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Discussion Starter #1 (Edited)
Here's some pics of my buddy's 4 link rear he just built. The truck is an '81 short bed (well, no bed now), with a SBC 350/TH350/203, Toy axles, welded rear, 38.5x11 boggers. The front is leaves for now. The rear is aerostar coils, PTO tractor joints and DOM. Still left to do is shocks and brake lines, and get offset rims, and believe he is going to lower the upper spring mounts as well (sits to high right now). I'm looking for ideas/suggestions on link design for when we build the susp. for mine. Does this link setup look like it will work well? I know the lower link mount is below the axle, I know it will hit on rocks. We don't have a lot of rocks around here, thats not such a big deal, although when we build mine, the lower mount will most likely be higher up. Thanks for you help!









Edit: I should add that my truck is a long bed, so the links on my truck, when we build it, will end up somewhat longer.

Edit 2: He is going to to go either NP 205 or toy cases and get a longer slip rear drive line also.
 

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How much longer are you lower contol arms? Looks like quite a bit and not seeing a real bad effect on the pinion angle, you have a shot showing the pinion angle at ride height?

Thanks,
 

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should have used a wider rear end.
 

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If that cherry picker is holding up the rear end(it appears that it is) then there are no pics of pinion angle at ride height.
 

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scmb said:
there already is a shot of the pinion angle at ride height w/o the tires on sitting on jackstands
Why thanks dude :rolleyes: :rolleyes: looks to me like the coils are at full droop..

DUH! :flipoff2:
 

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Well I'm not an expert but who is. First off it's hard to totally critique it cause it is still unfinished. I would guess you will be adding some more weight to the back which would bring the ass end down and level the link angles out to at least some degree. Upon first glance it seems that the angles of the uppers and lowers are pretty steep in relative to the ground which I don't particularly care for as it will create some unsitely characteristics with the gas pedal. It appears as though the seperation between the uppers and lowers is adequate but the placement of the links should have been higher at the axle to help eliminate some of the extreme angle of the links. Since it is pretty custom I would have put the lower links at least at the center line of the axle tubes but preferably just on top of them. Then you would have course had to have raised the mount above the third member but who cares cause you don't have anything back there for it to hit anyway. Of course such link placement on the axle means more torque, but that just means you gotta build it strong which doesn't nessessarily mean heavy, i.e. camo's or desertoy's setup. I also see that your upper v link is shorter than your lowers which means the pinion is gunna rotate down when the entire axle droops which you may or may not care about and could be solved with a limiting strap at the center of the axle. Next your lowers being parallel are going to create some unsitely features like rear steer and push and pull effects at the sides of the frame when you are flexing which contributes to wanting your vehicle to roll over, again something you may or may not care about. Also can be controlled to some extent with limiting straps at the ends of the axle tubes. Personally I would have triangulated the lowers cause why not since you have a centered diff and t-case out put flange. This would have gotten rid of rear steer problems and the push and pull effects on the frame rails. Roll center in the center of the vehicle and gas pedal pushing from the center instead of vector forces on the sides. The links appear to be more than long enough just the placement is a bit off. I would have put the attachment of the lower links at the frame higher so that it doesn't create a point of contract for rocks to hit, which you may or may not care about cause you don't have many rocks. Also looks as though the frame mounting point for the uppers could have been lower thus resulting in less of an angle. And finally I would cut those bump stops out and build a bracket of some sorts attaching it to the frame to get the entire ass end down more. Lower is tipically better in my opinion. Anyway others may disagree and that's ok cause it's about trade off's in suspension design to some degree. Just my .02
 

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Discussion Starter #8 (Edited)
Thank you ECF, that is a lot of helpful stuff. Must have taken a while to type! keep the advice coming guys.

EDIT:
measurements: uppers 33", lowers 36"

here's some pinion angle shots:



 

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Holy chit................... How much research was put into this project before the links were hung...........???

EDIT: I appologise if I come off as an asshole but......
 

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ECF pretty much nailed it, but if your not looking to build a west coast rock crawler it might work for what you want. I would guess that the anti-squat is going to be a little much.
 

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PIG said:
Holy chit................... How much research was put into this project before the links were hung...........???

EDIT: I appologise if I come off as an asshole but......
I was going to say that but then I decided be nice.
 

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Discussion Starter #13 (Edited)
Once again, this is on my buddies truck. Mine will have a bed, and lower spring mounts. What I've gathered as your comments so far:
1) triangulate the lowers and make all 4 links longer and more level, and mount them higher on the axle
2) wider rear axle

what would you recommend changing on his suspension? the links are more than likely not going to be changed in length. I'm trying to help my buddy as I can. Thanks again.

