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Old 17-07-2014
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Default 13.5 v 17.5 Brushless in GT12 - The debate part 2...

OK, so as a Club organiser, I always offer a warm welcome to fellow RC racers from other clubs and we have quite a few members who race at more than one club in the region and having spoken to some of those clubs over the past few days we are all in the same position right now about the Production Cup v Super Cup Classes that the BRCA have now passed in the GT12 class, as voted and put forward by it's membership.

So the question is, what will club's be doing to introduce the two classes, if they do at all! We are stuck between a rock and a hard place as many of us are trying to help beginners and those who find handling a 13.5 too much in GT12 but are they really going to be going out and buying a 17.5 Brushless?

Well you could say that they'd save in the long term from all the breakages and chunked tyres, but they won't see it that way

If this class was starting from scratch then we wouldn't have a problem, but with so many racers with a 13.5 stuck in the back of the car we are left wondering in the Production Class is even worth having!

It would be great if all clubs agreed to a single set of rules and stood by it over a set period to introduce it but I cant see that ever happening.

I'd be really interested in hearing from other club officials to see what others will be doing to try and introduce the 'slower' class into the GT12 class over the coming 12 months it at all...

I think the only thing we can do as a club is enforce those who can't handle the speed to turn down the throttle by at least 80% if not more and continue to educate and promote clean driving, that way if they do improve they can turn the speed up without having the burden of paying for a new motor.

The thinking behind the introduction of the Production Cup Class I'm sure was all very good, but in practice I don't see it lasting more than 12 months with it being dropped at next years AGM.

Over to all fellow club organisers - what's your thoughts?
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Old 29-08-2014
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Hi mate,

While I'm not a club official, I do get to go to a few different club nights around the place and see different rules and approaches. After reading this and your other thread on the pace of trechnology, I've got to say I'm onboard with your thinking. But I have a suggestion, a cheap one which I don't think anyone else seems to have suggested.

in Karting we have spec gearing. and maybe that might be a cheap way for clubs to bring down speeds yet keep the overall spec in line with a regional/national car that would allow drivers to progress. If it works there then maybe it can be put forward in the next years EGM.

Maybe either limit the whole Production Cup or just your F3's(or equivilent) and call it something snappy PC(25:70) or F3(22/68) - gear as appropriate. Yes you still have the roll out difference in the tyres but its still a simple and cheap (just over a tenner) way of controlling speeds even of a 13.5t. Then by the time someone feels brave enough to go off to a regional they'll probably be able to handle stepping up a few teeth.

To me as an outsider looking into GT12 as a second(third,fourth,fifth class) having a full spec GT12 Super cup car 'just with a 17.5t' doesn't seem like much of beginners or entry level class, its more of an intermediate step just before Super Cup. But thats a different discussion, maybe for your other thread

p.s. I think the sport pack waiver is a great idea BTW

Last edited by RobChalmers; 29-08-2014 at 06:35 PM.
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Old 30-08-2014
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Scott, I think you are worrying unnecessarily here. The object of the exercise is to slow down the new drivers so they have fun, but don't wreck their cars. Whether you do that but turning their throttles down, or enforcing a lower gearing, it doesn't really matter.

I doubt we will junk the ProductionCup. If no one uses it now, that doesn't mean it won't be used ever. Most people buy a GT12 and a diff anyway, so then it is just a case of what motor they run.

Have you thought of doing a rental deal for the new drivers? You can get some pretty cheap 17.5 motors now, so if the Club invested in them and then rented them out to drivers for a couple of quid a night, that would soon pay for them.

That way it is even better for new drivers - they don't get to shell out for a motor at all, and once they do they can decide which one it is. With the long life of BL motors these days, and the lack of maintenance needs, I wonder if you and considered a double helping of cost saving for your new drivers this way - no motor to buy and a slower car reducing damage to tyres and bodies? (I also think if you decided to do this and approached a friendly shop or distributor, you could get some discount for a bulk buy.)

Lastly, fixed gear ratios - not viable with foam tyres. To get a fixed ratio needs a fixed tyre diameter. Those able to afford to buy a new set of tyres for each meeting will have the tallest gear ratio and the fastest car. Fixed ratios work if the tyre has a fixed diameter, like rubber tyres in TC and karts! HTH
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Old 31-08-2014
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Think Pete's covered most of it, tyre chunking is caused by bad prep and hitting things, which will happen irispective of motor.
The previous years no one ran production cup in its old form, its there if some one wants to, racers may choose not to,
Pete explained why fixed gearing does not work on foam tyres.

