My 4 Link buildup

[RockMonkey]

My prediction is that it will work best with the least amount of antisquat. You'll end up with the control arms in the bolt holes that creat the most seperation (closest to the amount of seperation you have at the axle).

 

[Greg]

My prediction is that it will work best with the least amount of antisquat. You'll end up with the control arms in the bolt holes that creat the most seperation (closest to the amount of seperation you have at the axle).

What kind of percentage are you thinking, 75% of Axle Seperation at the Uppers... or more?

 

[RockMonkey]

What kind of percentage are you thinking, 75% of Axle Seperation at the Uppers... or more?

My current one is at around 95%, or maybe more. I think I made it like .5" less at the front just to make sure I didn't have more seperation at the front then the rear, cuz I didn't know how that would behave. When I redo the suspension on the YJ (to bring the axle forward a bit, and swap to coilovers) I'll do it the same way, I love the way it works. I predicted you would not have bolt holes that allow you to get close to the same seperation front and rear, so you would end up using it with as much seperation at the front as you could. Of course, that's all changed now that I've divulged my thoughts, and you may have bolt holes allow more seperation, and you may not use the widest ones. I have read a lot of people who have said they wish they had less antisquat, but I really haven't read many (any?) people who wished they had built in more. I have a buggie all built in my head, and when I actually get to building it, it'll have nearly zero anti-squat too.

 

[Greg]

My current one is at around 95%, or maybe more. I think I made it like .5" less at the front just to make sure I didn't have more seperation at the front then the rear, cuz I didn't know how that would behave. When I redo the suspension on the YJ (to bring the axle forward a bit, and swap to coilovers) I'll do it the same way, I love the way it works. I predicted you would not have bolt holes that allow you to get close to the same seperation front and rear, so you would end up using it with as much seperation at the front as you could. Of course, that's all changed now that I've divulged my thoughts, and you may have bolt holes allow more seperation, and you may not use the widest ones. I have read a lot of people who have said they wish they had less antisquat, but I really haven't read many (any?) people who wished they had built in more. I have a buggie all built in my head, and when I actually get to building it, it'll have nearly zero anti-squat too.

OK, scary enough... that makes sense! Thanks a ton for the info, I'll remember that when I'm building my adjustable upper mounts!

I should have paid more attention to how the rearend was working when I wheeled your rig!

 

[I Lean]

Greg, the very fact you DIDN'T notice how the rear end was working, means it was working well.

I'm one of the guys Braden's talking about wishing I had a bit less anti-squat. I think that's what's causing the little bit of hop I have, though it's certainly not bad. (and not bad enough for me to actually do anything about it)


Carl Nielson is wanting to add anti-squat to the rear suspension on his EB, since his squats pretty good when he gets on the throttle. (so he tells me) I have a suspicion it's just because his AirShox are nice 'n soft, but it's cool he has the ability to adjust the suspension to his liking anyway.

 

[Herzog]

I have way to much anti-squat. A center limit strap has helped out quite a bit, but not enough. I'm still messing with it. I might end up redoing it soon. But for this season, it's fine enough to wheel!

 

[Maverick]

I promise to stick to the thread...PMS is over, sorry for all the contention.

I have kind of a basic question regarding 4 links and lateral location, kind of a theory vs reality question. In theory this stuff works...but I'm wondering how well it actually works on the street and trail, most interested in the street performance, when I do mine, I wanna continue driving it around town.

Greg, you are gonna use the two "V's" right? upper V with the wide ends at the frame and lower V with the wide ends at the axle?

Upper "V": how well does it really control the side to side movement? It should, just want to know if it does, and at what percentage compared to a panhard? (70% as good, 90% as good, etc) I'm guessing a big part of this is the amount of deflection in the mounts, since higher forces are required to do the same job than a panhard.

Lower "V": in my understanding, the main advantage to this is that as the axle articulates, "roll steer" is reduced. Again, does this really happen?

Brett (no btdt t-shirt)

 

[I Lean]

Upper "V": how well does it really control the side to side movement? It should, just want to know if it does, and at what percentage compared to a panhard? (70% as good, 90% as good, etc) I'm guessing a big part of this is the amount of deflection in the mounts, since higher forces are required to do the same job than a panhard.

Lower "V": in my understanding, the main advantage to this is that as the axle articulates, "roll steer" is reduced. Again, does this really happen?

