3 link ???

[Goose]

Im in the process of figuring out my front link build.
Ive settled on a 3 link, because it just doesnt look like I can fit a triangulated four link.
I am going to run a full hydro double ended ram set-up, for steering.
my question is, using full hydro, what are my limitations or worries when I build my panhard?
I plan on mounting it as flat as I can, how much does the length matter?

 

[lewis]

I ran a three link with no panhard but that was probably a different 3 link then you are putting together. I ran 2 outer link and one center link that was attached at the frame at 2 spots making a triangle.

The longer then panhard the better. Look at rockmonkey's build, I think he did something similar with a panhard.

 

[Goose]

I ran a three link with no panhard but that was probably a different 3 link then you are putting together. I ran 2 outer link and one center link that was attached at the frame at 2 spots making a triangle.

The longer then panhard the better. Look at rockmonkey's build, I think he did something similar with a panhard.

yeah , my upper link is going to have to be closer to the frame, I wish I could fit something like you had.
thanks for the panhard info!

 

[LT.]

I stayed away from a three link because of the diving the front end will do under braking. Whatever side you don't have the other link the vehicle will dive to that side under braking. I guess it is fine if you are only an off road rig. Just something to think about.

LT.

 

[Goose]

I really wanted to run some tiangulated uppers, but its just so tight. unless I made them short.

 

[LT.]

That was another lesson I had to learn. You have to work with what you have. What may be ideal may not work for your application. Sucks sometimes but, when you try and re invent the wheel sometimes you have to make do with what you can. Good luck. I hope yours works out better than what I had.

LT.

 

[Goose]

That was another lesson I had to learn. You have to work with what you have. What may be ideal may not work for your application. Sucks sometimes but, when you try and re invent the wheel sometimes you have to make do with what you can. Good luck. I hope yours works out better than what I had.

LT.

I know what you mean. It wont be my first choice but Im sure it will work out.

 

[Bluecrush]

I really wanted to run some tiangulated uppers, but its just so tight. unless I made them short.

I did triangulated uppers, but I have a 3" body lift so I made new motor mounts to raise the drivetrain. If you have a body lift you might think about it. It looks cool because now everything is above the frame rails, even the oil pan!

 

[Silly Willy]

I did triangulated uppers, but I have a 3" body lift so I made new motor mounts to raise the drivetrain. If you have a body lift you might think about it. It looks cool because now everything is above the frame rails, even the oil pan!

Thats not street legal is it?

 

[Tacoma]

It probably is in CO.

 

[RockMonkey]

So, based on your question about the panhard bar, you must be talking about the "missing link" type of three link. If you were using two lowers and one triangulated upper that attaches at one point on the axle and two points on the frame (or the opposite) you wouldn't need a panhard bar. With the missing link type suspension you don't need to run full hydraulic steering. You can run a steering box and just match the panhard bar to the length and angle of the drag link. Could you fit a non-triangulated 4-link with a panhard? I think they work better, though I can't exactly quantify why.

As for the panhard itself, the length, angle, and height all matter. The panhard is going to determine your roll center center and roll axis. You can play around with this if you're going to run full hydraulic steering and don't need to match it up to a drag link. The center of the panhard bar is the point at which the chassis is going to pivot around, so the higher this point is, the more stable the chassis will be on a side-hill (or high speed turn), given the same center of gravity.

You're going to be pretty limited in where it can fit. Don't sacrifice center of gravity to make your panhard bar higher, but I would say in general a long, flat, high panhard bar is better than a low, short, highly angled panhard bar.

I ran a three link with no panhard but that was probably a different 3 link then you are putting together. I ran 2 outer link and one center link that was attached at the frame at 2 spots making a triangle.

The longer then panhard the better. Look at rockmonkey's build, I think he did something similar with a panhard.

I did a three link front on my buggy several years ago. I used one lower, two uppers, and a panhard bar. It worked okay, but I was never really very happy with it. On my XJ (probably the build you are referring to) I made triangulated radius arms, and a panhard the same length and angle as my drag link. It works a lot better.

