4 bar, bags, shocks, panhard... I'm having trouble making all this stuff fit. I have been planning on a parallel 4 bar/panhard, but I don't really have anyplace to put a panhard bar... There's no room above the axle, the bags and gas tank are behind, etc. So now I'm contemplating a triangulated setup, but I have some questions. How long should the upper (angled) bars be in relation to the lower bars? All the kits I've looked at have shorter upper bars. It seems like the upper and lower bars would be travelling in a different arc and something would bind at some point... Should the upper bars be as close to a 45 degree angle as possible to keep the rear in place side to side? Mine would have to be prety short. (Is that the reason for the different bar lengths in the kits?) Here's a cheesy mock up pic of what I'm dealing with. You can see it's not even close to 45 degrees, but will it work? Also, the length of the bar will only be about 18-20". Is that long enough? Seems pretty short to me, but any longer and there won't be much triangulation at all. How 'bout the bottom (straight) bar- how long should that be if the top bar is 18-20"? Thanks.
Yeah, it LOOKS like there's room, but between the 4 bar, driveshaft, underside of the car and the ground, there's not much space. Also, I need to squeeze a couple exhaust pipes into the mix. I should mention that I'm trying to cut as little as possible out of the trunk floor, otherwise I could put the p-hard above the axle. How about a parallel 4 bar where the bars are not directly above/below each other? I could fit the lower bar under the frame rail with my bag between the bar and the frame, and the upper bar on the inside of the frame rail. Then I could maybe squeeze in the p-hard in back of the axle... I dunno... This is givin' me a headache...
I into the same **** with the tri-4 bar on the back of my roadster. I will be running curved '36 radius rods outside the frame for the bottom bars and standard triangulated bars on the top. I'm pretty sure they're 18" on the top and the brackets that weld to the inside of the frame I bought because I didn't know the angle they needed to be at. Nimrod, on this board, is the originator of the "curved bottom tri-4-bone" idea. Here's the link in tech-o-matic. http://www.jalopyjournal.com/forum/showthread.php?t=13921 Here's where I at on mine. Casey
Since there isn't a lot suspension travel in your setup..., the different lengths between your upper and lower bars shouldn't be too detrimental to the performance and ride. Another option is to run a Watts linkage off the front pinion of the differential. Or You could Try running a Z-bar diagonally between the upper four bars to keep everything in square. (one end connected to the p***. side diff. and the other end connected to the Drivers side front part of the 4-bar) Mark
The airbags should give me 8" of travel overall- I guess you mean I won't have a lot of suspension travel at ride height going down the road, so I should be ok? I'd love a watts link, but it would eat up more floor space than the panhard, unfortunately. A watts link off the front pinion is a cool idea though. Wouldn't the Z-bar be like a track locator- good for going straight, but bad for cornering?
Grab this book http://www.amazon.com/exec/obidos/ASIN/1557880557/103-4079093-1171047 Most book stores have it. It is a great tool to have. I have read it several times. Try setting up a double triangulated 4 link to be almost nuetral, have no/very slight roll steer, control 350 hp with 40" and work through 4 feet or articulation! Cars are easy
Have you ever heard of an A-pex bar? It mounts to the forward end of 2 4 link bars (one on each side) and then mounts to the center of the housing. I've seen many veryations of the center mounts. Some above, some below the housing. The forward end is solid and the housing end is Heim. This lets the housing tilt on ch***is center line while cornering. The Wizzard
I'm with PistNbroke, The Apex bar is a nice setup. Perhaps someone has a build pic of FleshGordons HAMB Drag Coupe.He ran a Ford 9inch w/ the center point attachment on the back side of the housing but there is no reason you couldn't attach to the top of your center section. It eliminates the need for the panard bar and leaves plenty of room for exaust.
Ride height is where you want all the geometry to be dead-on. When your car is going down the road you'll have a couple of inches of travel and it should maintain good ride characteristics very well...! (unless you cross Thermal to Metric by Wells branch at any speeds above 5 mph!!! ) With the bags you might consider a Double Watts link off the pinion for the centering your differential through a greater range of motion. (my Watt's is on a bearing and rotates effortlessly!) Panhard bars tend to pull the rearend to one side or the other when the ride height is affected. leaving an unbalanced look when you let the air out of the bags. Your Triangulated four bars should work as long as you set up everything for your "RIDE Height"! "Oh"..., and if your by that intersection..., could you look for my friggen teeth...??!?!?!?!
