bent_wrench

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Hello,

I am building a Truggy Kit. Before I get into the Q and A I will give bit of back ground.

Where I live the LHS has folded up and the next closest one is an hour away. There is no race club anymore. I used to race 1/8 buggies a long time ago. I had a TT Mirage with a stock pro BR21 engine and when set up right it was competative against some very expensive machines. After I quit racing a got a Savage and had that for the last 4 to 5 years or so. I had a ton fun with it, but I wanted to get into something a little more like the buggy I used to race. These Truggies are the prefect mesh between buggies and MT's and I looked around at quite few before I jumped on a Thunder Tiger ST-1 Pro kit. I looked at Kyosho, Ofna, and AE but I liked the TT design and they have genrally always made a pretty good product so I bought it. I wanted a kit because half the time you have to tear down a RTR and put it back together to get it set up right anyway. With a kit you get the set-up right the first time (or at least get closer to it). Since I have no parts locally it really dosen't matter what I buy, I have to buy everything online.

So I have a TT ST-1 Pro, and there is a ton of info on the ST-1's as they have been around for a while. I have researched and decided on shock and diff oils, etc. But the engine has me wondering.

Intially I have set my sights on an LRP .28 spec 3 as its cheap and makes pretty insane power and I figured on matching it with a Jammin JP-4 pipe. There a lot of reviews and comments on this engine so it looks like a good choice.

So my question is this, is an engine like the LRP really nessecary? Will it do more harm than good, making the truggy harder to drive and casuing more driveline damage? Is .21 still a better choice even for just messing around?

I remember that while the "hot engines" were faster than my buggy, it was tires and won races not power. Not to mention reliability and above all else the driver . And I never in 3 years of racing broke a driveline part on my Mirage. Mabey I was just lucky too. I went through piles of rims and tires and wings etc, but never broke anything important. All I ever did in the Mains was pull in and fuel up.

This ST-1 kit is really nice and I will have a ton of fun with it either way I am sure. But what do you guys think? Jump on the bandwagon with a crazy .28 or put a .21 in. Like an OS or even TT engine? Mabey even an Ofna Hyper or an SH .21.
I will be running in all kinds of terrain, gravel roads, a moto-cross track, snow (lots of snow) and general off road bashing. No racing though.


My Shock oil will be 40 wt all around and the diffs will be 5k, 10k, 3k which seems to be in the ball park. Any suggestions here?

Also for genreal off raod mayhem what do you guys run for tires? Good tires for racing gerneally don't last when you are just messign around. What should I look at?

rc person 577

The LRP .30 will be fine. Most racers use .21's for fuel economy. In fact, most of the RTR truggies come with .28's in them.

Fluids look like a good start.

As for tires, I would look at the pro-line Badlands.

Good luck and have fun

stussman

If you are only going to bash id go with a 28. Many decent/great 28s around depending on how much you want to spend. In my old truggy ive used k4.6ho, lrp 28, sts 30 and os28.
The best truggy mills are bump starts so you will need at bump box. If not you can get decent pull starts mills such as the lrp 28/30, big red etc. I hate pull starts tho, they always break quickly.
I have found the best, most powerful, easy to break in and tune engine out there is the os28. The os is fairly expensive tho but is worth it. Ive had 4 os28s and all have lasted over 8 gals. Just change the bearings after a couple of gals to be safe. I have found GO bearings to be very good quality, way better than the os bearings.
If you have the $ to spend i suggest an os 28 drag modded by AB mods or clockwork racing.
The thunder tiger st has a strong drive train so it should handle the power.

Ive used many tyres for bashing but the ones that have lasted the longest are badlands. Great bashing tyre.
To increase accelleration and straight line speed iam using 100k in my centre diff. No good for racing but good fun for bashing.
Let us know what you get.

bent_wrench

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I personally love OS engines, you wouldn't have to pull my arm very hard to buy one. I was looking at the OS .30vg but that to me isn't going to produce the rpms like a smaller motor, I would guess it is more for the MT crowd. Any one run that engine?

