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Whats a good 4 link calculator

krackem

Build-Bend-Weld-Break -Repeat
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Mar 8, 2012
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Chattanooga,Tn
Getting ready to link my rig and was looking for a good link calculator compatible with windows 7 and possibly a crash coarse on how to use em i kinda under stand. ive played with one on my phone but didnt really get the jist of it so any help is greatly appreciated. i ask this here because theres alot of good smart fabricators here with alot of know how, and not a bunch of idiots that spout off at the mouth, like on pirate where you gotta figure out who really knows what their talking about vs people just post contradicting info. But to any one that helps thank you in advance.
 
Those of the same reasons I do not mess with pirate and only mess with hardline... As far as the four link calculator, good luck my friend. About two minutes worth of looking at that, and I decided that I did not need the four link calculator.. My rig performs just fine.. All of that Weighing each corner and all that bullshit, hellll nawww... If I would have used it I would still be trying to figure it out! From what I know about it that is not easy to work. Then again I'm not so great on computers. Good luck keep us posted.. Like you said I'm sure someone will post up some good info. There are a **** ton of folks on here that blow my mind with their knowledge.. And willingness to help dummies like me :dblthumb:
 
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Re: Whats a good 4 link calculator

I will trade you an excellent Texas instruments 4 link calculator for that shiny side arm you are tryin to unload.....
 
Re: Whats a good 4 link calculator

LightBnDr said:
I will trade you an excellent Texas instruments 4 link calculator for that shiny side arm you are tryin to unload.....

:flipoff1: its done sold buddy and I got the kinppin dana 60 i was after to now just need a rear one with a 67.5 wms and kush you are correct there bare some good folks on here thatll help anybody on here and ive learnt alot from reading there threads and i know i can build it i would just like to see what the numbers will say its gonna act like ya know
 
Patooye thats how my head felt after reading on it after an hour :****: but i just wanna be able to put in my info and then take a picture and post it on here to see if you and some of the other smart fellas think itll work ok . i downloaded one that actually had your name on it Pat now just gotta figure out how to use it
 

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To me, not knowing how to use Excel is like not knowing how to breath. It is the basic building block of any business endeavor. If there was only one program on a computer that someone could know it would be Excel to me. BUT you do have to know basic math, arithmetic, logic, and how to make and derive formulas to make any use of it at all. That is all stuff you learn in grade school. So if you're saying that that stuff is too complex and you will never be able to learn it you are saying that you are incapable of successfully completing grade school. And before anyone goes crazy about that statement, I do not believe that anyone here is incapable of completing grade school. If you are building rigs, using a keyboard, using the internet, you can probably make it through. So the alternative is that people are just mentally lazy. In today's society I would easily believe that could be the case. A lot of people today think that they can make up for mental laziness by working hard. A lot also think they can make up for physical laziness by being smart. But most truly successful people both work hard and are mentally very active.

Using the link calculator is pretty easy to me. You have to have some semblance of suspension knowledge to make it useful but you should have that if you're going to build a suspension anyway. One could type up a step-by-step how to for it but no matter what way you look at it, suspensions are not that simple. The concepts are complex, have to do with force vectors, physics, and upper-level stuff that a lot of people don't learn until they specialize in engineering in college. You don't HAVE to know all that stuff to use the calculator, that's why it was built in the first place. But its also why a basic write-up would necessarily glance over the more complex stuff. And even then it would be lots and lots of WORDS. And if someone is so mentally lazy that they won't take the time to learn basic Excel / computer skills, I highly doubt they're going to read a few pages of single-spaced text on a topic that they're already too lazy to learn in the first place.

I am not a suspension guru by any means. I've barely skimmed the surface. But I wouldn't build a suspension without the calculator. The first one I tried failed miserably. The calculator fixed everything after that. Just like anything you want to do right, you have to start at the bottom and work your way up. I would argue that you shouldn't be doing it in the first place if you're not willing to learn about it. My TIG welding is a great example of this. When I bought my machine I had ZERO expectations of laying decent beads any time in the first few years. I had no expectation that I would plug it in and start welding up fuel cells. I honestly figured it would be years before I was comfortable enough to do anything useful and I was fully prepared to not produce anything useful with it until that time had gone by. I had fully accepted that there would be no payback whatsoever on that investment for a long, long time. But I knew that, by understanding and learning the basics, I would build on them to eventually produce useful things. It hasn't taken years, I'm thankful for that, but I'm also not nearly a master welder. I'm comfortable enough to work on my own stuff now, fiends' stuff for free, but I still won't take on paid jobs. Same goes for suspension. Why would anyone expect significant results without taking the time to learn even the most rudimentary stuff? Excel, suspension basics, math = rudimentary. Do people luck out, wing it, or copy **** and get something that doesn't fail? Of course they do. But people also wing it and fail miserably when they could have just postponed the project, done some learning, and do it right the first time.

