4 link or 3 link because 2link stinks (1 Viewer)

[cruiserrg]

do i still need to switch the way the heim sits on the pumpkin with the single upper

If you go with a single link upper and have a panhard bar, you need the single line to be mounted like you have on the end of the wishbone. The panhard bar hiems should be parrell with the axle (perpendicular to the single link hiems).

See the panhard and wishbone are taking side forces to keep the axle from moving side to side. The links are taking foward and back forces from accel and braking.

Only difference is angles links which see both forces.

 

[Eskimo]

If you're going to use the upper solely to control the axle torque-twist, you're fine with it as-is, though it needs to be moved over some to the passenger's side... I'm assuming you're gonna run a panhard?

 

[Gumby]

Just an observation. I was working on a XJ yesterday and noticed the upper panhard bracket was bolted to the frame. Looks like an easy swap to put it on a custom application.

My panhard pushes the tire into the coils at about 15" of axle droop. I suspect a center strap will fix that. Currently I have to chain the axle to the frame to put it on the hoist.

 

[FJ40Dude75]

the way i built it is the way it is currently in the rear of my buddys samuria exept his has a bushig on top of the axle it works awsome no panhard either thats why I tried it

 

[woody]

key difference is rear suspension and no steering back there.....the 3-link is common for rear suspension designs. Mine is similar, except a triangulated 4-link...

major difference once you get in the front.....

 

[Rock Taxi]

It's tough if not impossible for me to tell in the pictures, but where is the instant center of those links?

Ed

 

[Roswell Rat]

Just noticed that at the frame side of the lower links the zerk fitting is facing down (first picture). You may want to relocate this to prevent shearing it off on the trail.

 

[FJ40Dude75]

cener of the axle and center of frame I noticed the zerk to planed on flipping that arm

 

[FJ40Dude75]

what I am not understanding is i=f my upper link is centeron the axle and center on frame and only trvels up and down and alows the axle to move why would that not work on the front its almost the sam e as a 4 link

 

[woody]

I don't understand where you are getting your upper link is centered...it's not.

It's offset to the passengerside......on the inside edge of the frame rail....and the front axle-side link would be just outside of the pumpkin (passenger side as well.)

gawddammit....just did a nice photohell drawing, and the program crapped......

 

[FJ40Dude75]

well I am not saying everything was dead on but that is my plan to have the y end up center its close now but that was all comming of so as to make brackets and clean up and paint

 

[woody]

lets try again...

red line is the panhard (should be under frame tho, program crapped

black = axle

blue = lower links (again, below frame)

green = single upper link

puke green =- frame rails

 

[FJ40Dude75]

if it is centered will it work then

 

[FJ40Dude75]

that does seem eazyier

 

[lowtideride]

Is there a good place to read up on 4,3, and 2 link setups....me wants to know....everything and anything about it.

 

[lowtideride]

what is the panhard attached to?

 

[woody]

I used to have a page on suspension crap, but never finished organizing all of it....understanding all the percentages and such and effectively describing them is difficult.

As a friend of mine told me once, the biggest issue with a link suspension when retro'd into a "normal" frame/bodied rig is to whatever fits....

Oh yeah, in the photohack above, the red line would connect to the frame on the left side and the axle on the right side, most likely above the axle centerline, NOT in front of it.

pirate4x4.com has LOTS of good threads on links....and also lots of bad ones. I breezed thru those over a year's time and still don't know much...but learned enuf that my rear setup worked right the first time.

 

[lowtideride]

thanks...im slowly learning...

haha i dont want to go over to pirate...I like it here...haha

I'll keep searching.

 

[Rock Taxi]

Is there a good place to read up on 4,3, and 2 link setups....me wants to know....everything and anything about it.

Sprint car and stock car chassis design books are where it's at.

Internet forums is not where it's at. It's way to confusing to try and determine what is correct and what is not while you are learning .

Ed

 

[woody]

BTW: if you ever wanted an over built and well designed bracket, the upper link mounting to the axle is critical....(Lance and I were just discussing, good points from him). The axle will effectively try and dive the pinion down when under load....the leverage on that upper link axle-side mount is tremendous, and you'll want to be triply sure that is well designed, welded, braced, etc or you'll tear it off the first time you are under power and end up with a pile of damage. Frame side is just as important, but much easier to support since the rotational leverage is much less.

Ed is right on the theory...Millikan (sp?) is the book to get from what I hear....good theory, lots of information....webhoe's like us are good to see what's been done and what works/breaks, but the numbers are best from the pro's.