Overdrive

Discussion in 'The "Juice Box"' started by dfish1247, May 22, 2018.

  1. dfish1247

    dfish1247 Active Member

    Hey folks, after I get the cooling system to my liking, an overdrive transmission is next.

    The car is a 1964 skylark 455/th400/3.08 10 bolt with 215/65/15 tires. Very mild engine, idles smoothly at 500rpm, stock converter.

    Anyway, turning 3000 at 70mph is painful. So, either 700r4/2004r is in order. Or, if not too difficult, a 5 speed(my knees ain't bad yet.)

    I know the 700r4 I'll need the bop adapter plate, how about converter to flex plate, any issues there? Plus, if a bbc should find its way under there, I'm good. Not gonna happen unless the 455 is not rebuildable, but some versatility sounds nice.


    Never been around a 2004r, but it seems a popular swap, and a couple places claim it can hold the power.

    5sp, I know I'll need a bellhousing, someway to make a clutch work, etc.

    Now, the wildest the 455 will ever see is edelbrock heads, maybe a cam in the low 220* duration. Nothing annoying to drive. So, how should I go about this? I know crossmember and driveshaft will need to be taken care of. Driveshaft is covered, but where would I find a crossmember?

    Thanks in advance.
     
  2. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    If you change to a 200R4 you'll have to change the gear to at least a 3.42:1(with a 455 you could probably get away with a 3.23) so the engine can shift into O/D @ 45 mph without lugging the engine.

    The 700R4 needs at least a 3.08:1 rear gear for it to be able to shift into O/D @45 mph without lugging the engine down.

    With either trans the driveshaft length will need to be addressed, with the 200 though you'll need a longer D/S but with the 700 you can have the one you have shortened.

    As far as the manuals go, my knees have been shot for years so I don't know!?:(
     
  3. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    200 will bolt to Chevy or Buick engine...
     
  4. rkammer

    rkammer Silver Level contributor

    Here's a handy chart to show you what your RPM will be in overdrive with a 2004R transmission. If it were me I'd think about either the 3.73 or the 3.91.

    (RPM) (MPH ) 3.42 Gear 3.73 Gear 3.91 Gear
    5500 RPM 186.38 170.89 163.02
    5000 RPM 169.43 155.35 148.20
    4500 RPM 152.49 139.82 133.38
    4000 RPM 135.55 124.28 118.56
    3500 RPM 118.60 108.75 103.74
    3000 RPM 101.66 93.21 88.92
    2500 RPM 84.72 77.68 74.10
    2000 RPM 67.77 62.14 59.28
    1500 RPM 50.83 46.61 44.46
    1000 RPM 33.89 31.07 29.64

    The overdrive ratio-0.70 for the 700-R4, 0.67 for the 200-4R-is virtually identical, but the 200-4R offers a better ratio spread (2.74, 1.57, 1:1, 0.67), which reduces rpm drops during gear changes. The 700-R4's ratios (3.06, 1.63, 1:1, 0.70) cause a drastic 46 percent rpm drop on the 1-2 upshift.
     
  5. LARRY70GS

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

    Or you can go with a Gear Vendors Overdrive as I did years ago. They bolt on to the back of the transmission and you shorten your drive shaft. They are pretty expensive, but maybe you can find one used. Rated for 1200 HP, they are nearly indestructible. Ratio is .78 so that would bring your final drive to 3.08 X .78 = 2.40.
     
    rmstg2, 1973gs and Harlockssx like this.
  6. 455monte

    455monte Well-Known Member

    I run a 3.55 rear gear
    28 tall tire
    200 4r trans with lockup.
    At 80 mph 2300 to 2500.
    On flat road its 2300 on a steep hiway
    Hill its 2500 to maintain 80
     
    Bygblok likes this.
  7. rkammer

    rkammer Silver Level contributor

    Agree that the Gear Vendor Overdrive would be a good option but at 2.40 ratio RPM would drop below about 1500 at 45-50 MPH. Depending on cam, timing, etc. the engine might lug at that speed. With that setup I'd recommend a rear ratio change to at least 3.42 or higher (numerically).
     
  8. LARRY70GS

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

    I think it is pretty hard to bog a BBB, maybe with a lock up torque converter, my GV comes in at 40 MPH and it is never a problem. These engines have so much low end it shouldn’t be a problem. The GN has a 2.29 final drive.
     
  9. dfish1247

    dfish1247 Active Member

    I don't know the cam numbers, but it idles very very smooth at 500rpm and picks up instantly. 1500-1800rpm feels like where it wants to cruise at, just going off throttle response anyway.

    I haven't looked at the back of the th400 to see if there's room for an overdrive unit, well transmission tunnel wise. They have the control box to manually operate it if needed.

    I'd like to be roughly 2000rpm at 70, give or take a 100. And I believe in but once cry once so I'm not trying to be a tightwad, but I don't need a trans for a pro stock car either. If I can get the parts and be around $4000 or less, I'm good. Labor is free, I mean me.

    To be honest, being I don't want wider tires, lower gears in the rear would hurt. I haven't found the point for pulling out quickly without lighting the tires. Would 3.23 or 3.30 be a good compromise? It doesn't take much at all. Granted, I've owned the car only 2 weeks and have driven it 3 times since I got it home. Bad weather and working 12 of 14 days, doesn't leave much play time.
     
  10. rkammer

    rkammer Silver Level contributor

    Ahh, but you have a higher stall converter. The OP has a stock converter. A bud of mine installed a 2004R in his GS455 with a stock converter and 2.93 gears and the bog was terrible. He had to change both the converter and the rear gears to be happy. Just relaying a personal experience. :)
     
  11. LARRY70GS

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


    That is true. All stock GS455?. That would be 1.96 final drive.:)
     
  12. knucklebusted

    knucklebusted Well-Known Member

    Unless you plan on a lot of road trips, I find I don't do nearly as much long distance cruising I thought. Most of my driving tends to be on more back roads than interstate.

