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Technical What ratio Saginaw 4 spd would you choose for 2.75 ratio axle and 29" tire

Discussion in 'The Hokey Ass Message Board' started by oldrelics, Sep 9, 2018.

?
  1. 0 groove = 2.84

    0 vote(s)
    0.0%
  2. 1 groove = 2.54

    2 vote(s)
    15.4%
  3. 2 groove = 3.11

    5 vote(s)
    38.5%
  4. 3 groove = 3.50

    6 vote(s)
    46.2%
  1. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,729

    oldrelics
    Member
    from Calgary

    What 1st gear ratio Saginaw 4 speed trans would you choose? 3000lb? 47 ford pickup, . , ,75% street 25% highway ,mild 350 sbc , 2.75 axle and 29" tire
    0 LINE INPUT -2.84/2.01/1.35/1.00

    1 LINE INPUT - 2.54/1.80/1.44/1.00

    2 LINE INPUT - 3.11/2.20/1.47/1.00

    3 LINE INPUT - 3.50/2.47/1.65/1.00
     
    Last edited: Sep 9, 2018
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  2. RichFox
    Joined: Dec 3, 2006
    Posts: 9,405

    RichFox
    ALLIANCE MEMBER

    Weight of car? Engine size and tune? Rear end ratio? use expected? Need more info to even pretend to have an answer.
     
  3. chubbie
    Joined: Jan 14, 2009
    Posts: 2,256

    chubbie
    Member

    I have 31" tires 3:08 gears in a model A, I had the 3:11 low gear sagi and worked fine till it sounded like it had a bear in it (growl). so I changed it out for one with 3:50 low gear, just because that's what I had. like it more better, but the space between 3x4th is huge.
     
  4. jimmy six
    Joined: Mar 21, 2006
    Posts: 3,570

    jimmy six
    Member

    I'd go with 3.10 low. Pretty EZ on the clutch much better than the 2.54. 3.50 first would be the easiest on the clutch. If you could get an older OD unit it's pretty easy to install it and then go with a 3.90-4.11 rear gear.
     
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  5. Now Rich , you're really pushing it ...for a HAMB inquiry ;-)
     
  6. DDDenny
    Joined: Feb 6, 2015
    Posts: 10,821

    DDDenny
    Member
    from oregon

    The Muncie version.
    M-20.
     
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  7. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,284

    Kerrynzl
    Member

    3.11 will give you 8.55:1 overall 1st gear ratio [similar to a Muncie M21 with 3.9 gears]

    You can cruise at 65mph in 3rd doing 3044 rpm and you get to click it into "O/D" [4th] and the revs drop to 2057 to give your eardrums a rest.

    The lower 3 gears would almost be the same as the old Corvette close ratio 3 speed manual with a 4.0 rear end behind it
     
  8. 2.56 or 2.52 1st depending on the year. Mine was a 2.56 until I broke it, now its a 2.52 with the new parts. I would not use a Saginaw 4-speed myself. The old ones made for the V8 muscle cars are getting hard to find and really not worth putting any $$ into. At least someone re-pops the Muncies for us.
     
  9. Jimmy2car
    Joined: Nov 26, 2003
    Posts: 1,706

    Jimmy2car
    Member
    from No. Cal

    With that axle ratio, there's no good transmission option for what you've listed.
    Change the rear end gears
     
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  10. '51 Norm
    Joined: Dec 6, 2010
    Posts: 620

    '51 Norm
    Member
    from colorado

    I ran a 3 groove for years and loved it.
    Currently I am assembling one for my latest project.
    I'd like to put an overdrive behind it but that isn't something that is under every tree.
     
  11. DDDenny
    Joined: Feb 6, 2015
    Posts: 10,821

    DDDenny
    Member
    from oregon

    Bob
    I can honestly say I haven't heard the word "musclecar" used relating to Saginaw 4 speeds.
    Always thought they were commonly matched with the low hp 283's and 327's, never seen one but I've heard of 6 cyl/4speed Camaros, then of course there are the Vega and the Pontiac Astre 4 cylinder cars.
    I'm most familiar with Chevys so not sure what other GM divisions used the Saginaw 4 speed in V8 applications.
    The one oddity (to me) is the 67 Nova with the 325 hp rated L79 327, GM chose to put Saginaws in them and 10 bolt rearends, where the 66 L79 Novas (350 hp) had Muncies and 12 bolts.
    You are right about investing money in a Saginaw, and regardless of people claiming they don't plan on hot rodding their car, it goes without saying people generally increase a cars performance capabilities more than decreasing them.
     
