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Rack and pinion on a 56 solid axle pickup

Discussion in 'The Hokey Ass Message Board' started by dubie, Oct 18, 2012.

  1. dubie
    Joined: Aug 17, 2004
    Posts: 698

    dubie
    Member

  2. I build and own race cars that use this exact type of steering system, and I would NOT recommend running one on the street; for one very simple reason.

    The rack is mounted directly TO the axle, so it moves up and down with the suspension. While this fixes a lot of bump steer problems, it means the intermediate shaft is telescoping in and out constantly as the suspension cycles.

    On a supermodified race car, the shaft is almost horizontal and there is only a couple of inches of travel, so there is actually very little sliding motion of the shaft. On your truck, with the rear mount steering box, the shaft will be sliding quite a bit. That's a big risk in the long term. Sure, they sell them and people use them, but I'd personally be doing constant maintenance on that intermediate shaft and I'd still worry about it binding up...
     
  3. richie rebel
    Joined: Oct 8, 2007
    Posts: 1,184

    richie rebel
    Member

    how about a telescope shaft?????,just thinking out loud..
     
  4. It does telescope Richie. ALL the time...
     

  5. richie rebel
    Joined: Oct 8, 2007
    Posts: 1,184

    richie rebel
    Member

    ok,i'm with you
     
  6. mj40's
    Joined: Dec 11, 2008
    Posts: 3,301

    mj40's
    Member

    "Perfectly designed to give you the best steering you can have with a straight axle".
    Not sure what they are trying to say here. But No Thanks!
     
  7. dubie
    Joined: Aug 17, 2004
    Posts: 698

    dubie
    Member

    so what would happen to the geometry if you used a later model steering box and placed it further forward?
     
  8. apache matt
    Joined: Feb 8, 2011
    Posts: 55

    apache matt
    Member

    I have the rack and pinion kit from no limit it seems to work pretty good. I had to use lowering springs on because the kit wouldn't work with a dropped axle.
     
  9. Ned Ludd
    Joined: May 15, 2009
    Posts: 4,251

    Ned Ludd
    Member

    The obvious way to use a rack & pinion with a solid axle would seem to me to set up the front end as for cross-steering, with a Panhard bar, only reversed left to right. Install an idler arm on the passenger side; both the steering cross-link and the passenger side tie rod off the rack & pinion attach to this.

    A moment's reflection reveals that there are lots of geometric possibilities in this arrangement. The idler arm can have any orientation as long as the free end moves substantially side to side; and the rack & pinion can have any orientation as long as its effective angle to the idler and its steering column connection are within limits. I can even think of cases where the rack & pinion ends up vertically beside the radiator - or alongside a frame rail.
     
  10. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    tommy
    Member Emeritus

    There was a short lived fad back in the early 70s when using flex shaft steering columns from Pintos. They look like shit and the fad died pretty quickly.
     
  11. rustang
    Joined: Sep 10, 2009
    Posts: 710

    rustang
    Member

    A guy I know mounted a R&P to his '57 chev pickup a few years back. He has the original front axle in the truck but lowered, so there is not much travel in the susp.

    He built his from Jeep parts if I recall, and everything is set up on the front side of the axle... he has put a ton of miles on the truck, and he does not drive it like a pussy, runs it hard.

    So far it seems to drive well.....I'm not clear on all the details of how he mounted it, but it does not seem to have bump steer or any nasty habits, and I've ridden in it quite a numbr of times...
    Tom
     
  12. Here's a pic of the same type of setup on an OT race car. Note how the inter shaft has a slip joint (kinda hard to see) and is angled down slightly. At ride height, that shaft will be almost horizontal. The more down angle the shaft has, the further it MUST slip as the suspension cycles. If it doesn't slip, something WILL break...

    THe closer the rack is mounted to the steering column, the more down angle you have, and the harder that inter shaft has to work over bumps.

    (Oops, here's the pic)
     

    Attached Files:

  13. willymakeit
    Joined: Apr 13, 2009
    Posts: 1,326

    willymakeit
    Member

    If your looking for less steering effort see if the large [1 ton up] boxes will work. They do on the F100's but have a extra turn lock to lock. There are kits for saginaw cross steer and toyota conversions. Something else to look into.
     
