Sunday, February 24, 2019

TRF 103 First Weekend on Carpet

This weekend I had the chance to go racing for the first time in a long time.  My local track was having a leg of the USVTA Series traveling around the middle of the country.  They are also going to have a Tamiya TCS regional in about a month, so I figured this would be  the perfect time to get the TRF 103 set up for carpet.

Not really having too much of an idea beyond a "typical" carpet set up, I initially had the car in a transverse battery configuration.  I was also using the T bar instead of the links, and the short wheelbase, which are both not typical, but worked very well on asphalt.  This is not to say it would be right for high traction carpet as well, but I wanted to give it a go.

Right off the bat, the car got around fairly well.  The main problem became lifting of tires, and a tendency to over rotate out of the corner on power.  The over rotation stems from the tires getting light, since I had pegs in the diff to lock it into a spool.  As a tire comes up, it just rotates the car off the outside wheel.

The car was driveable, but touchy in areas and not stable enough to attack.  I tried changing side dampening and t bar settings at first.  5000, 7000, and 10,000 in the damper tubes provided enough feed back to see that lighter would be better, and really the T bar needed to be tightened.  I settled on 5K in the tubes and moved on to the t plate.

There are a few ways to change the t plate characteristics even without changing the t plate.  I started with an orange o-ring, which is fairly soft.  Going to a stiffer black o-ring, and then even the outer o-ring in combination with the black o-ring, as was used on the F104 T bar cars still was not quite enough.  The t bar needed less tension so it could pivot, but the overall travel was a bit too much.  In this case, I replaced the smaller black o-ring with a similar thickness nylon washer.  The larger o-ring was retained.  Now the t bar could be set with less tension, but the washer reduced the overall travel as it pivoted.  This made the car feel more stable and reduced the tire lifting.

The first qualifying run I made was not bad, but as the race wore on and the tires heated up, the tire lifting came back into play.  There was some time to practice, so I was able to try a longer wheelbase on the car.  Surprisingly, the car did not lose much steering at all, and the tires stayed in contact with the carpet much more consistently.  I tried a few other things, including raising the rear ball stud on the upper arms of the front end.  This usually helps to quell a bit of the tendency to traction roll while taking a little steering away, and indeed, it did help. This car seems to have plenty of steering, so it was  a worthwhile trade off.

By this time, the track was about to close for the night, so any more experimentation would have to wait until morning.  Reflecting on the car's main problems, it seemed an overabundance of weight transfer was happening at the pivot point of the t bar.  There is really no forward/aft movement of the battery in a transverse setup on this car.  This left me with an inline setup as the only alternative to change the weight bias.  I have not been a big fan of the inline battery over the transverse on carpet, though there has been quite a few racers using an inline battery on high traction very successfully over a range of different cars.  On day 2, I decided to test it out.

Arriving at the track the next morning, I ran through a couple quick changes before reconfiguring the battery.  Mostly front and rear width, which was maxed out close to 190mm at the end.

After fighting the wiring and electronics onto into a suitable  configuration, I dropped the battery into the car inline and went out onto the track to test.  In the past, I have found inline cars to be overly aggressive off center, even a bit jittery, so I was apprehensive.  Imagine my surprise as the car was very docile and had to be thrown around to make it want to pick up a tire.  The over rotation problem was gone as well,  and I could drive it hard through the chicane leading onto the straight with fear of having to make a correction and upsetting the car.  A miscue was met with a smooth response instead of a jerky reaction when corrected. My car was now a good .3 seconds a lap better, being able to drive it confidently at all points on the track.

For the final qualifier, I was able to move into P2 for the mains, and lap times were much closer to the TQ driver.  The car handled in traffic very well.

What really capped off all the progress I made was a small change to my tire dope strategy.  I began applying more tire sauce, but wiping it off about 5-6 minutes before the race, as opposed immediately before setting the car down.  The front tires were more or less dry, though they had been sauced for about 10 minutes wet time.  This really settled the car, but still provided enough steering throughout the race.  Starting second in the main, I was also able to be ready to fight and apply pressure immediately, and twice I made a pass on the first or second lap to get into first place at the start of a race. I had one first place and two seconds, for a second place final position.  In the second main, I actually had first place for a bit, but I crashed when a marshall screened my view of a chicane.  I probably should have gave myself a little more room there, but I was going for the win.  For the third race, I did not have quite as good of a start, and made a mistake on the left side of the track, costing a little time.  Ultimately, I was able to close down on the lead car, but never get close enough to try to pass.  The winning car and driver were very good, so congratulations are in order.

