Positive Traction

Newkid8 · 03-09-2008, 08:26 PM

What sort of positract would a 1970 Cutlass "S" with the 455 engine need? Especially if it is going to be used for drag racing.

J-(Chicago) · 03-09-2008, 08:38 PM

Drag racers use lower gearing like 3.73, 3.91 or 4.11
The motor runs at higher RPMs with lower gears.
The higher the rpm, the more Hp it's pushing, blah blah etc etc.

Bottom line.... they only have 1/4 of a mile to squeeze as much juice as they can out of the lemon.
It's easier to get there if you hit the ground running instead of walking.

Chaney3000 · 03-10-2008, 08:07 AM

Eaton posi with some Richmond gears (3.73 or 3.91 or 4.11). If you plan on just using it as a drag car go with the 4.11

3.73 will give you a little more streetability out of the vehicle.

buzzbomb · 03-11-2008, 10:32 AM

Go for a 3:42 gear and if you need more put smaller diameter tires or slick on it like a 25" and that will give you an effective ratio of about 3:70 or so and when you drive it on the street use the standard 26.5" tire for the true 3:42 ratio

Newkid8 · 03-11-2008, 04:49 PM

Is there a certain brand I should get? Are there brands I should not get?

J-(Chicago) · 03-11-2008, 07:52 PM

Go here and contact Jim.
Most helpful rear end builder on the Olds/Buick forums.
http://www.jdrace.com/about.htm

03-09-2008, 08:26 PM	#1 (permalink)
Newkid8 Member Join Date: Jan 2008 Location: Texas! Posts: 34	Positive Traction What sort of positract would a 1970 Cutlass "S" with the 455 engine need? Especially if it is going to be used for drag racing.

03-09-2008, 08:38 PM	#2 (permalink)
J-(Chicago) Seasoned beater pilot. Join Date: Jan 2007 Location: Chicago Posts: 1,588	Drag racers use lower gearing like 3.73, 3.91 or 4.11 The motor runs at higher RPMs with lower gears. The higher the rpm, the more Hp it's pushing, blah blah etc etc. Bottom line.... they only have 1/4 of a mile to squeeze as much juice as they can out of the lemon. It's easier to get there if you hit the ground running instead of walking. __________________ I'd rather have a numbers matching poker hand.

03-11-2008, 07:52 PM	#6 (permalink)
J-(Chicago) Seasoned beater pilot. Join Date: Jan 2007 Location: Chicago Posts: 1,588	Go here and contact Jim. Most helpful rear end builder on the Olds/Buick forums. http://www.jdrace.com/about.htm __________________ I'd rather have a numbers matching poker hand.

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03-10-2008, 08:07 AM	#3 (permalink)
Chaney3000 Member Join Date: Feb 2008 Posts: 29	Eaton posi with some Richmond gears (3.73 or 3.91 or 4.11). If you plan on just using it as a drag car go with the 4.11 3.73 will give you a little more streetability out of the vehicle.

03-11-2008, 10:32 AM	#4 (permalink)
buzzbomb Member Join Date: Oct 2007 Posts: 28	Go for a 3:42 gear and if you need more put smaller diameter tires or slick on it like a 25" and that will give you an effective ratio of about 3:70 or so and when you drive it on the street use the standard 26.5" tire for the true 3:42 ratio

03-11-2008, 04:49 PM	#5 (permalink)
Newkid8 Member Join Date: Jan 2008 Location: Texas! Posts: 34	Is there a certain brand I should get? Are there brands I should not get?