Looking to solve the leaf spring wrap up problem on my 47 cadillac. Leaf springs in good shape, are 2" wide and wrap up so much that I cannot give more than 1/4" throttle off the line. Get on the gas off the line and the rear axle rotates enough for the front of the drive shaft to hit the X member in the center of the frame. The car is lowered in the rear with 2" blocks, which doesn't sound like much but it lowers the car enough that traditional ******* bars would hang too low. Before tearing out the suspension and changing to a triangulated 4 link I want to try and fix what I have. Has anyone tried a factory style GM traction bar but mounted on the top of the axle instead of underneath? This is what was used on early first gen camaros and firebirds before they went to staggered shocks. I wanted to try two of these, but mount the arm to the top of the axle instead of the underside. I would put them at the ends of the axle over top of the leaf spring and tie to the frame rail, one on each side. Putting them on top of the axle keeps the arm length shorter and makes it easier to tie directly to the frame rail, but it would be possible to put them underneath. Not sure if putting the arm in compression is much better than putting it into tension. It seems like it would work, if the axle tries to rotate the arms would go into tension and stop the rotation. Thoughts?
You could probably rig a torque arm that ran up beside the driveshaft like they did on Camaros a few years ago.
First gen camaros just used 1 bar, p***enger side. I'd think 1 would work on your ride, why not mount on the bottom, or slightly ahead and even with the bottom of axle, it wouldn't hang lower than the center section that way.
3rd and 4th gen F bodies had the torque arm, but they had coil springs and a panhard bar. Good setup but I think I would go parallel 4 link first. True they only had one, just concerned with uneven suspension movement if I made one side move less than the other. I could mount the bars underneath, not sure if one way is better than the other. Cant be even with the axle or the axle would still rotate up, has to be above or below to work.
Line up the top of the bar with the bottom of the axle tube, build the mount so the bar connects in front of the axle. Mount 1 end with a rubber leaf spring bushing, use a quality heim joint on the other end to adjust length if you are having any suspension binding. The triangulation up to the floor pan will keep it from rotating. 2 bars may act like ladder bars, your call, ladder bars can have undesirable handling while turning, binding the suspension. 3rd Gen camaro bar may create more clearance problems, they mounted to trans crossmember and were close to center section. If theres a rear crossmember on the frame that would be a good mount. Get under there and see where you have the most room. Let us know what you decide. Any pics?
I don't see any way for one side to "move less" than the other...if you're referring to the axle housing twisting (which is the problem you're trying to fix), the axle housing is one piece, and both sides move together. The torsional stiffness of a 3" tube like an axle housing is very very high, it will move the same at both ends, if you use one traction bar like the type shown.
If your leaf springs are in as good of shape as you say they are in, I think I would add a clamp at the end of each leaf in the front 1/2 of the springs. Really, if your leaf springs are wrapping up as easily as you say they are, I would be looking pretty closely at each spring in the spring packs, I'm betting you have some broken leafs at the springs centers Gene
Also check pinion angle. Too high on the nose will cause the rear axle to "climb" on the ring gear causing excessive wrap up. Get the pinion nose down some, so it comes up to 0 under acceleration, or just slightly more.
That sounds exactly what I was thinking, but possibly putting it on top of the housing Well if one bar will be enough to do the job then that is less work for me to do. I like it! No broken leafs, took them all apart for cleaning and painting during the build. Car is not a rocket but has 100+ more HP than stock and more torque as well. I can add extra clamps if they will stay in place, the existing ones have bolts that go through the springs. Considered it but wont that limit suspension upward travel? I would have to have it pretty close to the rear axle to be effective. Pinion angle is 5 degrees up at ride height, matches engine / trans which are at 5 degrees down, needed that angle for A/C compressor clearance should I install A/C. Runs smooth down the highway at 70mph so I would rather not mess with the angle if I can avoid it, but I could try removable angled shims. I am in the middle of a 1941 cadillac "mini build" and the 41 has the same suspension at the 47, so whatever is decided will be tried out first on this car. If it works then I will move it over to the 47. Only difference between the two is this car I am not lowering the 2" yet, may need to keep it at the stock height to match the front better. Once I have the engine in and can see what the front end height ends up at I can lower the rear if needed. I can get pictures tomorrow, I have the 41 on the lift and just started doing the rear suspension updates. Does anyone see any advantage to running the bar from the bottom of the axle rather than the top? Also I will not be tying the bar to the floor like the F body, I will be tying directly to the rear frame rail.