Overall, I was really happy with how quickly the car setup came together, and even more, how easy it was to drive the car at race pace.  It's also encouraging as this was outside of the body, a TCS legal setup.  For typical races, you could use an aftermarket spool or gear diff, and also front end pieces that could offer more caster and camber settings than the stock parts.  There are more tenths to be had out of the car, but this was a good weekend.  I plan to also try the link setup as well for comparison, but I have always liked the solid feel of a t bar car.  Don't be afraid to try it if you own the TRF 103.

EDIT: Turns out I also managed hot lap of the weekend!!  Not bad.

Inline car

 Please excuse the somewhat disheveled

 Note the short shock configuration.  Also, 42 g of lead was added to the car to make weight with a standard short pack.  Lead was distributed close to midship.

Electronics were directly in front of the battery.  The lead was tried at more forward positions (on the side of the servo, under the lower arms).  No bueno, mucho oversteer.

Sunday, January 20, 2019

Some stuff I have been working on

It's been a long time since I have posted.  I bought a house, so my rc time has been much limited.   Lately, i have had a bit more time, so here's a few new things I'm goofing around with.

TRF 103

I got the new TRF 103 last summer.  At the final TCS Nationals at the Aliso track, I was able to qualify 3rd.  I didn't get the car really good until the main, when, in the warmup, I could tell it was fantastic.  The start didn't go very well for me.  I had some racing contact that put me down to last, though I was able to make a small comeback.  The car I had in the main was excellent, and if I had it working like that in qualifying, I think I might have had a chance to maybe started one place higher.  The two guys in front of me are excellent drivers, so I would have needed a lot of luck to have started any better than I did.   

The second car will be a carpet only setup.  If it's as good as the asphalt car, good things will happen.

Mutant V2

Once again the F104V2 pops up, this time with an IRS axle turned into a spool, and a couple CRC left side hubs for good measure.  This is possible with the Exotek 1/4" axle conversion.  It's a great idea, allowing the use of 1/4" axle parts like the many spools available and the Xray gear diff.

I also have the Tamiya carbon front end lower, with an Exotek upper arm setup for adjustable camber and caster.  I tried some other setups, but this works really well.  All that it needs is a small piece of carbon to mount the upper arms to the bulkhead.  It's fairly simple.

"Speed Jam"

So I bought some random parts online from a Japanese hobby shop to make my Speed Passion SP-1 into a Street Jam SJF01.  The rear end of the car has always intrigued me due to the amount of travel it has.  I mocked up some changes to see if the would work.  The upper links and top plate are too close to the rear of the car to transversely mount the battery, so I was able to bolt them to the SP-1 upper deck to allow a short pack sideways on the car.  At some point, I need to make a one piece top deck to mount the links, as this setup is flimsy.  The suspension does move well but I'm not familiar enough with this style suspension to know how lengthening the links affects handling.  

Eventually, this will get the same front end as the Mutant V2.  It worked well when the car was 100% Speed Passion.

That's it, just a fun update of what I'm keeping myself entertained with when I have some non-remodeling time.....

Monday, March 19, 2018

TRF 103 Manual!!

Thursday, March 16, 2017

What about your tires?

I haven't posted in a while, no reason other than laziness..... Anyway, this came up at a race recently.  My car just seemed to be a pile of junk.  Nothing I did seemed to make any difference or change to how it worked.  Looking back, it reminds me of how an F103 would get when the T bar went bad.  Hind sight is 20/20 as they say.

Luckily, one of the other locals, Mark, happened to be sitting nearby and asked how old my tires were.  I hadn't thought too much of it, but I had put them on the car for the Hudy race in St. Louis, in January.  I had run the car for countless packs since that point in time.  Mark is pretty sharp, and has a lot of ideas on tires, including the idea of rotating between two sets during the day to keep the tires from getting too soft.  In any case, he got me to change tires on the car.

On a car that would barely crack a 9.8 second lap, a newer set of tires got the hot lap down to a 9.5 in the first minute of practice.  On the older tires, it was on skis, pushing all over the track.  The new set got back all the steering the car was missing.

This is not to say that your car needs to be fed a constant diet of new tires.  Far from it, new tires take 3-4 runs to get broken in, and they will last quite a long time.  They last so long, that the deterioration can be hard to notice.  2+ months of running is a long time to get out of any set of tires.

The lesson is that when nothing seems to help the car, it might be the tires.  Just like when nothing seemed to help an F103, it was usually the t bar.  Or when a new set of front and side springs brings a link car back to life.