You do make me laugh tho, you slated the brca for not doing something, until I pointed out they had done some thing, now your questioning if its a pointless exercise?
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Old 31-08-2014
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I might be opening a can of worms here, but I'm puzzled why racers haven't asked for rubber tyres that fit the supastox/mardaves?

IMHO it would certainly help in keeping the cost down for beginning racers, and make life a little easier aswell.

- no tyre trueing, hence no tyre truer needed, and not to much prepping
- tyres have a longer lifespan
- no chunking
- since the diameter stays somewhat constant, not many spurs/pinions needed
- maybe a little less grip, but that also reduces speed, so impact speeds are lower and chances of axle bending and other significant damage is less likely to happen

Furthermore, stop the discussions about what motor to buy! No beginner notices the differences between the "pro top motors" and the cheap red ones that can be bought for two tenners at the king of our hobby. Reliability issues? N O. And even if there were some, you still have enough left over for 2 more motors.

Just my 2 eurocents.
Rambling over.
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Old 01-09-2014
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Old 01-09-2014
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I agree with SLEENAD, rubber tyres would be a good way to go. GT12 is meant to be a fun and low cost class. Start adding things like a tyre truer etc, bumps up the cost.
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Old 01-09-2014
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I disagree with SLEENAD...

For a rubber tyre to work it requires an insert. To get it to work with an insert requires knowledge of the insert type, the air gap required and the proper method of mounting.

For a rubber tyre to control a car with its single homogenous contact patch requires a suspension system that places it in steering, acceleration, braking and cornering. A GT12 has arguably the least adequate suspension to achieve that, resulting in a car that would grip, grip, grip and then "bang" would let go at one end of the other without warning. That situation is made worse by its narrow track, short wheelbase and low weight.

A foam tyre has a discontinuous contact patch so it lets go progressively and is easy to control with rudimentary suspension. The transition between grip and slip is easy for a driver to detect and control, so making the car easy to drive and forgiving for the average driver. That's just what you need with a small, light car.

The grip you can get from a foam tyre is much more than from a rubber tyre. That allows the cars to be driven with a much wider margin of error and still stay on the track. Rubber tyres do not offer that level of grip and so are harder to drive.

Rubber tyre performance gets worse as the tyre wears. IME, new ones are not always the best, scrubbed ones work well for a few runs and then performance goes off. If new tyres did work best, then drivers would need new rubber tyres more often. Foam tyres in GT12 wear like iron and never drop in grip from the packet to the bin. They get changed because there is an accident and they get chunked beyond repair, or they simply get so small you can't keep the chassis off the deck any more! Foam tyres last longer than rubber with no performance drop-off.

A rubber tyre and its insert has at least twice the rotating weight of a foam tyre. On 1S, that would make them slow to accelerate and hard to slow down. On small indoor tracks that's not a good thing! It makes the car a bit driver-unfriendly to say the least. Combine a lethargic car with one that lets go and needs a lot of slowing up so it can regain grip and it's a bit of a handful!

If a rubber tyre worked that well with simple, cheap cars then 12th and the Oval classes would have had it decades ago. That fact that it hasn't is because it has been tried innumerable times and every time it is abandoned because the cars are so hard to drive. With a TC that is twice the weight, has full independent suspension and shed loads of power, or an Off-Road car needing a tread to get through the dirt to a solid surface for grip, rubber is the best solution. Both classes have raced foams in the past with marginal success.

Rotating weight, grip, very progressive transition from slip to grip and no deterioration in performance as the tyre wears are just four good reasons why foams are the low-cost choice for GT12, and rubber is a distant second best.

The tyre truer? Red herring. Every club and meeting I have ever been to in 35 years of 12th and latterly GT12 racing has had someone with a truer very willing to true anyone's tyres. And these days, the Contact tyres come in sizes that can be used straight out of the packet. And they cost £6 a pair mounted, trued and glued - a rubber tyre couldn't come close to that.

