F103gt Help...which Tyres & Set Up Advice

[GRIGGY 0]

As the title says...

What are the best tyres for smooth tarmac? Am I right in thinking that foams would be better than rubber? If so What shore ratings & brand. Someone suggested Kawahara but I've not heard of them before.

Also any advise on diff & suspension tuning would be appreciated.

This is my first car of this type & it's prooving to be a real handful at the moment with super slicks on the rear, I only have to look at the throttle & it spins out.

Overall I think this a great chassis & I'm determined to master it.

[GRIGGY 0]

Anyone??? Please

[bakaguyjean 7]

Anyone??? Please

Hello

Did you buy this used or new? If its used you should look at the diff,O-rings on the T bar,and front spacers on the uprights. Make sure all three of these things are how they should be in the manual to start with.

If its new then you can go straight to tuning the chassis,and getting tires for where you are running it.

Are you serious about tunig the chassis or are you just driving in the street?

If you are just driving in the street then you can get some Kawahara rear tires that are really wide. 35mm and 30 shore. They wont last long being 30 shore but it will not over steer any more.LOL

BUt if you are trying to get around a circut then there is alot more to tune. Not so much spending money just settings.

Kawahara makes a great tire but they went out of bussiness and the racing team manager took over the tire side of the bussiness and they are now just called Zac project and unfortunally they do not have a website right now so i cant give you part numbers easly. People in Japan still call ZAC Project Kawahara so it gets a little confusing.

Hope to be able to help you a bit more when i get more information from you.

[GRIGGY 0]

Thanks for the reply.

I bought the car used but with all my cars I totally strip, clean, replace any worn parts & rebuild again from the ground up. I built it according to the manual with new O ring & diff balls & spur gear. It has a standard silver can motor, 0.4 module 20T pinion & 93t spur gear & a CVA oil damper. Tyres currently are super slicks rear & M grip radials front.

Whilst we only race in the parking lot all of us take it very seriously and squeeze as much performance as we can out of the car. We have a mix of TL01s, TT01s, TA02, TA05IFS. I usually like to run something different & my current runner is a TT01 with the 3Racing Mchassis conversion. I've got this car really well set up & balanced & its currently the quickest car around the circuit. Trouble is its too easy to drive & I wanted something more challenging which is why I went for the F103GT.

I have found a supplier in the U.S. that can supply Kawahara tyres but I am open to any other suggestions.

I am very interested in chassis tuning especially if it doesn't involve spending any money!!! I have tried tweaking the chassis but can't seem to stop the oversteer so I am thinking that this chassis is very sensitive to tyre choice. I can drive it in a straight line and chuck it in to a corner whith a little understeer but when I exit the corner I only just touch the throttle & it spins out as if I'm driving on ice!!!

Any other advice greatly appreciated.

[bakaguyjean 7]

Good to hear you rebuilt the car,some small things really matter with the F103 series of cars.

First about tires,sponge tires are not all the same but I would think you can find some tires in England rather than buying them from overseas. I use Tamiya,Kawahara(Zac project) and even some cheap tires from Eagle. If you stick with one brand that has shore rateings then you can choose tires based on what you used before. Lower numbers softer tires.

For the rear you should be able to use 30mm without any body issues,the F103GT is rather narrow. The fronts are normally 26mm. Kawahara does make a 35mm rear that is made to be used on GTP style nitro cars.

Front tires i range from 40 shore to 35 shore

Rear tires i use from 35 shore to 25 shore

I hope that helps you a bit with tires. IM not even going to get into tire additives unless you really want to get crazy.

Now some easy tuning. "T" bar you have two screws that attach your "T" bar. The front one doesnt even need the "O" ring,you can replace it with a washer if you like as it should be tighten down . The rear screw on your "T" bar is where you get down to tuning. Tighted down the rear screw and back it off a turn. Driver the car around, then wiggle the "T" bar to feel how tight the whole "T" bar feels. Most likely you will want more grip in the rear so back it off a half turn and drive the car around. two turns is about the most you can get out of the rear screw. You will get used to the correct wiggle feel for you.

The front needs either the Tamiya black springs or something harder.

Personally I do not use any grease on the friction damper,but you can use silicon diff lube as it has thicknes ratings much like shore ratings. But if you use a hard grease it doenst let you adjust the roll of the "T" bar with the rear screw so light enough grease to let the "T" move and hard enough keep it from flopping around. Like i said though i dont use grease.

Your Pinion sounds about right, I run silver cans 540s only and i used 19 to 22 pinion with the standard Tamiya .04 gears. Its a comfortable range for where i run without the motor getting to hot.

You can get your chassis lower with the height adjustments in the gear box and the spacers in the front. Get it as low as you can.

Are you running Lipo? If you are then there isnt much weight in the rear and it needs to be softer. also you might need to lose a few teeth on you pinion to keep the motor from getting to hot.

This has me a little confused

"I can drive it in a straight line and chuck it in to a corner whith a little understeer but when I exit the corner I only just touch the throttle & it spins out as if I'm driving on ice!!!"

If you are getting understeer going into the corner and letting off then giving it throttle you might want to try driving a bit different. Were i race my F103gt i only let off the throttle for 4 turns out of 10. I create the understeer with the throttle. A little less throttle to make tight turns. It just how I drive. the rear does slide around a bit on through the wiggly section but it doesnt spin out. Also these are not 4WD so think of it as a Hornet or different RWD buggy if that helps.

Thats a long responce but playing with your "T" bar and trying different shore ratings on the tires is your best tuneing options for the car.

