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Technical Can a Saginaw take 300 horses?

Discussion in 'The Hokey Ass Message Board' started by ol55, Dec 22, 2018.

  1. ol55
    Joined: Oct 1, 2008
    Posts: 475

    from Virginia

    Have a ‘63 327 block with modifications that I want to put in my ‘55. Colllected two Saginaws (3:11 and 2:85 first gears) that I thought would be ok and 60s correct. Can the Saginaw handle that horsepower/torque for awhile? Have 3:08, 3:55, 3:70, and 4:11 stock rears to use.

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  2. RichFox
    Joined: Dec 3, 2006
    Posts: 9,930


    Mine did. But it depends on how you treat it. I didn't really bang shifts.
    mad mikey likes this.
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 46,096


    yup, if you bang shifts it'll wear out. Go easy on it, should last a long time, if it's in good condition to start with.
    LOU WELLS and mad mikey like this.
  4. thirtytwo
    Joined: Dec 19, 2003
    Posts: 2,628


    If it’s a good Saginaw I would think your about at its limit. And should take mild abuse.... if you go to the drag strip with slicks... expect to trailer it home
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  5. Nostrebor
    Joined: Jun 25, 2014
    Posts: 1,001


    I ran one in a street car for a long time with right at 300 horses. Hammered on it, but never made drag strip traction. They are actually pretty tough.
  6. oldiron 440
    Joined: Dec 12, 2018
    Posts: 1,507

    oldiron 440

    Get the right clutch and presser plate...
  7. '51 Norm
    Joined: Dec 6, 2010
    Posts: 691

    '51 Norm
    from colorado

    I ran a "3 ring" Saginaw behind a Pontiac 421 tri power for many years. I didn't abuse it too often and the only time it broke was when I got it crooked installing it. That resulted in breaking off one of the mounting ears. It ran with 3 mounting bolts and some JB weld until I could find a new case.
    I am currently putting one behind a Pontiac 455 and I'm a little worried that I'll manage to break it this time around.
    kidcampbell71 likes this.
  8. I ran one in high school behind a blown 327. I beat the crap out of it, it lasted for a while then the abuse caught up with it. Still that 4 speed took a lot .;)
    bchctybob likes this.
  9. Hollywood-East
    Joined: Mar 13, 2008
    Posts: 1,197


    It's All in the Left foot.... Make note:
  10. southcross2631
    Joined: Jan 20, 2013
    Posts: 3,750


    No slicks and make your clutch disc your disposable item in your driveline and they will run a long time.
  11. Joeh123
    Joined: Dec 22, 2018
    Posts: 9


    It will take more abuse than you expect. Probably the cast iron case helps a lot, the aluminum case Muncies would explode easier, in my opinion. If you bolt on slicks and try too many high rpm launches, the rear end and axles will break first. I ran a Saginaw 3spd, the original 6 cylinder unit, behind a strong 350" in a 68 Camaro for about a year. It didn't break, but I was also using a stock replacement 10.5 clutch assy. A stock clutch will have a little slip to it, and may help the other drivetrain components on down the line, survive longer.
    '51 Norm likes this.
  12. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,215


    First of all, stay away from the 3.11 and 3.50 first gear units; they were designed for the Vega/Monza class cars. Compare the "thickness" of those gears to the other one you have (the 2.85:1 first gear). Then, use a REAL shifter with gear stops (like a Hurst unit that's been fully adjusted). Secondly, compare the 3.08, 3.55, 3.70, and the 4.11 ring gear thicknesses; the 3.70 and 4.11 ring gears are very narrow (think gear deflection). Stay away from those. So, you're kinda stuck with a 2.85 first gear Saginaw, and a 3.55 rear end gear ratio (I would't use a 3.08 as it's just to high, and the others are too narrow). Even after all of that, if you beat on it, it'll beat you right back, and break when you really don't want it to. JMO. I am Butch/56sedandelivery.
    Last edited: Dec 24, 2018
    Nailhead Jason, Elcohaulic and raven like this.
  13. ol55
    Joined: Oct 1, 2008
    Posts: 475

    from Virginia

    Thanks, I’ m listening. I do have an older Hurst Competition Plus. Plan is to use 10” Cragar with L60- 15 metric replacements.
  14. I ran one in a Chevy II years back behind a 301 and it shifted well, gotta have a good shifter on it. The car was light and I was conservative on the hole shots. Like Butch said, avoid the ones made for the Monzas and Vegas. Mine came out of a '68 Chevelle with a 396.
  15. It's all about the torque you put into it. A 500HP motor that makes 300 ft-lbs of torque won't break it, a 300HP motor that makes 500 ft-lbs of torque will....
    G-son, Blues4U, wicarnut and 3 others like this.
  16. DDDenny
    Joined: Feb 6, 2015
    Posts: 13,433

    from oregon

    Every time one of these Saginaw threads come up I just want to ask "what do people have against using a Muncie 4 speed", or anything else for that matter, but a Saginaw?
    Hell, even when I was a kid we all knew not to waste our time with them.
    One response I hear over and over is "It's what I had laying around".
    I know for a fact; hot rodders rarely detune their engines and Saginaws are what GM put behind their low performance engines.

