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Linked suspension FAQ
PostPosted: Tue Feb 26, 2008 7:03 pm Reply with quote
Global Warmer
Global Warmer
Joined: 21 Oct 2005
Posts: 6432

Cody suggested that I do a FAQ about linked suspension. I thought I'd kick it off.

These are the excel based calculators
4 link
3 link

This is the web based calculator: (old and not bug fixed as often as the excel versions)

I wrote this on pirate to explain anti-squat and it was well received. It's a little easier to understand that the usual explanations.

Go through this mental exercise.

1) Stand on the side of you rig, maybe 12' away.
2) Estimate you COG. (Center of the t-case output?)
3) Find the point where your upper and lower links meet. This is your instant center.
4) Picture an imaginary line from the tire's contact point (below axle) through the instant center and keep it going until it's above the front axle.

Compare the height of that imaginary line in step 4 when it's above the front axle to your COG. If it's twice as high your anti-squat is 200%. If it goes right through the COG it's 100%. If that line half the height of the COG it's 50%, etc. It's hard to tell based on your pics but I think your imaginary line from step 4 will be really steep. Of course a steep anti-squat line will rise way above the COG by the time it gets to the front axle so if I'm right your rear end will rise as you put power to the ground and when traction breaks it will drop again.

If your rig tends to hop in the rear and hump rocks as you climb you'll know what you need to do to fix it.

I'll go on further about anti-squat. If your anti-squat is 100% that means when you apply the throttle the impact on your rig (we'll say rear end) is neutral. If your AS is over 100% the rear tends to rise and if it's under 100% the rear tend to drop.

I'm told that drag racers and street racers like anti-squat above 100%. The idea is that when the rear rises the opposite and equal reaction is more pressure on the rear tires which equates to traction. Street racers can get on the throttle sooner coming out of a turn and drag racers have put more power to the ground without burning out.

In the rock world the situation is different. If the rear end rises under torque it's sure to drop as traction breaks. That starts a hop which causes another drop and another hop. This hopping often leads to carnage/broken parts from the sudden gains in effective weight/traction.

05 buggy
Places to wheel
Why do you keep putting gear oil in that axle? It's obvious that it doesn't like it. --Max
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Linked suspension FAQ
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