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Steering rod type question

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rooman:
On a Don Long car there are four radius rods which determine the arc that the axle swings through as the suspension articulates, The torsion arm is a lot shorter and swings in a tighter arc so the holes where the arm attaches to the axle are slotted so that things don't get into a bind. On a regular two radius rod deal this is not necessary as the torsion arm is in effect the lower radius rod.

Roo

LZ:

--- Quote from: rooman on March 01, 2013, 05:26:47 AM ---On a Don Long car there are four radius rods which determine the arc that the axle swings through as the suspension articulates, The torsion arm is a lot shorter and swings in a tighter arc so the holes where the arm attaches to the axle are slotted so that things don't get into a bind. On a regular two radius rod deal this is not necessary as the torsion arm is in effect the lower radius rod.

Roo

--- End quote ---

Thanks Roo;
I was always wondering this in the back of my mind. But I am still thinking about this though. As you describe, the slot length and location would be a critical item then. As this is holding Caster as she swings.  Even though it is a small amount and the  4 point long Radius Arms would keep the caster at set more so the a double radius arm. But the one Arm is not controlling Caster with slots.
With the Long style front end the one Radius Arm would be a safety of sorts if one failed.
I have a hard time putting thoughts to sentences, but do you get what I mean?? :-[

I seem to remember a couple dragsters but more-so Altered s with a Torsion front that had a link between axle and torsion arm and this accounted for the different swing arcs.

Mike hey we need more shots of your car, very nice.
On a side note with your front the way it is it nice you can get the tank way up there.
FED's nowadays carry so much more items on them ( then in days afar) .
Thanks
Luke

hotrod316:
new thought,
 if the slot will let you move the axle back 1/4"of and inch, lets say, on the right side, will this move the right wheel back 1" or may be 2"  and then a stagger in the car?
will lay it out today on our car and I will let you know what I find out.
this came to me in my sleep last night 8)
just a thought?
man I need to start drinking more mountin dew or quit thinking :-\
steve m.

rooman:
Luke,
       on a car with a single radius rod per side the torsion arm can't have a slot because the arm is the lower radius rod. Back in the day some cars had a small wishbone between the torsion bar tube and the axle. That provided lateral location of the axle (I guess they felt that the torsion arms were not enough) and also acted as a radius rod so in that case a slotted arm would work. Long's set up is the best engineered of all because it maintains castor and the way he puts the king pin axis, radius rod attachment and drag link/steering arm attachment all in the same plane means that the car does not tend to steer itself as the suspension droops at the launch.
 The oft posted Old Master build story is really the best way to learn how to build a front motor dragster. Some of the technology has changed (motor angle and location etc) but the basic engineering theory is still true. With a copy of that story and a set of SFI specs you can't go wrong (well, maybe some people could but they are the ones who should not be allowed out in public).

Roo

hotrod316:
I pick up 5/8 of and inch of stagger with a 1/4" slot  :o

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