Ideal rear end for a th200R4?

Discussion in 'Transmission & Driveline Topics' started by Skaal-tel 79, Jul 28, 2006.

  1. Skaal-tel 79

    Skaal-tel 79 Veteran Member Gold Member

    3,417
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    Jun 20, 2004
    CFB Petawawa, Ontario
    quote off some other random forum:

    "TH200-4R........TH350
    2.74.................2.52
    1.57.................1.52
    1.00.................1.00
    .67


    One thing to keep in mind with the TH200-4R is the lower first gear. A TH200-4R pushing a 3.42 rear gear will give the same overall gear reduction as a TH350 and a 3.73 rear gear."

    Should I start looking for a 3.42 or 3.08 rear end?

    I have a 2.41 in the car now which is starting to act its age.
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    Apr 14, 1999
    Bismarck, North Dakota
    The 2.41 will really suck with overdrive. You will never get your engine revving high enough to get up and over a mole hill. I used to have a Caprice with 700R4 with .70 overdrive and 2.56. It ran OK downhill, but could barely hold its own on level ground. It got great mileage, but wasn't fun to drive.
    If I had to guess at a good ratio for the 200R4, I'd try a 3.42 because it gives you about 2.29 in overdrive, which should be livable, and the 2.74 first gear coupled with the 3.42 should be a good strong off the line gearing too, unlike the nasty combination you get when you use a 700R4 and its 3.06 first gear with deeper rearends.
     
  3. hardline_42

    hardline_42 Veteran Member Lifetime Gold Member

    Why not go for the 700r4? The lower 1st gear will launch you like you have 3.73's with a set of easy-to-find 3.08 gears and the overdrive coupled with a torque converter that locks in 4th will make for comfortable cruising RPMs.
     
  4. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

    26,204
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    Feb 26, 2004
    Bloomington, MN
    I've got a 2.73 rear hooked up to my 200-4R. (305 eng.)
    The time it takes to pass another car in OD can be logged using a calendar and sundial! :eek:

    It's pretty easy to hold the speed steady @ 65-70.

    TC locked at 1500 RPM @ 60 mph nets great gas mileage for one of these heavy cars but you need to step into it to drop back to 2nd gear for any acceleration.

    Gary has the gear info right. (as usual ;) )
    I agree with his suggestion too. 3.42 gears is the plan for mine.

    Since I've stepped up the gearing in 1st by 10% and added a 33% OD. I figure lowering the rear gears by 25% (2.73 to 3.42) will still give me about the same mileage as I had with the TH350 and 2.73 gears (in OD). But... much better performance! :cool:


    3.73 gears would be another acceptable choice but even more performance oriented. It depends upon the plans for your car. If most of your miles are on the highway... get the 3.42s.
     
  5. Skaal-tel 79

    Skaal-tel 79 Veteran Member Gold Member

    3,417
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    Jun 20, 2004
    CFB Petawawa, Ontario
    "Why not go for the 700r4?"

    ease and $ of installation :p

    Guess a 3.42 it is!
    I like to use my car for looong cruises. Like, 800km one way trips :)

    unfortunately for my gas mileage it looks like I'll have to replace the rear end before the transmission... which will probably come next year... ay ay ay.
     
  6. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

    26,204
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    Feb 26, 2004
    Bloomington, MN
    3.23 is another option but I think you would need to find a used set. These are tough gears to find anymore.
     
  7. 3_z28camaro

    3_z28camaro Veteran Member Lifetime Gold Member

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    Dec 17, 2004
    Acton, CA
    Another 3.42 vote here, I have 3.42 with a 700R4. I have not had much road time but what I have had I liked.:)
     
  8. ZS10

    ZS10 Moderator Staff Member Lifetime Gold Member

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    Jan 18, 2003
    BC, Canada
    3.42-3.73 whichever you find first. 3.42 will be a couple hundred revs lower in O/D but you'll love the 3.73 with slicks on.
     
  9. Skaal-tel 79

    Skaal-tel 79 Veteran Member Gold Member

    3,417
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    Jun 20, 2004
    CFB Petawawa, Ontario
    found myself a 3.42 in town, I can't believe it. 200$ and non-posi.. but.. that can be changed easy enough.... right?

    Sound like a fair price? I'm going to go look at it today... I'll post a pic if I get anything worth looking at.
     
  10. 80'427

    80'427 Veteran Member

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    Jan 1, 2005
    Fairbury, NE, USA
    I would go for the 3.90 gear. That will equal a 10 to 1 first gear (the ratio I have heard quoted as the best drag 1st gear). This would still get you a 2.53 final drive ratio. Why not a 700? Cause there deep 1st gear causes a huge jump to 2nd and makes it so you blow off the tires in 1st and dog in second. I would go 200 all the way.
     

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