3 linking a 3rd gen

Theblackflag

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#21
Curious why you didn't push the upper link mount way forward as well as extend the lowers more? I'm curious how much roll steer you get, correct me if I'm wrong but that's purely a function of link length since as the axle flexes the arc of the link pulls one side forward and pushes the other side back, and it seems you didn't significantly increase the length of the links? Likewise seems like a marginal increase of the upper link length, which the upper link in my experience is the direct limit to maximum droop since it goes vertical so far? It seems like you could of had a lot of room to move the upper link mount forward on the frame and get your roll axis angle down to 0 or even negative potentially? Curious how it does, and not bashing it, just wondering why you did certain design choices. Also, I fully admit my exceeding lack of knowledge of link setup and suspension design.
Roll steer is effected by much more than link length. Having the lowers triangulated as it goes forward will reduce the roll steer, as it changes the axis and instant center of which it pivots around. Also the height of the links can change how the roll steer behaves at ride height. Long, Flat, Triangulated links will pretty much eliminate roll steer. He did all of those things to a small degree. He extended his lowers a hair, his lowers are parallel rather than reverse triangulation, and he made the links a little flatter at ride height.
The reason he went with the design he did was A) He bought the links from 530 Motorsports before he decided to take on this project. B) It was much easier to go this route than buy new links, buy and relocate the muffler, and easier to work around the stock crossmember.
You are correct that the upper links are the limiting factor on droop, but he did lower the upper frame side mount down and forward 1.5". So it's a hair longer and lower, giving him more room to droop. He isn't planning to achieve mega travel numbers, he is only trying the increase the performance of what he has to work with with the least amount of effort. I think he did a kickass job at that.

Correct me if I'm wrong on any of this @Theblackflag
@AssBurns pretty much hit the nail right on the head with that one, especially regarding the roll steer. The main factor for not making more dramatic link mount changes was because I was fairly limited to what I could do since I had bought the links a few weeks prior to deciding to do this project and they were already being machined to length. I could have sold the links and built longer ones out of steel but that presented another issue, for one I got the aluminum links for 80 dollars which you can't beat, and if I were to make the lower links much longer the driverside would contact the gas tank as the axle articulated.

Regarding the upper link, with the stock cross member there you can't really extend much past it if you look in the picture of full bump you can see the angle the upper link goes to because of the axle side mount. So if I were to go too much further forward then there is another clearance issue that restricts what you can do.

I don't claim to be an expert on link setup, I am well versed but no expert, and this setup is far from perfect. However, it is considerably stronger and really did make a huge difference in how the truck drives. Yes, I do still have roll steer, but I no longer feel the axle pushing me around like I have rear steer so on the highway the truck feels incredibly stable. You make a good point about the upper link limiting droop, however, this setup should I want it to will support 18 inches of down travel which really is pretty impressive in my book. And at the end of the day this truck isnt a race truck, it's my daily/wheeler. When it is no longer my daily I may look at doing a full 4 link but honestly for what I need it to do this truck works amazingly well, and I plan on building a much more capable 60 series at some point anyway.

So bottom line. Room for improvement from where it is at? absolutely! this is by no means the perfect solution. Negligible gain? I would argue not, there was a huge difference felt in the driver's seat and I have no fear of breaking anything in the rear suspension now.

I have also had a few people ask me about the upper link and voice concerns about it being too far off center. This really is not an issue for two reasons. 1: the purpose of the upper link is to control the axle from wrapping under load, but no matter where you put that upper link along the axle within reason it maintains the same line of action and can do the same job. Thats the beauty of a 3 link, it allows you to package around certain things that cant move, unlike a 4 link. 2: the mount really isn't that off-center, only about 6 inches. Look at and solid front axle with a 3 link, they have offset diffs and the mount is typically right on top of the center section. Here is a picture of my axle compared to a 62 series axle, dont ask why I just have that laying around lol, you can see the mount would land right on top of the center section
IMAG0572
by Phoenix Black, on Flickr
 

Plastics Guy

You love my bumps, My bumps, My lovely Yota Bumps!
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#22
@AssBurns pretty much hit the nail right on the head with that one, especially regarding the roll steer. The main factor for not making more dramatic link mount changes was because I was fairly limited to what I could do since I had bought the links a few weeks prior to deciding to do this project and they were already being machined to length. I could have sold the links and built longer ones out of steel but that presented another issue, for one I got the aluminum links for 80 dollars which you can't beat, and if I were to make the lower links much longer the driverside would contact the gas tank as the axle articulated.

Regarding the upper link, with the stock cross member there you can't really extend much past it if you look in the picture of full bump you can see the angle the upper link goes to because of the axle side mount. So if I were to go too much further forward then there is another clearance issue that restricts what you can do.