 

[Goose]

So, based on your question about the panhard bar, you must be talking about the "missing link" type of three link. If you were using two lowers and one triangulated upper that attaches at one point on the axle and two points on the frame (or the opposite) you wouldn't need a panhard bar. With the missing link type suspension you don't need to run full hydraulic steering. You can run a steering box and just match the panhard bar to the length and angle of the drag link. Could you fit a non-triangulated 4-link with a panhard? I think they work better, though I can't exactly quantify why.

As for the panhard itself, the length, angle, and height all matter. The panhard is going to determine your roll center center and roll axis. You can play around with this if you're going to run full hydraulic steering and don't need to match it up to a drag link. The center of the panhard bar is the point at which the chassis is going to pivot around, so the higher this point is, the more stable the chassis will be on a side-hill (or high speed turn), given the same center of gravity.

You're going to be pretty limited in where it can fit. Don't sacrifice center of gravity to make your panhard bar higher, but I would say in general a long, flat, high panhard bar is better than a low, short, highly angled panhard bar.



I did a three link front on my buggy several years ago. I used one lower, two uppers, and a panhard bar. It worked okay, but I was never really very happy with it. On my XJ (probably the build you are referring to) I made triangulated radius arms, and a panhard the same length and angle as my drag link. It works a lot better.

I can see how the angle of the panhard can completely affect the way the suspension reacts. It seems that it would still react simillarly with a 4link.
Is this tue?
I could possibly fit a 4 link W/pan hard (still pretty tight)
I already have my full hydro so thats a done deal.
Ill have to take some more measurements tonight,
I just dont want something funky under my frontend! & I am feeling pretty limited.

 

[RockMonkey]

Yes. If all of your 4 link arms are parallel (as viewed from above/below) or close to it, it will behave similarly (better). The panhard bar will determine a lot of how the suspension will behave.

Just don't make a triangulated 4 link and throw a panhard bar on it as well. They'll fight each other, and regardless of which one wins, you'll invariably lose.

 

[I Lean]

If your 3 link has similar vertical separation at the frame end as at the axle end, you won't have weird body-roll issues under braking. If you have a larger difference in the two numbers (more anti-dive) then you can get some weirdness--basically, you hit the brakes, and the anti-dive only acts on one side of the vehicle. If you have 4 links that won't happen, and if you have less anti-dive that won't happen.

 

[Goose]

If your 3 link has similar vertical separation at the frame end as at the axle end, you won't have weird body-roll issues under braking. If you have a larger difference in the two numbers (more anti-dive) then you can get some weirdness--basically, you hit the brakes, and the anti-dive only acts on one side of the vehicle. If you have 4 links that won't happen, and if you have less anti-dive that won't happen.

thanks for the great input guys! It always helps to get a few oppinions to find a good solution.
I took some more measurements last night & looked really close at my posssibillities.

It looks like I might be able to squeez some triangulation in on the uppers.
A) either 2 uppers with a few inches of spacing inbetween them at the axle mount.
B) Or a wishbone style upper that would be shaped more like a U than a Y.
What potential problems might I face using a U shaped design for an upper link?

MEASUREMENTS:

42" upper wishbone (eye to eye)
45" lowers straight
8" sepparation at the axle
4" separation at the frame
this looked like the upper would be fairly flat.

How much triangulation is necessary?
since this upper link will be locating the axle under the rig, Is this a weak point?

 

[DaveB]

Yes. If all of your 4 link arms are parallel (as viewed from above/below) or close to it, it will behave similarly (better). The panhard bar will determine a lot of how the suspension will behave.

Just don't make a triangulated 4 link and throw a panhard bar on it as well. They'll fight each other, and regardless of which one wins, you'll invariably lose.

So how much triangulation is allowable to still use the pan hard ? On my commando project it has some triangulation on the uppers to miss the motor mounts and some on the lowers to allow the lowers to not rub the tires at full turn. The only way to lower the upper triangulation would be to bend the upper arms.

 

[RockMonkey]

So how much triangulation is allowable to still use the pan hard ? On my commando project it has some triangulation on the uppers to miss the motor mounts and some on the lowers to allow the lowers to not rub the tires at full turn. The only way to lower the upper triangulation would be to bend the upper arms.

Any binding caused by triangulated arms and a panhard bar will have to be accomodated by something giving way. Stock Jeep suspensions get away with a little triangulation by having big rubber bushings at both ends of every control arm.

