how do you do a 3-link set-up
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hemi_fan
Active Member
Are you referring to a 'poor man's 3-link' (PM3L) type set-up, or a legit one like the s197's?
In the PM3L set-up, guys put on a panhard bar. This locates the axle laterally so the upper control arms no longer need to do this, that means that one of the two upper control arms can be removed to minimize bind. Supposedly this works fairly well, but you get increased bushing wear on the remaining control arm so it will need to be replaced more often. It would be useful on a budget road-race type suspension.
In the PM3L set-up, guys put on a panhard bar. This locates the axle laterally so the upper control arms no longer need to do this, that means that one of the two upper control arms can be removed to minimize bind. Supposedly this works fairly well, but you get increased bushing wear on the remaining control arm so it will need to be replaced more often. It would be useful on a budget road-race type suspension.
thanks that what I thought I might try the poor mans 3 link for a little until I can afford a 5 link. I have spherical bushing on the upper control arms wonder how that will work out.
Cobra912
Active Member
Shaolin Crane
Banned
The spherical bearings will work great for the track but not so good on the street. The dirt and salt from the roads will tear them up and cause them to wear out. They also tramsmit more vibration and noise into the car body.
Cobra912
Active Member
yep exactly. I can't stand driving my car on the street especially around here with all spherical bushings. Sounds and feels like a dump truck!
Shaolin Crane
Banned
Someone have a labia injury? I drive my car just fine with solid everything
just bustin your balls dude, Ifeel you, thats why i drive my car once a week for about an hour haha
I have Edelbrock adjustable upper control arms on my Stang with spherical bearings at the chassis end and urethane bushings at the axle end. They work very well on the street especially since I also have MM lower control arms with spherical bearings on the axle end. Suspension bind is all but eliminated. The only small downside is slight road noise transmitted into the cabin but it's only really noticeable between 45-55mph and I've got used to it.
thats what I thought about, if a normal 4link can rip them up then I bet a three link would definitely do it especially with spherical bushings.
Shaolin Crane
Banned
A couple of technicalities here.
A torque arm isn't technically a 3-link in the engineering sense of the phrase, because the front of a torque arm is decoupled in one plane and because the load paths are so different. It slides in and out of its front mount, or otherwise accomodates a change of length in some linkage arrangement as the rear suspension compresses and decompresses. And, its control of axle housing rotation depends on vertical compression and tension at the front mounting point and resisting a bending load, whereas the upper link in a 3-link resists tension and compression loads in the horizontal plane and bending is hardly a factor.
Also, the PM3L is less destructive to the torque box than an overly-stiff 4-link because all the mount really has to deal with is the tension and compression, whereas the upper torque boxes in a 4-link without a panhard bar also have to deal with gigantic twisting loads.
I'd take (and the torque boxes will take) a PM3L with the required panhard bar over super-stiff or spherical upper bearings all day long.
There are way better approaches than the PM3L, but there are worse ones too...and they're way more common.
A torque arm isn't technically a 3-link in the engineering sense of the phrase, because the front of a torque arm is decoupled in one plane and because the load paths are so different. It slides in and out of its front mount, or otherwise accomodates a change of length in some linkage arrangement as the rear suspension compresses and decompresses. And, its control of axle housing rotation depends on vertical compression and tension at the front mounting point and resisting a bending load, whereas the upper link in a 3-link resists tension and compression loads in the horizontal plane and bending is hardly a factor.
Also, the PM3L is less destructive to the torque box than an overly-stiff 4-link because all the mount really has to deal with is the tension and compression, whereas the upper torque boxes in a 4-link without a panhard bar also have to deal with gigantic twisting loads.
I'd take (and the torque boxes will take) a PM3L with the required panhard bar over super-stiff or spherical upper bearings all day long.
There are way better approaches than the PM3L, but there are worse ones too...and they're way more common.
Rumor is that a Panhard bar and the stock style rubber bushing upper control arms are not happy working together. Since the Panhard bar is supposed to relieve some of the sideways load that causes the upper control arms to bind, I find this questionable. Has anyone heard any pro or con to this rumor?
Shaolin Crane
Banned
Ive never heard that rumor, if anything it increases the upper control arm's ability to do their job
They're not entirely happy working together, because the upper arms define one roll center and the panhard bar defines a different one several inches lower. But here's the critical thing: There can be only one roll center. So there will be only one roll center, and that will be the one defined by the panhard bar. It will come at the expense of extra stress on the upper torque boxes and control arm bushings as they are forced into compliance with a roll center outside their geometric scope, and it will result in non-linear cornering behavior (snap oversteer) as they reach the limits of their compliance. But it'll be better than not having a panhard bar at all IMHO.
As a sidebar, this is exactly why the "poor man's 3-link" or PM3L came into being. Having only one upper link remaining instead of two converging links sharply reduces the binding and stress caused by the conflicting roll center definitions, and frees the remaining link to focus its existence on controlling axle housing rotation and nothing more, which it's free to do because it's no longer part of the roll center and side loading equations. And that's the paradox: When coupled with a panhard bar, the one upper link is actually more durable, with less potential for damage and with better handling characteristics, than keeping two converging links.
So, back to the panhard bar with the stock uppers...the increased stability and predictability the panhard bar provides when added to stock uppers is a fair tradeoff IMHO. Ideally the uppers need to be removed altogether and replaced with a torque arm, 3-link, or "5-link", but short of that, adding a PHB and keeping the stock uppers is a better solution than anything you can try to do to the 4-link without a panhard bar. Just don't try to add stiffness to the upper bushings at the same time, like the poor sap here in phoenix who took some bad advice and put a panhard bar on his car where all 8 of the control arm pickup points were spherical bearings and wondered why the rear end hopped and skipped in hard corners. It might have had something to do with the fact that all the suspension compliance at that point was coming from the sheetmetal
Rumor is that a Panhard bar and the stock style rubber bushing upper control arms are not happy working together. Since the Panhard bar is supposed to relieve some of the sideways load that causes the upper control arms to bind, I find this questionable. Has anyone heard any pro or con to this rumor?
i have a pb with stock upper & lowers, rides like stock to me until i take tight curves & i can feel the rear staying with the car. without the pb it felt like the rear would fly out. pb are a must for these cars
i have a pb with stock upper & lowers, rides like stock to me until i take tight curves & i can feel the rear staying with the car. without the pb it felt like the rear would fly out. pb are a must for these cars
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