Here are some pics from the 47 caddy build so you can see the design. Having a bar on the underside of the axle will make for a very long bar to reach the frame, which is why I was considering one mounted directly over the leaf spring and tied to the frame rail as it starts to curve up over the axle.
They will work fine mounted on top. Have a look on this link to see what Ford Australia did on their high-performance Falcon models - it is pretty much what you are suggesting ... http://www.aus-ford-uk.co.uk/html/underneath_2.html#Tramprod2
Great info and pictures, thank you! Wonder why they laid back the mounting bracket on the axle, maybe for upward clearance? Or to make the bar long enough to make the turns to the frame rail? Mine should be a straight shot to the frame.
Great picture, I planned on using square tubing for the bar, maybe overkill compared to the factory pieces.
The 65 Shelby GT350R Mustang also used bars over the rear leaf springs. The forward mounts went into pockets above the front leaf spring bushing.
Traction bars over the top have been used successfully as someone no doubt already pointed out. If I recall there was a company marketing an over the top setup for lowered cars a few years back. Something else you can do that would be just as easy is to mount your shocks in front of the axle and go with a stiff shock. We used to race and drive a '55 Stude that set plenty low enough, we used air shocks and at the track we would just add a little air. Last time we raced it was cruising the coast, driven from KC added air to the shocks and ran 12s on street tires with a warmed over 283. Anyway just another option for ya. One other thing while I am thinking about it, we used to take leaf spring cars and jack them up to relieve the weight on the springs then add spring clams in front of the axle, or spring clamps made from 2x1/4 flat bar and a couple of bolts. 4 or 5 added clamps would stiffen one right up.
Caltrac bars. I have had over 20 first gen Camaros, still own one. The 67 p***enger side traction bar was ok but replaced with staggered shocks for a reason. To make the Camaros really hook without doing irreparable damage I buy these Caltracs. They are adjustable, easy to install and they work! Look kinda cool too. No more wrap, no more axle hop, the rest is up to your reaction time and 60 footers.
Thanks for the suggestions, On the 47 the shocks are already in and mounted, so I will add one bar to the p***enger side and see if that helps, if not I will revisit the shock mounting. Makes sense that having them in the front of the axle would help. The 41 I have not mounted the shocks yet, at that point now, so I will see if I can mount one or both in front of the axle and not be in the way if I wanted to add a traction bar. I could probably mount the drivers side shock in front of the axle and leave the p***enger side in the rear. If I have room to do that I will test that before adding a bar. The Caltracs are cool, but as I referred to earlier they would hang too low.
Just jumping in here and not trying to steal the thread but, will the staggered shocks do the same on '51 Chev factory leaves with an open rear? It seems to me that the shocks wouldn't be stiff enough to limit twist..? What about a second main leaf directly under the original. It wouldn't change ride quality all that much I wouldn't think and it would only change ride height a quarter inch or so. Thoughts?
I built ten sets of these many years ago, they were a version of the old 60's style Traction Masters. They were for 62-67 Novas, these mounted directly to the leaf springs and never had any ground clearance issues that Caltracs have. Sorry about the lousy picture quality.
Why don't these type of traction bars need a shackle? Doesn't it cause the spring to bind during flex?
Bob these traction bars were for street cars for the most part and like the OP, myself and some of the Nova guys I knew did not want ground clearance issues on lowered cars. I'm sure you know this but the gen. 1 and gen. 2 Novas are a mono leaf car so there is considerable "give" in the spring which is also why these cars needed help back there. The end with the two bolts "sandwiched"the spring with two 1/4" thick rubber pads for some cushioning and a little movement, they were left just short of tight and locknuts were used.
DDD, so there is enough movement in the bushing to compensate for the spring swing? Probably not enough arc (lateral movement) to worry about? In my head, this binds, so I'm trying to get a grip on it (see what I did there). edit: I looked at Caltracs website, so the front mount is a shackle of sorts. Now it makes sense, I didn't see that it does swing a little bit.
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