  12. I stuck a 3 groove, 3.5 1st gear 3 speed in my 40 coupe, with 2.79 gears. It replaced a 350 turbo, so it totally changed the personality of the car.
     
  13. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,284

    Kerrynzl
    Member

    I disagree with that [unless the OP considers a 5 speed conversion with a lower rear ratio]

    What he is trying to achieve is a useable range in a lightweight vehicle . As long as the vehicle handles ok and isn't over cammed , it will make a pleasant highway cruiser.
    Too many people take the Neanderthal approach and build a "chest thumping nightmare"

    I am considering doing exactly the same as the OP to a '57 Chevy. [a car originally designed for 50mph speed limits]
    My choice of gearbox would be a 3.11 Saginaw using a modified column shift [behind a very mild 283 stroked to 307]
    Muncies & ST10's don't have a reverse safety needed for column shift.


    If I want to beat the shit out of a car, I'll jump into my race car.
     
  14. 34Phil
    Joined: Sep 12, 2016
    Posts: 150

    34Phil

    Personal experience is get biggest 1st gear with reasonable shift RPM drops to allow lower RPM starts. My worn out 6 cyl. F150 OD T170 4 speed was replaced by a Zoom non OD 4 speed. The original 4 speed had too large a drop between 2nd and 3rd, 48%. Zoom bigger 1st gear allowed starting at lower RPM while ratios were better. Keep ratio drops less than 30%. That is 4000 RPM shift is 2800 RPM in higher gear. For that reason I'd go 3.11.
     
    Last edited: Sep 10, 2018
  15. I knew some 396 Chevys came with a Saginaw, so did some Pontiacs and Buicks. One was a pretty stout factory Buick Skylark with a 400. Some Impalas with the 327 came with them too. I ran a 3.11 Saginaw with a Mr. Gasket shifter behind my 301 powered '66 Nova SS. I was conservative on my holeshots and it held up fine. Also a big consideration is parts availability, there is a raft of new parts around for the Muncies, but Saginaws very little.
     
  16. DDDenny
    Joined: Feb 6, 2015
    Posts: 10,821

    DDDenny
    Member
    from oregon

    Bob
    One other oddity that I recall is the 65 Corvette 396 was available with a three speed, not sure who mfg it.
     
  17. porknbeaner
    Joined: Sep 12, 2003
    Posts: 40,637

    porknbeaner
    Member

    That must be a New Zealand Speed limit. In the US many states had open speed law. IE "Whatever road and weather conditions allow."

    I may be mistaken but I have never owned a Sag with an OD 4th gear so all of them listed would be 1:1 final drive. Now this is going to sound mean (I hope) but you traditional 5 and 6 speed guys need to crawl back in your hole. he is trying to choose a sag not a tremac.

    If the car is very heavy with the airplane gear I would choose the lowest first gear available. If you are not canyon carving or racing of some sort the wider ratio won't really be a problem. I would also hope that your engine is a low RPM engine. If you start climbing up on the cam at say 3K you would be running in the neighborhood of 90 MPH just to keep from lugging your motor.
     
  18. I ran a 3.50 Saginaw in my 3300 lb 50 chevy delivery. Engine was a 406 SBC with mild cam. I used this setup because I was planning to drive the car on trips and picked a 2.29 little 10 bolt rear from an 83 cutlass and a 31 inch rear tire and a 12 inch clutch. It all worked perfectly. Low 1st gear meant easy starts in town.....high 4th gear meant effortless cruising on the interstates. Big clutch and mild cam worked great in this setup.
    No, I didn't drag race the car....if I'd planned to I'd have built it differently...made a wonderful street/road car. deliveryN48chev.jpg
     
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  19. There was a local guy with a Saginaw behind a built 396 in a '69 Chevelle. He later got killed in a gruesome car accident, but not in the Chevelle. That had a 3.10 or 3.50 1st gear, he tries to pull a hole shot off a parking lot speed bump and promptly grenaded the Saginaw.
     
