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02-04-2016, 04:45 PM | #1 |
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Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: Need Help choosing a transmission
The 700R4 and lots of torque do not mix. It beats them up.
Stick with the TH400. A big block can turn 6000rpm all day
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02-04-2016, 05:05 PM | #2 |
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Join Date: Dec 2015
Location: San Antonio, Texas
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Re: Need Help choosing a transmission
That's great news. That's really the only thing I'm worried about. I plan on making trips to Austin from San Antonio often (140 miles round trip). I just want to make sure that's not going to kill my engine cruising at 65 - 90 MPH. I appreciate both of your responses. Thank you.
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1970 C10 Stepside SWB - 468 BBC |
02-04-2016, 05:10 PM | #3 |
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Location: Austin, TX, USA
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Re: Need Help choosing a transmission
A TH200 4R can be built to take the power and has a better gear split than the TH700R4. Along with 3.73 gear will be a beast out of the hole and on the highway.
The 4L80E can be built to take big power but factor in the $$$ of the electronic controller and it gets pricey. Hot Rod drag week cars mostly run TH400 with Gear Vendors overdrive on the back. No electronics to deal with. Running a non-lockup converter and a TH200 4R is my plan behind my 427 I'm building for my short step. I'm guesstimating 450hp and 550tq. Most likely I buy from Bowtie Overdrives but other vendors are out there. I even found one that had lifetime refreshes for $550. Something to consider.
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02-04-2016, 05:42 PM | #4 |
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Location: sutton WV
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Re: Need Help choosing a transmission
I know for a fact a "stockish" 700r4 will not hold up behind a 550-600 hp big block. Mine lasted 515 miles!!! If you want to spend about $2k some are supposed to hold up?
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02-05-2016, 12:35 PM | #5 |
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Join Date: Mar 2015
Location: Utah
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Re: Need Help choosing a transmission
That's true with a stock 700r4, but a build 700r4 will hold up to it all day long, as long as you don't race it, haul a bunch of weight, or beat on it really hard. But if you are not concerned about gas mileage, i would just stick with the th400, they are quite a bit stronger in the stock form.
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02-05-2016, 03:25 PM | #6 | |
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Join Date: Mar 2003
Location: Colfax-California
Posts: 8,402
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Re: Need Help choosing a transmission
Quote:
You have to use the HP or it will go to waste, the only thing that will live behind that engine is either a built T400 or a built 4L80 with coolers |
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02-05-2016, 05:01 PM | #7 | |
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Location: San Antonio, Texas
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Re: Need Help choosing a transmission
Quote:
Believe me when I say it will be raced. I just wont be going to a track. I know a couple closed roads. :P
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1970 C10 Stepside SWB - 468 BBC |
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02-05-2016, 05:08 PM | #8 |
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Location: San Antonio, Texas
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Re: Need Help choosing a transmission
The biggest concern is the life of the engine. I expected to get 4-6 MPG. Which I'm ok with. I'm not building it for the gas mileage. I was worried about cuising at 4000-4500 rpms for an extended period of time (3-4 hours). But if the engine will be fine with it, I will be too .
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1970 C10 Stepside SWB - 468 BBC |
02-05-2016, 05:23 PM | #9 |
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Location: Tucson AZ by way of WI & CA
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Re: Need Help choosing a transmission
So here is some numbers to consider. For every inch in diameter your tire grows you gain 2 mph at a given rpm. For every inch your tire grows you reduce your rpm by 100 at a given speed. An overdrive transmission will reduce your rpm by 600. Changing rear gears to 3.42 drops rpm by 250, and 3.08 by another 250. Assuming these are available for your axle. Estimate gears to cost 1k per axle, or tires 1k per vehicle, or transmission 2k per vehicle, best bet is to go the tire route. Might be a dog off the line. So for my 2 cents, i would go with the TH400, and change tires, at least on the rear. Might be able to find some taller tires on the cheap, and at least see if this is the right direction.
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02-05-2016, 09:32 PM | #10 | |
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Re: Need Help choosing a transmission
Quote:
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02-05-2016, 05:32 PM | #11 |
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Re: Need Help choosing a transmission
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02-06-2016, 11:18 AM | #12 | |
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Join Date: Jun 2014
Location: Farmington, New Mexico
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Re: Need Help choosing a transmission
Quote:
Why would you ever want to build big power and limit your application of it? I'd drop the rear gear down to 3.42 or 3.08, with that kind of torque I don't think it would be much of a dog off the line and would still be decent on the highway. However I agree as well that higher sustained rpms aren't gonna hurt your motor much.
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4l80e, 700r4, th400, tranny, transmission |
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