Edit: I've done TONS AND TONS of searching and researching and looking for info on this board on this topic, and have a pretty basic idea of what to do when I build the suspension on my truck. The triangulated uppers and lowers thing I get, but as soon as you guys start talking antisquat, roll center stuff, I get lost. I do not understand how to calculate that to build a good suspension. I'm trying to learn as much as I can before I torch the leaf springs clean off of my truck.
 

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Heavy Metal Toy said:
Once again, this is NOT my truck, it is my buddy's truck. I am trying to take what he did and improve on it before I build mine. Mine will have a bed, and lower spring mounts. What I've gathered so far:
1) triangulate the lowers and make all 4 links longer and more level, and mount them higher on the axle
2) wider rear axle

what would you recommend changing on his suspension? the links are more than likely not going to be changed in length. I'm trying to help my buddy as I can. Thanks again.

Have him mount his upper links at the frame in double shear instead of single... and redo the mounts on top of the diff, make them higher to lessen the upper link angle a little. im no expert though, im sure someone else will chime in..
 

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Its hard to tell, but that kinda looks like Diverging links.....originality points. What the hell are those tab things near the hiem joints? He should also paint it black so he doesnt have everyone noticing it. :flipoff2:
 

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The upper link frame mounts look a lil wimpy, and the angles might be a bit off, but overall, i think it looks good.Nice thing about fabwork like this is that it doesn't hafta be permanent.....you can fix your fuck-ups at any time.....
 

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Links below the CL of the axle is a VERY good thing. To many people get so concerned about that extra inch that they compromise the strength of the suspension. The lowered links support the torque of the axle much better, and reduce the stress on everything. Besides, and inch right beside the tire really has no effect on rock clearance. Do you ever see anyone bitching about portal gear boxes, even though they hang down further than a standard axle?

Tractor joints may be cheap, but they suck. You get what you pay for, and he will figure that out soon enough.....

And, like what has been said a dozen times above..... Get him to put something on the other side of those top joints! That bolt hanging out there in mid air is just not safe... ;)
 

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okcrawler, Did you take the time to READ what ECF so eliquintly and longwindedly posted?
Mounting your lower links on top of the housing has little to do with ground clearance and ALOT to do with getting your links as level to the ground as possible (anti-squat).
 

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See if this reads better than that run-on-looking paragraph he posted above ;)

ECF said:
Well I'm not an expert but who is.
First off it's hard to totally critique it cause it is still unfinished. I would guess you will be adding some more weight to the back which would bring the ass end down and level the link angles out to at least some degree. Upon first glance it seems that the angles of the uppers and lowers are pretty steep in relative to the ground which I don't particularly care for as it will create some unsitely characteristics with the gas pedal.
It appears as though the seperation between the uppers and lowers is adequate but the placement of the links should have been higher at the axle to help eliminate some of the extreme angle of the links. Since it is pretty custom I would have put the lower links at least at the center line of the axle tubes but preferably just on top of them. Then you would have course had to have raised the mount above the third member but who cares cause you don't have anything back there for it to hit anyway. Of course such link placement on the axle means more torque, but that just means you gotta build it strong which doesn't nessessarily mean heavy, i.e. camo's or desertoy's setup.
I also see that your upper v link is shorter than your lowers which means the pinion is gunna rotate down when the entire axle droops which you may or may not care about and could be solved with a limiting strap at the center of the axle. Next your lowers being parallel are going to create some unsitely features like rear steer and push and pull effects at the sides of the frame when you are flexing which contributes to wanting your vehicle to roll over, again something you may or may not care about. Also can be controlled to some extent with limiting straps at the ends of the axle tubes.
Personally I would have triangulated the lowers cause why not since you have a centered diff and t-case out put flange. This would have gotten rid of rear steer problems and the push and pull effects on the frame rails. Roll center in the center of the vehicle and gas pedal pushing from the center instead of vector forces on the sides.
The links appear to be more than long enough just the placement is a bit off. I would have put the attachment of the lower links at the frame higher so that it doesn't create a point of contract for rocks to hit, which you may or may not care about cause you don't have many rocks. Also looks as though the frame mounting point for the uppers could have been lower thus resulting in less of an angle.
And finally I would cut those bump stops out and build a bracket of some sorts attaching it to the frame to get the entire ass end down more. Lower is tipically better in my opinion.
Anyway others may disagree and that's ok cause it's about trade off's in suspension design to some degree. Just my .02
 
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