  14. yellowf100
    Joined: Oct 1, 2011
    Posts: 26

    yellowf100
    Member Emeritus

    we put the no limit kit in a 52 ford f1 this spring and it has driven flawlessly all summer, our only snag was we had to fabricate our own mounts for steering pump on the flathead, the truck is a pleasure to drive now
     

    Attached Files:

  15. Ned Ludd
    Joined: May 15, 2009
    Posts: 4,251

    Ned Ludd
    Member

    I'll bet it's occurred to more than one builder to use the steering column itself as one of the axle-locating links.
     
  16. 48FordFanatic
    Joined: Feb 26, 2011
    Posts: 1,335

    48FordFanatic
    Member
    from Maine

    I don't understand why there is so much concern about a telescoping shaft. Telescoping shafts are in use everyday and transmit lots of HP and torque in agricultural machinery. If properly designed and lubricated I can't see why it would be an issue.
     
  17. Absolutely, and every driveshaft on every solid axle car on the road does the same thing. Now, to put it simply, would you think it was safe to run a telescoping driveshaft at a 45deg angle?

    Like I said earlier, I put guys in my race car and run them 150mph with the same setup... I know they sell them and we've heard that they can be trouble-free. From a design standpoint, that high down angle is STILL not a good idea.
     
  18. Licensed to kill
    Joined: Oct 4, 2009
    Posts: 214

    Licensed to kill
    Member
    from Alberta

    I know this is an old thread but I'm considering this R&P on straight axle setup and I don't quite get the concern about the a slip joint in a steering shaft. Every highway truck has one (because the steering box is mounted on the frame but the cab is on air ride) and they will go a million miles without a problem. That slip joint gets quite a work out on off road trucks as the cab does a lot of rockin and rollin and they still are relatively trouble free. Why would the same concept be less reliable with the axle mounted R&P?.
     
  19. okiedokie
    Joined: Jul 5, 2005
    Posts: 4,308

    okiedokie
    ALLIANCE MEMBER
    from Ok

    The best driving hot rod I have ever driven is a 39 Ford coupe with a rack on a dropped axle. An old school machinist built it and I am copying it on my current 40 tudor build. Several 40/46's around here have been using them for years.
     
  20. gnichols
    Joined: Mar 6, 2008
    Posts: 10,989

    gnichols
    Member
    from Tampa, FL

    ^ Cool. Got pix to share? Gary
     
  21. BJR
    Joined: Mar 11, 2005
    Posts: 6,998

    BJR
    Member

    Is the slip shaft designed differently on a big truck, compared to the ones used for cars?
     
  22. Licensed to kill
    Joined: Oct 4, 2009
    Posts: 214

    Licensed to kill
    Member
    from Alberta

    I don't know what the ones that come with the R&P are made like. On the trucks it is a rather coarse splined shaft. The thought has occurred to me that I could maybe go to a truck wrecker and get the slip shaft to use if the one that comes with the R&P doesn't look very rugged.
     
  23. okiedokie
    Joined: Jul 5, 2005
    Posts: 4,308

    okiedokie
    ALLIANCE MEMBER
    from Ok

    Here ya go Gary. Still have to bend dropped steering arms up about 5/8" and take about 1" off each end of rack threads 100_9230.JPG 100_9231.JPG 100_9232.JPG 100_9233.JPG
     
    40 Coupe Since 69 likes this.
  24. I drove a 2000 [or so] IHC truck with this setup. The sliding joint was super simple and worked like a driveshaft slip yoke except it was almost half-again as big.
     
  25. gnichols
    Joined: Mar 6, 2008
    Posts: 10,989

    gnichols
    Member
    from Tampa, FL

    I've got the same deal planned for my model A coupe, but I'm still on the fence for beam or tube axle. Since it will have a 4-banger with exhaust on the right, I figure the steering linkage / slip joints will be a breeze to fab up. Gary
     
  26. OLDSMAN
    Joined: Jul 20, 2006
    Posts: 2,422

    OLDSMAN
    BANNED

    I would never do this, they just don't work right. A case in point, with all the money manufactures have, Freightliner trie this on some of their class 8 trucks, and now are changing them back to normal steering gear. An experiment that just didn't work out
     
  27. okiedokie
    Joined: Jul 5, 2005
    Posts: 4,308

    okiedokie
    ALLIANCE MEMBER
    from Ok

    Oh boy are there several around here who would disagree because they are driving the wheels off of their's with ibeam mounted racks.
     

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