Ultimate RC NetworkRC Sites & TopicsRC ForumsRC VideosRC Photo Galleries
Ultimate RC
Ultimate Tamiya
Ultimate Traxxas
Monster GT forum
Kyosho Monster Trucks
Mini Off-Roaders
Associated RC10T4 info
Beginning RC info
Toy-class RC Reviews
Unbelievable RC

Project: TT-01 Budget Racer

December 2009

tt01

Summary

  • Created: 2008
  • Purpose: Low-budget carpet racer
  • Based on: TT01
  • Gallery: View
  • Scale: 1/10
  • Use: Onroad
  • Style: Touring car
  • Config: MA
  • Driveline: Shaft-drive
  • Body: Polycarbonate
  • Susp. front: Wishbone
  • Susp. rear: Wishbone

Introduction

Used in this build:

  • Novak GTB ESC
  • Novak 13.5T sintered rotor brushless motor
  • Airtronics 94257 servo
  • Airtronics MX-3FHSS radio system
  • Tamiya clear mesh wheels, +2mm offset
  • Take Off RP30 tires
  • Protoform DNA-2 body
  • Tamiya adjustable a-arm set
  • 3Racing aluminum center driveshaft
  • Traxxas Rustler/Stampede front wheel hex set (2)
  • Tamiya option pinions set, 24t & 25t
  • Tamiya option spur gear set, 55t & 58t
  • AMBrc Direct Powered personal transponder
  • Tamiya Hard Spring Set, Limited Edition Milky White
  • Team Orion Platinum 4800mAH 2S 7.4V LiPo pack

Let me start by making something very clear. The TT-01 is not a racing chassis. It will never be competitive with competition-designated cars, no matter what you do with it. It is the worst-performing car in Tamiya's sedan lineup. However, it is also the least expensive, and it's available in the widest range of variations and body styles. It's also Tamiya's best-selling RC, period (as of this writing). For what it is and what it costs, it's an awesome, versatile little car, which is precisely why I've owned three of them.

The Mission

Given the popularity of this chassis, I know for a fact that there are TT-01 owners out there who want to try their hands at organized onroad racing, but aren't confident that they'd like it quite enough to spend big bucks on an all-new, competition-spec car. However, trying a fairly stock TT-01 against a field of those competition-spec cars would be an exercise in embarassing, frustrating futility. The mission for the Budget Racer is simple: Make the TT-01 mildly raceable in a Novice or Sportsman class while spending the least money possible.

Making it Happen

This car began as the Calsonic Skyline GT-R 2003 kit, an early base-level TT-01, not an improved R or E model, or even a D. This was truly as low as I could go. Upgrades were done in distinct steps.

Step 1: Power

The very first thing I wanted to do was ensure that speed wouldn't be any sort of issue. If your local track has a "silver can" class, the motor that comes with the kit is already perfect, so you can skip this step. You'll also have a much easier time getting this car around a track than I did. At my nearest track, the lowest class was called "Sportsman" and at the time they were using 13.5-turn brushless motor systems. They've since switched to slower 17.5 turn BLs. Some tracks run 21.5. In my case, I was confident that I'd want to really get into racing, so I went ahead and invested in the brushless system, knowing I would simply transfer it to my next car. You can save a lot of money with your first taste of racing by purchasing a 19-turn brushed (conventional) motor like a Trinity Komodo Dragon for about $35 USD. If you already have a motor that's faster than what's allowed in the entry-level class, just politely explain your situation to the race director. Most places will have no problem letting you "run what you brung" when you're new, as long as you don't just go crash into everybody else because you're so overpowered that you're out of control. For proper gearing I also picked up the #53665 speed spur gear set and #50477 pinion set. Finally, I installed a 3Racing aluminum center shaft for the sake of durability. This is not a must-have, but it's recommended whether you're racing, drifting, or just bashing around because the stock plastic shaft is terribly flexible and can become wobbly or even pop out under enough power.

