TinyRC.com - Chassis Tweak! Pics!

Well, like most new DRR owners, I had to do some tweakin' to get them to run right. Ordered two from Ehobbies - and got two black cars. Both on Channel 3. :mad: Fortunately, I ordered a set of ch.6 crystals as well. :D

So, of course, the first problem was the oversteer to the left. Car would do mad spins leftwards but not rightwards.

Tweak #1 - the washer, placed underneath the steering knuckle.
http://members.aol.com/modemjunki/drr/washertweak.jpg

Now the mad spins were not so bad, but it would still do it - mostly when the steering angle was set high (steering angle setting wheel on the controller handle). I took a closer look - the problem is the servo wire boot! If you have the steering angle set to max, the left front tire contacts the servo boot, effectively locking that one tire as shown here.
http://members.aol.com/modemjunki/drr/servowires.jpg

Tweak #2 - Simple fix - push wire back with finger pressure, hold for a bit, and it will stay back.

The cars (both!) still didn't track right. And one of the two was put together kind of poorly, it seemed, the rear end was noisy and rough. I began a complete teardown, checking every bushing and screw. While I was reassembling the chassis, i noticed something important: tightening the screws to the upper deck would tweak the upper deck off to one side! The holes in front did not line up to the king pins. Aligning it to the king pins would cause the car to rack (torsion flex/twist) to the side!
http://members.aol.com/modemjunki/drr/chassistweak1.jpg
I think this is caused by the rear center mount not being "perfect" in form.

Tweak #3 - hog out the holes(see next pic) in the upper deck and the matching holes in the radio/esc box. This allows you to wiggle the chassis a bit, you're not dependent on the shape of the rear center mount for aligning the deck/radio box. Carefully reassemble chassis to eliminate torsion (took a couple of tries).
Be super careful not to hog the holes out too much. A half a millimeter is enough.
http://members.aol.com/modemjunki/drr/chassistweak2.jpg

On the car that was noisy, it was just put together badly. I trimmed some junk off the spur and pinion gear, and I opened the diff up, as it's screw was all the way backed out. It really is kind of a poor performer. I found that using one of the orange donuts that hold the car body on during shipping made it work a bit better than the stock black O-ring. Somewhere in my garage I have a collection of tiny O-rings, I'll experiment with them in the future, and with some different greases in the diff itself. I also paid close attention to rebuilding the front end. Both were assembled in a way that required a lot of steering trim, I re centered everything (might was well do it right while you're in there). I'd like to find a way to make toe adjustable on these cars, I think this would make for some interesting handling possibilities (not to mention new ways to wear out your foams!).

Now the "bad" car runs great! Purrs like the other one (which I also did a tear down on, it was pretty much OK except the front end). The stock rubber tires are good on carpet, but on Armstrong linoleum they are a challenge to come out of corners with.:eek: Ran three sets of alkaline batteries through each car today, was a blast. After the first set, the motors seemed to run a bit smoother. Next I have to budget for a couple of sets of NIMh and a dual charger (or two chargers, anyway).

And I can tell I'm going to spend a lot of time cleaning these cars. Cat hair... yech.:D And one of our cats tackled the GT-1 as it passed by....

Oh, and a hint for the indoor racing crowd: pick up a bag of multiple-size bungee cords. Stretch them between table and chair legs etc. along the floor, and you'll have something to bounce off of when you get run under the couch/end table/ etc. by the competition (or your mad driving skilz). :cool:

Comments? Suggestions?

I'll shut up now....