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tufluv82toy

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Discussion starter · #1 ·
just curious if anyone has experimented with leaf spring angle. What i mean is the angle of the spring when mounted to the chassis when compairing the front eye to the rear eye. Seems the rear springs usually are more level but front springs usually are higher twards the front. I am playing with trying to get my front end planted more on steep ledges. Currently when i hang the front end over a ledge, and the suspension droops out, Im having trouble with the front axle trying to "walk forward" Dont say link it because for this project I have becomed determined to play with leaf springs and make them work the best they can. So far it works great accept for this one problem. I need to lower the front down some so I am thinking of either goign to a shorter shackle or moving the rear through the frame mount up. Opinions? would this help my condition? Have read some on race car leaf spring tech and dirt modified leaf spring tech and trying to get the most "planted" front end on leafs. Any experience would be appreciated. Looking for real world what works.
 
#5 ·
If the front eyes are lower than the rear eyes, the leafs will resist axle wrap better. Also pending on where the center pin/axle center is in relation to the center of the leafs will dictate how much the axle will move front to back. So if the center pin is nearer one end of the leaf, with the longer portion between the axle and the shackle, the axle will move very little, and then the opposite is also true.

I think thats correct, its been a bit since i played with leafs in my mud racer.
 
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Discussion starter · #7 ·
measured the height of front and rear spring eyes on several different 4x4s to compair. A shackle reverse yj, sprung over cj7 w longer front shackles, 71chevy w slightly longer shackles and my toy. the difference in height on all of them is within 1.5 inches with my toy having the most angle by .5in. I am running a custom deaver spring with the axle pin moved forward away from the shackle. I am thinking the best way to keep it working the way it does now and drasticly improve hill climbs is to make a suck down set up for the front. I may also shorten my shackles by about 1in to lower it down a tad and get rid of some spring angle......
 
#8 ·
mustange70 said:
If the front eyes are lower than the rear eyes, the leafs will resist axle wrap better. Also pending on where the center pin/axle center is in relation to the center of the leafs will dictate how much the axle will move front to back. So if the center pin is nearer one end of the leaf, with the longer portion between the axle and the shackle, the axle will move very little, and then the opposite is also true.

I think thats correct, its been a bit since i played with leafs in my mud racer.
Click to expand...


THIS

I build front hangers as low profile as possible so long as the angles are good and run the shackle tube up as high in the frame as I can then run as long of shackles as it takes to make the spring pack go flat just as the rear eye of the spring nearly touches the bottom of the frame. The eyes of the springs usually end up about level at ride height. I don't have many issues with climbing with this setup but I sure did years ago when I ran things like the bolt on companies wanted.. :homer:
 
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#9 · (Edited)
So Front hangers climb better? Is this on just ledges or climbing in general? I ask b/c Im still in the planning stage of an Leaf sprung SAS project and its posted everywhere to do rear shackles but we dont really have rocks where I play its steep dirt hills and washouts. Not to menting front shackles would be a metric shit ton easier to package with the shape of the frame.
 
#10 ·
I honestly don't know where the notion comes from That rear shackles are better on the road. I think there are a lot of other contributing factors that may lead to a better ride. Here's how I look at the climbing aspect of leaf-sprung configuration. With the shackles in front, the axle is pulling on the fixed mount, just like a link does. It is a direct pull on the chassis. With the shackle in the back, the axle can and will walk out from under the chassis due to it's design. A spring with a lot of free arch (like a Deaver) will be more likely to do this compared to a clapped out home brew spring, but I wouldn't trade the ride of the deaver's for anything.
 
#11 ·
From my viewpoint... shackle forward or back depends entirely upon if the springs you're using are flat or arched at ride height... Arched springs get longer... so a rear shackle would be better for ride quality... flat springs can only get shorter when compressed, so shackle up front will ride better.


To the OP: The term you're looking for is leaf spring datum angle.

I attempted to gain some tech on the issue a while back... but based on what I was reading in a rear application what I was thinking about trying would make it feel tippy due to completely fucking up the rear roll axis inclination. In the front I imagine having the front higher than the rear of the spring will be favorable(within reason) for ride quality... much like how flat control arms work better than angled down control arms such as a short arm lifted TJ.


Here is a link where I posted a pic illustrating the leaf spring datum lines... though no tech was added and I never really did anything else.

http://www.pirate4x4.com/forum/showthread.php?t=932981


FWIW I ended up just buying OME leaves and used my existing mounts and love them... The Jeep sits right and rides very well so I have no reason to do anything else for the time being.
 
