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Unread 01-01-2012, 11:05 PM   #46
Joe Dillard
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Okay gents, I edited some comments in an effort to get things back on track and reopen this thread.

Lets be civil and not be too harsh.

Thanks,
Joe

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Unread 01-01-2012, 11:34 PM   #47
Scooter402
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Joe--

Much appreciation for cleaning up this thread and re-opening it. I hope from here we can all "just get along." Even if we don't share the same opinions/ideas of others.

Back to the tech....


Quote:
Originally Posted by Cresso View Post
Ya lost me there. Horizontal spread of the links from the frame end to the axle? That's the length of the link itself. A two foot radius arm has two feet of horizontal spread from the frame attachment point to the axle attachment point (assuming the radius arm is parallel to the ground). There doesn't actually have to be triangulation between the axle and the frame. The triangulation just has to exist anywhere in the square formed by the four attachment points of the main links.
What I meant by this was the horizontal distance between the links at the frame end vs. the distance between the "lower" links at the axle end. I suppose this is not necessarily needed in this scenario, but I don't think it would hurt either.

Climbit -- I wasn't trying to prove anyone "wrong" or "right" by the picture I posted...as I said before I was simply looking for an example of something similar. By no means was I trying to prove someone wrong. I'm not trying to be argumentative here. I'm just trying to get your reasoning behind why this type of suspension I am describing, (and Cresso apparently sees the same thing I do) as to why it will not work. I am not looking (as I stated in my opening post) to get ridiculous amounts of wheel travel...this is a mud racer. Just to be even more clear, my coilovers I am mounting have a total of 9 inches of movement, and I think the biggest amount of that will be the front axle dropping straight down when I stab the throttle off the line. There aren't big obstacles I'm trying to cross....not crawling over logs or rocks...just mud.

I can't seem to find any solid/clear examples of it, but at the end of the day, I guess this is a 2 link suspension...I know, it sounds crazy. But stick with me here for a minute. Is there any real reason why something like this would not work? Like I said...I'm not trying to twist this up like a pretzel...I don't need a slinky. I want it to be as light as possible, have more movement than the leaf springs provide, and be stable. Yeah, I understand that last one would be difficult with this setup. I guess I'll have to start burning some steel and see what I come up with.
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Unread 01-02-2012, 12:05 AM   #48
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Quote:
Originally Posted by Scooter402 View Post
Joe--

Much appreciation for cleaning up this thread and re-opening it. I hope from here we can all "just get along." Even if we don't share the same opinions/ideas of others.

Back to the tech....




What I meant by this was the horizontal distance between the links at the frame end vs. the distance between the "lower" links at the axle end. I suppose this is not necessarily needed in this scenario, but I don't think it would hurt either.

Climbit -- I wasn't trying to prove anyone "wrong" or "right" by the picture I posted...as I said before I was simply looking for an example of something similar. By no means was I trying to prove someone wrong. I'm not trying to be argumentative here. I'm just trying to get your reasoning behind why this type of suspension I am describing, (and Cresso apparently sees the same thing I do) as to why it will not work. I am not looking (as I stated in my opening post) to get ridiculous amounts of wheel travel...this is a mud racer. Just to be even more clear, my coilovers I am mounting have a total of 9 inches of movement, and I think the biggest amount of that will be the front axle dropping straight down when I stab the throttle off the line. There aren't big obstacles I'm trying to cross....not crawling over logs or rocks...just mud.

I can't seem to find any solid/clear examples of it, but at the end of the day, I guess this is a 2 link suspension...I know, it sounds crazy. But stick with me here for a minute. Is there any real reason why something like this would not work? Like I said...I'm not trying to twist this up like a pretzel...I don't need a slinky. I want it to be as light as possible, have more movement than the leaf springs provide, and be stable. Yeah, I understand that last one would be difficult with this setup. I guess I'll have to start burning some steel and see what I come up with.
I can't guarantee you that you will or will not have too much lateral movement with this setup. but you will have lateral movement with any suspension, as it cycles.

but unless you are running full-hydro steering you will need a panhard to keep the axle movement in line with the drag link.

if you aren't looking for more than 9" of travel then run a panhard, you won't notice any bind with that much travel.
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Unread 01-02-2012, 12:15 AM   #49
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Quote:
Originally Posted by Climbit View Post
I can't guarantee you that you will or will not have too much lateral movement with this setup. but you will have lateral movement with any suspension, as it cycles.

but unless you are running full-hydro steering you will need a panhard to keep the axle movement in line with the drag link.

if you aren't looking for more than 9" of travel then run a panhard, you won't notice any bind with that much travel.
I don't know, I may end up with the panhard anyway. I'm just trying to lower my Jeep back down to stock-ish height, and I don't know how much room I'm going to end up with there. I'm quite certain it will be too low for the traditional 3 or 4 link, that's for sure.

