Technical Can Anybody See Why This Wouldn't Work? Suspension...

OK, on my '60 Ford 'vert I'm going custom, so there's some mandatory lowering involved. Blocks will be by far the easiest method (no, I'm not doing bags...) but the added leverage allowed by the blocks may be an issue with spring wind-up under hard acceleration. So I started looking at solutions. Now, I don't want anything hanging down, both because of looks and I don't want to worry about dragging anything. A four-link or leaf-link system would work, but that's a lot of fab work and I do have exhaust I have to dodge as it crosses the frame from inside-to-outside just past the stock snubber and has to remain that way. The OEM leafs are outside of the framerails.

Slapper bars would be perfect if they didn't hang down so much. So I came up this this...

Basically a upside-down slapper bar, with a bolt-on 'loop' around the spring at the front to allow easy installation. Details remain to be worked out, but I see this as a 'three-fer'; traction aid, works as the lowering block, and should also give me sway bar function (which I also want). Where I'd like some input is length of the bar and how tight the snubbing should be, keeping mind I do want this to act as a sway bar but don't want to degrade ride quality any more than I have to. I haven't got the spring length in front of me, but they are long. Is there a formula for calculating bar length?

I know from past experience these can have axle tramp with bigger-than-stock power and I'll be running a manual trans too. Yeah, I know, customs are supposed to be low and slow, but I don't do slow well....

 

Like a cross between a slapper bar and a cal trak

 

I want to say there was something similar mentioned about the ram chargers from the early 60's where they did some thing very similar. It allowed them to get some great weight transfer on the strip.

 

IIRC, it was in the big Mopar chassis book.

 

According to this Traction Bars! The Way to Eliminate Axle Wrap! (how-to-build-hotrods.com) You don't want your slapper bar hitting the spring in that spot.

 

The ones I recall were on top of the springs and ran to the rear.

 

Why not just add half-leafs to the front of the spring? They would control spring-wrap and would be virtually invisible.

As to your reversed slappers functioning as a sway bar, I don't see how they would, unless they are connected to each other with a torsion spring bar of some sort.

 

Way back in the 50's before slappers, 3 and 4 link TractionMaster controlled spring wrap
for acceleration and braking....that will be no benefit for braking if you care. I heard concern re
hanging down. You are close to quarter elleptical design

 

If your 'contraption' is on the forward half of the spring, the 'snubber' should be under the leaf spring, and contacting under the forward spring eye. As the axle wraps, the bar end would want to move upwards.



Other than this, the only difference I can see compared to normal slapper bars is the amount of leverage it will have against wrap. Yours mounts closer to the axle center, therefore you have a smaller rotational moment (shorter lever), therefore you will have less leverage against the reactive force due to traction......(???)

 

URKK, URRRK, URRK, .... as I remember the noise coming from the rear wheels, as I dropped the clutch in front of the High School principal's office.

 

How about if where you have the rubber snubber you make a saddle that comes under the spring with the rubber in the saddle and attaches to the arm. Only the saddle would be visible under the car.

 

This is an excellent read. https://www.jalopyjournal.com/forum/threads/launch-issues.981344/

Have you thought about using top links with the leaf springs to create something that works like a 4 bar setup?
Like the pic below, but imagine the lower leaf spring as a full semi-elliptic. With the geometry worked out to minimise pinion angle change, it could be a neat solution.

 

I looked at the Cal Traks but those were going to hang down unless I relocated the front hanger which is more work than I want to do.

I looked at that too, and found more than a few applications stopped the snubber well short of the spring end. This isn't a race application, no slicks involved. I just don't want it to tramp when I punch it. And that's how Cal Traks work, they just apply the force to the top of the spring instead of the bottom. There won't be any high-RPM launches here...

Again, one issue is the blocks will raise the housing in relationship to the springs giving it more leverage, so how many additional leaves would I have to add? And I do want to retain the 'big car' ride as much as possible. Again, this isn't a race car. As to the sway bar function, these will be connected to the housing for the 'torsion' part of it, I'm thinking I can 'tune' this with how I configure the top and bottom snubbers. My main concern here is it may be too stiff. The top snubber will also prevent any 'thumping' noise under braking when the bar goes down.

I did look at them, but they do hang down a bit and as I'm lowering this the old-fashioned way (static, no bags) that's a real concern. I'm stuck with some pretty crappy local roads in places I travel, I don't want anything that can hang up under there. As it is I expect I'm going to weld a couple of skid plates to the bottom of the frame.

That's the plan.... and if I keep the snubber fairly short, you won't see it at all. This has been useful so far; I see a couple of small changes I can make to improve the design and remove some concerns.