#12 ·
Wilson said:
I honestly don't know where the notion comes from That rear shackles are better on the road.
Click to expand...
Never ridden a skateboard have you? Toss a yj into a corner and the wheelbase gets longer on the outside of the corner and shorter on the inside. That makes it a bit squirrly as the body roll changes the amount of steering input needed. Ever wonder why they have such large swaybars? You just learned what they are needed for. Same with the track bar, it can't be removed with a shackled forward setup either. Without it the steering would be more loose than a shackled rear design due to the shackles wobbling side to side on large rubber bushings. Add to that the axle moves forward into obstacles rather than rearward to absorb the terrain all adds up to a bumpy design on the road.

The easiest way to show how to set up a spring and shackle is to look at the rear of a full size American truck. Inverted "tension" shackles put the rear of the spring above the eye of the forward fixed mount. With no lift blocks there is very little to no axle wrap to cause wheel hop. Now do a common shackle flip moving the rear eye lower than the forward mount and the rear axle will try to crawl forward causing axle wrap and hop. The higher the rear eye is the more the axle will be driven into the ground when throttle is applied. Simple to setup and it works. :D
 
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Discussion starter · #13 ·
so in theory to get the best of both worlds i should leave it as is for high speed/handeling/ride quality and use a suck down for the steep climbs. Suck down would flatten the spring, push the shackle back and the spring eye up closer to the frame effectivly having the best of both worlds? if anything the axle can not hang and climb forward with a suck down so it should help....
 
#14 ·
DWT said:
Same with the track bar, it can't be removed with a shackled forward setup either. Without it the steering would be more loose than a shackled rear design due to the shackles wobbling side to side on large rubber bushings.
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cant take a trac bar off of a YJ? since when?. hell the CJ's never even came with trac bars and most didnt even have a sway bar
 
#16 ·
Wilson said:
I don't buy anything he says either. Sounds good in theory, but my experience speaks differently
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No problem what I say is free no need to buy it. :laughing:

Of course you can remove the track bar from a yj but the bushings in the springs and frame are much larger than those of a cj so it will lose precision in the steering as the axle moves side to side slightly while turning.

I don't claim to know much about links due to my limited time working with them. But I have leaf springs figured out pretty well from years of experience building packs and changing mounts and shackle locations around. 1/2 elliptical suspension ain't exactly rocket science. :flipoff2:
 
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#17 ·
I dont think I completely understand why a forward shackle would be better. I can see why it would stop the axle from walking forward when driving the front off a ledge, because as the axle droop, it moves slightly backwards (towards the rear). the problem I have heard is when you are climbing up something with a forward shackle and the axle is forced slightly forward, pushing you into the obstacle and not helping the climb.

I am sure I have something wrong and know there are others with far more knowledge on this stuff. I am building a slider setup like wilson above but was convinced against mounting them in front because of the reasons stated above.

School me so I aint talkin out of my ass anymore :D
 
#18 ·
1990GT50 said:
I dont think I completely understand why a forward shackle would be better. I can see why it would stop the axle from walking forward when driving the front off a ledge, because as the axle droop, it moves slightly backwards (towards the rear). the problem I have heard is when you are climbing up something with a forward shackle and the axle is forced slightly forward, pushing you into the obstacle and not helping the climb.

I am sure I have something wrong and know there are others with far more knowledge on this stuff. I am building a slider setup like wilson above but was convinced against mounting them in front because of the reasons stated above.

School me so I aint talkin out of my ass anymore :D
Click to expand...
From this thread in the LC section:

http://www.pirate4x4.com/forum/showthread.php?t=1024837


Wilson said:
You need to envision what happens after your tires cross the point where your imagination stops and it's time to pull the rear end up the wall. The shackle in front pulls from the fixed end of the spring, the shackle in back pulls the axle out from under the vehicle until it hits some sort of a "limit" and then it can start pulling. It's easy to push over the initial start on a climb, the rear does about 80% of the work, big climbs require the same performance out of the front.
Click to expand...
 
#19 · (Edited)
#20 ·
I agree with DWT on the fact that positively arched springs with a shackle in the rear will understeer and feel more comfortable on the road while positively arched springs with a shackle in the front will oversteer

I also agree with Wilson on the fact that when the front end is pulling from a fixed point (not a floating shackle) it will climb better

So what if u ran a flat spring with a forward shackle? This setup should understeer and climb better then a rear shackle setup, problem then is your spring mounts might end up hanging down pretty low
 
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