Buggy Front End Question

3times

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I am Building a VW pan based Fiberglass buggy with a full tube chassis, I have set the rack angle so gains 1/8th inch of additional toe in from ride height to full bump 9 1/2 inches of up travel. The beam is set at 10 degreees of caster. My question is it gets 2 inches of droop with very little toe out from ride height and then toes out almost an inch for the next 2 inches. It has fod 2 1/2 coilover arms and IH tie rods with Woods combos. Is this good or will changing to heim steering ends make it better.
 

TauMau

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Sounds like you have a cool project going. Changing to heim ends won't effect the amount of "toe" you see. It only effects strength. If you have the extra money, heims are great for their purpose and make changing them much more user friendly.

Essentially what you're seeing with your toe in/toe out is bumpsteer. I would recommend relocating the rack to where you end up with as little bump steer as possible. On our beam race car with 4" over arms and 16.5" vertical travel, we have < 1/16" bumpsteer throughout the articulation of the suspension. The best way to find the "sweet spot" for bump steer is to do something like the attached picture and move it around until you find it. You can also just tack it in place, cycle the suspension, move it, tack, cycle, etc.

Picture is taken from Tom Bird's thread in "Show & Tell". Fabricator credit goes to John at JFK. Coincidentally our front end was also done by John.

If you'd like to take a look at the build you can find it here: http://www.race-dezert.com/forum/showthread.php?t=53195
 

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3times

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Thanks for the reply, ok so no heim ends needed, I guess my question would be is 1/8 inch change in toe (bumpsteer) through 12 inches of travel the norm for 2 1/2 inch over arms.
 

DBMETALWORX

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i am building a vw pan based fiberglass buggy with a full tube chassis, i have set the rack angle so gains 1/8th inch of additional toe in from ride height to full bump 9 1/2 inches of up travel. The beam is set at 10 degreees of caster. My question is it gets 2 inches of droop with very little toe out from ride height and then toes out almost an inch for the next 2 inches. It has fod 2 1/2 coilover arms and ih tie rods with woods combos. Is this good or will changing to heim steering ends make it better.
1/8" is not bad, but the inch of toe out is. Iv'e found that the closer and higher you mount the rack, the better this gets. I had to make another mount that was a little higher,than the 1 that came the rack and mounted as close as possible, without clearance issues. It may take a few tries to get it right, but worth the time.
 

3times

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Ok thanks guys I will limit it at 12 inches with 1/8 change, the last 2 inches meaning to 14 inches the arms go a little crazy anyway, I am looking more for reliability and quality rather than quantity.
 

TauMau

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OK I see what you were saying now, I had misunderstood the part about the 1" of toe out coming after the 12" of travel.
 

DBMETALWORX

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X2... I didn't realize the 14" part.. After 12" w/ 2" longer arms the caster angle goes nuts, rolling the upper arm forward eliminating caster... Sounds like a cool build. Pics?
 
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