Transmission decision time. Little help?

Discussion in 'The "Juice Box"' started by Houndogforever, Oct 19, 2019.

  1. Houndogforever

    Houndogforever Silver Level contributor

    67 Skylark, 455 probably around 450 HP and 500 Torque once it is built.
    It has a 2:78 Posi O-style rear end.

    I currently have a mystery TH400 from a GTO of unknown age and condition. It has sat in my shop for 5 years alone.

    I was told to get it rebuilt and a decent converter would be just under $1000. Seems high, but then I also see some rebuild kits that are $400 so maybe 1000 isn't crazy. This would work ok unless I later decide to swap out that differential and change gears.

    On the other hand, for $2000 ish you can get a 200-4R overdrive trans that will fit really nice into that year frame and body. This would be the flat out choice if I had a rear end ratio in the 3:23 range. Will this 2:78 be just too steep of gearing for the overdrive to be useful?

    I will be having a new driveline made regardless of choice because.... reasons.

    PS, what is a reasonable price to pay for a BOP TH400 short shaft to be rebuilt?
     
  2. 1969RIVI

    1969RIVI Well-Known Member

    Pick the brains of Ben (Bens99gtp) he knows tons about transmissions he help walk me through my th400 rebuild and he has a few threads on here about them too.
     
  3. ravensbud

    ravensbud Silver Level contributor

    The 200-4R and 2.78 gears are a bad match. You’ll lug like crazy. Not to mention the major pain it is for many (including me) to get the TV cable adjusted properly. And 2 grand may not get you a beefy enough 200-4R to hold that torque.
    Having just done this swap I would highly recommend staying with the th400 with those gears. Way cheaper, stronger and no damn TV cable. Run the one u have. They’re great trannies and if it’s bad have it rebuilt for much less than a decent 200 will cost you.
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Or go the Gear Vendors Overdrive down the road. You might be able to find one used.
     
    docgsx likes this.
  5. Mark Demko

    Mark Demko Well-Known Member

    It cost me a bit over 800.00 for my T-350 including the heavy duty sprag. It was rebuilt by Vince Janice, cash deal, so it was probably a bit cheaper.
     
  6. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    I wouldn't bother with an OD with 3.23s. You'll be fine with a th400
     
  7. Fox's Den

    Fox's Den 355Xrs

    I run the 200r4 trans I have 373 gears 28" tires I use a lock up TQ rpm is at 2200 in OD with the convertor locked up. I ran nitrous with this thing a lot and has held up to the extra power. I had the trans built in 2005. Janis Trans in Akron OH.
     
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  8. Bens99gtp

    Bens99gtp Well-Known Member

    I think the 200 and your gears are not a good match.

    If you can have someone rebuild it and get a good converter for 1000 that's actually cheap. Good converters are 500-700 or more by themselves

    So I would assume un that quote it's not a great converter but a standard plain Jane unit.

    The converter is a major key element to the wat a vehicle performs, dont go cheap here. Dont call tci, or jegs, or summit. You will get a unit that wint match or live.

    I have hit used one yet, but many have and seen to be beyond happy the unit from JW at trip shield.

    A decent 400 kit will be 250-300. And you will want to upgrade the intermidiate sprag at 50-75.......if you have the correct direct drum if not a used drum could go 100 or more. So you could easily have 500ish in just parts to start the rebuild

    I would think 1500-1700 for a good converter and have someone else rebuild the trans is very much inline, anything less a corner could be being cut
     
    1969RIVI likes this.
  9. Fox's Den

    Fox's Den 355Xrs

    I paid 800$ for my Pro Torque lock up convertor for the 200 r4
     
  10. telriv

    telriv Founders Club Member

    This could be a good deal as the both of you live in Oregon.
     
  11. DauntlessSB92

    DauntlessSB92 Addicted to Buick

    The st400 with gearvendors sounds like the most durable, straightforward choice. A correctly working switch pitch trans is pretty fun in my opinion and having overdrive will make it even better.

    I went through 3 200-4Rs. I know they can be built to handle serious power but there are a lot of variables at play. The biggest being the correct setup of the TV cable.
     
  12. sailbrd

    sailbrd Well-Known Member

    No one runs more HP than I do through a 200-4r so I know that they can be built to take a lot. On the other hand I never use more tire than a Nitto drag radial so there is a bit of a fuse there. The sweet spot for the 200 is a 3:73 gear with a 28 inch tall tire.

    On the other hand we used to run 3:08 gears with a switch pitch converter when these cars were new. I think I calculated top speed at about 145 (hey I was 18.) The converters we have today can be set up to work really well with the 3:08. As said before good converters are not cheap.
     
    Mart likes this.
  13. black70buick

    black70buick Well-Known Member

    "Will this 2:78 be just too steep of gearing for the overdrive to be useful?" For an OD trans yes as others have echo'd. I would recommend finding another rear end that is atleast 3.42:1 or better, this way you are likely to be into the power range of the engine sooner and streetability and drivablity would be more enjoyable. You can still cruise comfortably with a TH400. I would believe no matter the transmission you change to, that 2.78 will still dog the engine out of its powerband and by the time you got into an efficient power RPM, you'll hit another street light unless this car is strickly highway only. idk, the best thing I did with my stock Riv in the '90s was go from a 3.08 rear to a 3.42 with the orginal TH400. Best choice I ever made.
     

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