Ladder Bars

[SRT8a911]

I haven't really seen ladder bars around much on street vehicles since the 70's. Is it because today's suspensions are better? Are Ladder bars a mod that would make a difference or does ESP make up for it? What you say?

[bluecar1968]

4 link has replaced ladder bars because they are more adjustable and cost about the same. Neither is practical on a charger unless you are planning a straight axle swap

[maneval69]

Ladder bars keep the rear axle from rotating eliminating wheel hop. They also keep the universal from tearing a hole in the floor pan.( I've done that)
You can also throw a drive shaft this way.


I am not positive but if you have a problem with wheel hop in an IRS car, there is something wrong with the geometry or the links are weak.
In a 4-link you generally just need to beef up the stock parts to handle more power and traction.

[Deuuuce]

I think a Quaiffe limited-slip differential would be a far better investment for the street, strip and track.

Ladder bars (or traction bars) they were made for leaf spring cars right?
If you did do that, your handling would go away, far away, into the dumps.

[SRT8a911]

Thanks for the info guys. Great learning forum.

[bluecar1968]

I think a 4 link and a dana 60 would be cool

[TripleTransAm]

Ladder bars (or traction bars) they were made for leaf spring cars right?

I think those were called "slapper bars". They were those boxed bars that attached to the leaf springs to give them a stiffer characteristic than the original leaf spring configuration. To understand a leaf sprung car, imagine taking a flexible flat rod like a thin plastic ruler, and flexing it into an arc, with the center portion pointing down. In real life, that center portion at the bottom of the arc would be attached to the axle tubes, and either end of the arc would be attached to the car's frame. With the exception of some diagonal links from the diff housing to the frame to keep the axle centered, the leaf springs were all that kept the axle located front-to-rear... centered in the wheel opening.

Under torque, the axle tubes would want to twist... and so would the leaf springs! They'd want to twist into an "S" shape (try it with the ruler example above to see what I mean). As the tires would grab/slip, this would cause a rubbery 'hopping' which could do a number on a car's chassis, and overall traction under high power launches. The slapper bars (also traction bars?) would attempt to keep portion of the leaf spring flat with respect to a similar point on the leaf spring on the other side of the axle, to prevent this "S" from happening.

Here's an image I found showing leaf springs at rest, and under huge torque:

http://www.rockymountainsusp.com/SL_axlewrap.jpg

http://www.rockymountainsusp.com/SL_axlewrap2.jpg
For coil spring cars, there is an actual coil spring between each axle tube and the frame. This takes care of the up/down springiness, but to control front/rear location of the axle tubes, lower control arms will go between the bottom of the axle tubes straight forward to a pivot point on the frame (pivoting in order to allow up/down axle travel, in a slight almost-imperceptible arc). Again, to locate the axle left/right, an upper arm was usually used from the diff to the frame, at an angle (to both keep the front/rear location satisfied, and to keep the left/right location fixed as well). However, high torque cars would also cause flexing of these components and also cause wheel hop. Traction bars could be used here as well, although it would be nothing but simple reinforcing of the control arms and wouldn't really address the mounting points and any flex at those locations.

The ladder bar rear suspension does away with upper and lower control arms. Instead, at the locations where the lower control arm would have been (usually close to the wheel hubs), there are mounting points at the top AND bottom of the axle tubes. These two points are tied to a common front frame-mount using a narrow triangular link: the top point of the triangle is hinged at the frame mounting point, and the two other points will attach to the top and bottom axle-tube locations. The result is absolutely NO chance of the axle tubes twisting forward or backward under torque... the triangle won't let them.

And to keep the axle centered? There is an extra bar going from the lower mounting point at one of the axle tubes diagonally over to the frame mounting point of the OTHER triangular link. This prevents the whole axle assembly from shifting left/right.

