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View Full Version : shackle reversal vs shackle up front

jeeper89
March 17th, 2008, 10:57 PM
Pros and Cons of each. what do you prefer? and why?

edit** changing the front of my Toyota to shackle up front so i can get it as low as i can. and have less force pushing back when i drive up a ledge
MR.ROCKAPE
March 17th, 2008, 11:26 PM
In theory the shackle forward should climb better than the shackle reverse....as the front axle tries to drive itself from under the rig if the shackle is out front the leaf is pulling directly on the rear mount that cannot move.

Now in the same situation but the shackle behind the axle...the leaf will bowe as it tries to push the rig up by the leaf spring and against the solid mount out front...plus you get a jacking effect pushing the nose of the rig up...and since the shackle is just a follower it has not effect on keeping the axle in check...(yes my buggy is shackle reverse and I would change it if it wasnt getting links!!!!)
RADDONKEY
March 17th, 2008, 11:46 PM
The shackle in the front will hang up on the rocks as you start your climb as it is pushing forward. It also tends to unload on steep climbs, sending you over backwards easier. :Big Grin: Although it might make you famous. The steering also feels loose compared to rear shackle. I prefer the shackle behind the axle. I had 2 vehicles that I swaped from front shackle to rear and they drove and wheeled much better with the shackle behind. My $.02

1 vote behind:Big Grin:
L.D.
March 18th, 2008, 07:50 AM
In theory the shackle forward should climb better than the shackle reverse....as the front axle tries to drive itself from under the rig if the shackle is out front the leaf is pulling directly on the rear mount that cannot move.

Now in the same situation but the shackle behind the axle...the leaf will bowe as it tries to push the rig up by the leaf spring and against the solid mount out front...plus you get a jacking effect pushing the nose of the rig up...and since the shackle is just a follower it has not effect on keeping the axle in check...(yes my buggy is shackle reverse and I would change it if it wasnt getting links!!!!)

DAMN SON, PUT DOWN CRACKMONKEYS PIPE AND STEP AWAY SLOWLY.
with the shackles in the front, as you try to force the axle up a step the shackles will fold flat, bowing the springs. this pushes the axle down and the body of the rig up. as the tires crest the top and the springs unload it vialantly bounces over (providing you didn't go over bakwards). this is why the military moved the shackles to the rear on their jeeps. watch some older jeeps clime. with the shackles in the rear they will fold flat as the spring flattens itself with the axle pushing to the rear. the axle is pushed up into the rig, lowering the front . better controle and handling. try and think of it this way, is it easyer to pull a trailer, or push it ?
Connect
March 18th, 2008, 09:23 AM
Oh snap Mr. Rockape getting... Dare I say... Schooled?


:popcorn1:
MR.ROCKAPE
March 18th, 2008, 09:27 AM
SO YOU MEAN TO TELL ME ITS BETTER TO PUSH THE RIG UP A CLIMB BY THE LEAF SPRINGS THAN PULL IT???IM NOT TALKING ABOUT HAVING THE TIRE IN AN UNDER CUT AND HAVING THE REAR DRIVE THE LEAFS BACKWARDS INTO A BOW...

IN A SHACKLE REVERSE AS THE PINION ROTATES DOWN IT PULLS THE REAR OF THE SPRING DOWN AND PUSHES THE FRONT UP.....


I LIKE THIS ANSWER.....

http://www.pirate4x4.com/forum/showpost.php?p=6009005&postcount=6


KINDA THOUGHT JEEPER WANTED TO CRAWL........:eek:
MR.ROCKAPE
March 18th, 2008, 09:29 AM
Oh snap Mr. Rockape getting... Dare I say... Schooled?


:popcorn1:

UMMM...NO!!!GUESS IM PREFER LOW SPEED PERFORMANCE OVER FAST DRIVING AND SMOOTH RIDE......AGAIN MY TWO SEATER,TRUGGY AND BLACK CJ5 HAVE SHACKLE REVERSES....THE YJ THEY ARE OUT FRONT.....(BUT BROKE IT TOO EARLY TO TRY IT OUT!!!:frown:)
Connect
March 18th, 2008, 10:43 AM
UMMM...NO!!!GUESS IM PREFER LOW SPEED PERFORMANCE OVER FAST DRIVING AND SMOOTH RIDE......AGAIN MY TWO SEATER,TRUGGY AND BLACK CJ5 HAVE SHACKLE REVERSES....THE YJ THEY ARE OUT FRONT.....(BUT BROKE IT TOO EARLY TO TRY IT OUT!!!:frown:)

Makes sense to me reading Tech Tim's post. It always seems to me shackle forward approaching a face and climbing would unload the shackle and lift the vehicle up while arcing the spring.... Alot of this would have to do with the angle of the shackle at ride height, and the angle of the face.
Sierra Valley
March 18th, 2008, 03:32 PM
I have spoke with lots of people regarding this and most seemed to agree that they are better up front to pull you forward.

I have driven another cj7 with a shackle reverse and it did drive better on the street but Im not worried about that.

The reversal would seem to give you a better approach angle though.
L.D.
March 18th, 2008, 05:06 PM
so let me ask this, if having the shakles in the front, thus arking the springs and lifting the body is the better way to go, then why do you attach that little winch to your front axle and pull it up into the frame, so it will clime better ?
MR.ROCKAPE
March 18th, 2008, 06:11 PM
so let me ask this, if having the shakles in the front, thus arking the srings and lifting the body is the better way to go, then why do you attach that little winch to your front axle and pull it up into the frame, so it will clime better ?

