School me on front 4 link

[Jinx]

I take it Dtoy is still running that drive shaft?
I don't know about "everything" but I try hard.
Thanks man.

I will be done with school in May and hope to be down that way some time or another... It would be great to see you and shelby

 

[Badbuggy]

We will be here.

 

[ravencr]

From your pic, it looks like you're going to have a ton of anti-dive built into your front suspension. Raising the uppers will definitely help stave off some unloading.

Could you tell me why this is the case and how'd he decrease it? I'm trying to figure this out on the front of my rig, but the doesn't appear any confirmed info on the front ends. What does raising and lowering the axle and frame ends of the upper links actually do?

Thanks,

Chris

 

[zukijames]

Chris if Jeff doesn't chime in talk to rockmonkey, or I lean on here I think there some of the best when it comes to suspension

 

[STAG]

I know this is a thread-from-the-dead, but what are everyone's thoughts/opinions on a wishbone 3-link/"y" link on the front. I had a buddy who ran it front and rear with tractor joints. And although it was crude, it seemed to work quite well. No latteral axle movement, no panhard bar. Although I understand a bit of a binding issue within the sides of the upper link, as when flexing one side wants to raise and the other wants to droop. Albeit this, any other cons?

 

[ravencr]

Chris if Jeff doesn't chime in talk to rockmonkey, or I lean on here I think there some of the best when it comes to suspension

Will do...thanks.

Chris

 

[I Lean]

Could you tell me why this is the case and how'd he decrease it? I'm trying to figure this out on the front of my rig, but the doesn't appear any confirmed info on the front ends. What does raising and lowering the axle and frame ends of the upper links actually do?

Thanks,

Chris

In the pic above, if you raised the frame end of the upper links--making the upper and lower arms more parallel as viewed from the side, then you would have less anti-dive. Just like the name implies, more anti-dive means the front suspension will resist compressing if you slam on the brakes. That's not a bad thing by itself, in fact it's kinda nice...but the downside is that there is more chance of getting some suspension-induced hopping when you're trying to climb stuff offroad, especially in loose or inconsistent traction surfaces.

That said, there seems to be a much wider range of what will work well on a front suspension with regards to anti-dive, compared to what works well on a rear suspension. (which would be anti-squat instead)

I know this is a thread-from-the-dead, but what are everyone's thoughts/opinions on a wishbone 3-link/"y" link on the front. I had a buddy who ran it front and rear with tractor joints. And although it was crude, it seemed to work quite well. No latteral axle movement, no panhard bar. Although I understand a bit of a binding issue within the sides of the upper link, as when flexing one side wants to raise and the other wants to droop. Albeit this, any other cons?

Can you explain more what you mean by "wishbone 3-link/"y" link"?

 

[ravencr]

In the pic above, if you raised the frame end of the upper links--making the upper and lower arms more parallel as viewed from the side, then you would have less anti-dive. Just like the name implies, more anti-dive means the front suspension will resist compressing if you slam on the brakes. That's not a bad thing by itself, in fact it's kinda nice...but the downside is that there is more chance of getting some suspension-induced hopping when you're trying to climb stuff offroad, especially in loose or inconsistent traction surfaces.

That said, there seems to be a much wider range of what will work well on a front suspension with regards to anti-dive, compared to what works well on a rear suspension. (which would be anti-squat instead)

So, if my links are already close to parallel and I move the axle end of the upper link mount up, this will further increase anti-dive, correct? You said it resists the compression of the suspension during braking, but what about when you give it gas? Does it force the tires into the ground like anti-squat does in the rear making it harder for the front end to climb a rock, for example? What about at the axle end of the upper links? If I move the axle end of the upper links up, what does this do for anti-dive up front? I'm less concerned with how it reacts under braking and more concerned how it handles climbing rock ledges under power. Thanks so much for the help,

Chris

 

[I Lean]

So, if my links are already close to parallel and I move the axle end of the upper link mount up, this will further increase anti-dive, correct?

