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What should I do? Gears or doubler or engine mods or both?

Discussion in 'The Garage' started by bitchin4x4, Jul 22, 2002.

  1. bitchin4x4

    bitchin4x4 1/2 ton status

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    Alright I am trying to figure out what I should do here. I have been throwing around getting my gears lowered to 5.13's then go with a 5 speed manual (nv4500) and a big block. If you were going to do it or do it over, how would you do it?

    I currently have 350/350, 4.10 gears, NP205, 39.5 Boggers.

    anyone? buehler?

    Thanks in advance!
    Sean
     
  2. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    Its all about what kind of wheeling you like. If you are big into rockcrawling then you want the super low gearing and torque. If you do mud races or tough truck you might want to lay off the gears and go all muscle with a 4.56 gear set and a slush box. The NV4500-doubler with 4.10 gears would be nice, you would have a great 1st gear with the reduction behind it...lets narrow it nown to your wheeling preferences and go from there...
    Brent


    BTW, that is one SAWHEET blazer....
     
  3. Swanson52

    Swanson52 1/2 ton status

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    I'm considering the same setup (essentially), but I intend to go with 4.88's, rather than 5.13's. As I understand it, with gears as low as 5.13, gear strength (pinion) begins to become an issue, and it appears that for MY purposes, the 4.88's are a good compromise between ratio and stoutness. I also run primarily mud, so (like was previously mentioned)the type of wheeling you intend to do will be the main determining factor.
     
  4. bitchin4x4

    bitchin4x4 1/2 ton status

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    Well I am located in Denver, so muddin' is kinda out! ;-)

    But seriously we a bit of rock crawling and that's what I am building it for. I hardly drive it on the road and hardly drive it. However, I would still like to be able to drive it to say Moab without trailering it!

    Any suggestions are greatly appreciated.
     
  5. bitchin4x4

    bitchin4x4 1/2 ton status

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    I have heard that the gears gets weaker the lower you go.

    Also, I have been told that the nv4500 is rather costly and requires all kinds of adapters now. So I am not against a Automatic tranny.

    The Jimmy is primarily for rock crawling.

    thanks!
    Sean
     
  6. Silver84k5

    Silver84k5 1/2 ton status

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    im running 39.5's and im getting the 4.88s in this week i hope (getting rid of 3.73's woohoo) id say you get a big block, or a 383stroke, then th400 trans, and a Doubler, those are some big bucks though, with 4.88s and a doubler im sure you will have low enough gearing to creep around on the rocks, all boils down to what you can afford,
     
  7. bitchin4x4

    bitchin4x4 1/2 ton status

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    Latest recommendation has been to beef up the 350 with an edelbrock Performer power package to get a bit more torque and hp. stick with my 4.10 gears and go with a doubler.

    My only concern with this option is my Interstate driving up through the mountains. I constantly shift between 2nd and 3rd going 55 -70 mph (70 mph 2nd gear 3500rpms), and will the engine upgrades be enough to correct this.

    According to the chart 2273 RPM's at 65mph in 3rd gear at 1:1 gear ratio. Is the turbo 350 really a 1:1 ration in 3rd gear? If so, that really isn't bad and I should be able to climb the interstate if my engine had enough umph I guess? Also with the higher gears is it really causing alot of undo stress on my transmission?

    I would be willing to go with a th400 even?

    thoughts?
     
  8. bitchin4x4

    bitchin4x4 1/2 ton status

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    So are you recommending I just go big block with a doubler or big block, doubler, and gears?

    yeah I am aware it costs some money! ;-)
     
  9. Silver84k5

    Silver84k5 1/2 ton status

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    well how much money you got? heh all three would be best but im sure you could get by with the doubler, a big block, or 383 stroker, and 4.10's ive heard that th350's dont hold up well against a big block, but ive also heard of people noit having probs with a BB and a th350, If i were you id just get the doubler, and see where you stand, if you need lower gears then that then go with 4:88's Do one thing at a time and then evaluate what you need from there, Take your rig out to the hills and test it, if you dont like what you got then do another Mod, Dont get ahead of yourself kinda like i am doing right now, gets real spendy real fast, but im sure you prolly know that already heh
     
  10. m j

    m j 1/2 ton status

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    the doubler is much better investment then gear swap.
    you get hiway capable and deep offroad gearing.
    best of both worlds, I would not put lower then 4.10 in another vehicle unless it is a drag car
     
  11. bitchin4x4

    bitchin4x4 1/2 ton status

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    I like the common sense approach here so far! ;-)

    I can live with the shifting up to through the hills, and doing some adjustments to my small block in the meantime might not be a bad idea aswell, I could always throw it into my blue 72 gmc jimmy or truck at a later date.

    Anyone else?

    Sean
     
  12. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Upgrading to a th400 can be another "problem" that will arise for your motor.
    A th400 will rob your motor of approximately 20 horsepower to get the rear wheels turning.

    I have not heard of the th350 using this much or any HP to get the meats turning.

    The 465 definitely does not rob you of anything. /forums/images/icons/wink.gif
     
  13. bitchin4x4

    bitchin4x4 1/2 ton status

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    Gotcha! But that 20hp adds stability to the transmission?

    I'm not saying I am going to do it, just throwing out other thoughts that I have heard!

    Would a 700 do the same? If I am not mistaken it is comparible to the th400 with an overdrive?

    sean
     
  14. BLUESMAN

    BLUESMAN 1/2 ton status

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    I would do the doubler with your TH350 trans,then see whar you have.If you want lower crawl gears,then either install a 3:1 203 case gears(or whole unit),or install the 4.88 diff gears.I went from the TH350 trans to an SM465 manual trans,mated to an NP208 t-case.It's got about 70:1 crawl.Now I'm going to install an NP241 t case and install 4:1 t case gears.that will take it down to about 130:1.I just got to cough up the $1000 to do it.You could install the NP241 and install the 4:1 gears.Just a thought!The 205 case you have now is bulletproof...just the gearing sucks!One steo at a time.I don't think you would be disappointed going to an double t-case.Just alot of cash....203 case,adapter,shifters,crossmember, and driveshafts.Br sure to get lockers front and rear before any of this....2 wheelin' only gets you so far when you're rock crawling.LOCK IT AND LOAD IT!!Then gear it down!Mike
    The TH700 trans is good(has an lower 1st gear..3.06 vs2.54 on the TH350).But you relly need the later model version(stronger innards).But mated to an NP241 case and 4:1 case gears that would be great.So that would be 3.06x4.0x4.10=50.2 crawl ratio x 2(auto trans) giving about 100:1.....or with 4.88 diff gears 120:1.
     
  15. bitchin4x4

    bitchin4x4 1/2 ton status

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    Wow! ;-) Ok, well I am already locked front and rear so that is taken care of! I had taken care of that immediately after this incident! ;-) http://www.lozensky.com/pages/photos/fourwheeling/070400_4thofJuly/images/billmoore11.jpg lol

    Thanks, I think I am going to go with the doubler and leave everything else as is and see how it goes after this!

    I am haven't fully researched the doubler yet but I have a general idea. So what am I looking at for my ratio with my current setup with a doubler? 84:1? 2.54x4x4.10=41.7 x 2 (auto trans) for about 84:1?

    Thanks for the info!

    sean
     

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