The other thing I should mention- I'm building this car for my better half and I promised to have it mechanically done by the Round-up. My marriage depends on it. I don't have a lot of time for fabrication or trial and error. I'm really hoping to just figure it out, take some measurements, and order a kit. I'm planning to order a kit from www.suicidedoors.com They're beefy kits, built to my measurements, and reasonably priced. What about a 3-link like this? Does it still need a panhard? Looks like it would. I suppose I could make a triagulated setup using the bracket that bolts to my diff. cover except run the bars diagonally to the frame.
A triangulated 4 bar with bags ****S and is worthless. There is too much travel for the pinion angle to stay in a decent range. I like to be able to drive my car at all ride heights. With the pics you are showing 8 degrees of pinion angle would probably be a good guess. I usually cut a hole in the floor below the seat just so the top link can be as long as the bottom. 32 inch bars is a good length but can sometimes be hard to fit. The longer the links the better the ride up to about 45". The lower you can mount the panhard bar, the lower the roll center will be and the better the car will handle. But this can be very hard to do, and should be very strong because it can and will bend. The longer the panhard bar is, is also very important so that the axle does not swing side to side through the travel. I try to put 42" panhard bars on most cars. That usually gets about 3/8" pull form top to center of travel and then pulls back at the bottom half. I try to set the panhard level at ride height which is usually in the middle of the bag travel. With 8 inch bags at 4 inches. The 4 link bars should be level at ride height so as to not have the wheelbase change when it lays out or is fully raised. If the bars are level at one end of the travel it will only swing farther away from the axle center line and looks BROKE OR STUPID. This is only my opinion and opinions are like ***holes eveyone has one just this ***hole Is speaking from experience. Triangulated 4 bars work great with coilovers that have MAYBE 2.5 inches of travel on a bumpy road.
Recently my friend and I completed a tri angulated set up on the rear of a 48 Chev and we have bags in it as well. The way the set up is in that car it only moves maybe a degree on the pinion anywhere thru the entire movement of the diff when the bags are down or inflated. It is a totally custom built set up and did take some figuring to create but it works good. Some set ups probably dont work as well depending on how they were designed so I woudlnt say anyone is wrong in their opinion, but what is done on this car works excellent and there is no panhard bar getting in the way.
No pan hard needed. The upper is a triangle and therefore holds the axle centered. I do not understand why they have it offset to one side, that could cause some issues under hard acceleration on a uneven traction service. Most 3 links like this in the offroad world use 2 mounts at the frame and one on the diff. You can build it off the cover, but depending on the rear end, I would question the strength of the cover. There are some HD covers and cover rings out there, again in the off road world, that are made to weld link points to. As stated, flat and parallel at ride hieght is where you want a DD weather it is 3, 4, 5 link. Unequal lengths become more of a problem with more travel. The closer to equal length the arms are, the less the change in pinion angle will be. Of co**** this is ALL a generalization and can vary depending on MANY factors!! I realized a long time ago that there is no IDEAL suspension. It is always an issue of give and take for your set of desires and cir***stances. HTH Just wanted to add a pic of what I have been building
Lucky, Think of that last pic you posted w/ the triangle turned around. Running from the frame on each side to the center section.
This setups not really a four bar, just a ladder bar that can be dis***embled. With the main leafs providing the axle centering I guess.
Hopefully these will show up. Not mine but illustrate a possible solution neverthe less. http://www.jalopyjournal.com/forum/attachment.php?attachmentid=60980 http://www.jalopyjournal.com/forum/showthread.php?t=35593&&showall=1 use a common crossmember for the forward end of the lower links and the front of the wishbone.
My 48 Fleetline is the one that Kruzer 63 was talking about. I have a triangulated set up with bag mounted behind the rear end. The lower bar goes from the center of the diffy tube hanging down about 4 1/2" below the tube, to the factory spring mount that is in front of the rearend. At ride hight that tube should be straight. The upper bar goes from where the tubes meet the center section of the rear end to the top of the frame. The mounts on the frame are just about the same place up and down from each other. Then we custom made the top bag mount from plate. I also put a sway bar under the rear end and it mounts to the lower bar. From being fully extended to being in the weeds, My pinon angle changes about 1 degree to 2 degrees MAX!!!. This set-up it excellent. I would do it again. And there is NO side to side movement at all. If you have a Panhard bar in there. When you lower the car the rearend will move to the side as well. And if you have skirts. You don't what that.
One thing to remember is that for a triangulated 4-bar to work properly the uppers need to be at 90 degrees to each other. Any less of an angle will not center the rear end and probaly will bind up. Look at a gm coil spring car. jerry
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