You're exactly backward. Moving the axle end of the upper link down, so the upper and lower links are closer together at the frame than at the axle, gives more anti-dive. (like Badbuggy's picture above) More convergence at the frame = more anti-dive (or anti-squat, if we're talking rear suspension) Less convergence at the frame = less anti-dive. (or anti-squat) If you had an unusual setup where the links had MORE vertical separation at the frame than at the axle, then you would tend to dive (or squat) actively, which wouldn't be too fun.

You said it resists the compression of the suspension during braking, but what about when you give it gas? Does it force the tires into the ground like anti-squat does in the rear making it harder for the front end to climb a rock, for example? What about at the axle end of the upper links? If I move the axle end of the upper links up, what does this do for anti-dive up front? I'm less concerned with how it reacts under braking and more concerned how it handles climbing rock ledges under power. Thanks so much for the help,

Chris

If it resists compression under braking, then it would resist lifting under power...it would try to "lift" the front tires (or compress the front suspension) when you're on the gas.

You say your current front suspension is generally parallel--that's exactly my preference to keep the suspension the most neutral you can, so it can behave predictably in all situations.

 

[ravencr]

You're exactly backward. Moving the axle end of the upper link down, so the upper and lower links are closer together at the frame than at the axle, gives more anti-dive. (like Badbuggy's picture above) More convergence at the frame = more anti-dive (or anti-squat, if we're talking rear suspension) Less convergence at the frame = less anti-dive. (or anti-squat) If you had an unusual setup where the links had MORE vertical separation at the frame than at the axle, then you would tend to dive (or squat) actively, which wouldn't be too fun.

Wow, you lost me here a bit...sorry I'm so slow. Can I make a general assumption based on what you've said above, but not assuming that I have more convergence at the frame than at the axle? I mean, if I move the axle end of the upper links up, I'm increasing anti-dive in the front and increase anti-squat in the rear, correct? Now, at the frame end, if I increase the height of the upper links, assuming all other things remain constant, I'm decreasing anti-dive up front and decreasing anti-squat in the rear, correct? Do I get it now?

If it resists compression under braking, then it would resist lifting under power...it would try to "lift" the front tires (or compress the front suspension) when you're on the gas.

I'm confused here too...surprised? So, if I have high anti-dive up front, during braking the truck should remain more level because the suspension actually is pushing into the ground harder and causing the suspension not to compress as much, right? But, under power, you're saying a vehicle with high anti-dive up front will actually pull the tires into the chassis or up, instead of pushing down, causing the suspension to compress and actually probably help when climbing steep hills, correct?

You say your current front suspension is generally parallel--that's exactly my preference to keep the suspension the most neutral you can, so it can behave predictably in all situations.

Like anything, if I can understand the above thanks to your help, this will drastically help me get it perfect...perfection is the key...lol.

Chris

 

[Badbuggy]

I just used a rear link calculator to figure out where to put the link mounts. I get the squat, anti squat, and all of that, but on the front, it turns out different. It is a little harder to picture it as it moves. The way this one works, is, when you gas it the front end raises slightly, and when you brake it drops slightly. With the huge amount of travel this Jeep has, I was tickled to see it have some manners too.
The more seperation, at the frame end, the better, to a point. That is easier to do in the rear than the front, but similar general rules apply.

 

[I Lean]

Wow, you lost me here a bit...sorry I'm so slow. Can I make a general assumption based on what you've said above, but not assuming that I have more convergence at the frame than at the axle? I mean, if I move the axle end of the upper links up, I'm increasing anti-dive in the front and increase anti-squat in the rear, correct? Now, at the frame end, if I increase the height of the upper links, assuming all other things remain constant, I'm decreasing anti-dive up front and decreasing anti-squat in the rear, correct? Do I get it now?

Exactly!

So, if I have high anti-dive up front, during braking the truck should remain more level because the suspension actually is pushing into the ground harder and causing the suspension not to compress as much, right? But, under power, you're saying a vehicle with high anti-dive up front will actually pull the tires into the chassis or up, instead of pushing down, causing the suspension to compress and actually probably help when climbing steep hills, correct?