The .21 vsepc would be the motor of choice if I were racing or a Nova Rossi, but I don't need to spend that much on a motor just to mess around with. If I got a LRP I would probably put a tiger drive on it. I have a bump starter but I converted it to a belt drive for my boat. I also have two 12v batteries hooked up because the boat needs 24 volts to turn over the .46 marine engine. So I would need another bump box if the truggy engine needed one.

So for truggies what is the tire size standard? I know they are not 40 serries, so are they a MT tire or something differnt?

stussman

The os 30 has big torque but ordinary top. The os28 has great bottom to top.
Another option if you dont want a bump box is the picco 28.

bent_wrench

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So after a short wait my kit showed up in the mail. I had to put it away for a few days becasue I didn't have time to work on it. Tonight I decided to start on something small so I took the parts bags out witht the shocks and put them together....

One small problem in the picture you will see the rear shocks are all fine and dandy but the front shafts are not the same length. It appears I got three rear shafts and one front. [:@] this sucks! So I sent TT an e-mail. These are available and pretty cheap so it may be faster to just buy them, but as I am not in a hurry and can continue building I will see how TT handles this little oops.

Other than that blunder I really like what I see in the kit, the parts quality is as good as any 1/8th scale buggy I have seen and the instruction manual is by far and away the best I have ever had with any RC car. I will keep this thread updated as the build progresses. Thare is a huge forum for the ST-1 on RC Universe but not one for the build up of the kit version.

bent_wrench

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Thunder tiger service responded to my e-mail in just a few minutes, I have to contact Hobbico for service in the US. Hobbico responded to me this morning and they will send me the parts when they find them. They are still handling the inventory change over from ACE Hobby. Thats good news. On with the build then...

bent_wrench

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Put the differentials together today. Typical for these Truggies they are way overbuilt kind of like a buggy on steroids. This weeked I should have some time to realy get into the build.

BChiz

Hi Bent Wrench. I really appreciate your build up and posting it here with pics as you go along. I have been thinking about getting a kit also and this will be a great help since I have never built one before. I am enjoying it. Thanks.

bent_wrench

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I got few more things done today. I took out all the carbon fiber pieces and sealed the edges with CA glue. I like to use glue with a brush in it for gluing the tires and the brush also makes this job easy. I said in an earlier post that I liked parts quality of this kit and as you can see the carbon fiber parts are practically a work of art. The shock towers are nearly 3/16" thick and the machining is beautiful. I still am not entirely sure why most manufactureres reccommend sealing CF parts, I only assume it's to prevent de-lamination or splinters from breaking off. I selaed all machined edges, and faces, but not bolt holes as they are captured by a fastener.

Next I assembled the 4-bar steering setup and servo saver. It helps to note which side of the tie-rod is which and install them in the same oreintation everywhere. That way the turn buckles will adjust the same way when turned in the same direction. Its one of those details that makes adjusting easier expecially if you race. I use a caliper to keep the lengths equal too.

bent_wrench

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Next are the differntial housings. Any time a ring and pinion gear run together the clearence is important. The differntial needs to be shimmed to one side or the other so the "lash" is correct. Too tight or too loose and the gear will wear and fail early. This is a trial and error process by feel. You also have t0 torque up the housing bolts becasue that will affect the clearence, so it can take a bit of time to get it right. You can see the shims on the left side of the diff in the close-up picture. After I get the shims figured out I coat the gear faces in synthetic bearing grease (the red stuff) before final assembly. Bevel cut gears should have some lubrication, where as straight cut don't always need it.

bent_wrench

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I started on the chassis assembly today. The center diff shows off the composite brake pads and more fancy carbon fiber. The main plate is 7075 Aluminum and the control arm pins are held in very stout aluminum blocks. These toe blocks can be changed out to change the angle the control arms sit with respect to the frame centerline. There is a whole set of them included in the kit, though only the initial sizes are made form red annodized aluminum. I didn't install the center CV shafts for a reason. I'll elaborate more on that later.

