Why shackles instead of springs?

I was driving around today and saw some SUV's with springs for the rear-end suspension instead of shackels. What is teh advantadge / disadvantage of one over the other? Any insight on the XJ engineering on this?
Thanks
BSD

BSD said:

I was driving around today and saw some SUV's with springs for the rear-end suspension instead of shackels. What is teh advantadge / disadvantage of one over the other? Any insight on the XJ engineering on this?
Thanks
BSD

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You mean coils instead of leaf springs? As far as putting it on an XJ I believe that there are a few slinky jeeps out there.

sorry, meant leaf springs and was typing shackles.
BSD

the advantage to having a longer shackle is increased movement at that shackle which increases flex. On a short shackle the spring has to start flexing iimediately with a shackle twice as long the shackle moves forward allowing more dorrp before the spring needs to react

Another effect of changing your shackles is changing your spring rate. The more vertical the shackle the higher the spring rate (can carry more load). The more it lays down the softer your spring rate will feel.


Erik

Trailbst said:

Another effect of changing your shackles is changing your spring rate. The more vertical the shackle the higher the spring rate (can carry more load). The more it lays down the softer your spring rate will feel.


Erik

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but conversely, the more you angle the shackle the less travel you are allowing it. but the only real way to change the angle of a shackle is to use a longer spring, or move the mounts. in general you wont run into this unless you are modifying the system.

BSD said:

sorry, meant leaf springs and was typing shackles.
BSD

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So the question is - Why do XJs have leaf springs in the back as opposed to coil springs on other vehicles, such as the TJ?

(Some people don't read thoroughly before replying :laugh3: )

My shackles are old and rusty.


I've been considering a conversion,
but walmart has too many too choose from:

The Cherokee was built more as a utility vehicle. Leafs (more than likely) were used because they offer more weight carrying capabilities over a coil spring suspension. Late model SUV rear suspensions are designed more for "ride" over function.

Les

RTicUL8 said:

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Those parts look all to familiar when I had to overhaul my drum brakes....those springs are annoying as hell

LBEXJ said:

Late model SUV rear suspensions are designed more for "ride" over function.

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More or less, thats the bottom line.

Most trucks and early SUVs also featured leaf springs because they help to locate the rear axle - you'd need a track bar or similar to fully locate the rear axle from side-side movement, but the leaf springs will help to take stress of the locating mechanism.

Coil springs offer an additional degree of freedom, meaning that the axle will be free to move more if a stronger locating mechanism is not used. However, coil springs are also more compact - which is why they're used up front and leaves are still used around back.

Since coil springs are easier to "tune" WRT suspention performance, it's easier to make for a softer/smoother ride - which is what people want in everything (although, frankly, I like the way a truck rides, and I like to be able to feel the road under me, so I can respond to conditions faster.)

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