I was looking through the pages associated with the beast build up and had a couple of questions. Although first I must say thanks to all of the people with build up photos on the page, it is great to be able to track a build through.
Firstly, you say it is based off the Terrible Herbst truggy, is that just from internet photos etc to get general ideas, as I assume you didn't get to go and measure it up.
Secondly, and this is more general. Looking at the photo
The wheels have a bit of a lean on them (I have seen this in a lot of other buggies too), was that a deliberate thing or just a side affect of other aims for steering and suspension geometry. I can understand on the road getting the wheels to lean in, but off road when you are on opposite lock a bit it looks like it wouldn't be the best set-up. Am I missing something here?
I went through alot of books, asked alot of questions and hassled Aztek with quite a few questions when we designed our car.
The lean is negative camber, designed so that when the car rolls around its centre of gravity it puts its weight to one side the tyre leaves as full a tyre print as possible on the road surface. If you ran with zero camber gain only the outside edge of the tyre would make contact with the road.
When the car is opposite lock the weight is still on that wheel and keeping the largest contact spot possible on the road.
I'd suggest reading up if you want to get a grounding in the basics of front end geometry as designing a front end is always a mish mash of trying to get the best possible combination of camber gain, castor loss, ackermann, minimal bump steer, scrub radius and because we run offroad you have to add travel into the equation.
Ask aztek how many front end mods he's made in the development process!
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Green Sally up. Green Sally down. Lift and squat, gonna tear the ground.
I understand the concept of negative camber and camber gain but looking at the right front wheel it appears to have positive type camber compared to the ground, I would have thought it would be better for the wheel to be where the red line is rather than the blue, if that makes sense.
That said, all A-arm off road buggies I have seen look the same as Aztec when in this sort of position.
To me it looks like the front right wheel wants to tuck under.
Hope that all sort of makes sense, just wanted to reinforce I am definitely not having a go at Aztec's design, just trying to learn.
dre, your observations are valid. If the chassis stayed level you would be able to keep the built in negative camber all the way through the travel. Unfortunately with the amount of travel and bodyroll that A arm chassis allow, when you have a situation such as the picture you have attached, the top arm effectively gets longer relative to the wheels geometric relationship with the ground. This has the effect of pushing the top of the wheel out. (see attached pic). Aztec's design using unequal A arms and non parallel mounting is the best compromise I've seen yet. I would encourage you to give Aztec a buzz, he is usually very approachable, though he may stop at lending you his car!
Hi Guys, sorry I'll have to give you the short answer today.
1. No sway bar fitted when photo was taken. 2. To help turn in we run lots of caster and lots of Ackerman, so in an oppersite lock situation positive camber will be more evident. 3. I am a printer! 4. car goes really fast!
Happy to talk to you dre...but please take point number 3 into consideration!
Its all about coming to a compromise with everything. I spent months designing my front end and drawing it up with autocad before finally ending up with what I have. My car uses parallel mounting wishbones with unequal length arms and I looked hard at achieving as little positive camber as possible especially on turns with body roll taken into consideration. There are so many things to take into consideration as Wolf said but with running parallel mounting arms there was one less thing to look at and that is castor gain/loss. My castor is constant through the entire travel.
I set mine up with a bit of negative camber at full droop and the camber changes through the entire travel with more coming in as it gets to full compression. I'm very happy with the handling of the car as it is and the front end on this buggy allows me to place my car on the track in places others can only dream of.
