Shackle Lift

[GM4Life]

Who here knows how much shackle lift i can put on the front before i start to get the dreaded "DEATH...WOBBLE!" Im looking at making new front shackles and making them 2" over stock so i can get 1" of actual lift. Does this sound good or what is the max i can lengthen them without having to turn the front axle?

[ALLJACKEDUP]

Quit being a cheap fuwk and buy a real lift kit

[GM4Life]

arent you that arrogant guy in general chit chat that everyone gets pissed off at occasionally? anyway i have limited options as to lifts and this is gonna be part of the total lift that will include a "real lift kit".

[ALLJACKEDUP]

every one in chit chat that way most of the time

[Donahue]

Originally Posted by ALLJACKEDUP

Quit being a cheap fuwk and buy a real lift kit

i agree with this statment. and i am not the board asshole.

[Donahue]

the length of shackle should not be used to "get more lift". it should simply be to keep the leaf from maxing out. and with a question this vauge, dont expect a good answer. i assume you gave a jeep? with shackles in the front? if this is true, i would concentrait on getting them in the rear. that is a better question, "how do i change my shackles to the rear?". and while you are at it, make the spring mounts lower, then you can get more "lift". because ride height is what wheeling is all about...

[HsOffRoad]

I really wasn't in the mood to type out all this on the board, but since no one else is helping you out I guess I will.

What you're referring to as "death wobble" is caused by the front knuckles losing their positive caster and going into negative caster due to the longer shackle rotating the axle housing forward. Stock front axles generally have between between 4-6 degrees of positive caster from the factory (the knuckles are angled backward, like the forks on a chopper motorcycle). This keeps the wheels wanting to track straight, and allows the tires to return to center on their own if you let go of the steering wheel.

By lengthening the distance between the frame & the spring (adding longer shackles) on the front end of the leaf spring, you change the angle that the leaf spring sits on, altering the angle of the knuckles. You can get away with around 2 degrees of positive caster and still possibly operate the vehicle on the street, but any less than that (moving towards 0 deg. or into negative caster) will make the thing next to impossible to drive at speed. You will constantly be correcting the vehicle just to keep it in the lane. If the shackles are in the back, lengthening them will do the opposite, it will add caster... but it will also add angle to your front driveline.

Now for a quick rundown on shackle location, since Donahue mentioned it earlier. In my opinion, for off-road use (provided the springs on your vehicle have some kind of arch to them), you want your shackles up front. people do shackle reversals to make the vehicles ride better on road and increase flex, but for rockcrawling, shackles up front is the way to go. Reason being, with the shackles up front, as the spring compresses it forces the front tire forwards, into the obstacle. This generates contact pressure, and with the weight of the vehicle pushing on the tire, it can generate a lot more grip to pull it up & over the obstacle. Also, by having the tire move forward as the spring compresses, the tire dosen't rub the rear of the fenders, and the front driveshaft slip yoke dosen't need to travel nearly as much as the suspension cycles.

If the shackle is in the rear, all of these ideas are reversed. The tire wants to move rearward as it encouters an obstacle, reducing contact pressure, shoving the tire into the body, and requiring much more movement of the driveshaft slip yoke.

The only negative effect of having the shackles up front is that they whack on everything and can invert the spring. The simple solution is to run boomerang style shackles (with a minimum thickness of 3/8") backwards on the front... the crossbar will bottom out on the frame before athe spring gets bent, and the thick shackles are tough enough to get whacked on rocks and survive.

As for lengthening the shackles, as the shackle gets longer, you increse leverage on the components it is mounted to, and the shackle plates themselves - which is bad. It also hangs lower to hit more things. Generally, for a compression shackle on a rock crawler, you want the shackles as short as necessary... desert race vehicles sometimes run very long shackles in tension style to increse travel, but that is a different story. Keep your shackles short and up front.

Lastly, regarding lift height, you do not want to increase the ride height if the vehicle if you can avoid it. This is a common misconception among beginning 4wheelers... everyone thinks that the more they lift their vehicle, the more capable it becomes. The exact opposite is true. When we build a rock buggy, we go out of our way to keep it as low as possible, so that it can opoerate on steep inclines and retain stability. You jeep will perform it's best keeping it as low as possible. You'll never run the extreme obstacles if you're jeep isn't low and stable. Consider cutting the fenders, lowering bumpstops, relocating the axles to fit larger tires, as opposed to lifting the suspension. Lifting the drivetrain is another good way to keep overall vehicle height down and still gain clearance. Keep it low, trust me.... it will work much better that way.

Hans

[GM4Life]

if i had a cj7 or something cheap that i wouldnt feel bad about cutting up, i would deffinately cut the fenders and relocate axles. i know about keeping it low and hitting the shackles. I probably wont have to extend the shackles but i would still, for reference, like to know if anyone is running 2" longer shackles on their jeep without any problems. Anyone know?

[fullygruntled]

I'm running 2" longer shackles, but then I'm also running 2" longer springs....

FWIW, I had the extended shackles with stock length AAL'd springs for too long. Shackle angles were horrible, astounded I never inverted them. It was completely impossible to flat tow, steering wandered, but I had no "death wobble." I thought "death wobble" was more a problem with front leaf-sprung trucks.

[Donahue]

"death wobble" usually refers to one of two things. not enough caster, and or not enough preload on a kingpin bushing (dana 60 style).

and for the record, i was telling him to go with rear shackles for on road driving reasons.

[HsOffRoad]

Donahue, Sorry if that post came off as me knocking you, that wasn't my intent. I agree, for on-road driving, the shackle reversal takes the hits out of potholes and such, keeps the vehicle tracking straighter, and helps with bump steer. Good mod for a street driven jeep.

Hans

[Donahue]

no prob, im not butthurt. i did however not know as much about front shackles for off-road. thanks for the info.