For sake of experimentation, I actually ran my first race with the car completely stock except for the motor system & gearing. It was terrible, to put it mildly. I was struggling into, through, and out of every turn as the car shifted violently between extreme understeer and dramatic oversteer. I couldn't count how many times I was lapped.

Step 2: Traction

With great power comes great responsibility, and in my case, I had a responsibility to find more grip to handle the torque & speed of the new motor. This is another area where the decision is basically made for you. Find out what most folks run for tires at your track, in your class, and get those. Don't experiment, and don't try to cut corners here. Any expert will tell you tires account for about 80% of the handling performance of any wheeled vehicle, and that includes acceleration, braking, and turning. tt01 Most racing tires come mounted on lightweight, aerodynamic solid dish-style wheels with a standard offset. Unfortunately, when you mount these on a TT-01, you end up with a car that's about 10mm or almost 1/2" narrower than the 190mm an electric touring car is legally allowed to be -- an automatic handling disadvantage. To make up for some of this discrepancy, I replaced the stock 5.4mm-wide hex adapters with 7.7mm-wide Traxxas wide units, part #3654 used on the front of the Rustler and Stampede trucks (see the comparison image at right). To fit these you'll need to switch to normal, unflanged 4mm wheel nuts. I was lucky enough to find the local hot tire in unmounted form as well, which let me use 2mm offset wheels to get very close to the legal limit.

For yet another bump up in grip, racers use traction compound, often referred to as "the sauce" or "juice." Here yet again, you use what the locals use, and make sure you put rubber compound on rubber tires and foam compound on foam tires. Just follow the directions on race day between each heat. I use Paragon Ground Effects, which is about $10 USD for enough to last many months of regular use. It's a thin but highly aromatic liquid that comes with an applicator sponge that you use to liberally coat the tire. You let it sit for a minute or so until it starts to evaporate or get absorbed, then you wipe it off thoroughly with a rag (paper towels don't work so well). The compound actually softens the material the tire is made of, though this softened layer tends to wear down during a race.

With sauced-up race tires, traction was no longer a problem, but now I suddenly see with astounding clarity just how terrible the handling was. Instead of spinning out in turns, the car was rolling deeply, getting on two wheels and sometimes rolling clear over.

Step 3: Suspension

It's easy to just say, "I need new shocks," and go look up a fitting set of aluminum threaded-body dampers. After all, the stock "shocks" on this base-level TT-01 are just plastic pegs with no damping effect at all. However, there are a couple of problems with this approach. First of all, just changing shocks is not going to give you a good setup. You still need to tune the oil and/or pistons, and you'll need to also buy a range of springs to tune with. Secondly, this is a budget build for someone not sure if they want to race. tt01You can easily dump $40 US into a set of aluminum shocks and still need a $10 set of springs. Of course, if you have a higher-end TT-01 that comes with plastic oil shocks, you're in good shape! I opted to see what I could do with my stock "friction shocks," and just bought the springs (normally Tamiya part #53440, though I got the limited edition white colored set #49389). To give the "shocks" some actual dampening effect of which they normally have none, I coated the inside of each cylinder plus the head of the piston struts with medium Tamiya Friction Damper Grease, part #53175. This super-viscous material comes in a small tube and is actually meant for a completely different type of damper, but it works surprisingly well on the stockers, dramatically reducing the bounciness of the ride.

tt01After a fair amount of experimentation I settled on the hardest springs in the Tamiya set up front, and the second hardest at the rear. I run all four shocks at the outer holes on the suspension arms, with no preload spacer clips on the front and 1/16" spacers on the rear. This gave me a good ride height and suspension compression, but pick the car up and the wheels would fall and the arms would droop so far that the springs would go completely loose. The original TT-01 has no droop control, so I had to add this in by getting the updated "D" parts set made for the TT-01R & TT-01D. If you have one of the newer kits you're again in luck, though I found I needed to grind off the reinforcing ribs that extend down on the undersides of the chassis. This is important in carpet racing to let you set the ride height a couple mm lower without having anything extend below the 5mm minimum height tracks require. This weakens the areas under the droop screws and you'll see some flexing from the pressure, but I never found this to be a problem. When finishing setting your droop, it's important to put the car on a perfectly flat & level surface (glass coffee table, granite countertop, etc.) and lift each end of the car slightly to ensure that the wheels fall the same amount on both sides, otherwise the car will behave differently depending upon which direction it turns.