Foam tyres for GT12 - yeah! HTH

Last edited by SlowOne; 01-09-2014 at 07:06 PM.
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Old 01-09-2014
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Fully agree with SlowOne

Oh and don't forget, if it was rubber tyres we would all need/have tyre warmers......
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Old 01-09-2014
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Can I throw a quick question in?

What is the aim of Production Cup??

is it envisaged as a feeder series in to Supercup? I can't put my finger on what its objective is.

Calling it 'production' cup would imply to me its supposed to be closer to the stock off the shell GT12 cost capped car, but its the same spec as the Supercup cars (Except the motor)

its not really any cheaper... because the motors are basicallly the same price.

is this just me being an 'outsider' or is this why (as stated above) no-one seems to run production cup.
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Old 01-09-2014
JimboJames1972 JimboJames1972 is offline
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Rubber tyres have been used in the past (about eight or ten years ago) but, like Peter said, they mostly failed.

The tyres were for the Tamyia Mini - lightly treaded and with the "stock" foam insert. Tyre warmers were (generally) not needed since the tread did a reasonably good job of biting into the carpet.

However, there were other problems. While the inner diameter of the tyre meant that they fitted the Mardave/GT12 rims, the rims themselves lacked the moulding to allow then to be mounted well. Fitting them was, to be frank, a bit of a bodge at best!

The other problem was their external diameter - if memory serves me correctly they were around 55mm. This is way bigger than most GT12 cars run, which had implications on ride heights and overall handling thanks to their very tall side walls.

More recently, a couple of manufacturers showed an interest in making rubber tyres more suited for GT12 racing - this included a new, suitable wheel rim (with all the additional ribs for correct mounting), as well as a lower profile slick tyre in a few sensible compounds and matching inserts. Unfortunately, setup cost stopped any real development. It costs many thousands to get a mould for a wheel rim made, and the same again for the tyres and insert too (if you go for a moulded insert rather than a simple foam one). With no guarantee that this would be accepted as a suitable tyre option the manufacturers pulled out.

No, GT12 is a class that welcomes beginners, improves and expert drivers. A foam tyre is the best overall for all these abilities and the only real way to control a beginner's speed (and therefore improve their driving standard and learning curve) is through motor power.

James
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Old 01-09-2014
JimboJames1972 JimboJames1972 is offline
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Rob,

Sorry, while posting my previous reply on tyres I missed your question on Production Cup

The initial proposal at the EGM on Production Cup was that cars had to be run "out of the box" with the exception of adding a diff (if drivers felt the need) and the option to change spurs, pinions, tyre compound and shells.

A useful point was made at the EGM that if a new driver joined the class it was likely that they might buy second hand. In this case, their car was likely to have been modified beyond the options mentioned above and the driver would then have to dip in their pocket again to de-modify their new purchase. Therefore, a vote was passed to allow any specification of chassis to be eligible for Production Cup.

At the various clubs near me (ones that I attend on a regular basis) the majority have a "club" car that new drivers can borrow that is set up with a 17.5t motor. A significant proportion of those new drivers that I have seen start the class have opted for the 17.5t motor when they buy their first car too, mostly from trying the various clubs cars. As and when they feel like progressing they have then bought a 13.5t and entered Super Cup. The important point her is "as and when". There is no obligation to buy new motors and no time limit for when drivers must "upgrade". Drivers do it only when they themselves feel ready.

Also, Production Cup is not just for the absolute beginner. Several drivers that I have spoken to appreciate the challenges of slower racing - maintaining corner speed becomes more important, extremely close racing is frequent and they really learn the effects of setup, gearing and timing changes and many have stuck with the class because they find it less stressful and more fun. This is particularly so when their regular club has smaller racing areas that are more suited to less powerful cars. Having a "formal" set of tried and tested rules for this class gives clubs who follow BRCA rules as their guide a bit of extra clout when trying to persuade their members to try something new.

James
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Old 02-09-2014
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Quote:
Originally Posted by JimboJames1972 View Post
Rob,
The initial proposal at the EGM on Production Cup was that cars had to be run "out of the box" with the exception of adding a diff (if drivers felt the need) and the option to change spurs, pinions, tyre compound and shells.
James
I presume this means you couldn't use the optional battery strap? This is a bit a grey area as it's not 100% clear in the BRCA manual. It states as long as the battery is suitably secured any method can be used to retain the battery.

