Tuesday, May 24, 2011

Adding weight to your 104 for lower traction...

Tamiya Tires Part 2!!

Rambling about rubber...

This year so far, the tracks around here have been pretty green.  They have been preparing them, but there still a lot of grit and sand and junk out there, so it's been lower traction.  Most of my tuning has been to try to get the car to have grip enough to leave the corner better, and still steer.
I have been running the split upper deck sans damper plate, he car doesn't seem to miss the plate so far.  There really hasn't been enough traction to make the car roll hard just from the grip.  However, and this plays into the heavy pivot post's usefulness, as the car gets heavier, it may be worth while to try it.  The heavy pivot post is a nice part, especially for rubber tire since you save room on the chassis.  I have been adding an additional 1 oz. (28g) lead per side right behind the radio trays, so 2 oz. or 56g basically in the center of the car.  This is VERY helpful. in addition to that, I tried another 14g on each radio tray as a test, which i'm undecided about.  I also run 14g behind the servo flat on the chassis, and 7 to 14g on the wing right about even with the body mount for the nose.   This weekend I also added 14g (7 on each side) to the wing right in front of the camber plate.

 The nose weight depends on the track, and how much grip the car has.  Too much (usually more than 14g in the forward most position) and the car won't center up.  Too little and the car will push especially on power.

My car wound up as a tank with about 140g of lead spread around the chassis overall, not counting the additional weight of the heavy post over a plastic or aluminum piece.  The only bad thing was as I added the last 28g  to the car on the radio trays, it started to roll more and even wag the rear end a bit until the tires warmed up.  At this point I'm not sure if I just have too much weight, or if I need the damper plate back.  I tend to think maybe just a bit too much weight. I probably will try the damper plate just because it's worth knowing the effects.

I have found you can still use the camber settings (1.0, 1.5, 2.0, etc) to add overall steering without making the car totally bananas, if you reduce camber gain with a lowered,  flat upper arm.  I was able to go from 1.0 to 1.5 to get some more steering without overpowering the rear of the car.  I'd like to add even more just to see what will happen.  I know last year, adding camber always helped steering.  When the traction was really good, you could run 2* + and really get the car turning.

The other really important adjustment for rubber tires is shimming under the rear ball stud of the upper arm.  This controls the active caster effect, and is super critical for rubber tires since this car always wants to wash out the front end mid corner.  Adding shims under the ball stud will add mid corner grip.  I got up to 1.5mm in shims this weekend, had the extra steering, but it was still controllable. This is probably the most important adjustment for rubber tires, since it works very independently of the other front end changes.  You can maintain the fell you have and still add or reduce cornering power.

I recommend the split upper deck as well.  Right now I have it on, and I only have the screws in the pivot post securing the upper deck.  I'm using the FRP lower chassis, and I think letting the chassis flex front to back is letting my car get more forward bite.  It was able to launch pretty well out of the corner.  Usually, I would not think the front to back flex would help, but I think the funky T bar design needs all the help it can get putting the power down.

Sunday, May 15, 2011


It was 90* and sunny about 5 days ago...It's 45* and has been raining for 2 days, just in time for the weekend.  I'm going nuts over here..........

Friday, May 13, 2011

The Wide front end project

F1 is getting popular outside of Tamiya series racing, and that means the opportunity to be a bit more creative with option parts and cars.  The local series will be running F1, and 200mm wide cars will be legal (F103, F109, F104W, etc.).  Usually this means you stick a standard F103 or a 3Racing front end on your car with some F103 foams and you are ready to rock.  While the F103 front end is rock solid, it's also not adjustable.  The 3 Racing setup is not bad, but the plastic is only ok, and it's kinda sloppy.

So this is my amalgamation of parts to make a caster/camber adjustable front end that at least sort of looks like it might belong on a modern car.  It's not a final design, but maybe it will inspire some of you guys to try some new stuff.