Just keep an eye on your tires.

Sunday, November 20, 2016

V2.V2 pt.3

I probably should have posted this a long time ago, but I did finally run the V2.V2 after a Gravity RC Midwest All Star Series race.  I ran it with a 21.5 motor, as it was all I had available at the time.  The track was the new CRC black carpet, and after a day of racing, had a nice groove.

There was really only time to run one battery, but I was very surprised.  The car was actually really good for something that had a guess at the setup based on what I thought should work.  It was a bit twitchy, but generally got around well, and didn't traction roll.  I wasn't sure how it would react in the high traction, but it was fine.  Even more interesting was that it was very easy to get on the power, even with the 21.5 motor.  UF1 MIDWEST past champion/engineering genius Rick Vessel even gave it the thumbs up when he was passed the controller.  The long links do seem to be doing their job of getting the car some traction.

At some point I'll continue to work with this car.  Luckily, the new local track has now opened.  There hasn't been an opportunity to practice locally in the past several months.  I may not get to this right away, as the front end has migrated to another project, a very interesting prototype development...

Wednesday, September 7, 2016

V2.V2 complete

V2.V2  is complete, this time with the Tamiya carbon front end/Exotek combination.  As it turns out, the Exotek upper arms can be used if you make a plate to mount the camber links.  Now you have a front end similar to the other high end cars, carbon fiber, and the ability to adjust ride height at the lower arms.  I found the slightly shorter CRC front springs are a little better for this front end as the lower ball does not have a recess for the spring.

I have not had a chance to run the car........ yet.  

Friday, July 1, 2016

Basic geometry

So I have been thinking about a few things after a conversation at the track.  Lately, I have been feeling like the biggest things on an F1 car outside of the tire selection are the car track widths, and the steering setup.  I was talking to someone about what really gets F1 cars working.  The steering is gigantic, but not everybody thinks much about it.

A few years ago a friend who was a long time 1/12 guy, and national level A main racer, among other things, really clued me into how steering geometry works on pan type cars. Working with the concepts he explained to me really opened up possibilities I did not know existed.  Sometimes, there were things I wanted to change on the car that I didn't know how to get without big compromises, or even how to change at all.  The steering on your car can actually affect almost all areas of set up, things that would be counter intuitive in some cases.

The big one is the bump steer settings.  Generally, in a typical servo set up with the output shaft pointing up, you will use maybe 5mm of shims on the bottom of the servo saver.  That will generally get the tie rods somewhat level.  What is this really doing?
In general, the less shims you use on the bottom of the servo saver, the more the car will want to steer on exit, from mid corner on.  I have actually seen a car do pirouettes because the driver had NO shims under the servo saver, and an extreme angle upward toward the saver.  (CAUTION: bad paint program diagrams ahead!)
 A more typical setup has some spacers underneath the servo saver to get the arms sort of level.  A level tie rod will have a minimal amount of bump steer and make the car feel pretty much the same in all phases of the corner.  Usually, this is the best approach to take at first.  It's fairly easy to add or remove spacers in small increments like 0.5 or 1mm to tune things in.  Big changes are good to familiarize yourself to the extremes, but remember to look at the tie rod length to maintain toe as close as possible!

Adding spacers to the servo saver making the tie rods run down towards the inside of the car will make the car steer more in the beginning of the turn.  Additionally, spacers on the knuckle tend to make the car more reactive at first turn in as well.  This does increase the angle of the rods as the spacers on the servo saver does, but I think that the difference in height from the axle is a little different from just adjusting the rod's angle in general.
The other factor in the steering is Ackermann.  The difference in the steering radius of the two front tires generally affects overall steering and aggressiveness.  Generally, moving the servo saver ball studs forward, whether by servo position or length of the servo saver/steering arm, will increase aggressiveness and steering.  This will also kill some mid corner roll speed, especially on carpet.   On asphalt, this can actually be a benefit, since it's almost like drag brake.
Making a straighter tie rod will promote roll speed in high bite conditions (note most 1/12 cars are fairly straight), and be less aggressive.  Rubber tires do seem to like a bit of angle to make the tires work.
The other part of the equation is the actual servo saver.  The width of the space between the ball studs makes a difference.  Narrower spacing tends to be more aggressive.  Wider less so.

The other part of the equation is the track width on both ends of the car.  

