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Discussion Topic:
front end alignment
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autoluke |
09-15-2019 @ 5:38 AM
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Member
Posts: 86
Joined: Jul 2017
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Thought that I would tackle alignment of the front end on my '41 convertible, but have hit a brick wall trying to orchestrate the relationship between the pitman link and toe in adjustments. The box and column are new from Lares, so that the steering wheel is centered when the pitman arm is vertical, but can't find the sweet spot when adjusting the pitman link...controls basically the position of the right wheel , but throws the toe on adjustment out of spec, Ideas ?
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40cpe |
09-15-2019 @ 6:45 AM
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Posts: 477
Joined: Jan 2010
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The tie rod sets the toe-in. Then get the steering box on the center of its travel and adjust/attach the drag link.
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therunwaybehind |
09-16-2019 @ 8:15 AM
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New Member
Posts: 180
Joined: May 2019
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Now this is why I joined the club. In the book, 1941-48 Ford Book by the Early Ford V-8 Club on page 4-5 it clearly shows a cross over link to the right side from the steering gear box and two mounting locations the passenger knuckle for that link and the end of the tie rod on that side coming over from the opposite (driver's side) steering knuckle. This is how my 1948 was rigged and I have been shown it was like that since 1937???!!! Pitman arm? vertical? That is for the earlier cars. You did write '41 convertible. Call me a virtual virtuoso with no current hardware but I don't buy this post. OK I looked for the less slang term and found 11A-3590C arm, steering gear LHD draglink and straight end to go with the 3306 drag link on page 4-5. By vertical did you mean most forward and vertical in the car or straight down (perpendicular to the steering mast) with the steering gear out and lying flat on a bench. In the car,the arm swings left and right in a plane that is inclined to the earth and perpendicular to the mainshaft up to the steering wheel. http://www.vanpeltsales.com/FH_web/flathead_steerngear_adjstmt1937-48.htm "Pitman" arm is something that comes from lumbering and the way the saw was used by two men vertically one above and one in the pit just like "flathead" is a term for the guys who made the actual cutoff of the stump to fell the tree. Back me off 4 notches on this one.
This message was edited by therunwaybehind on 9-16-19 @ 11:52 AM
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autoluke |
09-17-2019 @ 5:37 AM
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Member
Posts: 86
Joined: Jul 2017
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The pitman arm is in a true 90 degree position plane when the steering wheel is in the center of travel. Not sure about your question.
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therunwaybehind |
09-17-2019 @ 11:33 AM
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I understand the special position of the 1941 steering arm in the parts world, the note in what I referenced in the Green book that says straight end , refers to the later cars having a bent end to the crossover drag link. This I would guess is because the 1941 frame is slightly higher in the car than the later frames. Page 4-5 says "An important feature of the 1942 Ford was the lowering of the body relative to the frame-which gave the 1942 Ford a 1" lower center of gravity. Hmm? I searched out a post of someone who installed a 1937-39 steering box and shaft in a 1935-36 Ford. There he points out the same crossover draglink design but gives some differences in how the steering box is installed. My previous experience with a Pitman arm was with a 1934 Ford where it is indeed vertical and outboard of the frame to connect with the left or driver's side wheel. https://www.hotrod.com/articles/1107sr-f1-steering-boxes-for-pre-35-fords/ and the pickup in 1948 had gone back to that earlier style. This is where my question about "vertical" came from.