  20. pitman
    Joined: May 14, 2006
    Posts: 4,484

    pitman
    Member
    from Hampsha

    Having a wide ratio allows use of a tall rear end gear. Best is that Fourth is 1:1, yet "overdrives".
     
    Last edited: Sep 11, 2018
  21. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,729

    oldrelics
    Member
    from Calgary

    Thanks for the replies, im definitely not straying from the 2.75, and not buying the 5spd $$$$, so i will find a 3.11 or the 3.50.
    I just drive, dont race, so im really not concerned with it holding up.
    What I REALLY cant stand is screamin revs down the highway.
     
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  22. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,729

    oldrelics
    Member
    from Calgary

    I had an off topic 79 malibu with the 2.29. Loved it....
     
  23. X-cpe
    Joined: Mar 9, 2018
    Posts: 326

    X-cpe

    Years ago one of magazines (Hot Rod ?) had an article on how to put the OD from a Saginaw 3 speed into a 4 spd,
     
  24. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,284

    Kerrynzl
    Member


    The 2.75 will work with a 3.11 sag. you're goals are realistic

    What you're actually doing is replicating what manufacturers did before the 5 speed came on the scene.
    They used higher rear end ratios and wider spread transmission ratios together.
    Just make sure the lower 2 gears have good synchros and the shifter is easy to use.

    Another alternative is a wide ratio Borg Warner Super T10 [ U-code or Z-code ]
    3.44 1st [3.42 1st on the Z code]
    2.28 2nd
    1.46 3rd
    1.00 4th

    I couldn't think of anything worse than sitting on an interstate at a constant 3200rpm for mile after mile. [which is a stock '57 chevy at 70mph for example]
     
  25. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 1,950

    GearheadsQCE
    ALLIANCE MEMBER

    I've done the Saginaw 4 speed with 3 speed O.D.
    I think the original article was in Hot Rod, July 1974.
    There are threads on other forums about doing this.

    The one thing I have never seen is how the disengagement of the O.D. when shifting into reverse was accomplished.
    I did it by welding a lump on the reverse shift lever shaft and shortening the rod that blocks the O.D.

    I don't believe I took pictures but if I find them I will post.
     
  26. porknbeaner
    Joined: Sep 12, 2003
    Posts: 40,637

    porknbeaner
    Member

    An OD car with a tall geared rear is not a good setup.
    He's running a 2.75 and tallish tires.

    the raven tried it thinking it would be the hot setup, I explained that it would not but he had to try it anyway. Before he put the higher winding 355 in the roadster he got a ticket for speeds in excess of 130, and he was just cruising. When he went to the higher winding mill he never used the OD, even at 1:1 final drive he was exceeding the speed limit just to keep from lugging the motor.
     
  27. pitman
    Joined: May 14, 2006
    Posts: 4,484

    pitman
    Member
    from Hampsha

    Good point about setting up, so your cruise rpm is ideal. 2200, 2400 or 2600, where ever your engine will pull from.
     
  28. jimmy six
    Joined: Mar 21, 2006
    Posts: 3,570

    jimmy six
    Member

    Pork... When I mentioned the OD I also mentioned going to 3.90-4.11's to be ez on the clutch. If he's staying with the 2.75 on the street; 3.5 or 3.11 low will be the ez est on the clutch for city driving.
     
  29. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 1,950

    GearheadsQCE
    ALLIANCE MEMBER

    Sorry, I got swept up in the OD talk. Definitely would not recommend an OD with the 2.75 rear gear.

    With the 1:00 4th gear, 29" tire, and 2.75 rear end 55 mph is 1907 rpm. That 350 needs to be 'tuned' to run at that rpm or it will be hunting. It will like 65 or 70 a bunch better.
     
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  30. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 5,231

    56sedandelivery
    ALLIANCE MEMBER

    Just remember, the 3.11 and 3.50 first gear versions were originally meant for Vega's and Monza's. As such, the gears are actually "narrower" (strength issue there), so don't beat on them like you would and Army mule.
    I am Butch/56sedandelivery.
     

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