So you are right about the tires being important,one other thing to think about is sticking with rubber tires and trying different shore ratings also. I would just stick with one brand that has shore ratings if you go that route just like the foams. Soft in the rear and harder in front.

Terry also had an great link to trouble shooting pan cars but i cant find it right now. It has a break down of problem with sollutions.

There are so many ways to fix one problem with pan cars so hopefully you will hear different ideas as its hard to tune a chassis without haveing it in hand and lots of ideas help if they dont cost to much Good luck

[GRIGGY 0]

Wow, What an in depth reply, loads of information. Thanks for that, much appreciated.

I'll start with the tyres first then tweak the T bar as you described.

The rubber tyres that are currently fitted are soft rear & hard front but as I said before I just can't get the power on so I'm guessing I need adjust that T bar &/or my driving style.

I have driven numerous RWD buggies & also raced an M04 in the Eurocup once with no problems at all. But I just can't get this one to handle properly yet. Maybe it's because I'm used to a damper on each corner instead of the friction plate/T bar set up.

When I go into the corner I let off before I turn & it understeers going into the corner but If I attempt to apply the throttle to stop the understeer thats when it spins. I thought perhaps I'm going into the corner too fast so I tried to brake before I turn but that just makes the car spin also.

I don't mind the understeer I can sort that out but the lack of rear grip is bugging me at the moment.

I would like to try the Kawahara tyres as I can buy them mounted on wheels with a 12mm hex drive but I have never used foam tyres before so could you confirm that they are more grippy than rubbers? What are they like in the wet?

Thanks again.

[Jumpinugly 0]

Griggy: Love foams in both wet and dry. But, you'll not get better advice than what Baka has written. Everytime he posts I learn something, he's a real pro. Best of luck with everything.

[terry.sc 16]

The biggest problem with the F103GT is that it's designed for touring car wheels. It's not helped by Tamiyas own tyres being terrible even on 4wd chassis. If you look at all the other cars based on pan car chassis the rear wheels are twice as wide as the front tyres. Now you can't get really wide touring car wheels, but you can go to softer tyre grades to generate grip.

You could try softer rubber tyres, but I have no experience of using them on pan car chassis. For foams, a soft grade on the rear will give you the grip, I usually use 30 shore rears with 38-40 shore fronts on Tamiya F1 chassis to get the balance right racing on carpet, and would probably be a good starting point. For the best foams you want Geckos, they seriously outperform any other touring car foam tyre available. For wet weather, foams fitted with Tamiya tyre caps will give you more grip than any tyre will in the dry (no kidding!) but they don't work in the dry. One problem with foams is that on dusty surfaces they will pick up all the dirt though.

Then it is all about suspension setup, which will make a lot of difference to the handling. Changing front springs, centre damper spring, lube in the damper plates and most importantly rear T piece stiffness, all make a big difference to the handling.

You also need to learn how to 'drive' pan cars. Just opening the throttle on a tourer will give you wheelspin, but it will go forwards. Do the same with a pan car and it will spin out. You can start to give it some power after the apex, but you have to feed the power in gradually. You shouldn't give it full throttle until it is going in a straight line. The same with braking, you should do it before turning in to a corner. Once you learn how to drive it you will get more satisfaction out of it than just throwing around a touring car.

Terry also had an great link to trouble shooting pan cars but i cant find it right now. It has a break down of problem with sollutions.

That will be this one:

http://homepage.ntlworld.com/terry.cresswell/trouble.html

[GRIGGY 0]

Thanks for taking the time to help me out guys, There's more than enough information there to get me running properly. (Excellent links Terry)

So...A good set of tyres first, The Geckos look like a good starting point, Cheap & available in the UK too. Then chassis tuning, I'm thinking that with a good set of tyres the tweaks to the chassis will be more noticeable.

The more I read about pan cars the more determined I am to master them. Whilst I love chucking touring cars around I long for something that requires a little more driver involvement & your last sentence summed that up Terry.

Time to go shopping now. I'll see how I get on with foam tyres & the chassis tweaks then if need be I'll come back & ask about tyre additves!!!

P.S. Can anyone recommend a good 190mm body for this chassis that will give me better downforce than my battered Enzo body. I like the Mugen Courage shell but it's too good & probably too fragile to run with.

[terry.sc 16]

The Mugen Courage isn't the best aerodynamically, it's designed for looks rather than handling.

Personally I use the Protoform Mulsanne, not that high downforce but good high speed balance. For more downforce I use an Active Hobby Toyota GT1, used to use a Colt GTOne (see my showroom)but prefer the looks of the Active Hobby version.

[mailboxck 29]

I run an F103GT too with a Mabuchi Motor and Lipo. If driven at max pace, it can actually run against the 23T touring cars.

We also run on smooth tarmac and surprisingly, this thing can run on either Foam or Rubber Tires except that the driving techniques between the tire choices are very very different.

For Rubber tires, I use 36R Sorex Tires all around. For Foam, I use Jaco 36 shoe rears and 40 or 38 in the front.

You can just play around with the front springs, rear springs and the o-ring tightness in the T-plate. It does take patience to set up but when set up well, this thing flies.

I use gold springs in the front (medium), red spring for the rear (soft) with 30wt oil and I just play around with the diff and o-ring set up every race day.

One mod I did though was to put an extra diff plate. In the instruction manual, it only says to use two that looks like this <>. But I got an extra diff plate to make it tighter so now it sorta looks like this ><>.