As far as full hydro...I've got other ideas in mind. I don't know if I'm going to stick with the crossover or not. It's definitely not going to be necessary once it loses 6-7 inches in height.
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Unread 01-02-2012, 12:27 AM   #50
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Quote:
Originally Posted by Scooter402 View Post
I don't know, I may end up with the panhard anyway. I'm just trying to lower my Jeep back down to stock-ish height, and I don't know how much room I'm going to end up with there. I'm quite certain it will be too low for the traditional 3 or 4 link, that's for sure.

As far as full hydro...I've got other ideas in mind. I don't know if I'm going to stick with the crossover or not. It's definitely not going to be necessary once it loses 6-7 inches in height.
It's going to be hard to fit radius arms in there at stock height. especially if you fully triangulate them like you are thinking.

and any steering system that uses a drag link IE Inverted T, Inverted Y, Crossover will require a panhard to be the same length and parallel to the drag link.
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Unread 01-02-2012, 12:33 AM   #51
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Quote:
Originally Posted by Climbit View Post
It's going to be hard to fit radius arms in there at stock height. especially if you fully triangulate them like you are thinking.

and any steering system that uses a drag link IE Inverted T, Inverted Y, Crossover will require a panhard to be the same length and parallel to the drag link.
Thanks, I'm aware of the steering geometry as well. That's why I have different ideas in mind for steering, if I can come up with the parts to make it work.

Outside the frame won't be any problem...getting anything inside under the frame rail might be an issue, though, since I'm wanting to go so low. We'll see what happens. It's supposed to be pretty cold this week, but I'm going to try to get at least something done on it.
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Unread 01-02-2012, 05:16 AM   #52
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Quote:
Originally Posted by Climbit View Post
I believe that with the proper amount of triangulation you could keep the axle centered to the links.
Good! I'm glad you changed your mind. Much better than your original statement: "with only the lowers connecting the frame to the axle, there is nothing to resist lateral movement of the axle. "


Quote:
however there are other things to consider. once you start moving that axle up and down and articulating it, twisting it, etc you are going to get a lot of side-side movement, you will change the link relationships and then you are going to be very unhappy.
Suspensions that use a panhard for lateral location move side to side as they travel. Triangulated suspensions that don't have a panhard do not. The center of articulation stays right in the center no matter how much the axle flexes or articulates.

Quote:
I can't guarantee you that you will or will not have too much lateral movement with this setup. but you will have lateral movement with any suspension, as it cycles.
Not true. See above.