One thing nobody mentioned and I didn't bring up is the size of the tubing used. Initially I thought a 2X2 or 2X3 square tube would be best, but now I'm wondering if something smaller might not be better. After reading this thread...
Technical - Launch issues | The H.A.M.B. (jalopyjournal.com) ... and the guy got a marked improvement with a chunk of uni-strut, that may be overkill. A little flex might be a good thing...

 

Worked on my Tri-5 Fords very well.

 

Nice drawing. Did you do it?

 

Yep, like I said in post #13.................. Good example...........

Unfortunately no. I found it on this thread. Post #30. I wish I could draw like that..............
https://www.jalopyjournal.com/forum/threads/quarter-elliptic-rear-suspension.143466/

 

Hate to have to go here, but just food for thought.
http://www.camaros.org/radiusrod.shtml

 

Steve, You said you modified the front spring hangers? Raised them up? How about the rear? Eliminate the shackles and use a slider kit..De-arch the springs, and then eliminate the blocks. How about that? might need shorter shocks then.
Next is the traction issue.Almost anything you do is going to make it ride stiffer. You're on the right track, but I might make a round link with L/R heims. Clamp it real close to the spring eye. Weld brackets to the housing. Set them at zero pre-load with you in the car, and see if you can live with that.

 

Another example drawing of 'radius bars' from early seventies Australian performance falcons (GT, GTHO and Landau hardtops). This would be easy to add, virtually invisible, and do the job with regards to spring wrap......

 

Mark, that's one option I looked at. But I'm trying to do three things; traction control, lowering, and a sway bar. It's really congested under there, the 'vert frame is considerable different from the 'regular' car frames and the exhaust is screwing me, it's everywhere I need to be. I can't re-route unless I cut holes in the 'vert bracing and I'm loathe to do so. I want to install larger exhaust tubing, that's going to be dicey as it is. My other choice is to end it in front of the rear axle, that's not an option.

I like this solution, unconventional though it may be, because it appears I can get it all with this design and I don't have to make major mods under the car. Anything else it looks like two out of three. It's too bad @ELpolacko isn't on here anymore, I may invest in a phone call to him and see if I can pick his brain.

 

You could put a series of u-bolt clamps on the front of each spring, one at the end of each leaf.

Gary

 

My OT 69 AMX has a similar set up.

 

Well, so far nobody has said it won't work... LOL

I'll note that my original idea was very similar to the drawing in post 13, although with the OEM springs. That would take care of the lowering and traction. To get the sway bar, I was going to make the upper links do double-duty, connecting them with a splined shaft for the sway bar function. I contacted a vendor who builds that type and he disabused me of that notion unless I wanted to spend big bucks for custom parts, as his usual parts are primarily for racing and wouldn't last long on a street-driven car configured like that. Degree of difficulty would be much higher with the body mounted, he recommended pulling it off the frame!

 

I’m a nobody on this subject but latterly thinking Moriarity and twenty28s radius rods look a simple mod and would do the job. Except the sway bar side of it, Imho.

 

How much clearance you figure you need between your bars and the frame if it's on top, between the bars and the leaf springs, and under the springs? And how thick are the bars? Might add up.

Other than that, should work.

 

Steve, my concern is that you are attaching your traction control to the lowering blocks rather then to the axle. I think that will add a lot more stress on the lowering blocks, the U bolts, and the center bolts on the spring and the blocks. You will be attempting to control axle wrap up with a sandwiched block.

If you attach your traction device to the axle, you will not add stress to the u bolts, center bolts and the blocks themselves. A process like in post 20 would be much better.

How much lowering are you going to try to accomplish with the lowering blocks? Gene

 

I expect to lower it from 2.5" to 3" but that's not set in stone. I'm going to lower the front first, then drop the rear to match so the car is level. The traction bar is going to BE the lowering block, not attached to it. Only two pieces, the bar and the removable 'loop' so that the springs won't have to be pulled to install the bar. And after reading this... http://www.camaros.org/radiusrod.shtml ... I'm thinking round tube might be a better choice rather than square tube as it's got a bit more 'flex' in it.

For all intents and purposes, this is still just a slapper bar set-up, just reconfigured. Tons of them were sold and successfully used on street and race cars, and this is NOT a race car.

 

I think you have missed the point @gene-koning was making. Your proposed "lowering block/arm assembly" will be only clamped between the axle pad and the top of the leaf spring, as per a normal lowering block. The pressure that will be applied to the end of the arm will, through leverage, try to rotate the block between the axle pad and leaf spring by stressing the u-bolts. It would be better to attach the arm to the axle tube in a solid fashion.