link length

userbmx1315

userbmx1315

builds more then wheels
Joined
Feb 8, 2008
Location
Bessemer City, NC
been looking into triangulated 4 link for the front of my xj. i know the uppers need to be longer then the lowers for a 3 link. most of the 4 links ive seen have the uppers shorter. why is this?
i'm most likely going to run coil-overs if that makes a difference.
 
Packaging, desired effect on the proforamnce of the rig. Use a 4 link caculator to see what the differences are. The shorter the uppers the more the pinion will drop more....
 
The reason you see shorter uppers in a triangulated four link compared to a 3 link is because it is a lot harder to fit long triangulated uppers with an engine sitting in the way. All things being equal and having a cv shaft, I would go for equal length uppers and lowers.
 
^^^this


There is no rule for length of uppers versus lowers. Unless you are building a buggy and can put them anwhere you want, then they should be placed where they fit and work well. Geometry is key, though. Finding the happy medium of proper geometry and fitting it into your current vehicle is the hard part.

Like snappy said, use the link calculator to find the sweet spot. Know your limitations on your rig and work within those parameters on the calculator
 
Like Braxton said, equal length uppers and lowers is nice for a front setup. That'll give you the least amount of caster change through the range of travel plus it makes for more predictable steering. If your ride height will be fairly high and you need to worry about getting enough travel out of the driveshaft joints shoot for longer uppers than lowers, this will make the pinion rise as the suspension droops but loose caster. I think you are planning to run full hydro so this wont be as big of a problem for you. Ideally you want your lowers to be the same length as the driveshaft from yoke cap to yoke cap. If you can do this you will need very little slip in the shaft, saving you money.

Keep in mind that equal length is a relative term. A lower link angled in towards the frame 10* thats 36" long will not travel the same radius as an upper link thats angled 25* out towards the frame and 36" long. To truly get 0 pinion/caster change you'd need to look at the truck from the side and imagine it in 2D. The measurement from frame mount to axle mount on the uppers and lowers should actually be the same not the link lengths if that makes sense. Truthfully you won't really need to be this exact but it's always fun to try to get it as close as you can.
 
userbmx1315 said:
anyone? i really dont want to ask this on pirate. i'll get flamed harder then the guy that did one tons in a weekend.
Click to expand...

I missed that one. I rarely visit pirate anymore. Link to thread?
 
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