Leaf spring sliders for desert use???

[DieselSJ]

"physics" aside, how about some experience?

I guess I just dont see how an angled slider is THAT different from a swinging shackle as far as spring movement to the point where it would be that ill-advised, or at least the way youre making it sound.

Experience...go back and read my posts.

 

[HeavyMetal]

Experience...go back and read my posts.

I did, and replied directly to yours, I appreciate the feedback based on your experience which is what I asked about originally..

I was specifically asking the poster I quoted in this next case.

 

[Milford Cubicle II]

BUT- the spring's natural movement is in an arc, which you are limiting with the use of the slider. in a crawling scenario where rapid cycling doesnt occur, this isnt an issue. the physical amount of force simply isnt there. going fast however, the leaf wants to move inside this arc more violently, thus causing a lot of premature wear, and from what dieselSJ has said in his experience, eventual failure of the bushings. i understand the angled slider is putting less stress on the pivot point as opposed to a straight one, but the problem is still there.

can you mimic the arc in a slider? yes of course. but there is still natural movement from side to side within the leaf bushings that will pull on the slider that a shackle can hold up to that the slider (eventually) cannot. and once you get to this step you're trying to re-invent the shackle, so why not just use it?

lastly, i understand the whole point of the slider is to maintain rate throughout the spring's travel, but a quality leaf spring is designed with the shackle in mind.

How is a leaf spring's "natural movement" an arc? I'm not trying to be a douche, I just don't understand that assumption.

Experience...go back and read my posts.

I don't think your "experience" is nearly as definitive as you're making it sound.



Also, this:
http://www.afcoracing.com/tech_pages/leaf.shtml
is an interesting read about shackles in general and has a section on sliders. It's in reference to pavement go-fast but makes sense none the less.

 

[XJLI]

How is a leaf spring's "natural movement" an arc? I'm not trying to be a douche, I just don't understand that assumption.

i meant the shackle end... this part of that article.

but the slider changes the entire way the spring works it seems, more than i've been learned previously... that article was a good read.

 

[DieselSJ]

I don't think your "experience" is nearly as definitive as you're making it sound.

I guess a factory backed race effort where we spent about half a season playing with it isn't quite enough for you.

 

[Milford Cubicle II]

I guess a factory backed race effort where we spent about half a season playing with it isn't quite enough for you.

Quick question, what angle was your slider at?

i meant the shackle end... this part of that article.

but the slider changes the entire way the spring works it seems, more than i've been learned previously... that article was a good read.

I agree. A leaf spring's "natural" behavior all depends on how it's constrained.

However, the maximum amount of travel in a leaf spring depends on the length of the shackle. With a slider you can have as much travel as you want without compromising lateral stability. Whether or not that's desirable depends on your application I suppose.

 

[DieselSJ]

Quick question, what angle was your slider at?

Don't remember exactly. I know we started with 0* and went up to about 20* or so. We tried lots of different angles to try to take some of the impact stresses off the sliders. They lived all day long at low speeds. As soon as we got up to about 50% of race speed they ate themselves quickly.

 

[tbburg]

1) The "natural" movement of a shackle is an arc. Not the spring. The only reason the free end of a leaf spring moves in an arc is because it's fixed to the shackle(which moves in an arc)

2) It doesn't surprise me that the sliders have a harsher ride. You're essentially replacing the rubber/poly bushings with a hard metal to metal bearing. Remove any rubber suspension bushing and replace it with a harder material, and you're going to get a harsher ride.

3) I'm guessing the most probable reason a slider dies under hard use is due to twisting forces, not necessarily pounding forces.( the pounding forces don't help though,...) When you compress one spring and droop the other, both springs try to twist in their mounts. With the stock setup, there's a big rubber bushing up front and 2 smaller bushings in the rear to absorb that movement.
Remove the shackle and install a slider, and you have effectively fixed the rear spring eye(rotationally, not back and forth) The spring has to twist instead of compressing the bushings. 'Lot of force to absorb there.
Maybe if you installed something like this:

"Orbit-eyes" from Alcan spring

In the rear spring eye position, then attached that to the slider(or build a custom slider around it), it would account for the twisting force. Other then that, the sliders I've seen for drag use have pretty small bearing rollers, and would be woefully under-sized for desert racing.