IT DOESNT MATTER...EITHER WITH THE SHACKLE FORWARD OR REVERSE THE FRONT OF THE SPRING ENDS UP LOW OR YOUR FRONT DRIVELINE ANGLE IS FAWKED!!!AND IF YOU HAVE LONG SHACKLES DONE LIKE THE PIC CONNECT POSTED FROM SHAFFERS....IT WOULD END UP WITH EASILY AS MUCH CLEARANCE....

http://pirate4x4.com/forum/attachment.php?attachmentid=340276&stc=1&d=1197056800

http://pirate4x4.com/forum/attachment.php?attachmentid=347215&stc=1&d=1200521528

THE RIGHT WAY WOULD BE TO TURN THE AXLE Cs AND MOUNT THE SHACKLE LIKE ABOVE....BUT FORWARD AND STILL HAVE MAD CLEARANCE!!!!
renojeepster
March 18th, 2008, 08:58 PM
The only complaint I have on the shackle reversal on my Jeepster, is that the front axle is so far out of phase with the driveshaft. It takes a lot of maintenance to keep a 14" spline driveshaft working properly. I wish the front was like the rear, with 1/2" difference in driveshaft length from droop to stuff.
rusty_tlc
March 19th, 2008, 08:39 PM
My sad attempt at a shackel reversal. It works but not near as clean as the pic above. Then again it took a lot less skill.
http://i11.photobucket.com/albums/a171/Rusty_clt/build/Dscn1555.jpg

Here are the front hangers, and my bird crap welds.
http://i11.photobucket.com/albums/a171/Rusty_clt/build/Dscn1502.jpg
NoBrainR
March 19th, 2008, 10:13 PM
with the shackles in the front, as you try to force the axle up a step the shackles will fold flat, bowing the springs.

I've heard this argument before, and if I were going up a step in 2wd it would be true. But being the fronts are pulling, that changes.

Only time I've inverted my shackles was when I caught the shackle on a rock and didn't have a way to block the shackle. Since I've corrected that, I've never tweaked a spring since. I'm also running a front mil wrap on the 2nd leaf, rear mil wrap on the third leaf.

Plus I can run a stock spline on my front drive line and not worry about it pulling apart.

As far as the front unloading in a verticle climb, it's far worse with a rear shackle.
rusty_tlc
March 19th, 2008, 10:24 PM
I've never felt the front shackle unloading but I've felt the rear shackles unload going down hill.

Wouldn't the same principles apply? What I'm asking is why wouldn't you move the rear shackles forward to stop them from unloading going down hill?
MR.ROCKAPE
March 19th, 2008, 10:32 PM
I've never felt the front shackle unloading but I've felt the rear shackles unload going down hill.

Wouldn't the same principles apply? What I'm asking is why wouldn't you move the rear shackles forward to stop them from unloading going down hill?

I KNOW MY BUGGY THAT HAS FRONT LEAFS IS SCARY DOWN HILL WITH REAR SHACKLES......BROKE A STARTER IN HALF DURING THE SHAFFER THING....BUT HAVE NEVER HAD A PROBLEM SINCE AND I DIDNT CHANGE ANYTHING....:redface:
rusty_tlc
March 19th, 2008, 10:47 PM
I KNOW MY BUGGY THAT HAS FRONT LEAFS IS SCARY DOWN HILL WITH REAR SHACKLES......BROKE A STARTER IN HALF DURING THE SHAFFER THING....BUT HAVE NEVER HAD A PROBLEM SINCE AND I DIDNT CHANGE ANYTHING....:redface:

I was with lumpys Dad on Big Sluice and the rear springs on his rig unloaded. I pissed myself and he just drove out of it:rolleyes:. I get antsy driving down hill on steep ledges ever since, I don't drive as good as he does.

With the 40 there is a lot of weight on the front and I've never felt the fronts unload even though every one I ever been on the trail in has a shackle reversal.

I guess weight distribution has something to do with it???
NoBrainR
March 19th, 2008, 10:53 PM
I've never felt the front shackle unloading but I've felt the rear shackles unload going down hill.

Wouldn't the same principles apply? What I'm asking is why wouldn't you move the rear shackles forward to stop them from unloading going down hill?


Because your using your brakes going downhill (usually). Think about the wheels turning. If your wheels are turning in one direction, the torque on the axle wants to twist it in the opposite direction under power. With the brakes applied the torque twists the axle in the same direction as rotation.

Also what your interpreting as unloading, is actually weight transfer.
rusty_tlc
March 19th, 2008, 11:12 PM
Because your using your brakes going downhill (usually). Think about the wheels turning. If your wheels are turning in one direction, the torque on the axle wants to twist it in the opposite direction under power. With the brakes applied the torque twists the axle in the same direction as rotation.

Also what your interpreting as unloading, is actually weight transfer.
No brakes, the rig has gears.
Call it what you want, you could feel the springs hit a certain point and then they went from compression to resuming their natural curve. Mike just drove forward on the front wheels until the rear wheels couldn't keep up. He's my hero, like I said I was busy peeing my pants in the passenger seat.