E Body rear spring angle

[rftroy]

So, as my first post to the site - Does anyone know the technical reason that E Body rear leaf springs are angled outward at the rear?  The fronts of the leaves are 3 inches closer together than the rear.

Robert

[Cuda Cody]

I had no idea they were different!  Learn something new.     And welcome @rftroy   Thanks for sharing that with us.  Do you have any idea why they did it like that?

[rftroy]

No.  That's what I'm curious to find out.  I can't think of a reason and I'm an engineer.

I have the Challenger up on its side on the overturning fixture and I just measured the distances.  The center to center of the front hangers is ~45 inches, the C to C of the rear hangers is ~48-1/16 inches.

I just looked in the 9th ed. of the DC Chassis book, and it shows that the E body springs are angled outward toward the rear by 1.67 degrees.
Something I just read that I didn't know was that 71 and later B bodies are angled inward toward the rear by 0.61 degrees.  And F Bodies have springs angled outward 0.85 degrees toward the rear.
A bodies and pre-70 B Bodies have parallel springs.

Robert

[Cuda Cody]

Do you think it could have been a by-product of a floor / seat design need and the small amount of angle was within a specification that would not affect the overall function of the spring?      Just guessing?  They must have done it for a reason, right?

[Roadman]

                                      Always wondered about that. 

[rftroy]

Do you think it could have been a by-product of a floor / seat design need and the small amount of angle was within a specification that would not affect the overall function of the spring?      Just guessing?  They must have done it for a reason, right?

I hope so.  I'd hate to think that someone put a crease in a final assembly drawing and didn't catch it until it was too late to fess up to management.  But you never know.
Bob

[Brads70]

I believe it has to do with helping to keep the rear end centered in the chassis when cornering. Sort of like what a panhard bar does.

[73440]

" installed rate is another rate all together. The installed rate is the rating of the spring as it is positioned within the chassis itself. Leaf spring rates can be increased or decreased based on the mounting positions and angles. For example, when the leaf springs are toed in (the front eye locations closer together than the rear mounts) the lateral rate or twisting resistance is increased, therefore one's side bite rate is increased."

https://landrumspring.com/technical/leaf-spring-technical-information/

The quote is from the link article.
I don't know the answer just found this info.

If I remember right , the Dodge pickup I rented in Nov had a panhard bar and it really handled well driving on the Colorado mountain roads.
My 59 Chevy Belair also used it.

[HUSTLESTUFF]

I think it was a little of both.  The tail of an E-Body is a little shorter than a B-Body and they probably spread the rear rails to get a big enough gas tank in and fit the exhaust.  It would also serve as almost like a tri-agulated four link does.  Mike

[HP2]

" installed rate is another rate all together. The installed rate is the rating of the spring as it is positioned within the chassis itself. Leaf spring rates can be increased or decreased based on the mounting positions and angles. For example, when the leaf springs are toed in (the front eye locations closer together than the rear mounts) the lateral rate or twisting resistance is increased, therefore one's side bite rate is increased."

https://landrumspring.com/technical/leaf-spring-technical-information/

This is the answer as to why. I'd also add that the wider the springs, and the wider the mounting position on the axle, the greater the the resistance that can be achieved with a lower actual rate so you get improved performance without a compromise in comfort.

The '71-79 B bodies and '76-80 F bodies  were splayed the opposite way for the same reason. A bodies never got it because they were going away in '76.

Don't forget, the 71 B bodies were late to market. They were originally supposed to be  '70 models to be released with the new E platform, but they were not ready.

[RUNCHARGER]

I have never seen an explanation however my theory is to package the mufflers beside the framerails underneath the trunk. Maybe the blueprints for the front hangars were cast in stone and they moved the rears later to fit around the mufflers and tank. I like Brad's theory too. You really have to hand it to Chrysler Engineers of the day. Look at the bottom of a 70 Mustang or Camaro. Then check out one of our cars. Work your way back, superior torsion bar suspension with great for the day geometry. Great clutch and the strongest 4 speed in the Industry, 7290 U-joints and a big driveshaft, Dana 60 rear axle with super Engineered, bias leaf springs. 2 1/2 inch headpipes with a superior exhaust system. It sure makes up for the crappy door panels and not so hot side window tracks and mounting.
That's why I love Mopars.

[HP2]

You really have to hand it to Chrysler Engineers of the day.

They were on it. There is a lot more engineering in a pair of mopar leafs and their layout than initial glance would imagine. The anti-squat percentage, instant center location, leaf width, leaf alignment, leaf taper, leaf ends, leaf interliners, leaf mounting positions, check rate, installed, rate, spring rate, axle location, control ratio are all factors  that make mopar leafs a lot more than simple buggy springs.

[RUNCHARGER]

They sure were. Just hit the throttle on a 480HP Stock suspension GM or Ford, no comparison.

[rftroy]

https://landrumspring.com/technical/leaf-spring-technical-information/

The quote is from the link article.
I don't know the answer just found this info.

This is interesting.  Thanks.  I'll have to do some math and see what the effect is.

Bob

[HP2]

https://landrumspring.com/technical/leaf-spring-technical-information/

The quote is from the link article.
I don't know the answer just found this info.

This is interesting.  Thanks.  I'll have to do some math and see what the effect is.

Bob

It reduces rear steer induced oversteer.

When a longitude mounted spring goes into a corner, the outside compresses and in the inside retracts. This has the net effect of shortening the inside wheelbase and lengthening the outside wheelbase which in effect, turns the rear axle towards the outside of the turn which loosens the car. Mopar's low arch design minimizes this motion and when combined with a splayed mount, reduce the roll oversteer effect which makes the corner turn in more linear.