Ground Clearance vs. CG / Articulation

[RevoRacer]

I've been trying to come up with a well thought out design for my crawler. Pouring over pic after pic reading posts and thinking. I'm trying to decide what a good compramise between center chassis clearance and low center of gravity is. What do you guys think? How much is enough ground clearance without sacrificing low CG and getting 'tipsy'?

Also I am trying to decide how much articulation it should have. It seems most lower CG crawlers use Maxx style shocks and have moderate articulation. Some though, use Savage style shocks and have crazy articulation but this seems to sacrifice lowering the CG and can lead to increased torque twist. How much do you think is enough and is there a point where too much articulation becomes a hinderance?

I think this can eventually be a valueable thread for helping Noobs (having limited experiance myself) make better crawlers!

As always, thanks for your imput!

[bbaXJ]

It can vary quite a bit depending on track, wheelbase, etc. How it'll behave is a lot more dependent on geometry and design than just height and shock travel. With the right angles you could get more travel out of Maxx shocks than Savage, but it'll probably sacrifice stability. With locked diffs and good tires insane amounts of flex aren't really necessary anyway. Beyond a certain amount of travel it just leads to an unstable rig. Do your research on here about what general setups work best and how they react to different movements, then base your design off of what works and performs how you want it to. There's simply no one design that does what everyone wants.....


That being said, here are some things that generally work well for crawlers. The flatter the links sit at static ride height the better. Longer links are usually good....the longer and flatter they are the more vertical the axle's travel will be throughout its range of movement. Vertical separation of the links at the frame end should be about the same or slightly less than at the axle end. Triangulate the links to keep the axles centered.

[RevoRacer]

I've been looking for good pictures of what you have described.
Are these good examples

(For some reason a couple of pics are comong up smaller than the others.
Just click on them for a larger image.)

[TwistedCreations]

the first truck looks gigantic....

although height and width do play a roll.. weight placement is the key. I have 5 1/2" of belly clearance under my moonbuggy and like 4 1/2" of diff clearance. Although that may seem to sit high, the chassis is only a total of like 11" tall and all the weight is low. the motor sits in the belly pan and everything is either made of CF or tubing...

Take teh 3rd pic of toyos truck... turn that trans sideays so the motor lays in the belly or use one of the front motor mount styles that my buddy makes to also lay the motor in the belly and you will go alot more places. It is all dependant of weight placement.

[mike]

My old maxx

[toyofast]

Holy crap! Those top two pictures are vintage 2003!! That's some old school RCRG Maxx crap. I bet Sean still has that Blazer body in his trash bag of bodies. He has to have at least 50 bodies stuffed into one giant trash bag.


My Maxx, the last 3 images you posted are in 3 different stages of build. I just recently rebuilt the setup. Slightly shorter WB(from 16.75" to 15 3/8").

My stats:
WB- 15 3/8"
Center chassis height- 4"
Front diff height- 2.25"
Rear diff height- 2.5"
Track width- Front 15.5", Rear 14.75"
Overall height(top of body)- 9"
Tires/wheels- HPI Savage wheels with Imex Step Dawgs(5.5"x3")

I have been trying to get the Maxx lower overall but still maintain decent clearences under the truck. Links are not all the same, fronts are shorter than the rears. I might even try to shorten up the front links a bit more to help push more weight towards the front... but I still have yet to test the most recent rebuild(rebuild #9, I think)

I have about 8" of total vertical travel, not much but here in the PNW we tend to have more short & twisty vertical climbs that are killers to the mega flexy rigs.

[RevoRacer]

Yeah, I know Toyo, I've had those pictures quite a while!
I don't even think any of those images exist on RCC anymore!
I still think there kewl rigs though!! Good designs!!