Correct with the exception of the end...it won't help climbing. A lot of climbing situations will benefit from having the front axle restrained, so it can't droop or unload. That can be from a limiting strap or winch rope, whatever--the idea is to keep the vehicles weight from transferring to the rear axle. I can see how you're saying high anti-dive could accomplish the same thing, and in theory it might--but in reality it will tend to hurt more than help. If you never lose traction at all it might, but if you lose traction ever, even just a small slip of the tire, now all the force you had holding the axle "up" goes away, and you get the weight transfer you were trying to avoid. If you have intermittent traction (slip-grab-slip-grab), now you've started hopping, and that's not good for anybody.

Like anything, if I can understand the above thanks to your help, this will drastically help me get it perfect...perfection is the key...lol.

Chris

That's the problem! Everything is a compromise somewhere. You can set up a "perfect" suspension for ONE scenario. Change that scenario, and you've changed what would be "perfect". You do the best you can, and optimize it for the way YOU like it, and where you use it, etc.

 

[I Lean]

I just used a rear link calculator to figure out where to put the link mounts. I get the squat, anti squat, and all of that, but on the front, it turns out different. It is a little harder to picture it as it moves. The way this one works, is, when you gas it the front end raises slightly, and when you brake it drops slightly. With the huge amount of travel this Jeep has, I was tickled to see it have some manners too.
The more seperation, at the frame end, the better, to a point. That is easier to do in the rear than the front, but similar general rules apply.

I should add--no matter how much anti-dive you build in, the front will probably still lift under power. If the center of gravity is above the axle centerlines (which it always will be in anything other than a low car) you will get some weight transfer toward the rear.

 

[ravencr]

Exactly!

Finally, I get it...thanks!

Correct with the exception of the end...it won't help climbing. A lot of climbing situations will benefit from having the front axle restrained, so it can't droop or unload. That can be from a limiting strap or winch rope, whatever--the idea is to keep the vehicles weight from transferring to the rear axle.

But, assuming I don't have a strap to limit the suspension from unloading, will the higher anti-dive help to keep the front end low?

I can see how you're saying high anti-dive could accomplish the same thing, and in theory it might--but in reality it will tend to hurt more than help. If you never lose traction at all it might, but if you lose traction ever, even just a small slip of the tire, now all the force you had holding the axle "up" goes away, and you get the weight transfer you were trying to avoid. If you have intermittent traction (slip-grab-slip-grab), now you've started hopping, and that's not good for anybody.

I'm not sure I get this yet...sorry. From what I've read, high anti-squat in the rear increases hopping on steep climbs when you're in a slip-grab-slip-grab situation versus a suspension with low anti-squat which tends not to hop. Now, up front you're saying that a high anti-dive setup is going to cause bad hopping too, which if it were act the same as the rear, this would actually cause the front not to hop based on the inverse relationship with the rear. But, you're not saying that, right? You're actually saying that if I had less anti-dive up front, it would actually climb better than one with more anti-dive, which to me doesn't make sense. We've all seen the rigs that pull up a big rock with both tires and before the front end even begins to climb the rock, the front suspension completely unloads (fully extends) before the tires begin to climb up the face of the rock. To me, this would be a low anti-dive front setup, correct? On the opposite side of that, a high anti-dive setup would not unload the front suspension, in fact it would suck up and climb the rocks with little to no binding, or at least less than one with low anti-dive, correct?

But, you're also saying that even though those above situations might be true, this all changes when traction is being lost when you're already on the steep climb, correct? Meaning that once on the steep rock face and attempting to climb the rest of the way up, you're in out and out of traction, the suspension that would work best in this situation would be one with low anti-dive up front correct?

If indeed the above is all true (I'm assuming based on what you said above, but doesn't mean I'm right...lol), I can see why having a neutral suspension is going to be the best of both worlds, right?

Chris

 

[DaveB]

When I put long arms on my son's jeep comanche it had fairly high anti dive numbers due to the difficulty in placing the upper and lower frame mounts. To improve it I would have to drop the lower mounts and lose ground clearance or go up through the floor for the uppers. As it is now the high anti dive has been great in emergency stops which has kept him under control, especially the one where he had a wheel bearing sieze up front and lock up one wheel at 40 MPH. The jeep climbs great on the slick rock but if he is in deep snow or sand it will start to hop up front.