Here's an image showing a set of ladder bars (the triangular units). Missing is the diagonal link.

http://web.inetba.com/autoweld/images/Prostr1new.gif


Edit: trying to figure out what the difference was between traction bars and slapper bars....
Seems traction bars are any additional members added to a suspension that has traction problems. This appear to range from a bar going from the axle tube to the frame to supplement a leaf spring system (ie. adding a "lower control arm" to a leaf sprung car) to a triangular type of "ladder bar" tied to the top and bottom of the diff and attaching to a crossmember or frame up ahead (think of one of those triangular bars but in the middle of the car instead of one at either side of the axle).

[1FST4DR]

I think those were called "slapper bars". They were those boxed bars that attached to the leaf springs to give them a stiffer characteristic than the original leaf spring configuration. To understand a leaf sprung car, imagine taking a flexible flat rod like a thin plastic ruler, and flexing it into an arc, with the center portion pointing down. In real life, that center portion at the bottom of the arc would be attached to the axle tubes, and either end of the arc would be attached to the car's frame. With the exception of some diagonal links from the diff housing to the frame to keep the axle centered, the leaf springs were all that kept the axle located front-to-rear... centered in the wheel opening.

Under torque, the axle tubes would want to twist... and so would the leaf springs! They'd want to twist into an "S" shape (try it with the ruler example above to see what I mean). As the tires would grab/slip, this would cause a rubbery 'hopping' which could do a number on a car's chassis, and overall traction under high power launches. The slapper bars (also traction bars?) would attempt to keep portion of the leaf spring flat with respect to a similar point on the leaf spring on the other side of the axle, to prevent this "S" from happening.

Here's an image I found showing leaf springs at rest, and under huge torque:

http://www.rockymountainsusp.com/SL_axlewrap.jpg

http://www.rockymountainsusp.com/SL_axlewrap2.jpg
For coil spring cars, there is an actual coil spring between each axle tube and the frame. This takes care of the up/down springiness, but to control front/rear location of the axle tubes, lower control arms will go between the bottom of the axle tubes straight forward to a pivot point on the frame (pivoting in order to allow up/down axle travel, in a slight almost-imperceptible arc). Again, to locate the axle left/right, an upper arm was usually used from the diff to the frame, at an angle (to both keep the front/rear location satisfied, and to keep the left/right location fixed as well). However, high torque cars would also cause flexing of these components and also cause wheel hop. Traction bars could be used here as well, although it would be nothing but simple reinforcing of the control arms and wouldn't really address the mounting points and any flex at those locations.

The ladder bar rear suspension does away with upper and lower control arms. Instead, at the locations where the lower control arm would have been (usually close to the wheel hubs), there are mounting points at the top AND bottom of the axle tubes. These two points are tied to a common front frame-mount using a narrow triangular link: the top point of the triangle is hinged at the frame mounting point, and the two other points will attach to the top and bottom axle-tube locations. The result is absolutely NO chance of the axle tubes twisting forward or backward under torque... the triangle won't let them.

And to keep the axle centered? There is an extra bar going from the lower mounting point at one of the axle tubes diagonally over to the frame mounting point of the OTHER triangular link. This prevents the whole axle assembly from shifting left/right.

Here's an image showing a set of ladder bars (the triangular units). Missing is the diagonal link.

http://web.inetba.com/autoweld/images/Prostr1new.gif


Edit: trying to figure out what the difference was between traction bars and slapper bars....
Seems traction bars are any additional members added to a suspension that has traction problems. This appear to range from a bar going from the axle tube to the frame to supplement a leaf spring system (ie. adding a "lower control arm" to a leaf sprung car) to a triangular type of "ladder bar" tied to the top and bottom of the diff and attaching to a crossmember or frame up ahead (think of one of those triangular bars but in the middle of the car instead of one at either side of the axle).
WoW,You got way to much time on your hands!! lol Nice write up!!

[smoke]

Just hearing about this makes me feel 10 years younger, had them on a 69 mustang GT I used to own, along with cragers and a lift kit!