Long travel front suspension, caster???

DaCajun

You guys with long arm suspensions, what kinda caster do you guys run???

Thanks!!!!

BGW

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slonomo

+4 to +6 degrees

DaCajun

Cool, I was thinking something like 5 degrees. Looks like I was right in the ball park. I really appreciate your input. I'll be posting up some pics of my little project I'm working on....Thanks again!!!!

slonomo

Pics are good!

UncleJerm76

Sounds like you are building your own long travel? Here's something I learned along the way that isn't ever mentioned maybe it will help you out.

I discovered the caster will drastically change as a result of adjusting front shock height. My front shock height is massively adjustable so I can go from minimal lift to nearly 10" above stock. But because the front is getting higher and the back is staying the same, it increases the caster. There is a point where the positive caster has increased so much that its extremely difficult to turn the wheels at slow speeds.

Moral here is just make sure you build-in the 4° to 6° of caster while at the proper sag and dont forget to give the back just as much love as the front. Now where are them pics???

slonomo

Yeah I grafted in a Yamaha Warrior front end that I widended 8" and used a rack and pinion unit. The caster is fixed once you locate the subframe angle, and won't change. I think what you are thinking is "camber"?

UncleJerm76

Whoops, I originally meant to quote DaCajun, sorry Slo - im very familiar with your build. But hey, since were on the topic...

Nope, I definitely meant caster. Step back looking at side of cart with the desired caster intended. Now raise the front of your cart higher, but the back remains the same. Some people call this look "bulldog" — anyways, the caster just changed! The wheelbase also gets longer... but thats another topic

If you don't adj your front height, then this is a mute point. I'm just advising that if you do change your front height for different conditions like me, you'll also want to change your rear height to keep the caster from changing.

Here, maybe this diagram I made will help...

Attached Images

CastorChangeWithFrontHeight.jpg (65.5 KB, 0 views)

slonomo

UncleJerm, I see what you are getting at. Caster is measured not from the ground, but from the most horizontal section of the main frame of the vehicle. So the actual caster setting doesn't really change, it just changes the position of the suspension related to the ground. This happens constantly off road, no way to adjust for that. For an on the road vehicle like a race car, this is more critical. But you are correct that the rear needs to be set at the same height as the front or you'll get negative handling results. So, I agree with you there. The main thing is the main frame needs to be parallel to the ground to maintain factory settings on the suspension. In most cases though people change a arm, shocks, spring rates, wheels, tires, etc, so the suspension settings are all over the place. Thus there is no way to make direct comparisons from one cart to another. Each cart with a lift kit will be different in the way they handle. The basics of suspension geometry are also all over the place, and people differ with opinions. So, there is no right or wrong answer here. LOL

UncleJerm76

Actually true caster is measured from the ground and not the frame while suspension is at its natural resting position. Everything I researched backed this up. Here's just one link (search for ground within the page):
http://www.anewtoronto.com/wheel%20alignment.html

I'm not referring to movement during a ride, I'm talking about setting up the resting height in the front will change your caster.

slonomo

If you measure caster from the ground, how can you be sure the ground is level and true. If you know your frame is straight, and your frame is level front to rear and side to side, and you know you want your frame to be parallel to the ground (not banked front or rear), then measuring off the frame is more accurate. Unless you have a perfectly leveled building platform to measure from, the ground is not true, ever. I guess it just comes down to how you build your vehicle. In a golf cart, measuring from the ground is ok since speeds and usage are not excessive. I prefer using bubble levels during suspension setups, the bubble never lies. Also having a true and square frame is essential. This is another discussion, however. Today many race team shops have lasers to help with measurements, very expensive. Most of these laser tools have a bubble type device inside to determine where level is. Whatever method you choose, be very careful to make both sides exactly the same or you could be in for some sketchy handling. To each his own.