Outer Limits 4x4 Board

ok, time has come to get serious with the vitara, sick of the shit flex and crap rampover angle, so its time to link the front. but i need to work out the best way to do it

i've done a ton of reading at pirate and here, and have semi-decided on a 3 link front with panhard rod.

was originally going to run a setup like this. but after reading sams posts on pirate, about the side with the double link jacking up under braking and pulling the car to that side, it put me off the idea.


red are the links, grey is the chassis, blue is the panhard

so, following his advice, refined the idea to two seperate links on the side, that are parallel to get rid of the jacking effect when under brakes



but now some questions that i've got

Should the upper and lower links on the side with the 2 links be equal length? what will the effect be of a shorter upper but with the links still parallel?

What about seperation on the axle? how much is enough with a 3 link? Should the two link side be on the same side as the pumpkin or doesn't matter?

its getting late know, and i've forgotten a heap of stuff i was gonna ask, so will have to update this post when i remember.

ask sam.........................

Dumb question, why don't you have the "upper" link on both sides?

XterraGuy wrote:Dumb question, why don't you have the "upper" link on both sides?

as he said . why not just do a 5 link if u have the room?

Why not have the upper link on the pumpkin side ? I thought the general consensus was that it was best placed there to control wrap effectively !!

just 5-link it man. takes a lot of load off that uppper link. you can also then properly tune your caster left/right (to a certain degree)
make the chassis mount for the upper links adjustable in height so you can adjust the anti-dive to a reaction you are happy with.
if you are really stuck on having a single upper link, put in on the other side closest to the diff. that's where all the rotational torque is starting from.

For on road stuff people generally go for the five link. This is because if you are going to run rubber bushings then the bushings move a little bit when it you load it up under brakes or power. What this means is that if you have a link setup that is not symetrical (ie a 3 link + panhard with the upper on one side) is that it will handle a bit funny under brakes and power cause the axle will steer it self a bit when under load. The car will always want to "pull" one way.

So you end up with a 5 link. Now the problem with these is that there is really one to many links to locate the axle properly (you really only need 4 links) so what happens is that this setup will bind a bit as it flexes. The more parallel the links are and the closer the links are to the same length the less they will bind. If the links are really convergent and have very different lenghts then it will bind a fair bit and it will really be relying on the movment in the bushings to articulate well. 5 links generally work well for most although they arnt perfect by a long way. Their biggest problem is that you carnt build in much anti dive and still have them flax well. To get the anti dive you need the links to converge on both sides (actually to the point where a normal radius are would connect) and if you converge them anything like this the setup wont flex. It amazes me that preople are allowed to pull out a radius arm setup and replace it with the 5 link cause the with the 5 link in without antidive and rig doesent stop anywhere near as well (it tends to just lock the front tyres and skid). That being said lots of people run them and they are generally happy with them. You soon get used to something that doesent have lots of anti dive - its just easier to lock the front brakes. I guess by the time you have lots of lift in the radius arm setup you might start to get to much antidive and maybe with the 5 link and lots of the lift the anti dive might be more reasonable (just thinking why lots of guys report the rigs handle so much better all over with the 5 link)

And then you come to radius arms which handle very well on the road (lots of anti dive) are very compact to fit under the rig. And if you are happy with maxing out 10in travel shocks with articulation is probably the way to go. Depends how much travel you want.

If it was an offroad only rig then the 3 link plus panhard is the go. As long as the links are parallel then it wont jack the rig on that side. Doesent really matter if the links are the same length or not for the most part. If they are different lenghts then the links start to converge as the rig articulates and will want to jack a bit but you probably wouldnt really notice it. The budgie has a single short upper and works well and Tony drives it like an idiot on the fast trails and only complains about his tyres not being balanced and his steering arm ball joint is stuffed.

Sam

thanks for the replies guys. seems that while its still a daily drive (hopefully not too much longer) i should just throw the whole bundera setup under the front seeing as its a damn near bolt in job, so it still drives alright.

anyone know anyone wrecking a bundera?

...

As a wise man once said

POS wrote:www.goasksamandbedonewithit.com

beebee wrote:As a wise man once said

POS wrote:www.goasksamandbedonewithit.com

To add a visual representation to Sam's comments on four links and radius arms. I have an excel spreadsheet that I made a while ago that will show you how different 4 link and radius arm designs will behave.

It is not a super friendly or sexy looking thing, but it will show you how the arms will travel (up/down and forward/backward) and the change in the orientation of the axle as it flexes.

The sheet only looks at one side of the axle but you can look at the graphs (tabs along the bottom of the page) and compare angles/location etc through the travel. For example if one wheel is at full droop and one is at full stuff, look at the difference as shown on the graphs and that will give you an idea of how much axle wrap or steering effect it may have (like the steering on a Billy cart, one wheel moves forward and the other moves back).

You can modify where the arms originate on the chassis, how long they are and the separation distance between where the two arms attach to the diff housing. You can also enter the travel of your shocks to get an idea of how the shocks will effect things.

There are a few bugs that will result in math errors for some configurations, but it may still be of use to some.

Measurements were intended to be in mm, but going to inches will probably still work??

I am somewhat short on playtime, but if there are questions post them and will try and get you an answer.

Feel free to down load the file and frig with the coding. If you come up with something better please send me a copy.


http://www.geocities.com/linkcalc/4_link_calc.xls

Paul.

PS. I believe that the results are correct, but do not take the results to be 100%. It was only ever meant to be a guide.