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Linked Suspension Query
Posted: Thu Oct 23, 2003 5:42 pm
by Fat Git
How do I work out the Angle and the Length of the upper links for a 4 Link Suspension?
Also, Is it better to have the Lower Links Parralell or Triangulated like the upper Links?
What are the Advantages/Disadvantages of a 4 Link Compared to the common 5 Link Setup?
Posted: Thu Oct 23, 2003 6:30 pm
by Fat Git
Where to buy Heim Joints and the cost?
Posted: Thu Oct 23, 2003 6:57 pm
by Strange Rover
you really need to find out how anti squat, the height of the roll centre and the angle of the roll centre effects the performance of the rear suspension. Once you understand these terms you can design it how ever you like because everything is just a compromise
dont start cutting until you find out. there are lots of bad ways to build a linked setup.
Sam
Posted: Thu Oct 23, 2003 7:13 pm
by Fat Git
Everything is calculated for a 5 Link, Just need to know if it's worth the hassle of a 4 Link setup instead.
Posted: Thu Oct 23, 2003 10:43 pm
by wanna
Ok sam i got one for yah i,ve got a fair idea about rear 4 link and 3 link but how goes all the rules apply to front never seen this explained
Posted: Thu Oct 23, 2003 10:46 pm
by wanna
Ok sam i got one for yah i,ve got a fair idea about rear 4 link and 3 link but how goes all the rules apply to front never seen this explained
Posted: Thu Oct 23, 2003 11:14 pm
by Strange Rover
Fat Git wrote:Everything is calculated for a 5 Link, Just need to know if it's worth the hassle of a 4 Link setup instead.
Your roll centre may be heigher with a triangulated 4 kink.
If your 5 link design doesent have a horizontal panhard rod then the 4 link may be worth wile doing.
Just draw the whole thing out to scale and measure the lengths if thats what you are asking.
Sam
Posted: Thu Oct 23, 2003 11:34 pm
by Strange Rover
wanna wrote:Ok sam i got one for yah i,ve got a fair idea about rear 4 link and 3 link but how goes all the rules apply to front never seen this explained
Not much has been discussed on this. It has only been recently that the rear design has been thrashed well on pirate BB in the link suspension for dummies thread
http://www.pirate4x4.com/forum/showthread.php?s=&threadid=168577&highlight=links+AND+dummies
The same sort of applies to the front. If you are using a steering box then you really need to use a panhard rod to eliminate bump steer and both the panhard rod and steering link need to be the same angle.
If you want it to drive well on road then you need a fair amount of anti dive. For example most linked front ends use radius arms (range rover/land cruiser/ nissan patrol) This puts the instant centre at the radius arm chassis mount point. So this is a good place to start if you are designing a linked setup.
If you are doing a 5 link (like the calbah one) then you really carnt get this amount of anti dive because to do so you would have to converge the upper and lower links at the chassis mount and this setup would bind badly and not flex.
So the compromise is to run a 5 link with little anti dive so that it doesent bind and flexes well but it will nose dive badly under brakes. Or the other way to do it is to run a 3 link plus panhard rod like a sarfari guard three link (SG3 link) They get the good anti dive without the binding but sacrifice in other areas (isnt a strong desigh but fix this with beefy components )
keeping things symmentric is important also so that it doesent self str under brakes.
If you go for triangulated 4 link then you can get the anti dive without the binding but it will bump steer a bit (not too bad if your steering link is horizontal at ride height) and will self steer when it articulates. Going full hydro will fix this.
The easiest thing to do is put up with the lack of anti dive and run a 5 lnk like the calbah setup.
Sam