Assuming all that would work, there's still:
A large complicated roller assembly with moving parts, custom sized spring eyes, probably 5-10 lb/side,... that has a probable failure mode(roller failure) that includes the rear of the spring flapping loose.

All this to replace a 1lb assembly who's most common failure(bushing failure) still leaves the suspension intact and working.

A slider can probably be made that would work for desert racing, but it's replacing a simple swing arm. "KISS"

 

[9T3XJ]

There's a lot of good info in this thread, just wanted to make a couple comments regarding some of my original thinking behind this...

2) It doesn't surprise me that the sliders have a harsher ride. You're essentially replacing the rubber/poly bushings with a hard metal to metal bearing. Remove any rubber suspension bushing and replace it with a harder material, and you're going to get a harsher ride.

I have mixed thoughts about this. IMO its better to get rid of bushings in suspension, bushings add an uncontrolled spring rate to your suspension. Using "hard joints" forces your springs and shocks to do all the work, making tuning easier by taking out the unknowns. BUT...leaf springs need some type of bushing because of the inherent bind.

3) I'm guessing the most probable reason a slider dies under hard use is due to twisting forces, not necessarily pounding forces.( the pounding forces don't help though,...) When you compress one spring and droop the other, both springs try to twist in their mounts. With the stock setup, there's a big rubber bushing up front and 2 smaller bushings in the rear to absorb that movement.
Remove the shackle and install a slider, and you have effectively fixed the rear spring eye(rotationally, not back and forth) The spring has to twist instead of compressing the bushings.

This also offers more lateral stability though, I do think it would be interesting to try this with something like Alcan offers, it would probably help with the two issues stated above.

Assuming all that would work, there's still:
A large complicated roller assembly with moving parts, custom sized spring eyes, probably 5-10 lb/side,... that has a probable failure mode(roller failure) that includes the rear of the spring flapping loose.

All this to replace a 1lb assembly who's most common failure(bushing failure) still leaves the suspension intact and working.

A slider can probably be made that would work for desert racing, but it's replacing a simple swing arm. "KISS"

The sliders in question use delrin bushings, no rollers or bearings and they fit tight in the they're guides to reduce slop. A bolt still constrains the rear spring so if the bushing fails you're just riding on the bolt, the springs not gonna come loose.

One of the main advantages I saw to this was the ability to keep the rear low, while still increasing the amount the spring was allowed to travel.

 

[HeavyMetal]

One of the main advantages I saw to this was the ability to keep the rear low, while still increasing the amount the spring was allowed to travel.

this is precisely one of the reasons why we are experimenting with this setup.

And I realize this is the Jeepspeed section and the original title had "desert" in it, but the build direction is general purpose, sprints of speed, crawling, street, so on. So perhaps while, in theory, not 100% ideal for a desert race truck, perhaps in this application it will shine.

We are experimenting with a removable slider box solution that can be directly swapped with a shackle relocation mount if we want to backtrack to experiment with a shackle.

 

[DieselSJ]

The thought of a slider failure somewhere in the middle of baja or even just out in the middle of the AZ desert somewhere would keep me from having any serious thoughts about running one on my XJ. I've seen the carnage from failures. Though I'll never be running at race speeds, knowing how much stronger and reliable a shackle is I'd be hard pressed to convert to a slider.

In regards to keeping it low...relocate the upper mount for the shackle. To run a longer shackle, you don't need to move the lower mount down...try moving the upper mount up.

 

[tbburg]

I have mixed thoughts about this. IMO its better to get rid of bushings in suspension, bushings add an uncontrolled spring rate to your suspension. Using "hard joints" forces your springs and shocks to do all the work, making tuning easier by taking out the unknowns. BUT...leaf springs need some type of bushing because of the inherent bind.

Wasn't trying to promote rubber bushings. Most high performance automotive builds have mods to get rid of the slop in the suspension. I'm OK with that,(prefer it for all out race car/truck) I was referring to a prior comment DesielSJ about ride/handling, and making more noise inside the car at speed.

This also offers more lateral stability though, I do think it would be interesting to try this with something like Alcan offers, it would probably help with the two issues stated above.