    But I absolutely love my 200-4R with 3.73 and 275-60-15 tires. With 3.73 and .67 overdrive, it cruises like 2.50 final drive. It runs about 31MPH per 1,000 RPM. I can cruise down the interstate above the speed limit at 2,500 RPM. It feels like a sweet spot with a TA212 cam.
     
  13. Golden Oldie 65

    Golden Oldie 65 Well-Known Member

    Scratching my head here, you have a 3.08 gear and you feel you need an OD? My El Camino (bone stock 402) has a 3.36 and I cruise down the interstate at 75mph with no worries at all. Why? Because there's no tach in the car, nothing to worry about, nothing to fixate on. My Skylark has a 200-4R but I also have a 4.10 gear in it and I rarely slip it into OD until around 50-55mph. With the .67 OD, that's a final drive ratio of 2.75, not far off from the original 2.78 that originally came in the car. I wouldn't even consider going lower than a 3.73.
     
  14. knucklebusted

    knucklebusted Well-Known Member

    Yep, these old cars were built to cruise above 2000 RPM all day long. I've got 3.08 gears in my 71 4 speed and they feel fine at highway speeds.
     
  15. rkammer

    rkammer Silver Level contributor

    Yes, it was a '70 GS455 with a 2.93 factory posi rear.
     
  16. Ken Warner

    Ken Warner Stand-up Philosopher

    The other thing that doesn't get a lot of consideration is that if you have any stall at all the lock up converter is pretty much like having a 5th gear when it engages.
     
  17. knucklebusted

    knucklebusted Well-Known Member

    Yes, it does. I've got a vacuum switch that keeps it from locking up in 4th unless it has sufficient vacuum. Problem is it either in-out, in-out if I set it too high or immediately hits lockup upon shifting to 4th if set too low. With my cam (TA212) and torque converter (2400 stall) there is not a good spot between them. I've found some delay relays that I can adjust for milliseconds to 10 seconds that I intend to wire into the circuit so that a 4th gear shift happens, then 4 seconds later it locks up. I've also got the vacuum switch set on ported vacuum so that if I let off the gas, it kicks out instead of lugging the motor.
     
  18. Ken Warner

    Ken Warner Stand-up Philosopher

    Vaccum switch can be a bit temperamental, I have been very pleased with the B&M lockup control. I've got it set to engage at 70MPH and it's typically won't disengage until you decel to about 67-68MPH. a tap of the brakes interrupts the circuit and drops the lockup as well. Note that the drop out feature requires you to spend about $15 for a later model stop light switch for a car that had cruise control.
     
  19. dfish1247

    dfish1247 Active Member

    Well, the rear can be addressed easy enough. It's a Chevy big 10 bolt, nothing weird there.

    I finally got the thermostat taken care of and got a break in the rain to go drive today. Anyway, this car doesn't need any lower gear at all. Floor it, first and second gears are useless, third finally bogs enough to hook. 215 tires don't help but they look right, my taste. And this engine would be great, actually perfect for a truck if that cements how tame it is.

    Anyway, an auto is my only choice because it has 72 Electra seats and console with a freshly restored console tach. My dad had the tach restored as a present for me getting a classic that wasn't a Chevy. So, that ain't changing. But, this will be a while before it happens, not for money reasons, but because everything works and I want to enjoy it a while before turning my property into a junkyard every long weekend.
     
  20. 70 gsconvt

    70 gsconvt Silver Level contributor

    I have a CKPerformance 2004R in my car. It's great. I think 70 mph is about 2200 rpm's.

    Just know as said above, realistically, it's going to cost you about $4K for everything. That's the trans that'll handle a 455, torque converter, TV cables and brackets, driveshaft work, etc. Good luck with it.

    There was just one posted on Facebook for $3K that would do it for you. I'll see if I can ad a link.

    Jeff Strubeto Buick Swap meet
    12 hrs ·

    CK Performance Trans New Never Used
    $3,000
    Brighton, CO
    2004R FULL BILLET PRO STREET/STRIP TRANSMISSION

    24RT/FBPSS

    The 2004R PRO STREET/STRIP TRANSMISSION is recommended for ultra high performance street and strip cars producing producing up to 550 hp and 500 lbs ft. and weighing up to 4000 lbs. It can also be used in lighter vehicles at power levels up to 800 hp and 800lbs.ft. in some applications.Perfect for low 11 to mid 9 second Turbo Buicks,as well as all small and big block Buick,Cadillac,Chevrolet,Oldsmobile and Pontiac vehicles.All of our 2004R transmissions are dynomometer tested and then in car tested and calibrated prior to shipment.

    COMPETITION COMPONENTS:

    3OOM STEEL BILLET INPUT SHAFT

    E4340 STEEL BILLET REINFORCED OVERDRIVE CARRIER

    E4340 STEEL BILLET REINFORCED OVERDRIVE RING GEAR

    300M STEEL BILLET SHAFT FORWARD DRUM

    4130 HTSR STEEL BILLET BAND ANCHOR PIN

    BILLET ALUMINUM OVERRUN CLUTCH PISTON

    BILLET ALUMINUM DIRECT CLUTCH PISTON

    BILLET ALUMINUM FORWARD CLUTCH PISTON

    BILLET ALUMINUM LOW/REVERSE CLUTCH PISTON

    BILLET ALUMINUM INTERMEDIATE SERVO PISTON

    Call for info 720-217-7859 Jeff
     
    Last edited: Jun 2, 2018

Share This Page