If any one has any pics and info on these rear suspensions please share. I have decided to go with a 2 link set up and air bags. I just want to see some pics for refference and get some Ideas. Thanks a lot guys. I always appreciate the info. SLAMIT
www.ifcustom.com has 2 links. they are similar to the trucks but unlike the trucks require a panard bar because they are like half a 4 link... the bottom half. They have been discused before. They have quite a few draw backs. but you'll need some of the suspension guys to show em to you.. because i have early onset CRS. Garth
This is a "4-link versus 2 link" submission I did for another forum.... The 4-link is a common suspension design that has been utilized, successfully, in many different applications. Typically, the design includes 4 equal or unequal length control arms, a lateral locating bar, springs, and shock absorbers. One benefit of a 4-link is that, when the bars are of equal or near-equal length, and the front and rear mounting points are oriented such that the bars are parallel, there is a reasonably unrestricted range of vertical motion for the axle, while maintaining an efficent coupling. In addition, because each pair of links is independent of the other, the axle can "rotate" freely, allowing for roll. In practical terms, this means that when one wheel has to travel in a different vertical path than the other wheel (over a bump, up a driveway), the unaffected wheel stays in contact with the ground. Or, imagine a turn: The body rolls to the outside of the turn, decreasing the distance bewteen the frame/body and the outside axle end, and increasing the distance between the frame/body and the inside axle end. The 4-link design, with it's parallel links that pivot at each end, is designed to resolve this relatively complex set of dynamic variables. This basic design is found in many factory applications. GM cars, like Chevelles, come to mind, as do late-model Corvettes. Of course, the design is very popular in drag racing, on sprint cars, and on street rods. Side-to-side movement is controlled by a Panhard rod or a track locator. A Panhard rod is mounted laterally between the axle, at one end, and the frame at the other. A track locator is mounted diagonally between the opposing front and rear pivot points of the lower 4-link bars. What about two links (which are, from an application perspective, the same as ladder bars)? From the perspective of a street-driven car, the basic problem is that the two link design does not resolve for axle rotation, except in the vertical axis...it's not an efficient method of suspension attachment for street cars. Visualize holding a door, like the front door of your house. In this visualization, you will be acting as the forward two link mount. Orient the door so that you're holding the hinges; the door should be horizontal, held out away from you, and swinging, up and down, on the hinges. Now, visualize a wheel, one at each of the two outside corners opposite the hinges; the long edge of the door, opposite you, will be the rear axle. What we've done is to model a typical two link suspension. To see how it works, visualize the door swinging up and down. As long as the door is pivoting on it's hinges, with no rotational forces involved, everything works great. Now, try moving the corners opposite you (The corners that we're calling "wheels") in different directions...one corner up, one corner down. See what happens? The door wants to rotate right out of your hands! This is precisely what happens when you turn a corner, or go up a driveway, in a two link-equipped street car. Ouch! The design considerations necessary to resolve this problem include lengthening the bar, moving the front two link mounting points closer together (triangulating), and using a large, soft bushing. Take a look underneath a mid-60's GM pickup ( or a Grand National stock car, for that matter...).or the Pete & Jakes ladder bar design. All use long, triangulated bars with big bushings. What's the bottom line? Obviously, two links are popular, likely because of the design's simplicity. The 4-link design is more complex, often requiring some engineering and fabrication. On the plus side, the 4-link is a superior method of axle control, especially in street cars.
my 50 Chev had the leaf springs in it with all but i think 3 leaves removed plus some 3 or 4 inch blocks. this got it on the ground. in fact the tires were bottomed out in the fender wells in the rear so it was as low as it was going without some major surgery. it had airshocks to raise it when i bought it but i quickly replaced them with regular shocks and made my own mounts to put a set of bags just ahead of the axle right on top of the leafe spring. this got it up in the air plenty and it rode fairly well. this was a quicky fix as i had planned to build a new chassis utilizing an S-10 front sub and custom built rails fromt here back with full air ride and a 4 link. it never happened as i sold it to build the "FnA". anywho, thats what i did and what i wanted to do. now lets see if i have a pic or two since that is what you really wanted....
DollaBill Thanks for the advice. A good way to put it in to perspective. Kustom builder I dig the look of your car. That sits very low with out cuting the frame. I am going to put the rear bumper on the ground and that is the objective with this suspension set up. I am still having a hard time deciding if I should go with 2 or 4 link. It seems sometimes that the more you know the less you know. Or something like that. Thanks for the help. Keep it comming SLAMIT
slamit, the only reason to go a 2-link is for simplicity. every other design criteria suggests a four link is better. if you plan on driving this thing more than onto the trailer and back, i suggest you put the time into going with a 4-link.