Any stability you pick up in a slider would be lost if you used the Alcan Orbit eyes style flex joint instead of a bushing. I've only talked to one person with experience with the Orbit-eyes. 'Rock crawler. 'Said it let the suspension flex like mad, but the on-road ride was really wishy-washy. I only suggested the orbit-eyes as a means to allow the slider to stay in one piece.

One of the main advantages I saw to this was the ability to keep the rear low, while still increasing the amount the spring was allowed to travel.

'Was looking at a Class 7 MJ recently where they had relocated the shackle mounts to the top of the frame rail, aprox. 6" shackles, straddling the frame rail, and the spring was hugging the bottom of the rail. Harder to do on an XJ, but a box up through the load floor connected to the cage on the outside and an extended brace from the uni-rail on the inside would allow practically any length shackle, and the spring eye could be located almost flush with the bottom of the uni-rail. 'Lot of fab work to make it happen, but probably not as much time as it would take to fab/test a reliable slider system.


After re-reading pgs 2&3, I picked up the reference to the Derlin bushings. Missed that before. I still think the main cause of failure is the twisting stress from the spring, but:
could a contributing factor be friction/heat buildup? The sliders work in low speed/crawling, but come apart as the speeds increase? As slippery as Derlin is, there is still friction. As the bushings move faster in their races, the metal and plastic will heat up. The plastic might be melting.
(Same reason basic hydro shocks work on rock crawlers, but desert runners need huge bodied, remote res cans to dissipate the excess heat,...)
Might go to a metal roller with sealed bearings to solve that.

HeavyMetal: Any chance you could get access to a infrared heat sensor gun when you go testing your slider setup? Would give you real time measurement of heat buildup.(if it exists, anyway.)

 

[HeavyMetal]

HeavyMetal: Any chance you could get access to a infrared heat sensor gun when you go testing your slider setup? Would give you real time measurement of heat buildup.(if it exists, anyway.)

Sure thing, I'll see what I can do, I'd be curious to see if nothing else.

We will be doing a lot of testing and experimenting with the setup, the most we can. So hopefully I have some useful results.

 

[CumminsJeep]

Sure thing, I'll see what I can do, I'd be curious to see if nothing else.

We will be doing a lot of testing and experimenting with the setup, the most we can. So hopefully I have some useful results.

Johnson valley :clap::clap:

 

[HeavyMetal]

update

these saw use in johnson valley during KOH week, lots and lots of desert running

and rausch creek trips (a few now). that means speed/crawling over rocky/irregular terrain, and about as gritty as it gets (especially the 2 weekends i was there)

the UHMW shows no sign (or so little i cant notice) of wear or irregularity. the boxes havent been stressed or anything. everything has worked out well.

the slider box is tied in through the original shackle mount location, as well as 4 hitch holes.

 

[FatCity Ryan]

Run them in junes Baja 500 and in Novembers 1000 and I would trust them.

 

[yossarian19]

Any new thoughts on these?
Yeah, resurrection.

 

[a1racer]

With liquid iron industries making a bolt in application id like to see how they hold up to higher speed usage to. I've debated replacing my hd drop brackets with them and some deaver leafs. But I don't do go fast mostly trail and rocks.

Anybody with some real world testing of this application would be helpful.

 

[Empty_Pockets]

Any new thoughts on these?
Yeah, resurrection.

Ran them, rode nice on and offroad, so nice I didn't need to use rear shocks.
Cons: Squeaky, hang low and hangup on rocks.

With liquid iron industries making a bolt in application id like to see how they hold up to higher speed usage to. I've debated replacing my hd drop brackets with them and some deaver leafs. But I don't do go fast mostly trail and rocks.

Anybody with some real world testing of this application would be helpful.

I had the LII bolt on ones rode really nice flexed like crazy, hung too low even on 9in of lift I was dragging them on everything.

 

[a1racer]

Any useful pics of them in action in the rocks would be nice to see if they could be modified or trimmed a little to get up out of the way of the rocks. Also did getting drug on rocks cause any issues like sticking or broken sliders ?

Would be interesting if some sort of plating with a ar400-500 plate to prevent damage on the bottom of them in the rear without interfering with their action.