4.10 Or 4.30 Gears In 8" Rear?

jimijuggernaut · 02-24-2003, 09:49 PM

I GOT A 67 COUPE THAT I'M GOING TO BE BUILDING VERY SOON!

I WOULD LIKE TO KNOW WHICH GEARS WOULD BE THE MOST BENEFICIAL TO ME.

I PLAN ON USING A C4 TRANS WITH A SHIFT KIT AND 2800-3000 STAHL CONVERTER.

A 289 BORED 0.30 OVER AND A LUNATI CAM WITH .512" LIFT.

WHICH GEAR RATIO WOULD HELP ME THE MOST 4.10 OR 4.30?

THANKS FOR THE HELP!

cheezsnake · 02-24-2003, 10:55 PM

It really depends on what you're going to use the car for. If you want it to be a driver for the street, I wouldn't put anything over 3.55 gears. 4.10 or 4.30 gears will cause the engine to really wind at highway speeds. You'll hate it if you try to take the car on a long trip. But, if you're going to take the car to the track a lot, the lower gears would help.

Technick · 02-28-2003, 01:01 AM

3.55:1 rear gears with a 25" tall rear tire will result in a 3,000 rpm cruise @ 60 mph with a C-4 or 4 speed for that matter! 4.10:1 will result in a 3,800 rpm @60 mph!!! Unless you can spin that baby to 8,000 rpm forget about doing 120 mph down the highway!

hobgoblin351 · 02-28-2003, 01:17 PM

If you're going to go all out with the motor and the trans, ditch the 8-inch rear go with the 9-inch. You'll spend all that money putting the rear together just to shatter it when you get a hard launch.

cheezsnake · 02-28-2003, 04:33 PM

I've never heard of anyone tearing up an 8" rearend. I had one for years with a 351CJ in front of it and didn't have any problems. But, I think that they usually are more expensive than 9" rearends. Changing out a center section in an 8" rearend can cost $700-$800. It might be cheaper to replace the whole axle with a 9".

02-24-2003, 09:49 PM	#1
jimijuggernaut Registered Member Join Date: May 2002 Location: FT. MYERS, FLA Posts: 5	4.10 Or 4.30 Gears In 8" Rear? I GOT A 67 COUPE THAT I'M GOING TO BE BUILDING VERY SOON! I WOULD LIKE TO KNOW WHICH GEARS WOULD BE THE MOST BENEFICIAL TO ME. I PLAN ON USING A C4 TRANS WITH A SHIFT KIT AND 2800-3000 STAHL CONVERTER. A 289 BORED 0.30 OVER AND A LUNATI CAM WITH .512" LIFT. WHICH GEAR RATIO WOULD HELP ME THE MOST 4.10 OR 4.30? THANKS FOR THE HELP!

02-28-2003, 01:01 AM	#3
Technick Registered Member Join Date: Feb 2003 Location: Seattle, Wa. Posts: 175	3.55:1 rear gears with a 25" tall rear tire will result in a 3,000 rpm cruise @ 60 mph with a C-4 or 4 speed for that matter! 4.10:1 will result in a 3,800 rpm @60 mph!!! Unless you can spin that baby to 8,000 rpm forget about doing 120 mph down the highway! __________________ No matter how much you spend, or how much you prepare, there is ALWAYS someone else faster or quicker than YOU!!!!!!!!!!

02-28-2003, 01:17 PM	#4
hobgoblin351 Registered Member Join Date: Sep 2002 Location: NYC Posts: 245	If you're going to go all out with the motor and the trans, ditch the 8-inch rear go with the 9-inch. You'll spend all that money putting the rear together just to shatter it when you get a hard launch. __________________ 1970 Stang Conv: en:Boss351 (balanced/blueprinted) mech cam(240*@.050/.540 lift) Scrw in studs/comp cams rllr rkr Mldn valves 2.19in 1.71ex ported polished cc'd hrdnd ex Keith Black FT pistons(10.25/1) Weiand Excellorator manifold Holley700 DP mech 2nds MSD 6 box and Dis Headers/2 1/2 inch duels tr: modified FMX re:9-inch/3.89 limited slip

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02-24-2003, 10:55 PM	#2
cheezsnake Registered Member Join Date: Feb 2003 Location: Indiana Posts: 6	It really depends on what you're going to use the car for. If you want it to be a driver for the street, I wouldn't put anything over 3.55 gears. 4.10 or 4.30 gears will cause the engine to really wind at highway speeds. You'll hate it if you try to take the car on a long trip. But, if you're going to take the car to the track a lot, the lower gears would help.

02-28-2003, 04:33 PM	#5
cheezsnake Registered Member Join Date: Feb 2003 Location: Indiana Posts: 6	I've never heard of anyone tearing up an 8" rearend. I had one for years with a 351CJ in front of it and didn't have any problems. But, I think that they usually are more expensive than 9" rearends. Changing out a center section in an 8" rearend can cost $700-$800. It might be cheaper to replace the whole axle with a 9".