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Philippines Cowboy
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Discussion Starter #1
Fifty years ago, I ran a leaf spring Chevy at the strip in Cordova. To fight the usual "wrap up" problems with the leaf springs, I played with various devices to "strengthen" the front half of the springs. These would hang down and always presented the danger of snagging on something.

Well, I haven't had much to do with leaf springs since then, but I was thinking of that car the other day and realized, if I were to do it all over again, I'd try something completely different. Compare the leaf spring with any one of the links of a 4link. When it comes to handling tensile or compressive forces, that leaf should work every bit as well. The problem, of course, is that the leaf must also handle a very large torque which tends to deform the front half of the spring, resulting in wheel hop. Okay, so, instead of bolting something on to the spring to more effectively absorb that torque, why not eliminate the torque in the first place?

And, here's where the chain comes in. I'm suggesting that a bracket extend up from the axle housing directly above the right leaf spring. From the top of this bracket, a chain would extend forward and slightly down to an attachment point on the frame. Why only the right side? Well, you could have one on the left, also, but you might as well kill two birds with one stone and go for cancellation of the driveshaft torque. (See the 3link page at my blog:

http://home.earthlink.net/~whshope

).

And, why a chain instead of a normal link? With a chain, this extra "link" will be effective only on acceleration. During braking, the chain goes slack and the car behaves exactly as before. (To avoid the possibility of kinking, the chain should be covered with rubber tubing, just as the NASCAR boys do with their suspension limiting chains.)

So, I'm just wondering if anyone has heard of this little trick being used.
 

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here to learn
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i think i understand what your saying, the chain would prevent the rear housing from rotating clock-wise (when viewing it from the driver side) canceling drive shaft torque by controlling the rear housing instead of the springs. did i get it right.

but i've never seen it.

would'nt a heavy-duty type telescoping device be safer?
 

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Philippines Cowboy
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Discussion Starter #3
53LEDSLED said:
i think i understand what your saying, the chain would prevent the rear housing from rotating clock-wise (when viewing it from the driver side) canceling drive shaft torque by controlling the rear housing instead of the springs. did i get it right.
The driveshaft torque cancellation to which I refer is the cancellation of that torque which tends to unload the right rear on acceleration. The offset of the single chain...to the passenger side...is the source of this cancellation.

53LEDSLED said:
but i've never seen it.

would'nt a heavy-duty type telescoping device be safer?
Don't understand your safety concern. If the chain breaks, you're no worse off than you were before, and, again, the chain goes slack during braking.
 

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BillyShope said:
Don't understand your safety concern. If the chain breaks, you're no worse off than you were before, and, again, the chain goes slack during braking.

i was thinking that if the chain broke at either end, it would be dangerous, but then again, any suspension part that broke of could cause a lot of damage. we might have a different picture of your idea?
 

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MGB's and a lot of that pommie dung ran leather/webbing 'straps' to limit torque reaction. They also ran 4 cylinder engines to ELIMINATE torque application.
Why not just clamp the foreward half of the leaf? Popular in the 60s and seems to work these days.
 

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Philippines Cowboy
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Discussion Starter #6
Yes, Ian, it worked in the fifties, also, but it's not the best solution. I just finished running the equation set in Excel, using the "solver" function. With a chain setup, you can have equal rear tire loading and no squat or rise. As soon as I solve the equation set, I'll add it to my blog. I think it will be Page 22. Should be there within 24 hours:

http://home.earthlink.net/~whshope
 

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Thinking about this a little and to me it seems that A, the chain and the leafs having two different motion paths would cause bind from the converging arc paths. Theortetically if you have a car that launches hard with a descent amount of weight transfer... your chain would in effect turn your pinion the opposite direction as the suspension compressed also binding the leafs....? I guess all depending on the length of the chain.........
 

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Race it, Don't rice it!
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How about changing to mono leaf and coil over in front of the housing on the right side. stacked leaf on the LS if desired.

The leaf will hold the car up while the coil over or slider will allow a tuning device to the axle wrap and increase load on the RR during accel. During braking, the coil slider will bottom out and limit the forward rotation of the rear housing.

Leafs would negate the need for a Panhard bar.
 

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Philippines Cowboy
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Discussion Starter #10
...the chain and the leafs having two different motion paths would cause bind...
Correct! I had a redundancy in my equation set and was fooled into thinking I had a valid solution.

The idea is still valid, but it isn't as "clean" as I'd like it. You have to assume a rear "pivot" point for the leaf, which would be roughly below the axle housing. Then, using the spreadsheet for the 3link in my blog, the upper chain link could be positioned properly. But, this is one setup where you'd definitely have to use the traction dyno to "fine tune" it.

