Gear Change

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Dr Jay
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Posts: 178
Joined: Sat Oct 05, 2013 6:12 pm
Location: North Alabama

Gear Change

Post #1 by Dr Jay » Sun Jul 23, 2017 8:57 pm

As I develop my ride (78 F100 short bed) I thought I would present what I have experienced concerning gear ratios as they affect my set up.
Tires are P275 R15 Cooper Cobras in the rear
Weight is 3900lb
Transmission TOD with a .79 overdrive in 4th
Engine is a 300 with a 240 head, MSD triggered by DS2,
252 comp can, Clifford intake, 390 Holley, fuel injected type exhaust manifolds, walker Y pipe, 2 1/2 "
diameter out the back.
I went from open differential 2.74 in a Dana 44.
This setup broke transmissions and clutches over
time. My guess is all that torque banging on an
immovable ratio.
Went to a 9" open with a 3.25. Waaaay better with great highway speed. Used this for 3 yrs.
So then I dropped in a TrueTrac and took the opportunity to go to a Summit 3.70 ring and pinion
Truck is lighter feeling. Quicker (important to me!)
Motor revs free and starts from a stop elegantly. This is the best all around ratio. Motor is up in RPMs at 70mph but comfortable for long rides.
Is this the consensus for light trucks with no real truck working and towing? (Mine is lowered and a daily driver)
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

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Re: Gear Change

Post #2 by bubba22349 » Sat Oct 07, 2017 10:31 pm

Sounds like a good combo what RPM's are you turning at 70 MPH? :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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