At the front, I like a wider car in general.  It promotes more on power steering, and helps the car be more stable under the brakes or on corner entry.  Narrowing the front will make the car a bit more nervous, and help turn in.  There is usually less overall steering, however.  Having on power steering is key in my estimation since the car's corner speed is important to lap time since they do not have the acceleration of a 4wd car.  I try to get the car as wide as rules allow, and the track conditions will permit.

As far as the rear I generally try to make the car narrow as conditions will permit, to gain rotation mid corner.  It will also feel like there is more side bite as well. In high bite, like carpet, this can work very well.  On asphalt, it pays to try to run as wide as you can while maintaining rotation.  A wider rear will be more stable out of the corner (launch), and will keep the tires from overheating during the run.  The overheating is less of a concern on carpet.  In the past, the 190mm width limit led some option part manufacturers to make widening kits for cars.  Enjoying some initial popularity, a lot of drivers wound up removing the kits and going back to stock width, looking for steering.  As it turns out, just removing the rear end parts and leaving the front 190mm would have been even faster.  Widening the rear of the car will lock it down and kill corner speed on a tight track, especially high traction carpet.  I like to use 0.5 mm spacers on the axle to widen 1mm at a time.  It's a change that you can feel but it's not too drastic.

To me, these are the basic settings after tires that will establish the overall feel and balance of the car, along with ride height.  Most of the rest like springs, oil, camber are finer, but still important, adjustments.  It's just that the things I have described about are more "macro" and will change the character of the car immediately.  I hope this will help get more guys into the ballpark a little faster.  Don't take my word for it, try it out!

Friday, June 3, 2016

TRF102 front end asphalt throw down show down!!!

The TRF101 180mm carbon front end parts are becoming somewhat popular among Tamiya TCS racers with the various F1 models due to the simplicity and less aggressive nature of it's geometry.  I personally like it on the TRF102 for carpet.  On pretty much any other model, for carpet racing, I prefer the standard F104 front end. My familiarity with it, and the amount of grip it produces in a higher traction setting has been an overall plus for me.

On asphalt, things are more of a toss up.  Most of the Tamiya F104 models have a little mid corner/on power push when the front to rear balance is right, unless traction is very high.  One of the most popular tire setups is the kit front, TCS (pit shimizu) rear combination.  The reason for this is the more forgiving nature of the kit front tire vs. a very grippy TCS front.

The TRF102 changed this a bit, since the more flexible 2.5mm chassis gives the front end of the car more bite, and a lot more steering throughout the corner.  This is my personal weakness, since more steering has always translated to speed for my driving style with the Tamiya cars.  The problem is that this also makes the TRF102 a hard beast to tame if the rear end of the car is not locked in.  Even if so, inconsistency and the dreaded traction roll can bite you...

I built and ran a TRF102 for the TCS nationals last year, which in hindsight may have not been the best decision.  The car was great, and I think is an excellent design, but the amount of time between its release and the nationals was not really enough to fully dial in the car in relation to how familiar and comfortable I was with my F104WGP on asphalt.    The temptation of the awesome steering feel was too much to overcome.  The problem was a lack of spares in the thin T bar department, due to how new the car was, and the somewhat unpredictable nature of the car for me.  Last year's champ Tyree Phillips certainly had no problem, winning with the 102, but he is also about 1500 miles closer to the Tamiya track than I am for testing sessions.

In any event, I was able to return to the Tamiya facility for the spring TCS regional race in a attempt to get some more testing there with the 102 car.  While racing was not particularly successful with a 7th place finish, I got a lot of good feedback and testing in. I had decent pace very quickly, more so than any other visit to the Tamiya track.  Even more important, I had a good car to bring back home and make comparisons at my home track.

While at Tamiya, I was able to check out past TCS champion Craig 'CUDA Hammond's TRF102, which he claimed to eclipse even his venerable  championship winning F104 in "monkey car" ease of driving and crazy speed.  His biggest departure from the norm was the carbon front end.  I had a TRF101, but I was never overly impressed with the front end. That version of the carbon front end, a bit of a half measure featuring the plastic lower arms of the F104, never gave me the steering feel I was looking for.  I had talked to some racers about the carbon front end, but nobody else seemed to have many conclusions either.  Craig, however, was a believer... A believer who regularly hands out beatings, so I figured it would be worth a try.  I got a second car, and I also happened to win a front end setup at a carpet TCS regional, to it all came together like it was meant to be.

In the opening weeks of the outdoor season at the local track, I brought out multiple cars to compare to the track tested stock TRF102 to get a baseline on performance.  The 102 tuned for the Tamiya track was certainly the best car of the lot, with the carbon front end car (CFE) close, but definitely lacking some of the steering of the standard car.

