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- Oct 18, 2007
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- Vehicle Year
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- Automatic
Not sure if this should be in the "Stock 4X4 & Off-Road Suspensions" forum, but whateve', a mod can move it if they feel like it. I'm basically throwing this out there to make sure I'm understanding things correctly before I set to work on modding my rear set up, and my pals Toyota.
I want to talk about leaf sprung rear suspension SHACKLES. More specifically, appropriate/desirable shackle length and angle. I am looking for input and to hear about some useful experiences guys have had changing their shackle situation. I know there is some very fancy shackle solutions out there, such as revolver shackles, and compound (double) shackles, and probably more that I'm forgetting. I don't want to get into those, I would like to just talk about basic, 1 hunk of metal per spring, shackles.
Length - Longer gains you lift, obviously. But long shackles can become a weak point when apply a side load to your axle, the most sever case would be whipping donuts on choppy ground. The most basic, and vulnerable (IMHO) is just two plates, the next step up is to weld a plate, or braces inbetween the plates. Thus making a C (or H) shaped cross section. This is significantly stronger. (eg, stock ford shackles, or the Belltech's)
Don't know how 'complex' the length part of this discussion might get. (I dont assume very...)
Angle - For a reference I'm going to refer between the angle measured between the frame and the backside of the shackle. I'm just gonna talk about my understanding of the situation here, I know there is some guys out there who are smart and worth listening to, and some guys who should be taken with a grain of salt, so whateve'
To have the shackle straight up and down is undesirable because the shackle does not offer you ANY droop when flexing. To have the shackle straight back is unacceptable because then it's not doing it's job, which is to allow the spring points to move relative to each other, because the curved spring has to flatten (bigger distance between the points) to allow the tire to go up.
Poor shackle angle on the left, no available droop from the shackle what so ever. I think the right pic shows good angle.
So, depending on your length of shackle (short shackle requires a larger angle) I think that approximately a 30 deg angle is what I'm after. I have Belltechs measuring 7.5" center-2-center, at approx 60 deg right now. They may get lengthened (1" or 2"), and I am considering moving the front leaf mount back a little bit, thus lengthening the wheelbase and reducing shackle angle.
There has to be enough rearward travel available (when at running height) so that the entire length of the (flattened out) spring can fit between it's mounting points. For us ford guys the spring is outside the frame, so when the spring curves up under extreme flex, and extreme tire stuff, there is no danger of the spring being interfered with by the frame. In the toyota camp, the spring is under the frame rail, then you would want the shackle long enough so that it still kept the hind end of the spring down far enough from the frame so that there was not interference and your still using all available flex.
This is just my understanding thus far, anybody with intelligent input please don't be shy!
I want to talk about leaf sprung rear suspension SHACKLES. More specifically, appropriate/desirable shackle length and angle. I am looking for input and to hear about some useful experiences guys have had changing their shackle situation. I know there is some very fancy shackle solutions out there, such as revolver shackles, and compound (double) shackles, and probably more that I'm forgetting. I don't want to get into those, I would like to just talk about basic, 1 hunk of metal per spring, shackles.
Length - Longer gains you lift, obviously. But long shackles can become a weak point when apply a side load to your axle, the most sever case would be whipping donuts on choppy ground. The most basic, and vulnerable (IMHO) is just two plates, the next step up is to weld a plate, or braces inbetween the plates. Thus making a C (or H) shaped cross section. This is significantly stronger. (eg, stock ford shackles, or the Belltech's)
Don't know how 'complex' the length part of this discussion might get. (I dont assume very...)
Angle - For a reference I'm going to refer between the angle measured between the frame and the backside of the shackle. I'm just gonna talk about my understanding of the situation here, I know there is some guys out there who are smart and worth listening to, and some guys who should be taken with a grain of salt, so whateve'
To have the shackle straight up and down is undesirable because the shackle does not offer you ANY droop when flexing. To have the shackle straight back is unacceptable because then it's not doing it's job, which is to allow the spring points to move relative to each other, because the curved spring has to flatten (bigger distance between the points) to allow the tire to go up.
Poor shackle angle on the left, no available droop from the shackle what so ever. I think the right pic shows good angle.
So, depending on your length of shackle (short shackle requires a larger angle) I think that approximately a 30 deg angle is what I'm after. I have Belltechs measuring 7.5" center-2-center, at approx 60 deg right now. They may get lengthened (1" or 2"), and I am considering moving the front leaf mount back a little bit, thus lengthening the wheelbase and reducing shackle angle.
There has to be enough rearward travel available (when at running height) so that the entire length of the (flattened out) spring can fit between it's mounting points. For us ford guys the spring is outside the frame, so when the spring curves up under extreme flex, and extreme tire stuff, there is no danger of the spring being interfered with by the frame. In the toyota camp, the spring is under the frame rail, then you would want the shackle long enough so that it still kept the hind end of the spring down far enough from the frame so that there was not interference and your still using all available flex.
This is just my understanding thus far, anybody with intelligent input please don't be shy!
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