Try looking at the front end ! what is the drag link / wishbone set up ? Maybe you have bump steer and don't realize it.
BTW, the front hairpin mounts are well gusseted. That's isn't clear from the photo. Rear hairpins are about 30" from rear end housing to the chassis mount point.
"If someone found 4" OD, 12 inch springs on Speedway, could you share the part number?" I did. See post#7. 2 5/8" inside diameter will fit a 4" spring pocket.
I don't see anything wrong with the car, why not try a different set of rear tires and experiment with tire pressure?.
It might demonstrate the issue if you pull the shocks and bounce her up/down. It appears the shocks might be mounted inverted too.
I'm really not nuts about those long tubes holding the front of your rear wishbones. I know they are gusseted, but they look like there is a lot of room for them to deflect. Maybe what you think is side to side is actually those tubes allowing the rear to move fore and aft a bit. Don
Hey I'm no T bucket guy and may be way off here, but, are the front tires riding much father out then the rears? It looks like that in the first pic. Looks like a reversed three wheeler? Is it acting like one? Dom
I think that what you are seeing might be camera angle. Are you talking about the hairpin mount or the panhard bar mount? The panhard bar mount has to be extended a bit to reduce the angle of the bar, so it does angle outward a bit. As I said earlier, this has been a problem since day one, so I'm suspecting that whatever the problem is, nothing that I've done has had much effect. I can't be absolutely sure though, since I've had to fix so many things. What I've found (and what everyone probably already knows): 1. Nobody builds anything the way you would 2. Some people should not be allowed anywhere near a wrench It's a good thing that I got this cheap. I expected to put time and $$ into it, so I guess that I can't complain.
I asked Pro Shocks if the valving was different up or down. They said it was the same. I may try flipping them just to see if it makes any difference.
Just had the rear end (and front tend) squared. Seemed to help slightly.Wheel base was over an inch different side to side. Now it's equal.
What I'd do is put the car up on jack stands, pull the rear springs out, if you have the ability make a cradle for the rear end that can go on a floor jack so you can raise both sides of the rear end at the same time, then have someone raise, and lower the rear end with the jack while you look at the suspension going thru it's movements (without getting underneath the car). You maybe able to see something flexing, or some binding going on.
I'm betting rear springs. I used to build industrial trucks, and an unbuilt (bare) cab/chassis will dance like a hula girl. So did my OT chev PU when I drove it bedless to the frame shop. Call speedway or afco and ask them. Good luck!
Okay, look at the spring cups on the left side. You don't see where it's been moved from the front to the top? And the mounting point of the rod on the left side looks to be in the wrong location. Something's not right with the way the panhard bar is mounted. In my first pic, it looks like the left side of the bar is mounted to the lower shock mount. Or is that camera angle? In the second pic, it looks like the bar is curved to go around the pumpkin.
Is there someone in your area that is held in high esteem when it comes to hot rods. You know the one who everyone thinks of as the "old master" when talking about the good old days. The guy who has done it all several times over and seems to always have the best overall car around. If you have someone who fits this description take your car to him and ask him to take it for a ride. Don't tell him the issues your experiencing just ask his opinion of your car in general after taking a spin. You might want to ride along just to make sure he duplicates the conditions that cause your malfunction. I'll bet if your car does what you say it does while he is behind the wheel he will tell you exactly what you need to do to make it right. Frank
From looking at the other panard bar mounts none of them cross over themselves like this one does. The body mount might need to be a bit above the rear mount so it continues to travel away from it's centerline. On yours the bar mount at the body is lower than the rear mount until the body lifts a bit then it goes even and then above the rear mount. That might be where your getting the reaction. -Pat
I'm thinking it is a combination of things. First of all the springs. I'd go to coil overs and play with spring rates till it was right. (even though you would like to avoid it, this might be your best way to go) The next would be an improvement to the panhard bar, a shorter bar with different and better mounting points.
My thoughts: Get rid of the wishbones. They cause the axle to act as an anti-roll bar, which means that the axle cannot really move independently; it must move up and down equally from side to side. This, in turn, makes sure that the panhard bar gives most side to side push. Next, look up "Watts linkage" and make one, Or, if you have room, a triangulated four bar would be ideal. Your current suspension works best when it has little travel. I had a stone stock '51 Olds 88A, with basically the same suspension. From the factory, completely stock, if I hit an expansion joint, the car would kick from side to side like you describe. The Olds had a lot of suspension travel, allowing the panhard bar to move a lot, bringing all the angularity to play. Just like your car. Just my 2 bobs worth. And free to you to ignore or contemplate. Cosmo
As I see them, both pics have the spring cups in the same place. On top of the axle. It looks like it's mounted to a bracket coming down from the frame and triangulated with a small piece of tubing. The shock mount is below the axle on the front. Looks straight to me. The reflection in the cover is curved, possibly creating an optical illusion that the bar is curved. Hold a straightedge to the monitor if you think it's curved. I'm not seeing what you're seeing in the same pictures.
The axle bracket for the panhard looks like it has a long tubing extension to put the panhard behind the axle. That will put a lot of torque on the rectangle tube riser. I think that needs to be more rigid to resist twist/deflection.
Measure the compressed height of the springs. A 12" spring should compress to around 9 to 9 1/2" under the weight of the vehicle. If not, the springs are too stiff. If you have high tire pressure and overly stiff springs the rear end could be skipping over bumps, getting airborne. Pro shocks for street rods are a pretty soft calibration, which is good for your light weight car. However, if they are mounted vertically they could still be too stiff. Can you bounce the rear of the car on the suspension by hand? Also, make sure the shocks are not topping out of bottoming out.
Okay. It's that bracket coming down on the left that was throwing me off. Anyway, I think the problem is the panhard bar set up.
This guy hit the nail on the head! If you follow my threads on here you'll know I do more than a little suspension work out of this shop and hairpins set up like you have them are a death wish. They work marginally at best on T buckets this way but your car Is way to heavy for this setup. You are essentially ringing the chickens neck every time you hit a bump. As we all know you don't run an anti roll bar in the rear without having one in the front. The car thinks it has an anti roll bar in the rear. In addition to introducing loads of weird geometry into the system, I garantee sooner than later your going to break something, usually the bracket or a chunk of tube out of the rear goes first. Swap out those hairpins for either a triangulated link or a pair of triangulated ladders along with the right coils, (4" dia., not 2 1/2" coil over springs if I'm ready you correctly), and you'll drive nicely. I do a lot of these and you're not the only one with this problem. This is not induced by any front end problems or anything else.
Once upon a time when I was young and stupid, I jacked up the back of my car and put muffler clamps around the shocks to make it look like I had air shocks. In my mind (at the time) it was cooler than hell, so I took it for a ride. Same as this one, every little bump would bounce you sideways. With your rear axle acting like an anti roll bar plus very stiff springs, you basically have no rear suspension. With most factory rear suspensions, you can push the rear of the body sideways as much as a couple of inches, so I doubt that your panhard bar has anything to do with the problem.
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