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1955 pontiac manual 3 speed trans-hard question

Discussion in 'The Hokey Ass Message Board' started by kurts49plym, Aug 11, 2008.

  1. kurts49plym
    Joined: Nov 2, 2007
    Posts: 386

    from IL

    2 questions: I have a 55 Pontiac with a bad engine, and missing its 3 speed manual transmission. I wish to drop in a small block chevy and manual 3 speed. Are the shift levers in the same location so I can hook it up to the column shift? Also, The steering box is huge and looks like it may be in the way of a center dump exhaust manifold. Anyone done this swap? Anyone convert these to a center bearing driveshaft (like 63 chevy) because of the X frame? Thanks in advance

  2. Kurt:
    I do not believe the Chevrolet and Pontiac shift mechanism is anything alike.The Chevy uses two levers;one for reverse and first and the other for second and third,whereas the Pontiac I believe is similar in operation to the Oldsmobile in that one lever controls all the gears and the second lever moves the first in and out to effect a gear change.
    I would keep it all Pontiac using a later engine(check the Pontiac threads here for interchangeability)and transmission.
    The steering box and column do not use a rag joint(it is all one piece)but a 605 steering box can be readily adapted.You then have to either cut the column and install a rag joint or use an aftermarket column.A 55-57 Chevy column may work.
    A two piece driveshaft to me would be a waste of time installing.They are a pain to center properly and offer no advantage over a single piece shaft.
    BTW if you are going to dump the Pontiac bell housing and clutch assembly,I'd be interested in buying them.
    Sixhundred sixteen likes this.
  3. Gman0046
    Joined: Jul 24, 2005
    Posts: 6,260


    You don't want the pontiac transmission, its too small and its junk. The Pontiac column won't work with a Chevy transmission. Make it easy on yourself and use a floor shift on the Chevy 3 speed.
  4. A '55 Pontiac is a ladder frame with an X-shaped brace.

    Changing to a Chevy motor in one of these means re-engineering the steering, clutch, brake pedals, defroster/heater setup, basically it's a ton of work - or you can put a 55-59 Pontiac V8 in it that will bolt in, run the stock 55-57 left manifold and the stock exhaust routing, and be driving it sometime this year. A '59 Pontiac 389 can be rebuilt for about the same money as a later 400, which is close to as cheap as the Chevy kits, and they produce a ton of power.

    The stock '55-'57 manifold dumps in the front - there's no room for a center dump and not enough for a rear dump unless you move the motor over an inch or two and use the tightest manifolds you can find, or make headers that will fit. The master cylinder and clutch linkage also take up room under there making it hard to route a pipe. If you elect to move the master cylinder to the firewall, which you can do fairly easily with a 55-57 Chevy pedal set (or even 58-60 are pretty close and should work), the defroster section of the heater is in the way. So, you take that off to find the rest of the heater is under the front seat and you have to replace everything with some other heater - a 55-57 Chevy unit may work, but it gets expensive if you can't scare up a $500 parts car to strip out.

    As for the steering, the 605 box is easy, it bolts up to the linkage and into one hole, you need to make two more holes by drilling them and adding a section of tubing through the frame. Once you add that, you can use pretty much any GM steering column you want. The only other option is a stock 56-57 power steering box - 56 was the first year for a rag joint only on PS cars, they didn't get one on manual steering for a couple more years.

    If you search the board there are a number of threads - V8'ing a 49-54 Pontiac is similar and 55-57 Pontiac have the same issues as one another, the frame was more or less the same for all of those years.

    If you do end up not using the motor I'd be interested in the flywheel/clutch assembly.
    Sixhundred sixteen likes this.

  5. 55chieftain
    Joined: May 29, 2007
    Posts: 2,186


    Use a rh manifold on the drivers side. And use a front exit setup like the 287. Thats how i've seen a few other 55-56 Pontiac with chebbys:( and they used a Hurst style mount.

    Where are you at in IL? I would be interested in the valve covers, how is the passenger side with the strato streak emblem?
  6. kurts49plym
    Joined: Nov 2, 2007
    Posts: 386

    from IL

    You guys really are in the know on these! Thanks for the info. I live in Durand, IL 1 hr. south of Madison, wi. Kind of hard finding these 60 389s in reasonable condition. How late of years will these 287 exhaust manifolds bolt on to 389s? Being used to a 55 chevy, these baby's are really a different animal:D. I'll keep ya all in mind should I peddle these parts. I would like to 4 speed this now knowing the trans linkage for 3 speed is different. It's a hard decision on what to do at this point. Can I machine the bellhousing to adapt a muncie or BW 4 speed??:confused: should I go with the same kind of engine?
    Sixhundred sixteen likes this.
  7. There's a rebuilt '59 389 in the classified on here right now -

    On Pontiacs, a D-port is a D-port is a D-port, I'd have to go look at the '56 motor on the porch but '57 up any manifold bolts up - you might be able to squeeze headers meant for a tight engine compartment like a Firebird, in there.

    The 55-57 bell would need to be bored out and adapted to run a later trans; you need a 58-60 bell to bolt to the later transmissions directly, and those are like hen's teeth.

    This is one situation where going to an automatic saves a lot of headaches, as much as I hate to say so.
    osut362 likes this.
  8. Sixhundred sixteen
    Joined: Nov 2, 2012
    Posts: 37

    Sixhundred sixteen
    from Utah

    I realize this is a 10 year old thread; I'm gonna' comment anyway. > If you use a '58 to '60 Bellhousing on a '55 to '60 Pontiac engine you can bolt up your 4 speed.
    town sedan, F&J and Texas Webb like this.
  9. stuart in mn
    Joined: Nov 22, 2007
    Posts: 1,896

    stuart in mn

    The original poster hasn't been here since March 2017, so he may not see your reply...
    F&J likes this.
  10. razoo lew
    Joined: Apr 11, 2017
    Posts: 443

    razoo lew
    from Calgary

    On the other hand, someone who is looking for this information may see it. (and good of you to keep track of everyone’s last visit.....)
    F&J and Texas Webb like this.
  11. Its good these older posts are here.
    F&J likes this.
  12. lake_harley
    Joined: Jun 4, 2017
    Posts: 1,334


    Dragging up an old thread yet again, but does anyone have a '58-'60 Pontiac manual transmission bellhousing, flywheel and clutch referred to a couple posts up? I just got a '55 Pontiac 287 and might consider putting it in my '31 Ford Coupe if the engine turns out to be good enough to merit a rebuild. I'd plan to use a T-5 behind it and believe the transmission/bellhousing bolt pattern is the same as a Muncie or BW.



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