So, if you're using rubber bushings I'd guess the answer is 'some'. If you're using more solid joints the answer would be 'almost none-ish'.


Theoretically, I suppose it would be possible to build a triangulated 4-link and a panhard bar with the same roll center and roll axis, so they don't fight each other, but my head would probably explode trying to figure that out, and whatever geometry that ends up being would probably have impractical (or impossible) mounting points and would probably not have ideal anti-squat or anti-dive.

It would be a good exercise in engineering. Now, we just need to find an engineer nerdy enough to undertake it. Know any engineers, Dave?

 

[RockMonkey]

thanks for the great input guys! It always helps to get a few oppinions to find a good solution.
I took some more measurements last night & looked really close at my posssibillities.

It looks like I might be able to squeez some triangulation in on the uppers.
A) either 2 uppers with a few inches of spacing inbetween them at the axle mount.
B) Or a wishbone style upper that would be shaped more like a U than a Y.
What potential problems might I face using a U shaped design for an upper link?

MEASUREMENTS:

42" upper wishbone (eye to eye)
45" lowers straight
8" sepparation at the axle
4" separation at the frame
this looked like the upper would be fairly flat.

How much triangulation is necessary?
since this upper link will be locating the axle under the rig, Is this a weak point?

There are two real issues with a U-shaped link. First is strength. Under forward acceleration the front axle will be putting the link in compression and trying turn your U into a W. Under braking or reverse acceleration conditions it will be in tension, so the axle is trying to turn your U into a V. Since straight links only see direct compression and tension forces, they can be built fairly light. Your U-shaped link will be under constant bending forces and will need to be built much stronger than a straight link would.

Second, there is no "right" way to mount the single joint at the point of the link. There are only two wrong ways to mount it. Ideally, you want the force placed on the joint to be in-line with the shank. You want the ball to be pushed forward and back in the joint, not side to side. None of the joints are as capable of resisting a force trying to push the ball out the side as they are resisting a force trying to push the ball forward or back. I'm having trouble verbalizing this concept... Since your U-link will be locating the axle side-to-side, as well as front to back, this joint should be mounted with the through-bolt vertically, instead of the typical horizontal mount, to prevent the ball from popping out the side of the joint. Now your problem is you are relying on the deflection of the joint to accomodate all of your vertical suspension movement. This will wear out the joint much more quickly, and unless you plan it carefully, you can max out the movement of the joint and break stuff.

Neither of these problems are insurmountable. You can build a U-link strong enough, and you can use a big-ass joint that is strong enough to locate the axle both side-to-side and front-to-back, or a joint that is rebuildable and has enough deflection to accomodate all the vertical axle movement.

I'd say radius arms or a non-triangulated 4-link and a panhard bar are both better solutions.

 

[DaveB]

Any binding caused by triangulated arms and a panhard bar will have to be accomodated by something giving way. Stock Jeep suspensions get away with a little triangulation by having big rubber bushings at both ends of every control arm.

So, if you're using rubber bushings I'd guess the answer is 'some'. If you're using more solid joints the answer would be 'almost none-ish'.


Theoretically, I suppose it would be possible to build a triangulated 4-link and a panhard bar with the same roll center and roll axis, so they don't fight each other, but my head would probably explode trying to figure that out, and whatever geometry that ends up being would probably have impractical (or impossible) mounting points and would probably not have ideal anti-squat or anti-dive.

It would be a good exercise in engineering. Now, we just need to find an engineer nerdy enough to undertake it. Know any engineers, Dave?

I've already been acused of being that nerdy engineer who over designs everything. I could probably take a look, however I am using rubber bushings at one end of every link so I might be ok. Its been a big enough headache to get everything to fit as it is. if I were doing some of the frame changes over again I would make things a bit easier on the link design.

 

[Goose]

yeah I think your right.
the U link would fit & work well without bindind, But I think I would end up bending it.

I think using parallels & a panhard may be my best option. I think trying to squeze in some triagulated uppers, would end up with clearance issues.
The 4link with a panhard, I know the least about.
with this suspension, what is the best way to se it up to acheive good pinion tracking?