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Old 09-18-2012, 09:07 AM   #1
superlifted
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Worth It.

I just rebuilt my th 350 and am wondering if I should have scrapped it and went with a th400. Is the fuel savings worth it? I have 3/4 ton axles with 4:11 gears and 35 inch tires and a 355 V8.
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Old 09-18-2012, 09:41 AM   #2
rsavage
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Re: Worth It.

A TH 350 and a TH400 both have 1:1 final drive ratio so there would be no fuel savings as the 400 is not an OD transmission. A 700R is an OD.
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Old 09-18-2012, 10:11 AM   #3
jjzepplin
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Re: Worth It.

If you have a 4wd then the th400 may require a different t-case or modification to your existing one. Also take a few more ponies to get going. I have a 406 700r4 and 205 and am very happy with results. You can always sell the th350 and get a 700r4. Or you could go for bigger and get a 4l80e with a th400 t-case and have bulletproof overdrive. Either case is pricey though..
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Old 09-20-2012, 02:06 AM   #4
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Re: Worth It.

All else being equal, you should get better mileage with the th350 as there is more parasitic loss with a th400 than a th350.
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Old 09-20-2012, 04:11 PM   #5
Firebirdjones
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Re: Worth It.

Quote:
Originally Posted by RED72blazer View Post
All else being equal, you should get better mileage with the th350 as there is more parasitic loss with a th400 than a th350.
YEP,,,,and the 350 has a slightly better 1-2 gear ratio to get moving (2.52/1.52 vs 2.48/1.48)

Hard to beat the durability of the 400 though if that's what you are looking for.
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