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    Anyone running a TH400, Chevy 4.3 L, 205 t-case, and 4.11s on 35" tires. My friend is considering this setup and is wondering about highway rpms. What's your top speed? Basically he wants the lowest gears and still be able to run on the highway 70mph.

  • #2
    Considering the TH400 is not an overdrive tranny, I think 70 will be awfully high into the RPMs with the gears and tires he's thinking about. A good friend of mine is running a full sized chevy with a 350, sm 465, 205 t-case, 3.73s and 33" tires and it's turning the 350 pretty hard at 65mph. The sm 465 is 1:1 in 4th gear (just like the TH400 in high) and the 3.73/33" combo would be pretty close to 4.11/35". Sounds like a good excuse to go with 37s! Or higher gears. PM eviltwin v2 if ya want the skinny on more GM stuff.

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    • #3
      I found a calculator at 4x4wire that says the RPM should be around 2500. Here's the link:
      http://www.4x4wire.com/tech/applications/gearandtire/
      Also, it's RPM not RPM's. RPM is already plural... revolutions per minute. You can't say revolutions per minutes.

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      • #4
        Originally posted by YellaJacket
        You can't say revolutions per minutes.
        I can and I did. Is this a little pet peeve of yours?

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        • #5
          Originally posted by willness33
          I can and I did. Is this a little pet peeve of yours?
          Am I wrong? Check any text on engine theory.

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          • #6
            Nah, your're right if you say out the abbreviation. However, just by saying rpm, IMO, you're taking out the plurality of the term and defining a single number value to a REVOLUTION PER MINUTE. Not trying to start an arguement, it's just the way I look at it. Besides, this is really off-topic.
            Last edited by willness33; 09-24-2005, 08:55 PM.

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            • #7
              My CJ7 with 33's and 3.73 gears was awesome at highway speeds. right in the meat of the power, I don't know what I got for mileage, but I could easily run 70mph, with a t-18 (1:1). My 304 with a 4 bbl had no problems, so a higher revving v-6 with fuel injection should have no problems either. Just one question though, why does your friend have to go ruin a perfectly good jeep with chevy parts like that?

              Ah, I shouldn't b!tch, keeps the real jeep parts cheaper!

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              • #8
                to 79duner

                I wouldn't chop it up either. It's an 81 Scrambler. To each their own though.

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                • #9
                  Originally posted by cj71981
                  Anyone running a TH400, Chevy 4.3 L, 205 t-case, and 4.11s on 35" tires. My friend is considering this setup and is wondering about highway rpms. What's your top speed? Basically he wants the lowest gears and still be able to run on the highway 70mph.
                  I have a couple comments on this.

                  1. The 4.3 would be way down on my choice of engines to swap into anything. It really isn't a great low rpm engine, and even though the Jeep is light weight enough, I'd go with something with better low RPM torque. Go for a few more pounds & put in a 350, period.

                  2. TH400 (in my opinion) is the absolute wrong choice or tranni for this application...especially if you're putting a 4.3 in front of it. A TH350 is a far better choice. Lighter duty, but still overkill for anything you'll do with a Jeep. Also less internal power loss than the TH400. Unless you're running a huge hp engine (which the 4.3 definately isn't), the TH350 is definately the better choice. Avoid the TH700R4 like the plague.

                  3. 70+ MPH in a lifted Jeep CJ-anything isn't exactly the safest or most enjoyable experience. If he wants a highway cruiser, then there are many better choices for vehicles than a Jeep.

                  My recommendation to him would be a sb350 engine, TH350 tranni, np208 lowrange box doubled to a np 205 transfer case.

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                  • #10
                    I have a small block, 350 trans and d300 t-case with 3.31 gears and 35's. It turns about 2500 at 65mph. I took out a np205 and it turned the same rpm.

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