    Ok, I have to finally just say it, sell that crap, spend the money, move on.

    B Bay Barn, das858 and Deuces like this.
  17. sdluck
    Joined: Sep 19, 2006
    Posts: 2,411


    My buddy had a SS 396 1966 we had the muncie out for repairs and installed a monza/vega 4 speed in it till we fixed the muncie we power shifted it behind the big block,but is was a lot newer then. We never it broke it but I am sure it won't take that for long.
  18. mtkawboy
    Joined: Feb 12, 2007
    Posts: 1,213


    I had a 68 camaro with a 327/275 in it with a Saginaw 4 speed. never had a problem with it except for hard shifting, dont even think about trying to shift it fast though. I didnt like it but it was trouble free in normal driving
  19. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,537

    dirty old man

    Friend and fellow club member ran one for several years,in a 502 BBC powered "A" sedan, eventually it sorta gave up the fight.

  20. Exactly! I used a "three ringer" [think Vega, 3.50 first gear] Saginaw behind a 406 SBC with a 12" clutch in a 3100 LB sedan delivery and a 285/70 tire. I never broke it, BUT!
    I drove a buddy's big block el camino with a Saginaw and the first time I banged 2nd gear it scattered.
    And I agree with using a quality shifter. I used a yard sale "new in box"[$5.00] Hurst syncro-loc 3 speed shifter with stops and a new installation kit. Used a separate Hurst shifter handle for reverse gear. Adjusted it properly and never had any problems..
  21. dan griffin
    Joined: Dec 25, 2009
    Posts: 468

    dan griffin

    I remember talking to Larry Sinota in erlay 57 and he said it was designed to take 300 HP but would hold close to 500 HP. Considering the tires we had back then and the slicks were like big hockey pucks he was right.
  22. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,847


    The big difference between a Muncie and a Saginaw $$$$$$$. In the 70s a kid down the street ran a vega Saginaw behind a 425 hp 409 in a 58 Biscayne no slicks but it was driven hard.
    Elcohaulic likes this.
  23. 31hotrodguy
    Joined: Oct 29, 2013
    Posts: 1,476


    My buddy has one in his “stock” injected 57 vette. It runs 13.90 with slicks. I ran a 3.11 low 4spd OD in an OT 4500lb 67’ pickup truck with 400 Chevy. It twisted the drive shaft but didn’t brake the trans.

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  24. WB69
    Joined: Dec 7, 2008
    Posts: 1,226


    Had one in a 55 chevy with 450 hp, Hurst shifter, rodded the hell out of it without any problems. Sounds like I was one of the lucky ones to not break it......
    Elcohaulic likes this.
  25. I see a lot of people with manuals that shift like a school bus driver. One guy I know well double-clutches every shift in his OT ride. We used to break the transmissions by doing stupid stuff like not using the clutch pedal or trying to power shift like Grumpy.
    Elcohaulic likes this.
  26. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 911


    It depends on your coordination...
  27. slowmotion
    Joined: Nov 21, 2011
    Posts: 3,191


    Lotta factors as mentioned. When torque meets traction, the weakest links (if any) become apparent...:eek:
    '51 Norm likes this.
  28. Yeah, I'm fortunate to be able to row a 4-speed well. My brother is even better. We grew up street racing and shied away from automatics. Just about anyone we raced with had a 4-speed of some sort. We quickly learned that the Muncie and T10 were superior boxes. Top loaders for the Fords held up well too.
  29. Blues4U
    Joined: Oct 1, 2015
    Posts: 4,669

    from So Cal

    ^^ what he said. It's torque that will kill a transmission, not horsepower. A 300 horse 327 is not a torque monster engine. Too many full throttle side step launches wouldn't be a good idea, but then they seldom are. For normally aggressive street use it should be fine, if it's in good condition now.
    G-son likes this.
    Joined: Jan 13, 2004
    Posts: 2,758


    I'm going to try one in mine ,because I have it and I hate the cast iron glide.
    Deuces likes this.

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