I cut an old upper arm from a 104 down, and drilled and tapped it so a short turnbuckle could run from the arm to a 104 camber plate mounted on a Tamiya F103 Link type lower arm.  You can substitute a 3Racing lower arm as well.  Another turnbuckle runs from the chassis where the rear ball mount goes to the top of the upper arm.  I had to remove almost all of the rear strut of the upper arm.  The turnbuckle is mounted to the arm with a Losi open ballcup fitted with a "top hat" sleeve from a sedan caster block.  This is to let the rear turnbuckle only have circular movement vs. a typical ball end.  I though everything would be too floppy with a regular ball stud on there, but I may try it out later.  The upper arm was drilled and tapped to mount the turnbuckle
So now the camber and caster can be adjusted infinitely, as well as the camber gain at the inner link.  The setup is a bit more complicated, as both links work together, so changing camber will change caster a bit and vice versa.  It's just something you have to be aware of.

I did want to incorporate more of the upper arm's rear strut, but I didn't have another short turnbuckle around to make that work.  There would be no advantage except that it would look a bit more scale.

One other idea would be to make a similar front end, but with both links coming off of the camber plate.  This wouldn't look as close to the modern cars, but it might have a bit more adjustment capability in terms of ball stud heights

Wednesday, May 11, 2011

Saturday, May 7, 2011

Tamiya Tire Test 2011!

Leisure Hours Hobbies opened the outdoor asphalt track for the first time this year, today.  I took advantage as this is one of the best permanent facilities in the US.

Video of Leisure's track

Anyway, it was in the 60's all day, and the track had been prepared for the first time all year, so it was a bit green.   Actually, I felt it was a great time to test tires just because the ability to make grip would be highlighted.

I only used the option soft rear and kit front tire, as they had been the best all around choice for most tracks last year.  The hard fronts may also be worth a try as well, since it might allow a more aggressive front end setup, but that will have to wait for now.

What I wanted to highlight was tire preparation.  This is to me is overlooked at times, but it is really critical with rubber tires.  You can look at race reports from big sedan races highlighting what small changes in tire prep can do for a car's performance. Last year I approached the tires from a sedan-centric viewpoint.  I more or less copied what i was doing with sedan tires.  I would clean the tires with SXT 1.0, apply Paragon FXII for a bit and then bake in SXT 2.0 or possibly Tire Tweak with warmers.  This seemed to be fine for tracks that had a lot of traction, but I'm not sure if it was the best thing overall. At the TCS Nats, only myself and one other guy were using warmers.  He did a lot better than I did, and I'm not sure of his routine, but my car was not all that great.  Most people seemed to be cleaning the tires or not using anything at all.  So in that vein, I went with a less aggressive regimen.

I tried a few different things, including Trinity Red Dot, PB Blaster, Simple Green, and Sticky Kicks Blanco.  I either cleaned with SXT 1.0 or the product itself.  Red Dot was ok, but I was not 100% satisfied with it.  The problem may have been that it made the tires too sticky, and it would up picking up junk off the track.  Either that or the tires were somehow greasing off.  PB Blaster made the tires softer, and even a bit sticky, but the greasy effect came into play here as well.  I think that these two, along with the other oil type additives (Tire Tweak, SXT 2.0, Paragon) may make the tires greasy or  prone to overheat somehow.   That was part of my problem last year.

I moved on to Sticky Kicks Blanco, which is more of an off road tire product, like Buggy Grip, but less aggressive.  I used a rag to wipe it on, since it is a spray.    This actually turned out to be the best overall for me.  It left the tire feeling soft and sticky, but not greasy.  The run I made with SK was really good, and the grip held up for the whole run.  Sticky Kicks makes three different sauces, and Blanco is the middle in terms of aggressiveness, so I will be testing the other varieties to see how they will work in different situations.