Play with the calculator. If there is a cell you don't understand, google it. Don't stop reading until you understand it. Many of the results will be on butt pirate. Eliminating that as a resource because you are easily butt-hurt is like saying you are a Christian but won't read the Bible. If you read everything, still don't understand it, and are afraid that Pirate is going to crucify you, ask here instead. Not everyone here understand everything about suspension either. We can all learn by directed discussion.
 
krackem said:
Patooye thats how my head felt after reading on it after an hour :****: but i just wanna be able to put in my info and then take a picture and post it on here to see if you and some of the other smart fellas think itll work ok . i downloaded one that actually had your name on it Pat now just gotta figure out how to use it

Haha, that's old and not a suspension calculator. Where did you even get it???

Stand by, I will get some links to what I use ...
 
Self-quote from Pirate:

patooyee said:
It is sad that we seem to have lost a resource like Triaged. I looked at his stats and he has not posted in 5 years but has been here as recently as last month. While I won't speak for everyone I hope he and others like him realize how appreciative I am of their work and willingness to share. That being said, here are the 3 versions that I had on file before Verizon decommissioned Sitebuilder 5 days ago.

http://www.patooyee.com/linkcalc/3_LinkV1.0b.xls

http://www.patooyee.com/linkcalc/4BarLinkV3.0c.xls

http://www.patooyee.com/linkcalc/4BarLinkV3.1d.xls

I'll leave them there for as long as I host a website, which has been almost 15 years and counting.

Right click, save as.
 
Sorry, just realized that the links didn't past right from Pirate. They're fixed now in case you couldn't download them before.
 
I guess Ive just been lucky then, I've never even played around with one of those calculators, never really had much faith in them. I always set them up similar to what we use to do when building drag cars, I worry about getting the instant centers right more than anything.
 
Here's my quick, dirty, super-over-simplified rundown of what is going on in each entry. I'm sure people are going to disagree with me, tell me I'm wrong, whatevs. Lets all learn here in that case. This is all using the 3.1d calculator that I posted:

Wheelbase = self explanatory

Tire dia. = self explanatory

Rolling Radius = Half of tire dia. for our purposes. In reality this relates to real-world tire measurements that should be made with the tire in question on the vehicle moving under power. But since we're building the suspension I'm assuming you can't drive the vehicle so just go with half of tire dia. for this. Or maybe if you know that your tire is 41" tall even though the sidewall says 44" go with half the measured height in that case. It does not greatly affect the overall numbers anyway.

CG Height = Again, since we don't know the exact height we have to approximate here. A general rule of thumb is to use the height from the ground to the top bell housing bolt of the trans. If you have really heavy axles it might be a little lower, really light axles higher.

Vehicle Mass = You're still building the suspension so you probably can't accurately weigh it. Approximate here but be realistic.

Front & Rear unsprung mass = Again, approximate. Remember, unsprung does not include the axles, tires, or wheels.

Link X dimensions = straight line distance from axle center line to link mount. Note that this is not the length of the link, it is single dimension distance as if you dropped a plum bob from the link mount and another from the axle center line and then that distance as measured on the floor between plums.

Link Y dimensions = half of the horizontal separation. So you can measure from an imaginary center line out or the total distance and divide by 2.

Link Z dimension = straight line height from floor to mount.

Static AS = the amount that the suspension will react under force / acceleration. Low numbers = not much, high numbers = a lot. AS is a matter of preference. It used to be that people liked 100%+ because they thought it would plant the tires harder but they found out that you had to tune your shocks around it to control it and it would also walk the rear axle under the rig when climbing which resulted in unpredictable hill climbs as the wheelbase rapidly got shorter. Then people started shooting for lower numbers. Now days it has almost become a moot point. People go for what they want and tune the suspension to react in accordance. I personally shoot for between 30% - 80% so that a small amount of energy goes to planting the tires but not so much as to waste it. The more energy used up in moving the suspension the less reaches the ground. Think of it as using up engine horsepower to move your suspension instead of the tires because that's exactly what it is. If you're not going to be doing a lot of suspension tuning I would think 30 - 80% would be a good range to be in anyway since it is between extremes.

Roll Center Height = the imaginary axis around which your body will roll. The higher this is the more stable your rig will be. With a 4-link it is impossible to get this higher than your center of gravity so take that into consideration when shooting for the stars. A 3-link with panhard bar is theoretically possible to get it above the CoG. In this case the body would actually roll uphill. That's just an aside though. Imagine your COG as a big huge weight sitting on top of a stick and your roll center as the point of the stick that is resting in the palm of your hand holding the big weight up. The difference between roll center and CoG is the length of the stick. Now with a big long stick when the weight on top shifts its going to be really hard for you to re-stabilize everything because the weight on top is further away from the fulcrum / the opposite end of the stick and has a longer lever arm with which to control you. Conversely, a shorter stick will be easier to control. When the weight at the top shifts it will have less power as a result of the shorter lever. This is Roll Center. When you go up an uneven hill do you want your rig standing on top of a big long stick or a short one? This is one of the most important things to get right IMO. I spend a lot of time trying to get this as high as possible / as close to the CoG as possible.