bent_wrench

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I spent some time today working on the control arms and drives. The front of the ST-1 is very similar to a Mugen. The pivot balls have a coated aluminum pall pinned to hardened steel bolt. The balls are captured with a nylon cap and large set screw. The camber and front tracking width are adusted by turning the pivot balls in and out of the control arms. The caster angle is adjusted with shims on the upper control arm pin. The control arms on this truck are massive, and for some strange reason Thunder Tiger provides the ability to run 8 shocks. The CV shafts have a tapper on them from the dog bone end to the CV joint. This is a method of reducing the shaft twist without adding too much wieght to the shaft. The attention to detail so far on the kit has been impressive. One feature I like about the ST-1 is that it has a substantial front bumber, something that will be put to the test bashing around this winter. Most of the other kits look more like buggies in that respect, I suppose to a hardcore racer a bumper is just extra weight to carry around.

The control arm pins are captured by steel plates in the front and aluminum blocks in the rear. Further adjustments to camber can be made buy using different bushings for the control arm pins, or you can use different mounts alltogether. The kit comes with 10 different mounting blocks for the front and rear, several pairs of offset bushings and some shims for the control arm pins. The redundant adjustability doesn't make sense to me. Why have three different methods to adjust camber and toe on each wheel? Seems to me that Thunder Tiger had one goal in mind here.... Overkill.

xjqkz

Hey, thanks for sharing the build experience. I too have an ST-1 that I've converted to electric now. As far as the engine I would not recommend getting a .28 they are just overkill all the extra torque that you get gets wasted in a dirt cloud and you end up replacing your clutch springs to the lightest ones you can find. I'd recommend the Werks b5 or if you wanna go cheap then look at the nova n21. Werks is a much better engines and would out run most $300+ mills

bent_wrench

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Thank you for the suggestion. I still haven't bought an engine yet.

Continuing with the build I installed the servos and radio box as well as the rear wing frame and the fuel tank. The St-1 Pro has a very stout rear wing frame and a nice overall layout of compopnents on the chassis. The Fuel tank has a spash guard and a drain tube that lets spilled fuel run off the top of the tank and on to the ground. I also got my shocks together, Hobbico is going to send me a whole set of front shocks under warranty so I bought the shafts to build the originals and will keep the replacements as spares.
I also am taking all the Cv shafts apart and re-applying lok-tite to the pin set screws. I don't trust any factory assembled CV's and would rather be at fault myself if they come apart. I am also going to try some Cv boots and see how well they work. On a side note I am impressed with how O'Donnell solves the problem of loose CV parts.... by getting rid of the CV parts! Universal joints are a bit more rugged IMO.

bent_wrench

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I bought my engine yesterday. I decided to go with the LRP mainly becasue of price. The bang for the buck is hard to beat. I bought the LRP .28 Spec 3 and a Jammin JP-4 pipe together for $220 with free shipping from RC Speed Zone. Thats a pretty good deal and a hard one to turn down. I have a few things left on the truck build and could be ready to break it in and go for a test drive by next weekend. I will post the completion of the truck as I work on it.

bent_wrench

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I got a box in the mail today with a couple of shiny new parts. I am making a significant upgrade to the kit by installing the aluminum center diff mounts. This seemed like a worth while upgrade and the whole piont of building a kit is to put it together the way you want to. The center mount is much more rigid than the two piece plastic setup that came stock. I also forgot to show the shrink wrap I used to secure my CV boot's. I used small sections of it to keep the boot from slipping off the jount. I did this on all 6 joints.

