1966 electra trans swap

Discussion in 'The "Juice Box"' started by Jonah Halbert, Apr 7, 2018.

  1. Jonah Halbert

    Jonah Halbert Well-Known Member

    My 1966 electra has its original turbo 400 trans. Someday I'd like to do a trans swap so I can be turning less rpm on the highway. Any ideas? Suggestions? Is a trans swap even possible since you engine is a 401 nailhead?
     
  2. LARRY70GS

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

    You have a few options. You can install a modern 4 speed OD automatic like a THM 2004R, 700R4, or 4L80E. You will need an adapter plate. The 200, and 700 will need to be built with all the good stuff to stand up to the torque in a heavy car. The 4L80E will likely take it in stock form, but you will need a computer to run the transmission.

    The second option is a Gear Vendors Overdrive. It is an add on to ANY transmission. It is rated for 1200 HP stock, so it is plenty stout.

    http://www.gearvendors.com/index.html

    None of this is cheap.
     
    Last edited: Apr 8, 2018
  3. buick64203

    buick64203 Just plum crazy Staff Member

    Or just buy a taller set of tires? :D Poor man's overdrive!

    Honestly though, how fast could that 401 be possibly spinning on the highway?
     
  4. Jonah Halbert

    Jonah Halbert Well-Known Member

    My tires are tall. 275 70 r15. At 60 mph it sounds like it's turning 3 1/2 K. I need to install a tach......
     
  5. LARRY70GS

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

    Those are like 30" tall. 3500 RPM? Are you sure it is shifting into 3rd gear?:)
     
  6. buick64203

    buick64203 Just plum crazy Staff Member

    A 275 is approx 28.5" tall. If your spinning that 401 at 3500, that would mean you have a 4.56 gear ratio. I would guess your Electra has a more sedate 3.07 ration is in it which means in third gear is probably pushing 2200 rpm. At 2200 that engine isn't even breaking a sweat.

    A tach would help
     
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  7. LARRY70GS

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

    A P275/70R-15 is a full 30" tall. If the rear is a 3.07, and the transmission isn't up shifting to 3rd gear (1:1), it is in second gear (1.48) 3.07 X 1.48 = 4.54.

    336/tire height X Gear X MPH = RPM 336/30 X 4.54 X 60 = 3053 RPM:)
     
  8. Jonah Halbert

    Jonah Halbert Well-Known Member

    I've also been trying to figure out if it's shifting into 3rd. It shifts first at about 10 mpg then it shifts again at about 20. Then from 30 and up its one speed. Once i get these brake reaction rod bushings on I'll take it for a drive and listen carefully. I'll come back and tell you the shift points.
     
  9. LARRY70GS

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

    I think it is a better idea if you get a tachometer on it and tell us what it is revving at 60 MPH.
     
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  10. BRUCE ROE

    BRUCE ROE Well-Known Member

    My switch pitch TH400 turns 2000 rpm at 60 mph, with a 2.41:1 rear axle. The
    switch pitch does this better because it slips less in low stall, of course not zero
    slip like a lock up converter that might allow 1500 rpm at 60. A lot of the
    performance is restored by using an electronic switch pitch control for high
    stall, so it feels like a much higher axle ratio. My 4150 lb Olds that gets 19
    mpg at 70 mph, manages 91 mph in the quarter mile with a mild mannered
    stock 403, switch pitch, and a good exhaust. Bruce Roe
     
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  11. Jonah Halbert

    Jonah Halbert Well-Known Member

    Is my trans a switch pitch? Also I'm not sure how to find out my axle gear ratio. I've looked for a tag but have never found one. There are numbers on the bottom of the gear housing but they don't tell me anything
     
  12. buick64203

    buick64203 Just plum crazy Staff Member

    Yes, you have a switch pitch.

    Get the rear wheels off the ground and put the trans in neutral. Make a mark on the tire and another on the driveshaft. Rotate the tire one revolution and count the amount of times the driveshaft spins. That's your rear axle ratio. For example, if the driveshaft goes around 3 times to one revolution of the tire, you have a 3.00 to 1.
     
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  13. Jonah Halbert

    Jonah Halbert Well-Known Member

    What exactly is a switch pitch?
     
  14. buick64203

    buick64203 Just plum crazy Staff Member

    Normally, a torque converter "stalls" at one rpm because the vanes in the converter are fixed. So you step on the gas, and the car starts to move at lets say 1500 or so rpm. That's when the converter makes the fluid coupling and the car starts to move forward. With a high performance car, you want a high stall converter that makes the coupling at a much higher rpm. So when you step on the gas, it revs up to 2500 or 3500 before the car starts to move. Great for a performance car, but you lose alot of drivability

    So on a switch pitch or a "variable stator" converter, it has two stall speeds- high and low. There's a switch on the throttle. When you accelerate normally, the torque converter stalls at low rpm like a regular car. But when you give the car some gas, it will stall at a higher rpm to give you a little more pep off the line. Basically you get the best of both worlds. You have low stall when your just driving around normally, but you have high stall when you need a little more torque off the line when that Camaro pulls up next to you.
     
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  15. Jonah Halbert

    Jonah Halbert Well-Known Member

    Ahh ok that's cool! I've noticed it's quite peppy.......don't ask how I know
     
  16. cobravii

    cobravii Well-Known Member

    First off I doubt an adapter and a 700R4 will work for you. I tried that on my '64 and it pushed the trans back into the firewall and the floor. I would have had to do massive floor reconstruction to make it fit. I sold the brand new 700R4 and the adapter and bought a new 4L60E and a bell housing from centreville auto repair....http://centervilleautorepair.com/transadaptors. I used an EZ-TCU controller for the transmission, I liked it the best. I also opted for an optional tail shaft housing that allowed me to use the factory speedo. The transmission (other than the harness) looks stock oder the car and fits as well or better than the TH400.
    Also, other than the obvious overdrive gear it also has a lower first gear giving it much better performance off the line. This big heavy Electra literally smokes the tires (255/70R15) for half a block!!!!
    HTH's
    Feel free to contact me if you have any questions.
     
  17. Jonah Halbert

    Jonah Halbert Well-Known Member

    Tell me more about the 4L60E swap! Did you have to do anything to the driveshagy or did it fit? Also what benefits have you noticed of swapping to the 4L60E? What computer do you need to run it?
     
  18. cobravii

    cobravii Well-Known Member

    I did have to shorten the drive shaft. I took it to the Gear Centre in my city and they did it up for me for $150. The computer I am using is an EZ-TCU. There are many advantages to it. I set up my manual shifting on hidden toggles so I can toggle down into lower gears (paddle shifter). I used this feature because I didn't want to change my shifter or shifter display. In other words when I put my shifter into drive it shifts normally however if I want to shift into lower gears I use the self centering toggle switches that I hid on the console. It looks completely stock in the interior. I did have to modify my cross member to fit better but if you have a mig it took me approx 20 minutes to do. I have not had it on the highway yet as I am just finishing a frame off resto on it. hopefully in the next few weeks I'll get to try it out :)
     
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  19. LARRY70GS

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

    http://www.buickperformanceclub.com/switchpitch.htm

    There is a tag on the passenger side of the transmission case. It has a two letter code and some numbers. Erich that you have the correct transmission in the car. It could have been replaced sometime in the past 52 years.
     
  20. Jonah Halbert

    Jonah Halbert Well-Known Member

    I clicked the link. User buick64203 said my trans is a switch pitch. But my trans pan does not have the shoe dimple shown in the picture. I'll go check for a tag in a little bit. The cars on jack stands right now anyway.
     

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