tt01 tt01

With this setup I found the front end of the car to work about as well as I could ask for, but at the rear I still experienced excessive oversteer under stiff braking or accelerating hard out of a turn. I tried different custom limited-slip differential settings, every spring rate I had (not just the ones in the Tamiya set), a chassis stiffener, and different ride heights. I also attempted adjustments to the front to introduce understeer, but only one thing made a truly useful difference at the rear -- slight negative rear camber. To accomplish this, I had to buy Tamiya part #53674, which includes adjustable front and rear upper a-arms. I found no need to swap out the fronts, but at the rear I found the sweet spot to be right where the turnbuckle spacing is at 6.5mm. I didn't and won't bother measuring the actual camber angle this creates, because there's so much slop all through the TT-01 suspension that camber and toe both move an easy 2 degrees depending upon what force is applied to the wheels.

Step 4: The shell

This step is completely optional, but if you want to get the most out of any onroad car chassis, it's useful to run a racing body. The faster the class you run in, the more important aerodynamics becomes, so with a 13.5 brushless setup I decided to go for it. I wanted something with the most downforce I could get both front & rear, and went for a Protoform DNA-2 shell. The benefits of a racing body aren't limited to aerodynamics! This shell is significantly lighter than the stock Skyline GT-R body my kit came with and lowers the center of gravity measurably. Again though, if your budget is strained, run the shell your kit comes with, and run it with pride!

Step 5: Fitting a LiPo pack

If you have 7.2V NiMH batteries, you can ignore this step altogether as you're good to go. However, if you have long-lasting hardshell LiPo packs, unless they're the rare type that have built-in ballast to make them weigh as much as NiMHs, you'll need to make an adjustment to give your car the proper weight & balance. I made a weight strip by cutting pieces of lead (some RC companies sell them or you can get them from a real car tire shop or sometimes general stores like Wal-Mart) and attaching them to a strip of Lexan with Shoe Goo. The pieces are trimmed to fit into the battery slots to be as low as possible, and they're aligned just a little to the outside of center to help with the weight balance. I also trimmed back the vertical ridges in the battery tray since my pack is rectangular, and added a little padding to the bottom of the hold-down strap for a firmer fit. Check with your region's rules governance (in the United States, it's usually R.O.A.R.) for the minimum fully-equipped weight for a sedan and try to match that weight. Even though the TT-01 is a fairly heavy car, LiPo packs are so much lighter than the NiMHs it was built for that they'll put you at an illegal weight and also make the car much heavier on the motor side.

tt01 tt01 tt01 tt01

Results

My schedule makes it difficult for me to make it to the races, so the last time I entered a competition with this car was actually before I had properly tuned up the suspension. At that time, I placed 5th out of 8 cars in a local sportsman class main event. It's not something to write home about, but the performance was a night & day improvement over the stock setup. With the tune-up complete, I should be able to race with some of the other cars and really get a feel for the unique spirit of sedan competition, focusing on my driving lines, turn-in points, passing & getting passed. On practice days, though my driving skill is still very limited, I can get around the track with decent speed and leave with a smile, not a frustrated scowl.

 

Things NOT to buy

There are a lot of aftermarket items that can added to a TT-01, but in my experience, most of them aren't worth the money & time. If you want to get serious about racing, skip buying the following hop-ups and use the cash towards the purchase of a race-worthy car.