I have the wheels on and the engine mounts installed and finally the bulk of the assembly work is done. I set up my Futaba 3PM-2.4 Ghz transmitter after installing the reciever and a 5 cell hump pack. This is the first surface RC that I will be using a 2.4Ghz radio and digital servos with and I am massively impressed the progress in radios over the last few years. I managed to make a trade for a very nice used futaba 3 channel and 2 recivers so I can also run the same radio gear in my boat. I have also ordered an extra set of wheels, pro-line badlands tires and some extra glow plugs. My engine and pipe are on thier way and I should have a brand new running RC soon.

bent_wrench

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I got another package in the mail today with more shiny new parts. My engine and pipe are now in the truck but it was not a perfect fit by any means. The motor mounts were too short for the LRP so engine's back plate hit the pan. I guess thats to be expected as most people would have a bump start engine and want it mounted as low as possible to keep the roll center down. I had to drill out some collars to use as spacers under the engine. The fix worked just fine, the only issue that resulted was that the carburator was a bit high for the throttle linkage so I had to put a bend in it. The clutch and air filter that Thunder Tiger includes fit with no issues and completed what is looking like one bad ass truck. I can't wait to break this thing in. I also started roughly trimming the body. I should get it painted this weekend if all goes well.

I also noticed I had good access to the backside of the engine so after I get it broken in I will install an in-line style Tiger Drive starter. I still am waiting on my bashing tires and spare wing to match my paint job. I am going to use a combination of Indy Silver, Black, and Racing Orange. I am not a very talented painter so it will be a pretty simple paint job. One thing to note it that the body on this truck is one of the thinnest i have ever seen. I am sure it is not the most rugged one ever made, but it will do for now.

BChiz

Hi again Bent. Did you seal the area where the carb goes into the engine block? It looks white around that area. If you did, what type of sealant did you use? Thanks.

bent_wrench

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What you are seeing is from the camera flash. No sealant on the carburator in that picture. I generally use Permatex Ultra Black on Nitro engines. You can get it at any auto parts store. It is pretty fuel and solvent resistant and has a good temperature range. The other option I have considered is Honda Bond 4, its for sealing motorcycle engine cases and would do a fanatsitc job anywhere on a nitro engine. I haven't tried it but I suspect it would do a great job as it is made to bond to aluminum.


I finished my paint job on the ST-1 Pro today. It turned out pretty well except for one nastly little problem. The can I had labeled as Pactra Thinner was a differnt solvent ( I think it was MEK or something similar) and damaged the lexan. It left cracks all over the place on the front where I used it to wype up some overspray. I guess I will have to try another body later on. I have got enough paint left but I need the right thinner. This one dosen't look too bad though and will do for a basher body. Like I said I am not the best painter, but it looks alright.

My wheels and trires showed up too. The Badlands tires are really nice, and the foams that come with them are very firm. The overall look of the truck turned out well and I forgot how much fun it is to build these from parts. I will start the break-in on the engine tomorrow. There are alot of reviews on this truck so I won't get into perfomace or tunning stuff.

stussman

Looks good. Should be a tuff,reliable basher. I use the jp4 on my os28. Really like that pipe. Although the os seems to go good on all pipes.

bent_wrench

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So after the break-in was finished I tunned the LRP and let it rip today. Holly CRAP!!! I am still in shock. This truggy hauls *****, and the .28 is a massive overkill. At half throttle the tires break loose on any surface. The St-1 Pro comes with a 13T clutch bell and runs out in a short distance. I was running up and down the dyke by the river and spared no mercy with the throttle. The clay dyke is about 20 feet tall and the jumps I pulled off where pretty epic. I landed on the roof a few times broke the wing mount and trashed the body. No serious damage though. The ground is frozen and there is no snow yet here so the truck took some very hard landings. I am very happy with thing so far. Definatly a differnement experence compared to a monster truck. I liked my Savage but the TVP design while innovative makes it a pain to work on the truck. The pan chassis layout makes service and cleaning much easier. I am really happy with the engine and pipe combo. The LRP was a bear to start durring break-in because the feul mixture was as rich as I could get it. After I got it leaned out it was a good starting engine and has a fantastic powerband. It runs as if it is "on pipe" all the time, it has great torque off the line and flat out screams on the high end.

I have a few issues to resolve though. First my clutch bell is blue it got so hot. I may need to put lighter springs in it, or try aluminum shoes. I have never burnt a clutch like that before any suggestions as to what I should use?

Second my standard digital servo isn't cutting it for breaks. Is there trick to adjusting the breaks to get the best grab fromt he linkage or do I need a high torque servo there as well?