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Technical Chevrolet 1948 steering upgrade question

Discussion in 'Traditional Customs' started by Kontra, Nov 17, 2022.

  1. Kontra
    Joined: Apr 27, 2007
    Posts: 25

    Kontra
    Member
    from Finland

    Hello guys
    I'm quite new owner of 1948 Chevrolet. I have tried to look better solutions to replace original steering gear... Is there any reasonable price or easily to modified parts available?
    It has original front suspension and steereing gear.
    Mustang II is NOT an option!
    Attached is the "patient"

    IMG_7293.JPG


    Best regards


    Ari Berghäll

    Päätoimittaja/Editor in chief

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  2. HEATHEN
    Joined: Nov 22, 2005
    Posts: 8,583

    HEATHEN
    Member
    from SIDNEY, NY

    Several years ago, there was an article in either Street Rodder or Rod&Custom regarding Pat Ganahl converting his '48 Chevy to a 1960s/70s style General Motors manual steering box and tie rod ends.
     
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  3. Mr48chev
    Joined: Dec 28, 2007
    Posts: 33,950

    Mr48chev
    ALLIANCE MEMBER

    46 48 chevy steering.png 46 48 chevy steering (2).jpg [This image (top one) came out of an old thread where someone had a rusted out 46 crossmember and was asking about putting in a 49/54 crossmember. MgtStumpy posted this image of the 46/48 suspension. Swapping steering boxes should be fairly simple, improving the steering geometry may be a real challenge. The lshort and long tie rods that are on it now look like it could cause some issues.
    an improved setup would be the later box, an idler arm on the other frame rail with a center link and the tie rods pivoting at the same point where the lower control arms pivoted very much like most all later independent front suspension vehicles do.

    As far as changing the box and keeping the linkage, that may depend on how much fabrication you can do on steering and pass inspection. An all factory looking setup that doesn't look modified to someone who doesn't have serious knowledge of that front end setup might be a lot better.

    My doodled up image in the second shot.
    Yellow lines = Pitman arm and idler arm.
    Red = center link
    Blue = tie rods
     
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  4. Kontra
    Joined: Apr 27, 2007
    Posts: 25

    Kontra
    Member
    from Finland

    MR48CHEV Thanks a lot!
    I have to check this!!

    Best regards


    Ari Berghäll

    Päätoimittaja/Editor in chief

    PRIMER MAGAZINE

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  5. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,317

    gimpyshotrods
    ALLIANCE MEMBER

    There exists a (well, more than one) tie rod end that has an tapered hole in in it, for a drag link, or in this case, another tie rod end.

    If you ran a GM box, with one of these attached to the pitman arm, heading out to the right, with the left side inner tie rod assembly in the hole in the right side inner tie rod, and then off to the left, you probably would be good.

    The tapers in the various components might need to be reamed to fit.

    Something like this:
    [​IMG]
    That one might be too big, though.

    This one is a little smaller, but has less offset:
    [​IMG]
     
  6. jimpopper
    Joined: Feb 3, 2013
    Posts: 321

    jimpopper
    Member

    I put PS on an underpowered keep and had to add a pressure switch and a normally A/C throttle solinoid to bump up the throttle when the PS was making pressure to prevent flame out.
     
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  7. BJR
    Joined: Mar 11, 2005
    Posts: 9,899

    BJR
    Member

    Seems like the stock steering box is also too far forward.
     
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  8. Budget36
    Joined: Nov 29, 2014
    Posts: 13,244

    Budget36
    Member

    I’m no steering expert, etc. but when you lower the rear, raise the rear, it changes the steering geometry. I confuse camber and caster all the time, but one changes more and affects steering.
    I guess I’m saying before replacing stuff, have the front end checked out.
     
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  9. Cosmo49
    Joined: Jan 15, 2007
    Posts: 1,554

    Cosmo49
    Member

    Don't skip Arm Day at the gymnasium.
     
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  10. FishFry
    Joined: Oct 27, 2022
    Posts: 293

    FishFry
    Member

    Rear lowering = more caster. Its easy to remember when you think of caster wheels at a shopping trolley.
     
    Budget36 likes this.
  11. Put the '48 end on a 525 boxes pitman arm and then mount the 525 box so the end is in the exact same place it was, then deal with column offset.
     
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  12. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,317

    gimpyshotrods
    ALLIANCE MEMBER

    Everyone keep in mind that he is not in the US. He is in Finland.

    I am not sure what the regulations are for modifying things like steering components are there, if there are any.

    He would need to weigh in on that.

    For all we know it is a US-style free-for-all where welding a pitman arm won't even get noticed, or that it would get your car impounded.
     
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  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,317

    gimpyshotrods
    ALLIANCE MEMBER

    When the steering arms move in any direction, the tie rod position moves forward on the y-axis.

    When the pitman arm moves in any direction, the tie rod position moves rearward on the y-axis.

    As best as can be done with this arrangement, the two movements cancel each other out.

    You will note that the passenger-side tie rod end that is on the pitman arm is not the same line as the driver's-side.

    It is farther forward. None of this design is an accident.
     
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  14. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,317

    gimpyshotrods
    ALLIANCE MEMBER

    The current steering on this vehicle is a compromise in design. As vintage designs go, it is not all that bad. There have been far worse.

    The driver's-side tie rod is mounted in the "modern theory" that it should approximate the average length of the control arms, at the point where it crosses the imaginary line that intersects the upper and lower control arm mounts.

    Where the compromise exists is the passenger-side. That is made as long as possible, to make the deflection on cycling as minimal as possible.

    This made for reduced-cost in construction, and more clearance than an center-link would allow.

    The designs of both sides do that, just with different methodologies, with the passenger-side actually doing a better job.

    Building a reasonable duplicate, out of brand-new (or good used), unmodified parts, save for custom tie rod tubes, is well within reach. This could be with either manual, or power steering, as is desired.
     
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