Straight Simple Green was next.  Simple Green is a cleaner more often than not, but I let it set on the tire a few minutes.  Much like Sticky Kicks Blanco, it got the tire clean and sticky again, but I don't think it penetrated the rubber as much.  I went out to the track thinking this would be as good or better than the SK.
My car was definitely hooked up at the beginning of the run, but it tended to break away in some corners as the run went on.  I think Simple Green works well, but may not work as well into the run as the SK.  This might not be as noticeable if the track temp is high, as the tires might heat up enough to develop more grip.

So maybe Sticky Kicks or something similar like Buggy Grip or Ragu may be the way to go.  I think that Simple Green may even be better than the Sticky Kicks as we move into the warmer months to prevent the tires from overheating due to too much softening.  I also like the way the tires don't "grease" over with the buggy style additives.

Wednesday, May 4, 2011

The motor game

I watch some of the threads on rctech and other forums, and F1 is in a weird place.  There are a certain amount of people who still want to run silver cans, and there are a lot of people who want to run brushless.  It seems like 21.5 and no timing esc is a good equivalent.

  Silver can is fun if everybody just runs the motors the way they come out of the package.  Otherwise, it just frustrates people if there are "tuned" motors.  Even so, the motors are pretty crappy, and it's easy to smoke one trying to keep up. 

It would be great if everyone got on the BL bandwagon.  Really, I think it's cheaper in the end and less frustrating.  I think that sometimes the desire to "use what we already have" gets in the way of what is the best way forward.  This goes for almost every class of racing.  Sometimes I wonder if people have 10 cars and one set of electronics mounted on velcro..LOL.  At the same time, I realize the transition is a fragile time for any class, since that's when there is the most chance for racers to walk away.  If silver can and 21.5 can run together, that really is the best of all worlds.  The guys in California have had success with this, and I have run in practice together with a 21.5 car and not known it was brushless.  At the same time, I have also read reports of it not being so equal.

Right now F1 is on the cusp of really taking off.  The cars have the realism and performance, and they are pretty cheap overall to run.  Somehow, there needs to be a unifying force to put it over the top.  Tamiya/TCS is great, but there are a lot of cars out there besides Tamiya or Tamiya parts only.  Only time will tell.

Sunday, May 1, 2011

First outdoor runs 2011

The local parking lot was open for a practice day for the first time this year, so I wanted to try a few things.

First off, I wanted to try the F104W with the kit rubber tires.  In the video, I outlined some ideas for the car, but basically it's a washout for competitive racing unless there is some way to make the tires work better.  The rears are ok, but the fronts really produce no grip.  The other problem is that I really have no way to soften them-I'm not aware of a traction additive that would work right on the tire.  Almost everything makes them feel greasy.  I went through a bunch of things, but unless I figure something out later concentrating on the normal F104 is the best idea.

I ran the F104 black car with the split upper deck, no damper plate, and weighted pivot post with a set of tires I knew to be good from last year.  With the initial setting I had, the car pushed a bit mid corner and out.  It was stable, which was promising since the track was dirty despite being blown off.  It was also windy with temps around 60* F and the pop sprayed on the track was very light- 2 liters per 3 gallons of water.

Normally, they spray the track with grape soda pop straight from the bottle, but last year the track was re sealed and that prep caused the tires to glaze over.  The winter seems to have worn off some of the sealant, so the lighter amount of preparation was not very effective.  This was good for me, however, as it would give me a chance to see if the car would perform in less than ideal traction.

I went back to the pits, and added 1mm under the upper arm at the steering knuckle and 1mm under the rear ball stud of the upper arm.  I wanted to get the car to bite in the middle of the corner and to be a little more aggressive overall.  This actually worked perfectly.  The car was just right, and got around very well.  I made a few more runs set up this way, and the car was great.  The wind picked up towards the end and dropped the temperature a bit, which loosened the car up slightly.  This didn't worry me too much as the other cars out there were sliding around a bit as well when the wind kicked up. If anything I would have taken .5mm out from under the ball stud, but that's a minimal change.

Next Saturday is the opener for Leisure Hours, a permanent facility with curbing and the whole nine yards.  I'm going to concentrate more on tires there and working with the new split upper deck post positions.