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post #1 of (permalink) Old 02-18-2003, 12:16 AM
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Tj coils, front to back

i know that a Tj's coils are smaller in the front and wider in the back, what happens if i put front coils on the back?? just wondering...
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post #2 of (permalink) Old 02-18-2003, 05:00 PM
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Re: Tj coils, front to back

Your Jeep will go backwards in first gear and forwards in reverse. Don't do it!!

Not sure what would really happen, but I think the diameter of the coils is different, so they probably wouldn't fir correctly.

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post #3 of (permalink) Old 02-18-2003, 05:18 PM
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Re: Tj coils, front to back

Why did you think of doing that? DO you need a set of rear springs?
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post #4 of (permalink) Old 02-18-2003, 05:45 PM
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Re: Tj coils, front to back

well it'll probably ride really funny.....the stiffness of the springs si different....companys that make suspensions, lifts etc, usually matcha spring and shock to the weight of the vehicle to make sure its properly tuned. you can get a really goofy ride if your combo is over damped or under damped....

[img]images/graemlins/givemebeer.gif[/img] ====> [img]images/graemlins/40BEER.gif[/img] ====> [img]images/graemlins/thud.gif[/img]

edited: so basicvally what i was getting at is its a bad idea and you should prolly stay away from it
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post #5 of (permalink) Old 02-18-2003, 08:49 PM
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Re: Tj coils, front to back

Bigger ain't necessarily better. I'd say the rears have a softer spring rate and would let the front sag.

Think about it, a coil is just a torsion bar wound in a spiral. The coils twist to compress. Given everything else equal, the larger diameter means more leverage and easier to compress. Wrap it into a 2" OD coil and it's almost solid. Wrap the same spring with a large enough diameter so I is a single coil, it's easy to compress.
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post #6 of (permalink) Old 02-19-2003, 02:28 AM
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Re: Tj coils, front to back

I have been studying coil springs for quite a while now for my custom coilover conversion (almost done).
2 factors are to be taken into consideration
1) Spring rate (measured in LBS/ Inch) which is how many Lbs does it take to compress the spring by 1 inch.
2) Load carrying capacity of the spring

It's a bit tricky to understand but both factors affect each other.

There are many variables that make a spring stiffer or softer...
1) diameter of spring wire
2) number of wounds (coils)
3) outer diameter of each wound
4) free length

here is a site with a formula to play with....

What you will need greatly depends on your particular application... For starters spring rate is lower (softer) in the front and higher (stiffer) in the rear. Front weight is constant, as opposed to the rear where load can vary... check out Old Man Emu's spring rates chart... if you have a winch, heavy bumper etc... u'll need a higher rated spring....

Angle is critical too.... It has to do with the forces under which the spring has to work.... Given the same vehicle with same weight, the needed spring rate will have to be higher the greater the angle in which it has to work. Check out the stock front coil spring in a suzuki vitara (a relatively light vehicle)... but because they are mounted pretty angled, their rate is double than if they were upright...

To get the rates right you'll need to known the following data"
1) total vehicle weight
2) front vehicle weight
3) rear vehicle weight
4) weight at wheel
5) unsprung weight (like springs, shocks, diffs, wheels and tires)...

It gets a bit more complicated [img]images/graemlins/smirk.gif[/img] if you want progressive or dual rate springs.... you can also try the formulae at SwayAway's website
There's a lot more to know ... be patient... and enjoy the ride.

And that was my 2 cents..... now someone [img]images/graemlins/givemebeer.gif[/img]

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