 

[I Lean]

Finally, I get it...thanks!But, assuming I don't have a strap to limit the suspension from unloading, will the higher anti-dive help to keep the front end low? I'm not sure I get this yet...sorry. From what I've read, high anti-squat in the rear increases hopping on steep climbs when you're in a slip-grab-slip-grab situation versus a suspension with low anti-squat which tends not to hop. Now, up front you're saying that a high anti-dive setup is going to cause bad hopping too, which if it were act the same as the rear, this would actually cause the front not to hop based on the inverse relationship with the rear. But, you're not saying that, right? You're actually saying that if I had less anti-dive up front, it would actually climb better than one with more anti-dive, which to me doesn't make sense. We've all seen the rigs that pull up a big rock with both tires and before the front end even begins to climb the rock, the front suspension completely unloads (fully extends) before the tires begin to climb up the face of the rock. To me, this would be a low anti-dive front setup, correct? On the opposite side of that, a high anti-dive setup would not unload the front suspension, in fact it would suck up and climb the rocks with little to no binding, or at least less than one with low anti-dive, correct?

That rig climbing the rock may or may not have low anti-dive--it could also have, say, short control arms and a fairly angled roll axis. The force of the rear axle pushing the front axle into the rock unloads the suspension.

Or, the front tires climb the rock, pop up on top and the suspension unloads. Again, doesn't matter much what anti-dive numbers are there, since those only come into play when you're applying torque to the axle.

But, you're also saying that even though those above situations might be true, this all changes when traction is being lost when you're already on the steep climb, correct? Meaning that once on the steep rock face and attempting to climb the rest of the way up, you're in out and out of traction, the suspension that would work best in this situation would be one with low anti-dive up front correct?

If indeed the above is all true (I'm assuming based on what you said above, but doesn't mean I'm right...lol), I can see why having a neutral suspension is going to be the best of both worlds, right?

Chris

That's the thing right there.

When I put long arms on my son's jeep comanche it had fairly high anti dive numbers due to the difficulty in placing the upper and lower frame mounts. To improve it I would have to drop the lower mounts and lose ground clearance or go up through the floor for the uppers. As it is now the high anti dive has been great in emergency stops which has kept him under control, especially the one where he had a wheel bearing sieze up front and lock up one wheel at 40 MPH. The jeep climbs great on the slick rock but if he is in deep snow or sand it will start to hop up front.

That's just another illustration that there is a fairly wide range of setups that work well up front.

 

[STAG]

I can go into some detail on the wishbone link but I am on my phone right now so am somewhat limited to Google images and youtube.The lower links are placed just as they would on a triangulated 4-link suspension, however the top links come in to merge into one joint before the links reach the axle, like so;

It does effectively locate the axle side to side, without a panhard bar. And also allows true vertical motion of the axle. Maybe another issue I could see is possibly bump steer unless the drag link is almost parallel with the axle housing?

And here is a YouTube video of my said friend who has it done front and rear.
http://www.youtube.com/watch?v=OkG5dGITRm0

 

[I Lean]

I can go into some detail on the wishbone link but I am on my phone right now so am somewhat limited to Google images and youtube.The lower links are placed just as they would on a triangulated 4-link suspension, however the top links come in to merge into one joint before the links reach the axle, like so;

It does effectively locate the axle side to side, without a panhard bar. And also allows true vertical motion of the axle. Maybe another issue I could see is possibly bump steer unless the drag link is almost parallel with the axle housing?

I can't see the pic, but I understand what you're describing. My confusion came from the reference to "Y link", which I equate to a radius arm setup.

It can work fine. It's not my first choice, since depending how the single joint is mounted on the wishbone it might be loaded wrong, trying to press the ball out of the race. If it's a threaded-in joint, the shank will be loaded in bending. If it's a welded-on joint housing, then it's not adjustable.

In any case, it's best in a full-hydraulic steering setup, just like a triangulated link setup is.

 

[STAG]

Yeah I had to add the pic afterwards it should be there now, and yeah if I were to do it I would have the axle end link be adjustable/threaded. But that makes a good point about the axis of the rod end. I guess ideally it would be with the bolt running vertical, and making sure that even at fyll droop/compression the joint would not run out of flex and transfer the extra load to bolt shear.

 

[ravencr]

Thanks to all of you for the help...it's really helped...I'll post my findings after this weekend's testing.

Chris