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| Rear Leaf Spring SLIDERS?? https://slantsix.org/forum/viewtopic.php?t=50930 |
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| Author: | 64ragtop [ Fri Jan 25, 2013 10:54 pm ] |
| Post subject: | Rear Leaf Spring SLIDERS?? |
I've been aware of them for years. Seems they've popped up just in passing in an article. Recently I saw a writeup that went into some detail, then the post here that mentioned rear shackle hangers unavailable prompted me to run the idea past the forum. The first thought I had was that sliders should resist sideways force better than shackles. Since they replace the shackles, they will lower the rear of the car by about the length of the shackles. Preserving the ride height will call for higher arched springs. I like the idea of better lateral stability a lot, but don't understand the dynamics of spring behavior under different kinds of loads. ATB BC |
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| Author: | Dart270 [ Sat Jan 26, 2013 4:51 am ] |
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I am also contemplating these, but have not used them. I believe durability for street use would be a concern if any dirt gets in there. You will probably want to lower your front leaf eyes as well so the angle of your leaf (looking from the side of the car) does not change drastically. Only way to know is to try it! Lou |
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| Author: | Joshie225 [ Sat Jan 26, 2013 8:10 am ] |
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Durability is one issue, noise is another. If you really want better handling I would first try a panhard bar, but setup is crucial and requires the springs to allow lateral movement so the bar doesn't causing binding. |
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| Author: | 64ragtop [ Sat Jan 26, 2013 9:29 pm ] |
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I've got lots of other upgrades in the works, including offset spring shackles and front mounts so my interest is purely academic for now. I'm not sure about the noise and durability issues. There is a bushing in the rear spring eye with the sliders, maybe two bushings would transmit less noise?? Durability, I found a bunch of info on an offroad Jeep forum. I'd bet those folks push their suspension a lot harder than I plan to. Thanks for the responses, more grist for the mill. ATB BC |
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| Author: | Sprag [ Mon Feb 04, 2013 1:22 pm ] |
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Grist for the mill, I like that  The Mopar Chassis book taught me a lot about chassis dynamics and I think it's a great read for any drag or twisty racing enthusiast. It's what finally drilled into my skull how a RWD swinging shackle/leaf setup provides "rear steer", something I wouldn't mess with beyond installing/changing the rear sway bar or a well designed panhard bar. I think Ma Mopar did us good here. |
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| Author: | 64ragtop [ Mon Feb 04, 2013 6:41 pm ] |
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Quote: Grist for the mill, I like that The Mopar Chassis book taught me a lot about chassis dynamics and I think it's a great read for any drag or twisty racing enthusiast. It's what finally drilled into my skull how a RWD swinging shackle/leaf setup provides "rear steer", something I wouldn't mess with beyond installing/changing the rear sway bar or a well designed panhard bar. I think Ma Mopar did us good here. Then "rear steer" is a GOOD thing?? Again, this is just an academic exercise for me, but it seems that "front steer" would be controllable by the driver and "rear steer" would not (not counting throttle induced rear oversteer) I get what Joshua said about the Panhard rod needing some spring side movement for it to work and not bind. And lots of folks swear by them. I'm sticking to my offset shackles and springs for now and looking forward to knowing more when (if) I change my mind. ATB BC |
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| Author: | Sprag [ Mon Feb 04, 2013 7:44 pm ] |
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Quote: ..........it seems that "front steer" would be controllable by the driver and "rear steer" would not
Hah! Yah, that would be scary BC  What I meant was how the axle swings in an arc because of the shackle, it's subtle but it does cause a change in wheel base side to side in turns which pitches the axle oh so slightly. I think it's the same thing that can make a hard leaving drag car with a stock type rear leaf suspension steer a little on the rear axle because so much weight shifts over to the right rear. |
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| Author: | Joshie225 [ Mon Feb 04, 2013 7:58 pm ] |
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I was under the distinct impression the leaf spring arch/camber was responsible for the rear steer and that the shackle caused changes in dynamic spring rate. |
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| Author: | Sprag [ Mon Feb 04, 2013 8:10 pm ] |
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I think you're right in both cases, but consider that the shackle allows the spring to change length which moves the axle back/forth. That's what I was trying to illustrate, it's a subtle thing but not something I'd want to alter for high speed travel, for off-road crawling type stuff I don't think it would matter much though. |
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| Author: | Joshie225 [ Mon Feb 04, 2013 9:25 pm ] |
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Double post. Phone snafu. |
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| Author: | nuttyprof [ Mon Feb 04, 2013 9:52 pm ] |
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If you really want better handling I would first try a panhard bar, but setup is crucial and requires the springs to allow lateral movement so the bar doesn't causing binding. A watts link eliminates the need for lateral movement and wont bind that way. |
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| Author: | Joshie225 [ Mon Feb 04, 2013 10:13 pm ] |
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Quote: I think you're right in both cases, but consider that the shackle allows the spring to change length which moves the axle back/forth. That's what I was trying to illustrate, it's a subtle thing but not something I'd want to alter for high speed travel, for off-road crawling type stuff I don't think it would matter much though.
The spring changes length due to the change in arch. The rear shackle accommodates the length change, but does not cause the change. Shackles do cause a change in spring rate, however and leaf spring sliders eliminate the spring rate change. Panhard bars change the rear roll center and keep it more consistent. Roll couple is another issue which we haven't even touched upon.
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| Author: | Sprag [ Tue Feb 05, 2013 6:04 am ] |
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Quote: The spring changes length due to the change in arch. The rear shackle accommodates the length change, but does not cause the change. ...... That's why I corrected myself in my last post when I said the shackle "allows", we're getting more precise here, less 'grist for the mill'. If ragtop is talking about a more dedicated race car, that's way out of my league, I wouldn't touch that in the racing forum. Heck, I thought "roll couple" was a break dancing move  I like the long, dopey, squishy swing of a shackle, at least in a 'street' car that is. It makes more sense to me to let the spring do what it "needs" to and look for control in a more basic way via panhard or other means. |
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| Author: | Joshie225 [ Tue Feb 05, 2013 9:15 am ] |
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If we want a constant spring rate we have to ditch the shackle. If we want an understeering rear end (rear of the car steered away from the corner) then we want a front spring segment that is flat at static load. A highly arched spring will steer the rear end into the corner. http://www.afcoracing.com/tech_pages/leaf.shtml A Panhard bar provides lateral control which differs from the leaf spring which is why the leaf spring's natural lateral location has to be deactivated if a Panhard bar or Watts link is installed. This is a separate issue from the spring rate change caused by the shackle angularity. |
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| Author: | 64ragtop [ Tue Feb 05, 2013 11:58 pm ] |
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My grist mill overfloweth! Seems to me that several different methods of suspending and restraining the live rear axle have proven to work better than others, depending on a number of factors. Thus, to say one method is superior to another (or to all others) in all cases is foolish. I'm pretty sure that for street duty, with perhaps an occasional drag strip blast, and maybe a little amateur gymkhana action my slightly relocated leaf springs, heavy duty shackles and larger tires will be an adequate solution. Next: a front swaybar! ATB BC |
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