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therunwaybehind |
09-17-2019 @ 1:10 PM
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We come to very old and simple measuring instruments when speaking or writing about "vertical." The plumb bob is an old way of determining if something is vertical. The king pins can be compared to a plumb bob and used to examine inclination. How you would use a plumb bob to find your steering arm is vertical I don't know. For the steering wheel with two spokes you could lay a level across the spokes to see when the wheel is truly centered once the issue of turns lock to lock is cleared. Now then we come to the steering arm. We would like to show that it's bore for the tapered rod end is the same distance from the frame at a point an equal distance from the front on both sides of the frame. Of course it is closer by a lot to the driver's side but we can allow for that. How high or low it is effects the slant length of the measurements and I would ask if you are familiar with Pythagoras formulas for right triangles to make useful the various ups and outs to get a hypotenuse. Now back to a more direct way that depends on what you have just written that the plane that includes the steering arm and the steering mast up to the steering mast is vertical when the middle is achieved so place a long bolt through the bore of the steering arm and then attach a plumb bob (string or wire and weight) to the end furthest from the steering arm and as you turn the wheel ever so slightly note how the string either lays or does not lay against the lower part of the bolt. Hmmm! It hangs beyond the tip of the arm so you must also attach, perhaps with clamp, another rod to the top of the steering arm laid along it to touch the hanging plum bob. Now probably it is on one side or the other of the string. You could back it off and make it pointed until it just touches the string at a point. Next you want to set the wheels so that they both point not only parallel to each other but also parallel to the frame. This where king pin inclination becomes important. Yes, it should be fixed on a beam axle as on a Ford and would require bending if it wasn't but also we come to issues with trail of the axle position behind the tire contact point which makes the dynamics of the alignment stable as we run down the road. (This is something motorcycle and bicycle folks like to fuss with.) Next is something called Ackermann which is how much the inside wheel leads the outside in angle in a turn and was once seen as important to low tire scrub but has vanished as an issue in modern race car design. So we have the king pins inclined slightly back and somehow figured out the exact value in a similar way comparing to other plumb bobs laid along them. Camber is out next thought. We should find the king pins inclined so the tops of the tires are slightly further out than the bottoms. This is also important for stability of direction on a road. (It isn't really to drive on crowned roads.) As I remember Ford toe-in it is best at zero which is how the wheels are angled to the axle centerline side to side in a horizontal plane. Typically what one would see is strap iron rods run forward and aft from the wheel spindles perhaps attached to the spindles beyond the castellated nuts hidden by the caps over the bearings. and with a simple joint out front and back so one could adjust two more straps laid on top of the fore and aft ones one forward and one back so these run from side to side or right to left. Now once we know that the two measurements of the rods one front and one back are identical we are ready to use our plum bob again. Make a straight line that will be under the car from back to beyond the front where a plumb bob exactly hanging from the mid point of the front side to side rod is located touches the mid-point line of the car. Yes you may need a tape measure beyond the plumb bobs to measure the rods in the wheel frame. Vertical has taken you a long ways.
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therunwaybehind |
09-17-2019 @ 1:33 PM
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Once the bores of the respective future positions of the rod ends are fixed in space is hoped that the tie rod end tapered pins and the cross link ends will simply drop in! Now wouldn't that be wonderful. The next steps are to use the clamps and sleeves on the loosen the threaded parts so the length of the active parts of the car can allow this drop in. This may involve some angular movements of the ball and slot until there is no push or pull to throw off the semirigid frame we have built to hold the steering knuckles and the steering arm and the steering wheel. Force free is the goal. It is my belief that all the tapered pins go down through their mating bores. Whether they are truly "vertical" is something you will experience. If not there is friction but these are not places to lubricate. Because they are tapered bores they will vary a bit in draw down as the nuts on them are tightened. The rigged fixture described in my earlier post is the way to maintain management of the overall alignment.
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autoluke |
09-22-2019 @ 8:22 AM
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Member
Posts: 86
Joined: Jul 2017
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Thank you for the lesson in angular physics, but my problem seems to be otherwise. In order to be sure that my steering system was within all tolerances I replaced king pins and bushings, the entire steering box and worm shaft, pitman arm, and the two adjustable links. With the steering wheel centered, and the pitman in true vertical, the front wheels turn well in one direction, but in a substantially smaller arc in the other. ( toe in has been set to spec. ). Has been driving me up a wall, so that any ideas would be much appreciated.
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37RAGTOPMAN |
09-22-2019 @ 10:44 AM
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Senior
Posts: 1969
Joined: Oct 2009
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HI autoluke its seems to me the splines on the pit man arm shaft , and the pit man arm are off, there should have been factory alignment marks, when assembling, grooves in the splines should match up with grooves in arm pull the pitman arm back off, there should be marks where it lines up., I guess you did not mark anything before removing the parts, you can center the wheels, pull the pitman shaft off, center your steering wheel go from one side to the other, try finding the center, now attach both parts only snug up,[for time being } make SURE Tight after everything is ok, now try turning the wheels and back and forth from one side to the other, when the wheels straight ahead you steering wheel should be center, you can tweak it by adjusting the drag link, if it is off a little, to make sure the steering wheel is dead center, It is important because if everything is center, this is were the least amount of play is, soon and it come off center, you get a little more play, make sure there is no binding between the sector shaft and worm, let us know how you make out, are you using a shop manual ? hope this helps, 37Ragtopman
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therunwaybehind |
09-22-2019 @ 11:23 AM
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Posts: 180
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Are you complaining about Ackermann? That the wheels do not track exactly parallel and even in reverse seem almost to cause upset? Let me look up that term as it has gone out of style in design circles. https://en.wikipedia.org/wiki/Ackermann_steering_geometry ????
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