Tuesday, October 1, 2013

RE-Xtreme RC Drift Bible - Wheel Position Decision

When considering how to run your wheel setup, I'm not going to vouch for one setup here or another.  Just outline some things to try. And try is what you will need to do to accommodate your style.

Here is a Yokomo DRB.  One of the most stable you could ever drive. Minimal camber for grip, a bit of rear toe-in for less breakaway, but do you want stable?

This is a dilemma that faces RC Drifters. Stable and Fast, vs Unstable, Aggressive and Wild. There maybe a  a line that at some point you will cross and never look back, or you will revert to the point that suits your style...

And lets face it, drift has a definite style component.

Deep dish rims and stretched look tyres create their own problems but  when you add, toe settings, dive, camber, castor, inclination, scrub, steering angle and ackerman, you will have more DEGREES of difficulty that ever before.

Which is right? Which will work? Which is too far? When does it stop working? these are all questions that require you to test! test! test!

What can you see in this picture? Its a Yokomo 7 degree castor C hub without ball bearings that might bind a little on the steering. There is an 8mm hub/spacer that requires a longer thread on the shaft and because of 13 degrees camber, the dog bones are 2mm shorter as the suspension leans closer into the center of the chassis.

As the steering rotates rearward the chassis will lift up as the arc created from 7 degrees castor pushes towards a trajectory below the chassis. With the contact patch of the +12 mm offset wheels now effectively 10mm from where it was originally designed to be. The wheel scrub/turn radius will be 10mm greater causing the wheels to move 10mm forward and rearward on full lock and the chassis to oscillate up and down. Maybe even behind the wheel arches leaving the mechanism very visible from the outside and the ride height to change noticibly.  

To accommodate some of these issues created by "cool" deep dish wheels pushed out to the limits, recently you can buy extended suspension arms, extended drive shafts, smaller hubs, hing pin inclined hubs and even totally redesigned hub and arm combos, constant radius tyres, rims with extended lips that actually place the tyres inward and all together counter some of the effects.

So what the trends created was moving away from stability and introducing a lot of things that shouldn't really happen in geometry. This has begun to return to a performance focus or at least somewhere in between.

D1 drift cars like zero rear camber to keep the most contact patch on the rear. Creating the fastest car and generating the MOST grip available that the 1000hp machines force the Advan Neova type radial tyres to cope with.

On the front they may incorporate a large scrub radius forcing the user to bang away at the firewall with a sledgehammer, re-position front oil coolers etc or tub the whole front end with new inner and outer fenders, but the results cause similar issues. Increased front track may create better front end grip for more control but, these real cars are not 4wd and can generate much larger steering angles with less scrub radius. Typically castor is not as great either.

D1 cars also run a very high ride height these days has questionable appeal, however the Haraguchi FC of the early days presents a totally different philosophy and abundant handling issues. Local guys running missiles might run massive camber, tuck the rear wheels with onicamber at 15 degrees and create a contact patch that's just a few mm on a 315 section tyre.

There is nothing wrong with going either way. Just be prepared for different handling.

What is right? there is no right or wrong. It just depends how you want to tune your car for what purpose.

And this is where the drift divide comes into play. Tandem missiles, super low s-chassis or D1 Professionals. 

Who would have thought that these few parts (namely the front Knuckle and C hub) come in more combinations than any other component.

Which do you buy? This is where you drive your friends car or buy another "test chassis" and a heap of components.

My 3 Yokomo DRBs have run many many many configurations over time and many different combos at the same time, all to evaluate settings and what they do.

I've gone from CS 2.0 with almost no camber and stockish castor and toe, to a CS 1.5 machine that runs around 13 degrees camber on the front with 8 degree KPI hubs, longer ackerman arms, shorter scrub radius hubs and axles constant radius tyres, mostly for a look that stuffs the front rims under a narrow body and enables slide with a bit of speed.

Change the surface, the tyre, the rim, the body or the reason and these components wont work so well.

Many people don't like my setups, because they are unstable and reasonably difficult to drive, but they just require a different driving style that also needs to be taught. For me, I created a chassis the allows the oportunity for an aggressive driving technique and the ability to run at a high level with many different situations.

For a comp... I'd totally rebuild the chassis. But that's another chapter.

This is my style. If you can find others with a similar style, that's where your journey begins.

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