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Discussion Starter · #1 · (Edited)
I am trying to design a true cantilever suspension for my silverado. As you can see in the attached photo, I would like to have a shockwave with 4.1" of travel attached to a rocker arm which in turns pushes on the parallel 4 link. I was looking for 10-12" of lift so i would need a 2.5-3:1 ratio. My questions are about the the two different leverages and the load capacity. The rocker arm i drew up is 2:1 so when the bag lifts 4", the rocker arm moves down 8" but where do i need to place the push rod on the parallel 4 link so I dont have too large of a ratio causing the truck not to lift. Also should i use bushings for all the pivots, heims or jonny joints?
My 4 link bars are 26" on center and the 4 link is inside the frame because the rear was narrowed for 24s. Any help is greatly appreciated.
 

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bitch
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geez man havent seen you on here in forever
 

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S - I - C
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Well you're getting 8" of travel out of the rocker arms so you need another 2-4" on top of that. So 1.25-1.5 to 1 ratio on the link will get you to the 10-12" total lift. I'm just wondering, do they make a shockwave with a high enough capacity bag to still ride good and lift the rear of the truck at that ratio? And why don't you just put the whole ratio in the rocker arms?
 

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VVVthat thing is deadVVV
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never mind i guess he got banned for abusing his priveleges as a moderator on here. the thread should still be able to answer any questions
 

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first problem i see is all of the weight on a single parallel bar. unless u have some completely beefy bar that is irregular on parallel's i would suggest having an underbar gusset to help support the weight. but u probably already know that
 

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Discussion Starter · #8 ·
First, the s10 was sold back in 2004 when i bought my silverado so I could bag it. Its still around though. I sold it to a kid that lives 1/2 hour from me and he took the bags out of the rear and left the front bagged so he's driving around in a bodydropped truck with a monoleaf setup in the rear. He hit a few potholes with front down and he completey ripped the rocker away from the truck so it was just hanging there last time i saw it.

Second, I wanted to keep the shockwaves as close to the notch as possible to keep from cutting a lot of my bed so that why i didn't put the whole ratio in the rocker arms. The skw2000 shockwaves have a load capacity of 3150 lbs but with a 3:1 its 1050 per bag.

Third, the parallel 4 link will be supported with another tube along the bottom.

So if need a 1.5:1 ration to get the 10-12" of lift on top of the 2:1 in the rocker arms, does that make it a 3.5:1 ratio overall? I'm not sure what the rear of my truck weighs but do you think its more then 2000 lbs? Anybody have experience with a canti system using shockwaves?
Thanks
 

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gumby green
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alright steve i did some basic statics for ya... if your bag can hold 3000lbs, and you have a 2:1 ratio on the rocker at the top that means the most it can hold is 1500lbs...

now on the parallel 4 link you said the truck could possibly weigh 2000lbs so the fact that you have two sets for parallel 4 links divides it by 2... so you have a 1000lbs load on the end of your 4 links bars...

so in order to not exceed the strength of the bag you must place the push rod no closer than 17.3" from your moment arm, or 26-17.3= 8.7 inches from your axle. so the closer you can get that pushrod to your axle the better, the only problem is your 10-12" of lift.

now through similar triangles with your push rod at 8.7" from the axle you will get 12.3 " of lift... but for safety factor reasons i would try to put your connecting rod closer to the axle.

Also steel is not great in compression so make sure whatever push rod you have make sure it can take 1000lbs at least of compressive load before deformation. I dont feel like pulling out my book right now to design you a good rod but let me know if you want me to. any ?'s PM me or just reply i'll check the thread out later. peace

Eric
 

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Discussion Starter · #10 ·
Thanks. I just had a statics class a few semesters ago and I cant' remember anything and I got a B in that course.
 

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gumby green
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i edited mypost, i did the lift for you too because i forgot
 

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S - I - C
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Bandit7 said:
So if need a 1.5:1 ration to get the 10-12" of lift on top of the 2:1 in the rocker arms, does that make it a 3.5:1 ratio overall? I'm not sure what the rear of my truck weighs but do you think its more then 2000 lbs? Anybody have experience with a canti system using shockwaves?
Thanks
No, it'd come out to 3:1 because it's a 1.5:1 of the 2:1. So it'd be 2*1.5 not 2+1.5.
 

