a kick (mostly he's pissed because he has my C-4 top end by 40 MPH - but I kill him on the road course ( I go much slower aroung the corners than my C-4 can handle - because it puts him in to big of a hole for his HP to pull him out.
Any way any suggestions on rear ends - we would like to be able to just change out the 2.73 with the new one - so we can go back and forth.
Carl Johansson
Race Director
Joined: Aug 2000
Posts: 18,479
Likes: 3
From: Quincy IL
choices could be 3:08, 3:36, 3:55, 3:73, 3:ninety something, have to check catalogs for that one. the higher the number, the more hole shot you get, but top end speed goes down. somewhere on the internet is a formula that will give you approximates on the top end with whatever rear gear you are using. I used it about 5 yrs ago. what year of vette, pre-80 with the cast iron diff, or 80 on up??? I would think the 3:36 gear would be good, 3:08 isn't much different from what you got. I'm running 3:55 in my 79 with a 700r4, and that might be too low or high numerically. I can't compare your set up to mine, kind of like apples and oranges. also, these aren't quick change rear ends, so you might have to buy complete whole diff set ups, so you can take them in & out, especially on the pre-80. good luck
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I am running a Tremec 5 speed with 3.70 gears. With this trans either the 3.55 or 3.70 gears is great. 1st gear is a little short but it sure gets the car moving in a hurry. I have seen some racers use a 4.10 with this tranny also. With a .68 OD you can run a pretty stiff rear gear and still be driveable.
Tech Contributor
Joined: Aug 1999
Posts: 15,187
Likes: 4,007
From: Connecticut, USA
If you buy gears be sure on the type you get as they are not all equal. I only use Tom's gears and 373's have been back ordered for a while now. I can get 273,308,336,355 but the 373 have been popular. Other 373 are out there but they are also harder to set up and noiser.
Let me know if I can help.
Gary
Let me know if I can help.
Gary
Team Owner
Joined: Jun 2004
Posts: 20,216
Likes: 4
From: Smile, it's just the internet.
The TKO isn't exactly the best gear spacing for road racing, but I'd have to throw in a vote for the "high threes" (3.55 to 3.73).
I've got 3.36s in my TKO and it's great for cruising, but 1st and 5th would be useless on a track. Pushing it up to 4.11 would make 5th useful, but may compromise 2nd to point where it would only be needed in the very slowest hair-pins.
With a Tremec TKO-500, 3.55 gears, and 27"(stock dia.) tires, you get this:
2000 rpm.....4000 rpm.....6000 rpm
14mph.........28mph........42mph
23mph.........46mph........69mph
34mph.........68mph........101mph
45mph.........91mph........136mph
67mph.........133mph.......200mph
With a 4.11 gear, you get:
2000 rpm....4000 rpm......6000 rpm
12mph........24mph.........36mph
20mph........39mph.........59mph
29mph........58mph.........88mph
39mph........78mph.........117mph
58mph........115mph........173mph
Calculator Page
I've got 3.36s in my TKO and it's great for cruising, but 1st and 5th would be useless on a track. Pushing it up to 4.11 would make 5th useful, but may compromise 2nd to point where it would only be needed in the very slowest hair-pins.
With a Tremec TKO-500, 3.55 gears, and 27"(stock dia.) tires, you get this:
2000 rpm.....4000 rpm.....6000 rpm
14mph.........28mph........42mph
23mph.........46mph........69mph
34mph.........68mph........101mph
45mph.........91mph........136mph
67mph.........133mph.......200mph
With a 4.11 gear, you get:
2000 rpm....4000 rpm......6000 rpm
12mph........24mph.........36mph
20mph........39mph.........59mph
29mph........58mph.........88mph
39mph........78mph.........117mph
58mph........115mph........173mph
Calculator Page
Thread Starter
Drifting
Joined: Sep 2004
Posts: 1,638
Likes: 3
Thanks for the input guys - looks like I am looking for 3:55 - 3:73 as the range of choices. Just by chance can I just buy the gear and install it into the dana 36? or is it more involved than that?
Maybe I need to have gary do it?
Carl Johansson
Maybe I need to have gary do it?
Carl Johansson
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Carl your brothers motor does lots of rpm. That why I went with 4.11 when I first went open road racing. With a .70 OD tranny and 4.11 rear gears and 28 inch tall tires 7500 was like 217 mph.
Register on www.smokemup.com and go to auto math. That way you can make informed decisions.
What was the repair on your motor?
Register on www.smokemup.com and go to auto math. That way you can make informed decisions.
What was the repair on your motor?
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Drifting
Joined: Oct 2003
Posts: 1,486
Likes: 10
From: Big Pine Key FL
I went with a ROD 6 speed and a 3.36 rear. It gives me a 11:1 overall in 1st and a 2.66:1 final drive in 6th (0.80 OD) and 4 more gears in between. I get a short first gear to make street driving easier, 2,3, and 4 are the same as had with the 4 speed, 5th is 3.36 instead of 3.90.
I theroy anyway I should have enough power to pull redline in 5th with 25 inch tires and maybe 6th but not likely in 6th with 28 inch tires. I'd expect many other problems before that speed...
I'm limiting RPMs to 6000 even after I get the beehive springs and roller rockers on.
I theroy anyway I should have enough power to pull redline in 5th with 25 inch tires and maybe 6th but not likely in 6th with 28 inch tires. I'd expect many other problems before that speed...
I'm limiting RPMs to 6000 even after I get the beehive springs and roller rockers on.
Thread Starter
Drifting
Joined: Sep 2004
Posts: 1,638
Likes: 3
Originally Posted by gkull
Carl your brothers motor does lots of rpm. That why I went with 4.11 when I first went open road racing. With a .70 OD tranny and 4.11 rear gears and 28 inch tall tires 7500 was like 217 mph.
Register on www.smokemup.com and go to auto math. That way you can make informed decisions.
What was the repair on your motor?
Register on www.smokemup.com and go to auto math. That way you can make informed decisions.
What was the repair on your motor?
Glad to hear from you. I was thinking of the same thing last night - we are not going to be going much more than 150 or 160 on a track - so it probably makes sense to go 4:11 - that thing out to scream out of the corners then - eh!
My engine just needed to have the heads milled down a little - back together and running great - I'm mad because I'll miss the Halloween Autocross - gotta finish painting the house before it starts to rain - and I need to be done so I can justify going hunting too!
Carl