Several weeks of testing between the two TRF cars resulted in the standard car remaining top dog.  I did not change the standard 102 except tire prep to have a good idea of what a car that worked at the nationals's track would perform and feel like while I worked on the CFE car.

The only thing I did not like about the CFE TRF102 was that it didn't produce the lap times of standard car.  It was quite a bit easier to get the car around, and got into the corner better under the brakes.  It was also really consistent over a run. The standard 102 shined best when the traction was up; it lost out if the traction was lower, becoming inconsistent.

I built the CFE car to the instructions with the spacers included resulting in a ride height close to 6 mm.  That may sound a bit crazy, but I wanted to run the front end the way the instructions said at first, and a little "motor boat" reverse rake will make a stable car. Besides, Craig's car was set up like that, so it's all good!  However, I decided to try a little change to see if I could get some more speed and steering.  I had a gut feeling that if I could get the car to roll through the corner a little better, it would be at least as fast as the standard car, but more docile. That would be especially important in varying traction.

I dropped the car down to 4.5 mm ride height, changing the lower arm spacers to 5 mm.  I didn't change anything else.  That may have also been part of what would come later.

The first run with the lowered car was after racing ended, at a time when the track usually loses a little bite.  My best lap during racing with the standard car was a 19.0, and after the races it would not match that lap as the track went away.  The CFE car was able to hit an 18.7 right away, better than anything I did all day.  Even more impressive, I assumed that car would be slow based on feel.  Easy to drive, but checking the lap counter after the run, the results were there.  I immediately prepared the standard car again, thinking possibly the track had gotten better somehow.  It would not break the 19 second barrier that run.  The second run on the CFE car I lowered the rear axle one position as well, thinking it might help add just a touch of rear bite.  That change resulted in a ridiculous 18.4 hot lap, 0.6 better than the standard car's best lap.  That was totally exciting, to the point of concern that somehow the speed might not translate to the Tamiya America track later in the summer.  I have been bitten in the past by the differences in track characteristics, but the more docile nature of the CFE car tends to bode well from my experiences at the nationals.  Usually, my problems come form a more aggressive, but faster-at-home car.

What made the car so much faster?....I'm not 100% sure.  The increased steering certainly was helped by lowering the car about 1.5 mm.  The other factor may have been in the bump steer and ackermann.  Raising the suspension arms did also raise the steering knuckle in relation to the servo saver.  This usually biases the steering more toward corner entry.  A car with the links much higher at the servo saver than the knuckle will bias toward corner exit steering, so much so that extreme settings can make the car pirouette on the nose.  That change must have been fairly subtle anyway, since the car drove almost the same as it did before the changes.

It is of interest to note that lowering the car brought enough steering that I was able to reduce or eliminate doping the front tire.  Typically I had sauced the entire front, but now 1/4 or no dope was plenty of steering.  Reducing steering should not be a problem, and adding should simply be a matter of more sauce on the front end.  That's also a positive sign, as a car that is good and can be tuned with small tweaks like tire sauce application will be consistent run over run during the day.  The driver will be able to concentrate on learning to drive the car at 10/10 and really find the subtleties to wring out the best lap times.

In any event, the testing will continue, but the carbon front end is winning right now.

V2 thing...V2!!

I still have the V2Thing that I wrote about some time ago.  I have run it a bit, but never put a ton of time into it.  It has had ups and downs in the small amount of time I have run it, but mostly it has been about trying some new ideas.

Anyway, I have been thinking of a way to get a transverse pack into the car.  Wider links would be needed.  I did want to preserve the long, angled link premise I was working with.  

Lately, a new 1/12 aluminum chassis conversion has popped up, utilizing the hanging link carriers from the Roche f1 car.  The makers are claiming a great increase in corner speed due to reduced touch down/scrub in the corner.

So in that vein, I decided to make a little change in the V2 Thing that would kill two birds with one stone....

I had a scrap chassis that was perfect for making some hanging link mounts, along with some F201 shock crank posts that made nice standoffs.  The F201 parts I had laying there, but Tuning Haus makes nice threaded standoffs in a variety of colors and sizes.

Now I have a super narrow chassis that will fit a transverse shorty pack, and approximately 8mm forward and aft movement for battery placement.  

Not shown in the picture is the 3mm spacer used to bring the link back down to a level orientation with the pod end of the link

Once I get the whole car together, it should be fun to get a little track time and see what I can do with the revamped V2-V2!