Quote:
It's going to be hard to fit radius arms in there at stock height. especially if you fully triangulate them like you are thinking.
Agreed. That's why I recommended going with a panhard as well. You can triangulate radius arms enough to provide all the lateral location you need, but it's a pain in the rear to package. As I mentioned earlier, using a mounting method with less give in it would require less triangulation. Replace the bushings with heims, for example. It won't articulate as well, but that shouldn't matter for a mud racer.
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Unread 01-02-2012, 05:25 AM   #53
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Quote:
Originally Posted by Scooter402 View Post
What I meant by this was the horizontal distance between the links at the frame end vs. the distance between the "lower" links at the axle end. I suppose this is not necessarily needed in this scenario, but I don't think it would hurt either.
Gotcha. This won't do anything for lateral location in a 2-link system (radius arm, y-link, whatever we're calling it). It would in a 4-link, but not here.
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Unread 01-02-2012, 01:23 PM   #54
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Quote:
Originally Posted by Climbit View Post
...and any steering system that uses a drag link IE Inverted T, Inverted Y, Crossover will require a panhard to be the same length and parallel to the drag link.
id slightly disagree here. ive seen a few 4 link (no panhard) with standard steering. a drag link doesnt necessitate a panhard. the suspension design dictates this. and i disagree with "same length and parallel" the best that most have done is to get it as close as possible. getting it the same is virtually impossible.
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Unread 01-02-2012, 02:24 PM   #55
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Quote:
Originally Posted by fratis View Post
id slightly disagree here. ive seen a few 4 link (no panhard) with standard steering. a drag link doesnt necessitate a panhard. the suspension design dictates this. and i disagree with "same length and parallel" the best that most have done is to get it as close as possible. getting it the same is virtually impossible.
Unless you've got some form of "front to back" steering setup, you'll have unending bump steer with a triangulated link setup that doesn't follow the same arc as the drag link. That's why almost everybody you see running a triangulated 4 link up front is running full hydro steering. IMO, if you've got a drag link you need a track bar--and it needs to be as close to parallel and in the same plane as possible.
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Unread 01-02-2012, 02:57 PM   #56
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Not only bumpsteer as I mentioned at the start of this thread, but it will unload the front end also, which is a know problem with the long arm lifts that use this setup
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Unread 01-02-2012, 03:26 PM   #57
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Quote:
Originally Posted by aw12345 View Post
Not only bumpsteer as I mentioned at the start of this thread, but it will unload the front end also, which is a know problem with the long arm lifts that use this setup
I don't think I'm following you on the unloading of the front....unless you're not following me. I'm not worried about unloading the front....on the contrary, that's what I'm trying to do. I'm not climbing anything, just racing. I don't want the front to stay all the way down on the ground. I want the weight transfer to the rear by the front end lifting.
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Unread 01-02-2012, 04:01 PM   #58
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Quote:
Originally Posted by Scooter402 View Post
I don't think I'm following you on the unloading of the front....unless you're not following me. I'm not worried about unloading the front....on the contrary, that's what I'm trying to do. I'm not climbing anything, just racing. I don't want the front to stay all the way down on the ground. I want the weight transfer to the rear by the front end lifting.
Than that is what the doctor ordered, I want my front wheels to stay on the ground when I climb steep stuff.
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Unread 01-02-2012, 06:24 PM   #59
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Quote:
Originally Posted by fratis View Post
id slightly disagree here. ive seen a few 4 link (no panhard) with standard steering. a drag link doesnt necessitate a panhard. the suspension design dictates this. and i disagree with "same length and parallel" the best that most have done is to get it as close as possible. getting it the same is virtually impossible.
if you have a triangulated 4-link the axle stays centered under the vehicle while the drag link tries to swing in an arc and pull the axle to one side. obviously it cant so the steering wheel, or the tire has to turn to compensate this is called bump steer.

and getting the same length/angle is not virtually impossible. I did it. my panhard and drag link are exactly the same length and (within .5*) of the same angle.

that said I am about to trash the whole setup, because I am not happy with inverted T, and go back to inverted Y (savvy) and I plan on making my Panhard the same length as the drag link and the same angle.
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Unread 01-02-2012, 08:03 PM   #60
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Quote:
Originally Posted by Climbit View Post
if you have a triangulated 4-link the axle stays centered under the vehicle while the drag link tries to swing in an arc and pull the axle to one side. obviously it cant so the steering wheel, or the tire has to turn to compensate this is called bump steer.

and getting the same length/angle is not virtually impossible. I did it. my panhard and drag link are exactly the same length and (within .5*) of the same angle.

that said I am about to trash the whole setup, because I am not happy with inverted T, and go back to inverted Y (savvy) and I plan on making my Panhard the same length as the drag link and the same angle.
i think we agree but are referring to two different worlds. i know perfectly well what bumpsteer is and why it happens. the inherent bumpsteer that would be experienced with a 4link and draglink steering i dont think would be that bad if the angles were conservative and we are discussing a primarily offroad vehicle. yes you eliminate a whole lot of issues with full hydro steering this is obvious and more and more are going this route. before that became so popular, however, there were a lot of 4 links with draglink steering. at some point any offroad vehicle with a drag link is going to experience some version of bumpsteer no matter how parallel of even the two units are. agreed not within normal operational range such as experienced on the road it would take a bit of articulation. i have yet to see a panhard frame side mounted directly behind the pitman arm and the axle end mounted as far out as the steering on the knuckle. there are always compromises to be made. getting a panhard and drag link parallel and with similar angles is relatively simple with a lift kit, off the shelf parts, and factory or near factory axle assemblies. doing so with a one-off is again a different world. im reworking mine now and it is a challenge.

its not necessarily the theories im disagreeing with but rather the physical building of what is being discussed.
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