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udidca302

What diff ratio to use

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I am doing a complete rebuild on my drive line and when it comes to diff ratio I have no idea what to go with. At the moment it is a 3.25:1 ratio ford 9 inch lsd. I would like the car to haul and not lag when it is given the boot. Any ideas of what ratios to look at. Engine is a 351 Cleveland with about 350hp, c4 gear box shift kit and 2500 stall. Tyre size at the moment is 255/50r15 looking at going 245/40r18

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What do you want to do with the car? Occasional street/strip, cruiser or a long haul driver personally I'd stick with the 3.25's as it would get you above you stall speed at 100ks and the are a good compromise between highway gears and low down take off

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Yeah Im with Thom, you will want to use the torque of the engine which happens better with a slightly taller gear. Shorter gears are for higher horsepower cars that rev higher.

If you did very little highway driving you could change to a 3.45 ratio as that will help with moving the car better.

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My mistake people I did the ratio test today looks like it's a 2.85:1 ratio. Kind of a bit pissed about that because it was meant to be a 3.25:1 anyway would it be better to change the ratio of t to a 3.251 or would the 2.85:1 suit

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Probably better to take the cover off the diff and see what is stamped on the gears so you know for sure.

9-inch is a drop-out centre, no cover to unbolt at the back. That means axles, brakes, tail shaft all need to come out.

 

I thought the closest ratio was 2.75, am I right? I was under the assumption that all factory ratios were non-hunting type vs Borg Warner type that were hunting

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9-inch is a drop-out centre, no cover to unbolt at the back. That means axles, brakes, tail shaft all need to come out.

 

I thought the closest ratio was 2.75, am I right? I was under the assumption that all factory ratios were non-hunting type vs Borg Warner type that were hunting

Thanks Gerg! I was thinking Borg Warner diff, my mistake.

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