DollaBill-your door analogy only works if the the 2 trailing arms used in a 2-link were connected together i.e. you had a bar welded horizontally between them or if none of the mounting points had flexible poly bushings like most 4-link bars. If you used tubular trailing arms with bushings on the ends (just like 4-links) in a 2-link application your rear axle would behave just like in a 4-link. I have seen guys that run 2-links with no bushings and a support beam welded between the 2 trailing arms(bad design), and yes in this case your door analogy is correct.
Ya hes right DollaBill, I havent seen a 2 link setup like you described on anything other than pre-runners or dancers. But a 2 link is still bad because you will experience axle rotation like you would with a mono leaf setup. The point of 4 link bars is to stop your axle rotation. A panhard bar eliminates your side to side movement. Even with a 4 link setup you want to run a panhard bar or a watts link.
that's right, i built a 2 bar for my 51 chubby, basically copied the chevy truck setup, but used rectangle tubing instead of the i beams. with the front pivots close together, it articulates just fine, not exactly a rock crawler though. them NASCAR losers have been using the same design for decades.
Its funny this post is back up. I think that I started it about a year ago. The other funny part is that I havent done the rear on th 49 yet. Although in the last month I think that I decided on the set up I am goin to use. I am going to build an adjustable ladder bar setup. 1 bar connects to the rear end at the bottom of the tube and the other bar is attached to the lower bar and to the top of the tube and ajustable on one end so I can adjust the pinion angle. This will also take car of axle wrap. I will also use a panhard rod. I am going to notch the frame about 10 inches as well. I have a pair of bags with 1/2 inch ports. I am going to run all 1/2 inch stuff so this thing will be very fast up and down. I am also thinking about running a potentiometer at each corner of the car to make achieving ride highth a snap. I will take pictures of the build up and post it on here. If any one has any suggestions about this set up please seel free to let me have it. Thanks fella's Eric
Sounds good, but you don't need a 10" notch to lay frame. Inorder to lay frame the rear axle only has to be just above the frame rail (depending on your tire/wheel size). Now, if you're going to use the step/tower notch to mount your upper bag brackets then that is cool. In this pic I rolled the rear end out, layed the frame on the ground, and rolled the rear end over it. The rear axle barely cleared the frame rails. The rims are 15" w/205/75R15 tires.
Here are some pics of my 4 yr old set up. It is a 2 link w/pan hard. Notch is approx. 8". I have driven the snot outta her too. Sorry the pics suck! FONZI
Those kind of 2 links work only if the arms are mounted solidly to the rear end. If they are connected by rotating bushings,the rear end will try to rotate! I found this out(I am using a transverse leaf) I added bars solidly attatched to the rear end,just above the others,and angled toward the rear u joint,to allow for a little chassis roll.so the car doesn't skate around a corner. Sprky
Check on Ruffrodders.com, chopt50ford did an install like that on a Merc. Looks good. Look under Buildz for the pics.
jalopy43, you are absolutely right in the case of an open drive line, but a closed drive line you DO want bushings on both ends.
My set up is solid mounted to the rear axle housing with NOISY eurethane bushings where the arms attach to the frame. I gotta grease those bastards. It seems to work well. I have had no broken welds or anything. (knock on wood). Has been to vegas, El Mirage, Paso twice, couple o ranch runs, and all over town. I like air bags. FONZI
One advantage of the truck arm/2-link/NASCAR setup is that you can go lower without eating as much into the floor of the body. You don't have to make room for the upper bars in the back seat area.
A two link can work o.k. if it is trangulated and has a panard bar.. . sort of like a wishbone . . . but the flaw in the design is still there. If it is over-designed enough the welds at the axle will hold. but .. . a four-link is sort of easier since you only have to design for tension and compression in each member and dont have to over-design for that unknown twisting force. . . and you don't have that nagging design flaw that makes you have to wonder when the axle will twist itself free of the bars. . . Lord knows we all have a few things on our cars that we wonder about as we drive 'em . . . it's either those bias ply's or the scrub line or something else. . . but the more you can eliminate those worries the more fun your car is. . . . I think Fonzi's car just floats along on coolness fumes anyway though. Someday, i'll divulge my crossed six-link insanity that I just did . . .WTF?
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