I don't claim to be an expert on link setup, I am well versed but no expert, and this setup is far from perfect. However, it is considerably stronger and really did make a huge difference in how the truck drives. Yes, I do still have roll steer, but I no longer feel the axle pushing me around like I have rear steer so on the highway the truck feels incredibly stable. You make a good point about the upper link limiting droop, however, this setup should I want it to will support 18 inches of down travel which really is pretty impressive in my book. And at the end of the day this truck isnt a race truck, it's my daily/wheeler. When it is no longer my daily I may look at doing a full 4 link but honestly for what I need it to do this truck works amazingly well, and I plan on building a much more capable 60 series at some point anyway.

So bottom line. Room for improvement from where it is at? absolutely! this is by no means the perfect solution. Negligible gain? I would argue not, there was a huge difference felt in the driver's seat and I have no fear of breaking anything in the rear suspension now.

I have also had a few people ask me about the upper link and voice concerns about it being too far off center. This really is not an issue for two reasons. 1: the purpose of the upper link is to control the axle from wrapping under load, but no matter where you put that upper link along the axle within reason it maintains the same line of action and can do the same job. Thats the beauty of a 3 link, it allows you to package around certain things that cant move, unlike a 4 link. 2: the mount really isn't that off-center, only about 6 inches. Look at and solid front axle with a 3 link, they have offset diffs and the mount is typically right on top of the center section. Here is a picture of my axle compared to a 62 series axle, dont ask why I just have that laying around lol, you can see the mount would land right on top of the center section
IMAG0572
by Phoenix Black, on Flickr

Damn Buddy!!! Keep up the good work!!!
 
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#23
@AssBurns pretty much hit the nail right on the head with that one, especially regarding the roll steer. The main factor for not making more dramatic link mount changes was because I was fairly limited to what I could do since I had bought the links a few weeks prior to deciding to do this project and they were already being machined to length. I could have sold the links and built longer ones out of steel but that presented another issue, for one I got the aluminum links for 80 dollars which you can't beat, and if I were to make the lower links much longer the driverside would contact the gas tank as the axle articulated.


....
I was thinking on this and remembered you 3-linked. I have a set of adjustable links already at factory length and I'm interested in 3-linking. Since you've looked into this more than I have up to now, did you ever think of or consider adding a link mount to the top of the diff pumpkin? Would there be interference with the frame there?
 

AssBurns

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#24
I was thinking on this and remembered you 3-linked. I have a set of adjustable links already at factory length and I'm interested in 3-linking. Since you've looked into this more than I have up to now, did you ever think of or consider adding a link mount to the top of the diff pumpkin? Would there be interference with the frame there?
Not really necessary to put the upper link on the top of the diff in a 3 link setup. It doesn't really matter where the upper link is at (side to side) on the axle. It just matters on height and forward/back of the centerline. Might as well take advantage of the stock link mount location so that it is closer to the frame rail and less space taken up by a link. Still gotta route the exhaust somewhere.
 

eimkeith

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#25
Not really necessary to put the upper link on the top of the diff in a 3 link setup. It doesn't really matter where the upper link is at (side to side) on the axle. It just matters on height and forward/back of the centerline. Might as well take advantage of the stock link mount location so that it is closer to the frame rail and less space taken up by a link. Still gotta route the exhaust somewhere.
I'd love to see some CAD on that - I can't get around the suspicion that the axle will arc differently side to side depending on the location of that 3rd link... :shrug:
 

AssBurns

will wheel for beer
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#26
I'd love to see some CAD on that - I can't get around the suspicion that the axle will arc differently side to side depending on the location of that 3rd link... :shrug:
Having the frame side of the upper link mounted on the same side of the frame side of the panhard will help keep everything swinging the same direction. You may want to have the upper link mounted a little more centered on the axle so that as it swings down, it follows the same/similar arc as the panhard bar. That'll probably help keep the axle from rolling forward as it swings down.
I don't think it's something super important to worry about as long as it's not swinging opposite of the panhard.
 
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#27
I'd love to see some CAD on that - I can't get around the suspicion that the axle will arc differently side to side depending on the location of that 3rd link... :shrug:
I've been thinking about this for a couple of months and that was why I ultimately asked the question. This piques my interest and want to commit to doing it if at all possible. @AssBurns I hear ya loud and clear. Ease of use is undoubtedly my first reason for using the stock link location, but it seems like there's room to move that link to (TDC) on the pumpkin and not have to worry about the arc so much under droop. I'm reading up to get myself up to speed on link location for a proper 3-link out back.
 
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