four link suspension, need the correct angles for the bars.
four link suspension, need the correct angles for the bars.
(OP)
I am building a 1936 Ford street rod. I am wanting to build my own four bar, three point rear suspension. But I am not sure of the correct angles for the bars, or the proper place to mount them to the frame. Can anyone please help me?





RE: four link suspension, need the correct angles for the bars.
The trick with multilink suspensions is to keep everything square and equally spaced, until you have to change it. Also maximise the dimensions if possible, but not by sacrificing squareness.
So for a starting point
in side view make sure that the length of the two longitudinal rods equals the length of the A arm, and that they are mounted as much below the axle centreline as the A arm is above, and that at design height everything is parallel tot he ground (ideally).
In plan view make it all symmetrical, and keep the arms square to the axle.
Now the fun starts.
Back in side view, that arrangement will keep the diff parallel to the gearbox output shaft (which is good), but if you have a lot of suspension movement the propshaft or the diff or the pinion nose may hit the floor, or the UJ may over-articulate. So often you shorten the upper arm to dip the pinion nose as the suspension rises, or move the body mounting point for the A arm down. You need to make a model or draw it out to make sure that you aren't plunging the prop shaft too much if you do this.
In plan view on our four link beam axle we angle the upper arms in a bit, but you've already got that in spades, so I'd leave the lower arms parallel.
You'll need to post some more details and dimensions if you want to go further than that. Incidentally from the drawings I've found most non racers angle the upper and lower arms towards each other in side view.
oh one other thing - what is this suspension supposed to do? How much suspension travel does it have?
Cheers
Greg Locock
RE: four link suspension, need the correct angles for the bars.
This street rod will not be used for racing, only touring. So ride quality is what I am going after with this set-up. I would be more than happy to get you bar lengths, angles, and axle travel if that would be helpful with more advise.
Again, thank you for the information.
Thanks
Opie
RE: four link suspension, need the correct angles for the bars.
I forgot to add that in side view the links are often angled upward to give anti-squat on acceleration, and anti dive under braking.
Cheers
Greg Locock
RE: four link suspension, need the correct angles for the bars.
I think I recognize the configuration you described ... same as on the late 70's & early 80's full size Chevy and Ford. If so, the side view will define the instant centers for the upper and lower arms. The line between the two IC's will describe the roll steer. If this is the correct configuration, let me know & I'll shoot you a link to a webpage that will be helpful.
Kevin