12th scale help

tom00182 · #1 13-09-2015

Hi everyone,
I have just got my first 12th scale (lmp) chassis as I am going off to uni and will be unable to race my touring car. I have wanted to run 12th since i saw them at my local track but i am a complete newbie and have no idea what i am doing so any advice would be appreciated. I have an Associated 5.2.

At the moment i was trying to balance it out but i can't get it any where near. Any suggestions.

Thanks in advance
Tom

Xracer · #2 13-09-2015

Well Tom 1/12 LMP is pretty much the pinnacle for sheer speed and adrenaline in the indoor racing world!

Now your plea for help is pretty much an open book of questions but if you need setup information then a good starting point is as the instruction book details, or you can look onto the Team Associated website for some actual setup sheets from various racers and the instruction book if you do not have one.

Tyres are an obvious starting point too but fairly straight forward really but this is only for guidance depending on the carpet type and condition, the club you will race at will give better advice I'm sure!
But for lower grip then Pink (30 Shore) or soft Pink (28 Shore) rear with full width additive, Double Pink (35 Shore) front with 1/3 to 1/2 width additive, from the inside the outside remains untreated.
For higher grip when the track is well 'rubbered in' then Magenta front and rear with similar additive.

I always put fresh tyres on for each heat but some choose not to but you will probably need to reduce the amount of additive for each repeat run.
Tyre diameter has quite an effect on handling and the top racers will have trued theirs down to something quite a bit smaller than as supplied.

Gearing depends on motor choice and track layout, something around 65mm/rev is not a bad staring point depending on your motor timing setting, 20-25 degrees is probably a safe starter, for a fast open track gear slightly higher. Blinky esc setting and 10.5T motor for standard class or the world is your oyster for motor wind and timing boost in modified (insanely fast).

Now the 5.2 does not give much option for lateral balance so just go with the standard layout of longitudinal lipo, speedo opposite side towards the rear with receiver just in front.

Ensure the diff does not slip when gripping the rear wheels and trying to turn the spur gear but do not over tighten either.

Steering travel should be set to give around a 1 metre turning circle and be equal in both directions when you hand push the car.

I'm sure the guys you get to race against will help if asked, except for the aholes of course!!!

Enjoy!

tom00182 · #3 13-09-2015

Thanks for the advice.
I was only concerned as under initial acceleration the car veered to the left where one side had significantly more load than the other but i have reduced the impact of the issue now. Thank you for the tyre suggestions almost completely new to foams so thanks for the tyre suggestions i will ask around when i get up there.

mark christopher · #4 14-09-2015

When you say balance, how are you checking this? Tweak is one of the biggest things on a pan car

tom00182 · #5 14-09-2015

At first I used the spikes using the small holes at the front of the chassis and the back of the pod but it was tilting and i couldn't move the electrics around in order to balance the chassis so i put them on a corner weighing system to see what the difference was and there was some 50 grams difference between the front right and left tires and the cross chassis percentages were around 60:40.

The springs on the braces where wound until they just touched so there was no compression and the pod had free movement so i couldn't see anything that would cause that much of a difference.

I ran the car after his in the front room and any kind of acceleration from a standing start made the car pull majorly. since then i rotated the battery 180 and it has reduced it but there is still about 30grams difference on the front wheels

tom00182 · #6 14-09-2015

the chassis and pod are flat btw there is no tweak in the car that i can see

Xracer · #7 14-09-2015

The levels of tweak Mark has eluded to cannot be checked by eye, the car has to be fully laden and its wheels on a suitable tweak gauge, very small degrees of tweak will cause a pull on acceleration and/or braking.

A slipping diff is another culprit.

My 5.2 is not fully laterally balanced either.

Do be aware that a corner weight system can have inherent errors too, especially if each of the balance pads are at different heights relative to your setup board, this will cause an apparent tweak giving false individual corner weights, I had to modify my system to allow height and tilt adjustment of each corner scale to create an effective flat plane!

Ah the joys of our hobby!

mark christopher · #8 15-09-2015

To check tweak, put tyre on car same size a cross axle,
Place a pound coin on top of each front wheel, just forward of axle so look at left wheel and about 5 to 12

Gently lift the front of the chassis in the centre with a model knife or fine Alen driver,
If the left coin falls off 1st (left of car) ad preload to the right rear spring, and to maintain ride hieght remove preload from the left rear spring.

Keep going till both coins fall together

Xracer · #9 15-09-2015

A £2 tweak gauge, quite a bit cheaper than Hudy's offering!

I must admit I have never tried that technique as it also relies on having even droop as you are unloading the front springs when lifting the chassis, this is probably fine for a 1/12 front suspension with a static lower wishbone though.

mark christopher · #10 15-09-2015

It's how all the top 12th guys do it, I have a laser tweak station, but above is how most do it

MattW · #11 15-09-2015

It's a flash way of doing it!! Most people use pennies!

tom00182 · #12 15-09-2015

Thanks for the advice my dad has been racing gt12 so i am aware of the coin trick and have used it the coin trick and both coins did fall together and the diff if you hold both the rear wheels you cannot move the spur there is no slipping. Is there anything else that could cause that sort of thing

tom00182 · #13 15-09-2015

I used 20 pence coins

tom00182 · #14 15-09-2015

Quote:

Originally Posted by mark christopher

put tyre on car same size a cross axle,

It might just be me being stupid but does that mean the same size front tyres?

Just wanted clarification

mark christopher · #15 15-09-2015

Quote:

Originally Posted by tom00182

It might just be me being stupid but does that mean the same size front tyres?

Just wanted clarification

sorry across axle is same left and right, so same size front, same size rear, front to back can differ

tom00182 · #16 15-09-2015

Okay thanks for the clarification both tyres on the front are just a shade over 44mm and the tyres on the rear are slightly larger but they are all more or less the same size

tom00182 · #17 15-09-2015

Where would you say is a good place to start in terms of truing down the tyres? I know they are supposed to be at their fastest when they are smallest but that will shorten tyre life so where is a good place for a newbie to start

tom00182 · #18 15-09-2015

I also need to cut out and mount the bodyshell does anybody have any tips for that?

Xracer · #19 15-09-2015

The starting size really depends on yourself, sponsored drivers do not really have to consider tyre life so can start as small as they like, us chaps that pay for our racing draw a compromise but when you consider that you can destroy a tyre in one heat as well!

I start at 46mm rear and 44.5mm front, some of my mates start 1mm smaller than that, so as I say, the choice is yours!

Happy grinding.

tom00182 · #20 15-09-2015

Okay thanks for the input