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View Full Version : Rear suspension kinematics--parallel 4 link vs offset 3 link?



formula
02-09-2011, 07:24 PM
Hey guys, I'm working on designing an offset 3 link for a friend, and I'm curious how much I can crib from basic parallel 4 link design ideology as I move forward. I've got a pretty good handle on IRS design but am still learning on solid axle stuff, so forgive me if this is silly.

Also, any good books I should run through for more advice? I've got Milliken's Race Car Vehicle Dynamics on the way....

JRouche
02-09-2011, 11:29 PM
I dont even know. Ive thought about it some. Like why cant you just drop the forth link, beef up the third link and call it done.

With a stout housing it should transmit the forces through the one link like it did with two upper links right? And you get the bennys of less bind. If it was a drag car I could see the weak side of the rear end ( the side thats missing the link) raising some (digging in) when it should be pushing up on the frame and keeping that side planted. So for a drag car maybe not the best. But for a twistys car where bind and control are common needs an offset third link shoud preform better.

Handling or tire planting? Thats the Q. Most parallel 4-links are designed for planting the tires during launch. The handling aspect in the turns comes in second for consideration. And bring on the three link. I like it!! JR

formula
02-10-2011, 06:13 AM
I've been thinking along the same lines. The car is a BIG MAMMA JAMMA so I'm gonna focus on maximizing handling as we're gonna need all the help we can get to get this thing around a road course. I'm trying to think of it in terms of heim-jointed links to make sure that I'm not relying on bushing bind to control the axle under loads (I won't be using heim joints on the finished product, though--just a thought experiment). I guess it's time to just dig into solidworks, build a 4 link, and then yank a link and see what the results are.

cheapthrillz
02-10-2011, 06:47 AM
:yeah:

Not working today huh? lol

Bryce
02-10-2011, 07:48 AM
Side view calculations are the same. A/S and IC.

LowBuckX
02-10-2011, 08:15 AM
basicly how I worked out mine. copy popular 4 link side view and find a good spot for 3rd in plan view,.

formula
02-10-2011, 08:37 AM
LOWBUCK! YES! I'd forgotten all about your awesome work. That'll be a huge resource!

And yes I'm working today--I'm just multitasking, haha.