Brett (no btdt t-shirt)

You're right about the mounts/ends being the controlling factor, along with the amount of angle present...the less the separation, you need stiffer mounts to retain the same control. Just for example, if you were intending on using rubber bushings in your links, but don't have a lot of angle, you can switch to poly instead. If poly deflects too much, you can switch to rod ends at both ends. (instead of just one, or whatever)

I can't see any lateral movement in my buggy's rear axle at all, ever. The front does move just a bit if I have worn bushings, since there isn't as much angle on either the upper or lower links as there is in the rear. It's probably only 1/4" though, and since I have full-hydraulic steering it doesn't really matter. New bushings next time I have the links apart will fix it.

Triangulating just the uppers controls lateral movement just fine most of the time. Triangulating just the lowers controls lateral movement just fine most of the time. Triangulating both is even better, since you now have more "total" traingulation to locate the axle.

Triangulating the lowers tends to lower the front end of the roll axis, typically making it more level at-rest and reducing roll steer. For most of our setups, that happens whether the uppers are triangulated or not. Triangulating the uppers also tends to raise the roll axis, and may or may not change the angle much...so it won't necessarily affect roll steer all that much (depending on how steep the horizontal angle of the links is), but it will affect the height of the roll center--which plays a big part in how stable the rig will "feel", as well as determining how much the tires will "tuck" into the body when articulated.

The only real disadvantage to driving on the street has much more to do with spring/damper selection than links. Most/many use really soft springs to get the articulation they want, which compromises street-ability. A swaybar goes a long way to correct that if that's the case.

That said, my buggy handles pretty well on pavement, up to it's maximum driveline-limited speed, around 45 mph or so. (different setup now will change that...) Braden's had his up way faster than that, I think 70 or so, and it handles great.

Edit: One of the Toy trucks I set up with a 4-link/coilovers is used as a daily driver. (set up really similar to the truck owned by "sibeta") It drove fine at first, but had more body roll than the owner liked, so we set him up with a full-time swaybar. That made a huge difference both on and off road--reduced the body roll onroad, and lessened the tendency for the front leaf springs to be "lazy" offroad.

Part of his problem is that his truck is pretty tall (like most built Toys), and that contributed to the body roll problem.

 

[N-Smooth]

if you sift through all the crap on pbb you can find some very helpful threads like links for dummies...
i think a good start would be to put your links parallel or near parallel when viewed from the side to achieve less antisquat. you could put the uppers down .5" like carl said to make sure you do have antisquat (good idea ) but it makes sense to me that you should make them parallel and have some adjustability in the upper frame mounts so you can move the uppers down and add antisquat if you don't feel you are getting enough "bite"
starting out this way is supposed to cause less hop/breakage and then when you get used to having the links and know how it acts, adjust it for more a-s

that is by far the most helpful info i have acquired on pbb, besides the obvious make them as long and flat as you can (basic stuff)

hopefully this helps, although you probably already know this junk

one day i will have links (i don't know what on, maybe a future project)

 

[Milner]

This is all kinda of funny....
Many of us have discussed this stuff together for years.
I agree with Carl and Braden. Close to nutral is where you want. It seems that most the comp rigs are also starting to realize this. A lot of guys are build very nutral suspensions. 2 years ago it was all about high AS.

I have 10" of separation at both ends of 48" links. The lowers are right at centerline of the axle. The links do have a slight down ward angle, but no much!
They are set up it opposing V's, with almost no roll steer, and what is there is anti-steer (steers away from the lean) (has a slight self leveling effect on side hills)

I Love the way it reacts....The first trip to Moab, It climbed stuff easily, that I always had problems with. Plenty of separation, no hop at any level of power.

I have had it up to about 65mph (unbalanced 38 sx's on beadlocks) As for lateral deflection, none is noticable, and I doubt very much that there is any....rodends at all 4 ends and a fair amount of triangulation. It handles very well on the road, the limited amount I have driven it.

Compared to another rig of similar size, wieght, that has a great deal of AS (converging links, lower has a fair angle), That I have driven, mine handles like a porsche!!

Brandons has always suprised me, he has very little triangulation with johny joints and poly ends, yet has very little latteral deflection. His handles well on the road as well, though it has more AS than I like the feel of....