  • Carbon fiber chassis conversion. There are some sick-looking aftermarket chassis kits out there. Unless you just want the looks, avoid these. The small performance gain you'll possibly get from one is not worth the money. Take that cash and use it to put a 50% down payment on a TA05.
  • Chassis stiffener. If you have a TT-01E, you already have an "upper deck" piece running along the center of the chassis to add stiffness. If you don't, don't bother adding one. I tried the 3Racing carbon fiber upper deck and was not able to noticeably or measurably improve the handling consistency of the car. There's so much flexibility and play in the suspension that this upgrade really doesn't help on this car.
  • Aluminum. I used one aluminum part on this car, and that's the center shaft. Honestly nothing else would have benefitted from it. Aluminum arms, shock towers, hub carriers, knuckles, etc., would just be "bling" on this car that add weight and eat up your money without providing any benefit.
  • Ball diff. I found that adjusting the diff action on this car did make a readily noticeable difference in the way it handled. However, this changed how I drove more than how fast the car could get around the track, as it didn't address the remaining performance issues.
  • Front one-way unit. A one-way removes the braking effect from the front end of the car by allowing the tires to freewheel under decelleration. This improves turn-in, but on a TT-01 with enough traction it will make oversteer come on even sooner than it already does. It's just not worth the expense.
  • Stabilizer or "sway" bars. Again, the TT-01's suspension is so sloppy, you're best off just tuning with proper springs and leaving sway bar usage to a chassis that can really benefit from them.
  • Adjustable front a-arms. As I noted earlier, the front of the budget racer car acts fine with the stock geometry. The wear pattern on the tires shows that it doesn't need adjustments here. Also, for the old base model TT-01, changing front camber would have required replacing the the non-adjustable steering links to avoid introducing toe-in. The TT-01R and TT-01E have adjustable steering links, but still, you might as well leave good enough alone.
  • Metal motor mount. I happily purchased & installed this Tamiya brand hop-up hoping to shore up the gear mesh and also help dissipate motor heat. Unfortunately it does neither. You can pass on it.

Limits of the platform

My first hobby-level RC was an entry-level, "bashing-only" offroad truck and with many months of tuning, upgrading, and custom re-engineering, I was able to race that truck very successfully against the competition-oriented trucks, regularly placing 1st through 3rd in local events. Unfortunately there can be no such Cinderella story with the TT-01, as it has some insurmountable fundamental flaws:

  • Suspension slop. You can hold any TT-01 by the center of the chassis and then grab any tire and wiggle it around in all directions like a bobble-headed doll. With not even 20mm of tire contacting the ground at each corner, even one degree of deflection can make the difference between sticking to the track and spinning out of control. The fundamental design of the TT-01 does not lend itself to the geometric consistency that's absolutely crucial for onroad racing performance.
  • High center of gravity. If you compare the component layout of a TT-01 to a true racing chassis like a TRF416, you'll quickly see why the TT-01 will always have more unwanted weight transfer in turns.
  • Excessive weight, especially at the ends. The TT-01 has a lot of plastic bulk about it, particularly towards its extremities. Even the differentials are big & heavy compared to other cars. In physics terms this adds to the "polar moment of inertia," essentially making the car not want to turn when it's going straight, and want to keep turning when you're trying to straighten up from a turn. This contributes to turn-in understeer, and turn exit oversteer.
  • Very limited adjustability. A proper racing chassis lets you work with & around its shortcomings and to tune to a specific track by finely changing toe-in, kickup, roll centers, dynamic camber, and shock progressiveness. The TT-01 doesn't let you do any of this with ease, and some isn't possible at all.

Summary

The TT-01 may be an entry-level car with a lot of faults and limitations, but with a limited set of carefully-chosen modifications, you can take it to a track and have a good time competing with it, without breaking the bank. If you just want to race very casually for the sake of experiencing the exciting competitive environment, this may be all you ever need. If you think you might want to get serious about it, but aren't 100% sure, the changes I've described let you get a good, solid taste of racing without risking a large investment, by using the car you already have. If you like it, you can take your motor system out and use it in a proper competition-spec car. If competitive racing ends up not being your thing, you haven't lost much, but you've ended up with a better-handling basher that will bring you a lot of joy on practice days and hopefully inspire you to try even more adjustments & customizations to get the most out of this inexpensive, fun car.

tt-01

Photo gallery samples

Visit the full TT-01 Budget Racer gallery >