Gear ratio ?????
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5th Wheeling
Joined: Nov 2010
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Gear ratio ?????
I have a 1967 F100 with a 300 I-6. I put a 4 speed overdrive tranny behind it out of a 1986 F150. The tag on rear end states it has 3.20 gears. Finally got it running and it's a real dog going up hill and cannot put into 4/od unless real flat. Should I go to 3.73 gears or ??? Not really sure how the gear ratio thing works. Thanks for all and any info!!
Logistics Pro
Joined: Nov 2003
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From: PA
i'm not positive on this but didn't the 67 come with a 352?
Elder User
Joined: May 2010
Posts: 957
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From: Valley Center, CA
3.73...
A 3.73 is a great all round rear end ratio...should have no problem hauling
or on the highway. A lot of camper specials I've seen have them...mine
also hauls with plenty of torque...it's a 66 F250 Dana 60 I swapped in.
or on the highway. A lot of camper specials I've seen have them...mine
also hauls with plenty of torque...it's a 66 F250 Dana 60 I swapped in.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
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From: Creedmoor, North Carolina
OK, so this ol boy has been around the block a time or two. Most 6 banger trucks form early 60s to early 70s should have high 3.** or low 4.** 28 tooth ratios.
The 3.75 or 3.73 will be much better. IMHO
John
The 3.75 or 3.73 will be much better. IMHO
John
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5th Wheeling
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I experienced the same after my 302/AOD swap...
That 4 speed has a final gear ratio of .67 to 1. The other variable is your tire size...
I agree on the 3.70 for smaller tires. if you run larger tires you may consider 3.89 or higher. I put 4.11 in my truck but it's got 30" tires and that same overdrive ratio - and it seems about right to me.
Google "engine rpm calculator". Enter the required data and enter different gear ratio's your thinking about to see where you'd be cruising. I'd be looking to cruise at 70 in OD at about 2000-2200 RPM. Good luck!
That 4 speed has a final gear ratio of .67 to 1. The other variable is your tire size...
I agree on the 3.70 for smaller tires. if you run larger tires you may consider 3.89 or higher. I put 4.11 in my truck but it's got 30" tires and that same overdrive ratio - and it seems about right to me.
Google "engine rpm calculator". Enter the required data and enter different gear ratio's your thinking about to see where you'd be cruising. I'd be looking to cruise at 70 in OD at about 2000-2200 RPM. Good luck!
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