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~~~~
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I love this forum you guys are so smart :tup:

Well done,
 

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AWESOOOOOOOOOOOOOOME
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Bandit7 said:
First, the s10 was sold back in 2004 when i bought my silverado so I could bag it. Its still around though. I sold it to a kid that lives 1/2 hour from me and he took the bags out of the rear and left the front bagged so he's driving around in a bodydropped truck with a monoleaf setup in the rear. He hit a few potholes with front down and he completey ripped the rocker away from the truck so it was just hanging there last time i saw it.
what a shame, that truck had a lot of work into it
 

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Here's my unprofessional, unqualified, opinion... :D

Unfortunately, a double convoluted style shockwave is limited in the travel that it can give the truck. With a 4.1" stroke, it doesn't give you much to work with, but its doable. Putting the linkage between the rocker arm and the 4 link bar isn't too bad of an idea to gain more advantage, however putting all of that weight onto a round bar isn't too healthy for the round bar without extra support on it, especially when the upper bars are under extension (rather than compression, like the lower bars) under acceleration.

Personally, I would aim to acheive a 2.5:1 ratio with the rocker arm, and mount the linkage onto the axle. For the linkage rod, use some 1"OD x 1/4" wall tubing. Drill and tap it out for 3/4" rod ends and use either quality heims or poly bushings (which one you use will determine how wide your rocker arms are from each other). You might be better off with heims since you are using a parallel link system, and unless you are using a watts link, will get some lateral movement that the heims will handle better.

The 2.5:1 ratio on the rocker arm will net you about 10" of useable travel. With a shockwave, that is about the limit that I would push on a full size truck. With some rough internet estimates, the rear of your truck weighs approx 1900 lbs. Assuming the shockwaves have an equivilant weight rating (i think it might even be less, due to the lesser volume of the springs) to normal double convoluted springs, you have approx 2800lbs of capacity from each spring... totaling 5600 lbs of capacity... divide that by 2.5 and you get around a 2200lb capacity. So at a 2.5:1 ratio, you are borderline on maxing out the shockwave.

Personally, that's what i'd aim for. Looks like you have a good design going, keep up the good work on it. :)
 

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SlammedDime said:
Here's my unprofessional, unqualified, opinion... :D

Unfortunately, a double convoluted style shockwave is limited in the travel that it can give the truck. With a 4.1" stroke, it doesn't give you much to work with, but its doable. Putting the linkage between the rocker arm and the 4 link bar isn't too bad of an idea to gain more advantage, however putting all of that weight onto a round bar isn't too healthy for the round bar without extra support on it, especially when the upper bars are under extension (rather than compression, like the lower bars) under acceleration.

Personally, I would aim to acheive a 2.5:1 ratio with the rocker arm, and mount the linkage onto the axle. For the linkage rod, use some 1"OD x 1/4" wall tubing. Drill and tap it out for 3/4" rod ends and use either quality heims or poly bushings (which one you use will determine how wide your rocker arms are from each other). You might be better off with heims since you are using a parallel link system, and unless you are using a watts link, will get some lateral movement that the heims will handle better.

The 2.5:1 ratio on the rocker arm will net you about 10" of useable travel. With a shockwave, that is about the limit that I would push on a full size truck. With some rough internet estimates, the rear of your truck weighs approx 1900 lbs. Assuming the shockwaves have an equivilant weight rating (i think it might even be less, due to the lesser volume of the springs) to normal double convoluted springs, you have approx 2800lbs of capacity from each spring... totaling 5600 lbs of capacity... divide that by 2.5 and you get around a 2200lb capacity. So at a 2.5:1 ratio, you are borderline on maxing out the shockwave.

Personally, that's what i'd aim for. Looks like you have a good design going, keep up the good work on it. :)
I don't think you know what you're talking about! :p j/k good explanation bro
I didn't want to get too descriptive into anything while I'm at work, heh
 
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