Check out this video (not mine) of the rear suspension on a dirt track car.
Check out this video (not mine) of the rear suspension on a dirt track car.
Man there's a lot going on in that video
AngryCorvair (Forum Supporter) said:Man there's a lot going on in that video
There's a lot of voodoo for sure 
It's just a 3 link.
With a spring in the 3rd link so the anti squat reaction is softened.
And a third shock.
And the brakes are decoupled from the axles, so the brake anti-s are not compromised by the acceleration anti-s, and can also be tuned separately.
And the brake linkage looks like it is also used for axle steering.
Which will also be dependent on the spring rate of the pullbar.
But, it's just a 3 link
Does the pinion angle change come as a result of the pinion gear interacting with the ring gear? I.e. the pionion gear is shoving the ring gear "downward" as it's trying to spin it? I kind of assumed I'd see the pinion rise up upon acceleration, because I figured the tires would be resisting a change in momentum, so the entire axle housing would twist the other way, but now I feel like the interaction there is actually occurring at the ring and pinion interface.
Or--and this is almost certainly the case--I don't have a clue how any of this voodoo magic works, and it's very pretty to watch!
In reply to confuZion3 :
The pinion angle changes because the suspension allows it. You can make a suspension where the pinion angle doesn't move at all, like the equal/parallel 4 links popular with stage rally cars.
But when you do this, you don't get any antisquat, which is the torque reaction force between the rearend housing and the tires forcing the suspension down. This requires pinion angle change because the pinion is kind of fixed relative to the housing and the housing has to rotate in suspension travel to get any anti-s.
Another way to look at it, axle torque tries to rotate the axle just as hard as it rotates the tires (every action has an equal and opposite reaction) and the suspension keeps the axle from doing this. If your suspension geometry is such that the axle rotates "up" in droop, then that torque reaction will tend to force the rear suspension down.
Likewise, brake torque tries to torque the rearend the other way. IF your calipers are mounted to the rearend housing, and not on a movable plate that has its own linkage...
If i'm looking at that right, it's a 3 link, but each side's "link" is actually 2 bars attached to a bearing such that they can rotate about the axle?
i'm also fascinated by the panhard bar that is short, hook shaped, and mounted to the pinion. Very cool
Here is what it looks like from the outside. This is a Hughes Chassis modified, but similar. Yes the left front is off the ground.
and the result.
budget_bandit said:If i'm looking at that right, it's a 3 link, but each side's "link" is actually 2 bars attached to a bearing such that they can rotate about the axle?
i'm also fascinated by the panhard bar that is short, hook shaped, and mounted to the pinion. Very cool
It's a four link, the lower link isn't really visible until stuff starts happening. I missed it at first too. I guess technically a five link since it also has the upper link that controls the pinion angle.
My assumption based on the motions is that there is no upper link on the right side. There is a semi parallelogram on the left that the brake is attached to, whose lower link is attached directly to the axle.
So when the pullbar stretches, axle steer also changes.
I think...
I'm guessing the massive pinion angle change isn't a big deal because on the rear of a dirt modified car where the wheels are slipping constantly anyway, wheel speed fluctuations with every driveshaft rotation aren't even noticeable.
Edit: I'm guessing the violence of hitting that completely inflexible all-metal limiting strap isn't noticeable over everything else either...
You'll need to log in to post.