Things I have learned that the calcs and books don't tell you....
Over build the lower links!!!! They will bend.... we play in rocks...if they were on a sports car-thin wall would be fine....add all the bending forces they are controlling then slam them on a rock
3/4 Heims are not strong enough for lower links, they wear quickly, and the shafts tend to break. They work ok for uppers but I like to use 7/8 for the uppers and over kill with 1 1/4" for the lowers (1" would be fine, but they are harder to find)
Most people use toooooooo soft springs.
Spend the money up front for good heims, joints or what ever....Cheap heims are dangerous. If you are trying to save $$$$ use rubber bushings, but never low quality heims!!!!!
A sway bar can help, but try to design it so you don't need one.
Quality shocks are well worth the $$$$
Research, study, ask questions, and WATCH rigs with different setups and drive them if you can.
Figure out what you want and don't shortcut it because it is easier/cheaper!!!! Suspension is not the place to shortcut. ( I have done it many times, still paying the price) Leave it alone, or go all the way!!
JMHO
Marc

 

[Hickey]

Over build the lower links!!!! They will bend.... we play in rocks...if they were on a sports car-thin wall would be fine....add all the bending forces they are controlling then slam them on a rock
3/4 Heims are not strong enough for lower links, they wear quickly, and the shafts tend to break. They work ok for uppers but I like to use 7/8 for the uppers and over kill with 1 1/4" for the lowers (1" would be fine, but they are harder to find)
Most people use toooooooo soft springs.
Spend the money up front for good heims, joints or what ever....Cheap heims are dangerous. If you are trying to save $$$$ use rubber bushings, but never low quality heims!!!!!
A sway bar can help, but try to design it so you don't need one.
Quality shocks are well worth the $$$$
Research, study, ask questions, and WATCH rigs with different setups and drive them if you can.
Figure out what you want and don't shortcut it because it is easier/cheaper!!!! Suspension is not the place to shortcut. ( I have done it many times, still paying the price) Leave it alone, or go all the way!!
JMHO
Marc

Very excellent tips. Brett, get a copy of the second edition calculator, I believe it will plot the graph for you like I posted earlier. The copy I have does...

 

[I Lean]

Very excellent tips. Brett, get a copy of the second edition calculator, I believe it will plot the graph for you like I posted earlier. The copy I have does...

The one I sent was V2.0a, is there a more current one? If so, wanna mail it to me?

 

[Hickey]

The one I sent was V2.0a, is there a more current one? If so, wanna mail it to me?

Yup, I have 2.0.

 

[Maverick]

Yup, I have 2.0.

Carl sent me 4LinkCalculatorV2(1).0a

It does the graph like you posted

 

[muleskinner]

I'd like a copy of the newest if anyone wants to send it over.
djm4@xmission.com

 

[Hickey]

I'd like a copy of the newest if anyone wants to send it over.
djm4@xmission.com

I'll try and send it.

 

[Caleb]

I'll try and send it.

you can send it to me on yahoo and I'll put it on my site...

 

[Maverick]

This is all kinda of funny....
Many of us have discussed this stuff together for years.
I agree with Carl and Braden. Close to nutral is where you want. It seems that most the comp rigs are also starting to realize this. A lot of guys are build very nutral suspensions. 2 years ago it was all about high AS.

Hmmm, 2 years ago....'bout the same time that Braden and Vonski cleaned some trash with their neutral set ups...coincidence.

<killer stuff snipped>
Marc

<4:40pm> Wow, I never sent this...

Yup, I 'member when Braden built his and I thought it was a mistake to not build in a-s...but then when they explained why, it totally made sense: sometimes tires slip, and when they slip then the traction that was providing part of the downforce is gone and so is the down force and then when the tires hook up again then a-s is back and then bouncy begins, not as bad as with just leaves, but still there. I loved the way he could just slowly spin his SX's while climbing impossible stuff and never get a bounce.

 

[I Lean]

Yup, I 'member when Braden built his and I thought it was a mistake to not build in a-s...but then when they explained why, it totally made sense: sometimes tires slip, and when they slip then the traction that was providing part of the downforce is gone and so is the down force and then when the tires hook up again then a-s is back and then bouncy begins, not as bad as with just leaves, but still there. I loved the way he could just slowly spin his SX's while climbing impossible stuff and never get a bounce.

He still does that, pretty much....the difference now is that he spins his tires REALLYREALLY fast instead of slowly.

 

[RockMonkey]

He still does that, pretty much....the difference now is that he spins his tires REALLYREALLY fast instead of slowly.