I don't believe the inherent bind would be troublesome. The rear roll stiffness would be increased slightly, but probably not enough to even notice. And, again, the chain would go slack during braking, leaving you with the stock suspension characteristics.
 

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Philippines Cowboy
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Discussion Starter #11
Usually, I don't bother telling others of my ideas. I'll occasionally have a good idea, but, for the most part, they're bad. THIS one was bad. VERY bad!!!

Yes, the chain link would act as a very stiff torsion spring to prevent the pinion gear from climbing the ring gear. But, unfortunately, the leaf spring and the chain "spring" are not in parallel; they're in series! And, when you place a high rate spring and a low rate spring in series, you end up with essentially the lower spring rate.

So, the chain link simply wouldn't work. On launch, the leaf spring would essentially ignore the presence of the chain link and wrap up just as it always had.

Sorry to waste your time, but, perhaps, this has caused someone to steer toward a GOOD idea.
 

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That makes sense.... So once that chain extended to its max, the rear would essentially wrap the bottom side in an upward arc.... unless acptured to the rear of the vehicle... which would now give us three converging paths........
 

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It's hard to reinvent the wheel. I did see a similar setup years ago on a 67 Camaro. He used a load leveling bar from a trailer hitch mounted on the spring plate with the bar running to the rear and the chain mounted near the rear shackle. For something cheap that works fairly well, it's hard to beat the old Lakewood slapper bars.
Bob
 

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BillyShope said:
...On launch, the leaf spring would essentially ignore the presence of the chain link and wrap up just as it always had.
Leaves don't like to be used as a "link" in compression as they will just buckle (wrap). They handle tension much better...but like you mentioned earlier that would mean putting a telescoping link below the leaves reducing ground clearance.

How about a torque arm with a slider, shackle, or bump pad at the chassis end offset to get the equal loading...Kind of like a single slapper bar but wouldn't need to hang down so much?
 

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Sounds like the "wishbone" that is made by Jerry Bickel Race Cars and Thomas Racing Components........
 

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I understand the setup you are talking about, and I also understand the inherent problems with it. With careful placement of the chain above the leaf mounting point on the forward end of the spring it will almost work...almost.

A solution I thought of a while back is a four wheelin part modified for this application. The problem with leaf springs isn't so much axle wrap, if the axle stayed wrapped during hard acceleration it would actually help traction, the problem occurs when the spring suddenly decides to return all the energy you just put into it (tries to straighten out again).

I don't have anything with leaf springs on it or I would have already tried this, but if you take your chain idea and replace it with either a plain old shock absorber, or, if you wanna get fancy a steering damper like those used to dampen steering oscillations in the front end of a four wheeler with a straight axle. This would slow the axle wrap initially as well as keep it from retuning all of the energy that it has stored up all at once.

And since it isn't fixed in length it will never bind up like traction bars or your chain idea.

For either more or less dampening, just use a longer or shorter arm on your axle housing.

My two cents,
Rick
 

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Here is the setup that GM put on some S10's. From my understanding it was part of the eXtreem handling package but might have also been used with the HO4.3L with a stick. FWIW the "hop shock" or "3rd shock" is VERY STIFF compared to a normal shock.

I wonder how much thought GM put into getting equal loading on the rear tires under acceleration :confused:

Edit: the picture is from roughneck427 @ s10forum.com
 

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Philippines Cowboy
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Discussion Starter #19
I still think mine was a very bad idea and I can't see the S-10 arrangement as being very effective. With the shackle at the rear of the spring, there is nothing to prevent the rotation of the assembly about the pivot point at the rear of the shock (or chain). As the shock is moved closer to the spring, the action tends to approximate that of any one of the products offered to strengthen the front of the leaf spring. In other words, why fool with a shock (or chain) when there are many options which have already proven effective? The only remaining problem is achieving equal rear tire loading on launch (which I had hoped to do with the chain), but this can be achieved by other means, such as a higher rate RF spring than LF. (Page 7 at http://home.earthlink.net/~whshope )
 

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Just an ole country boy that played around with a "stock" car in the early 70s, Drove 55 chevy with a 65 Impala rear end mounted on leaf springs, but the trick came with the eyelets on top of Diff., ran control arms BACK WARDS mounted to a wielded in crossarm just behind the Diff. added weight transfer and STOPPED spring wrap up. All pulled by a"STOCK" 283. (Bored to 4" with 12 to one pop ups) "STOCK". A lot of STUFF has been tried over the years, some worked some did't. Do what you need to do to correct the problem you are having at the time. Brought back some peasant memories. Just thinking out loud. Sorry I'll go now.
 
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