Trianglulation in suspension

Since there is already a thread discussing this it got me to thinking about triangluated 4 bars...again. I am not posting this to hack on other people's design, just to point out what my conclusions are and how I arrived at them.

Personally, I think the widest point of the triangle should be on the rear axle, not the frame mounts. If you think about the twisting forces applied if one tire had traction, and one didn't, the design with the axle mounts out toward the wheels is going to receive less stress to several times the magnitude than the design with the mounts close in to the punkin. To make the point, have someone hold a 4' long stick with both hands together in the middle and you grab the ends and try to wrench it free. Now hang on right next to the other guys hands and try it again.
Not only that, the arc of travel is a lot greater with the outward mount so suspension deflection (of one wheel) will be more on the axis of the bushing instead of twisting the bushing. Make sense?

WB3 you lost sleep over this didn't you. think about doing a wheel stand, what and where is the force that makes a car do a wheel stand.

Any taker on this.

I'll be back.

If you only had the top bars, what you are saying would be correct however, they are only part of the rear suspension, the lower bars are what take most of the load of the rear tires forward motion under traction.
To clarify, when one tire has more traction than the other that sides lower bar is what takes the bulk of the load of the twisting effect.

Dirtyrat said:

http://www.how-to-build-hotrods.com/triangulated-4-link.html

Click to expand...

That looks a whole lot like my rear suspension, although the longer, straight-ahead links are made up of ladder bars. When I get home and get my brakes bled, I'll go out and drive the car. Then we'll know whether or not it works.

Old Iron said:

If you only had the top bars, what you are saying would be correct however, they are only part of the rear suspension, the lower bars are what take most of the load of the rear tires forward motion under traction.
To clarify, when one tire has more traction than the other that sides lower bar is what takes the bulk of the load of the twisting effect.

Click to expand...

Right. I guess my line of thinking came from mine using the 1/4 eliptics in place of the lower links.

the main reason for running the small end of the "V" over the center of the rear end is to place the roll center on the same plane as the housing. if you put the small end of the "V" on the frame ahead of the axle plane you create a secondary roll couple unaligned with suspension.

also with the "V" on top of the diff the ride quality is enhanced due to smoother movement over one-side bumps or dips, because it allows greater vertical roll with less resistance. an anti-rollbar attached to the bottom arms is the traditional way to reduce or control excessive lean in corners.

Animal: if you are saying your lower links are "ladder bars" solidly attached at the rear housing and only pivot at the front, you will find a huge binding motion if you have also included splayed upper links as in the illustration. ladder bars on a leaf sprung car usually don't require lateral control. with coils or air bags a watts linkage, a diagonal link between the ladder bars' or a panhard bar is needed to control lateral forces.

Theres always an ideal situation but somtimes you have to work with what you got.

pinion walks up the ring gear due to friction of tires to road surface

Ricks Garage said:

pinion walks up the ring gear due to friction of tires to road surface

Click to expand...

When I started reading your post I thought it was going to be a joke

BlueNorther said:

Animal: if you are saying your lower links are "ladder bars" solidly attached at the rear housing and only pivot at the front, you will find a huge binding motion if you have also included splayed upper links as in the illustration. ladder bars on a leaf sprung car usually don't require lateral control. with coils or air bags a watts linkage, a diagonal link between the ladder bars' or a panhard bar is needed to control lateral forces.

Click to expand...

BlueNorther .... In my case I am running trailing arms on a 66 Chevy pickup...would these also act as "ladder bars " as you explained to Animal ?? Am I wrong if I just stick a panhard back in there...side to side like it was ?

Oldog

66 Chevy pickups have what is called Truck Arms with coil springs. There are no upper bars on this type of setup.
It should already have a panhard/track bar on it.

Old Iron said:

66 Chevy pickups have what is called Truck Arms with coil springs. There are no upper bars on this type of setup.
It should already have a panhard/track bar on it.

Click to expand...

Old Iron .....what I did was arch the rear and removed the springs for air bags I am not looking for a mean green handling machine , just to track well . Here is where I am now would you place the new panhard horizontal with the rear to frame arch ?
Can see on page 3 here ;

http://ratrodsrule.com/forum/showthread.php?t=30537&page=3

Since you're running bags, a panhard parallel to the axle at ride height would be the way to go. The longer the better.

Or a watts link.

OddRodsGarage said:

In my case I am running trailing arms on a 66 Chevy pickup...would these also act as "ladder bars " as you explained to Animal ?? Am I wrong if I just stick a panhard back in there...side to side like it was ?
Oldog

Click to expand...

I was in you shoes,I used a 69 rear and made short arms.A panhard bar was the best for this otherwise a tri upper has to be exact to prevent binding axle travel.

OddRods, what Sam said is correct.
Just make sure the panhard bar is at the same level horizontally as the center of the rearend housing at ride height.

This one's a little high on the right but, you get the idea

Ricks Garage said:

pinion walks up the ring gear due to friction of tires to road surface

Click to expand...

Bring on the wheel stands

OddRodsGarage said:

BlueNorther .... In my case I am running trailing arms on a 66 Chevy pickup...would these also act as "ladder bars " as you explained to Animal ?? Am I wrong if I just stick a panhard back in there...side to side like it was ?

Oldog

Click to expand...

Old Iron said:

66 Chevy pickups have what is called Truck Arms with coil springs. There are no upper bars on this type of setup.
It should already have a panhard/track bar on it.

Click to expand...

The 60's Chevy Pickup 'truck arms' work very well due to their own unique design. Their I-beam construction can flex and rubber front mounts combined with the U-joint being right at the front mounts allows good articulation and a sturdy setup. Panhard bar is essential of course. NASCAR racers still use a variation of it to this day.

That "truck arm" setup is what was under my 48 Olds originally.