Roll Axis Angle = how much your axle will steer and which direction it will steer as it flexes. Low positive numbers here are generally better than high negative numbers. Negative numbers will result in the axle turning out of the turns causing turning radius to be reduced and causing less predictable control at speed. Positive numbers will turn INTO a turn causing tighter turning. But too high positive can cause very sensitive turns at speed. General rule of thumb here is to be in the -7* to +5* range. 0* = no roll steer but that is difficult to obtain and probably not worth it anyway. Some designers actually tune roll axis based on the tracks they race.

Instant axis = I've never worried a ton about these. Maybe someone else can explain them better. I know that they are the instantaneous point around which the suspension is moving. A long x-axis will mean a longer imaginary fulcrum and more stability since forces will have further to react on the suspension? I would imagine a higher z axis means that the CoG has less leverage on the suspension to tip over also?

Travel AS = You can move the suspension around graphically by entering values in Travel Amount box. Negative values are down travel, positive are up. If you have a 16" shock and ride height is at 50% shock shaft showing then you have 8" of positive / up travel and 8" of negative / down travel, adjustable by the amount you enter. As you play with travel you'll notice that AS changes. You don't want large swings in AS, it will result in unpredictable suspensions. It's going to change some. But if at one end of travel you have 150% AS and the other you have 0% you're going to be in for one hell of a ride.

Travel roll center = how much your roll center changes throughout travel. Again, huge sweeps = not good.

Pinion change = self explanatory. This is a good tool to use to figure out before hand if your design will cause driveshaft problems though. If you're not using a CV joint then you probably want your pinion angle to change very little. If you are using a CV you probably want the pinion to continue angling upwards so that it keeps pointing at the CV joint. Conversely, if everything on your suspension is as you wish but your pinion points up through travel maybe you should think about using a CV. If it doesn't change much throughout travel maybe think about no CV.

Travel amount = see Travel AS above

Travel increment = a multiplying factor for travel amount. Enter 2 here and it will double everything you enter in travel amount. Enter 8 and it will octuple it. This was mainly put in the spreadsheet because of the two non-functioning buttons that you see below it. If you have some security features in Excel disabled and Macros enabled those buttons work and you can tap them to increase or decrease by the factors you enter. But for most people those buttons don't work and they are just a luxury when they do, not a necessity.

OK, so that's probably the quickest down and dirty on the suspension calculator possible. I'm sure I got everything wrong so let the blood bath begin.
 
Patooye your last post is what I was needing and I'll reply back more when in front of the keyboard and not a phone thanks you sir
 
Re:

Flat upper links at ride height, triangulate lowers whatever is reasonable.

That'll give you a start to something that doesn't completely suck.

Work from there.
 
Neal ill pm you my new number and call when your free ok and i'm doing double triangulated may be a bit much for my first one own my own but its what i want.
 
As and travel AS are high on my list. Want to kill a loose hill, blow all 4 tires off, and impress the hookers. Low AS is where it's at, lets the tires break loose and knock all the gazers windshields out at the bottom of the hill. Want to do some cone dodging on gunnite, let your buddy hold your hand while crawling over a culvert, high AS May be your thing. Transfers a lot more force to the ground equalling traction, but let the tires slip and grab (spinning) and you will have a bucking parts breaker on your hands.
 
patooyee said:
I believe you may have misinterpreted my first post. By no means have I eliminated pirate as a source of information, it has more good tech than any other site out there. It is deciphering between the good and bad tech that makes it difficult.Just like your butt hurt Christian comment not at all nessary and same as there you misinterpreted or didn't agree with me and attacked my character. I could care less what anyone on the net thinks of me. I'm new to using a 4 link calculator and i want good advice, tech and info with out starting a pissing match as every pbb 4 link thread ends up. Where as I've never seen that here.

That's why I asked here I'd rather not waist time ready peoples comments on how dumb I am and who can out flame who that's why we're here on hl and not pbb. As for your posted links and explanation on every thing thank you that's what I was after good ****in tech no two ways about it thank you for that sir

No for this comment....
( Play with the calculator. If there is a cell you don't understand, google it)
What is a cell on the calculator like I said I'm new to it but I've at least played with it now, but i will ask for help if I don't understand something .

Also if you learn everything there is to know about something it's time to move on to something else because when you stop learning your just wasting your time from there on out. Knowledge is the onething you can always benifit from. And with that being said please sir teach me more, hell anyone that's willing, teach me more I want to understand and be able to use this tool to my advantage
 
I am towards the end of my build almost passed the point of no return. But if I had to I could change some of my mounts.
Zack do you mind if I post up my numbers to see what the general consensus is. It might help getting the discussion rolling a little bit and help you out.
 
Ive been looking in all the wrong places for this lately. Thanks for the info.

Does anyone have a better (read more accurate) way to figure out a rigs Center of gravity? BTW I have no scales but could possibly borrow some if need be..
 

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