Something as simple as the optional battery strap should be allowed as the Velcro is just a faff.
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Old 02-09-2014
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Quote:
Originally Posted by JimboJames1972 View Post
Rob,

Sorry, while posting my previous reply on tyres I missed your question on Production Cup

The initial proposal at the EGM on Production Cup was that cars had to be run "out of the box" with the exception of adding a diff (if drivers felt the need) and the option to change spurs, pinions, tyre compound and shells.

A useful point was made at the EGM that if a new driver joined the class it was likely that they might buy second hand. In this case, their car was likely to have been modified beyond the options mentioned above and the driver would then have to dip in their pocket again to de-modify their new purchase. Therefore, a vote was passed to allow any specification of chassis to be eligible for Production Cup.

At the various clubs near me (ones that I attend on a regular basis) the majority have a "club" car that new drivers can borrow that is set up with a 17.5t motor. A significant proportion of those new drivers that I have seen start the class have opted for the 17.5t motor when they buy their first car too, mostly from trying the various clubs cars. As and when they feel like progressing they have then bought a 13.5t and entered Super Cup. The important point her is "as and when". There is no obligation to buy new motors and no time limit for when drivers must "upgrade". Drivers do it only when they themselves feel ready.

Also, Production Cup is not just for the absolute beginner. Several drivers that I have spoken to appreciate the challenges of slower racing - maintaining corner speed becomes more important, extremely close racing is frequent and they really learn the effects of setup, gearing and timing changes and many have stuck with the class because they find it less stressful and more fun. This is particularly so when their regular club has smaller racing areas that are more suited to less powerful cars. Having a "formal" set of tried and tested rules for this class gives clubs who follow BRCA rules as their guide a bit of extra clout when trying to persuade their members to try something new.

James
The original production did not allow a diff to be fitted
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Old 02-09-2014
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Quote:
Originally Posted by The Dark Knight View Post
I presume this means you couldn't use the optional battery strap? This is a bit a grey area as it's not 100% clear in the BRCA manual. It states as long as the battery is suitably secured any method can be used to retain the battery.

Something as simple as the optional battery strap should be allowed as the Velcro is just a faff.
Correct if it was not included in the kit it was not allowed, only springs,damping and tyres could be changed. The rule ur looking at is for supercup.

But that production class set of rules have gone.
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Old 02-09-2014
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Just a note to add to James' reply...

Any car with no diff is a challenge to drive. Making ProductionCup the class where only kit-standard cars can be used seems like the right thing to do, but the point was made at the EGM that making drivers with a kit-standard car drive something that was more difficult than a ProductionCup car made little sense... if any at all!

Add the that all the points James made and you are left with a desire to have a class that drivers can handle, is cheap and gives a lot of smiles per race. The best way to do that is slow it down a bit; 17.5 has a ready-made list of motors that work and fulfils that need. The vote was simple.

Over the last three years we have tried hard as a Section to create a class that is popular and easy to get into. By and large we succeeded in spades. However, to think we could get that right first time would be foolish, so things have evolved in the last three years. I hope that we have now stabilised the Rules, and it only remains to sort out a stable set of events at National level. We'll get there - the support of all you guys in the Clubs is essential to that, and greatly appreciated by the Section.

Lets go race GT12!!
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Old 02-09-2014
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Why do organisers/clubs/people keep expecting the BRCA to pull a rabbit out of their butts!!!

You have to run what suits your drivers needs!! We as a club have no formal arrangement for 13.5/1s or 21.5/2s, only thing we like to keep is blinky mode. Now, for MOST drivers, they opted for 2s as we don't run LMP but all mostly run buggies, so transition over is cheap (batteries, esc etc).

As for slowing cars, running a slower motor isn't going to stop the novice smashing a shell up or chunking tyres either. It is ALL part of the learning process and, to be fair, we all run Schumacher locally and I have yet to see one break, so, why would you encourage someone to buy a slower motor when, as soon as they get to grips, they got to spend more cash which they could spend on tyres and shells.

Tell you what, for a simple class there are some who are REALLY trying to make this class complicated and expensive!!
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Old 03-09-2014
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Once a car is in motion, nothing stops things breaking. Having driven slower cars over an extended period, I can assure you that damage is significantly lower - force of impact increases as a square of the speed so anything slower makes damage less.

The slower the car the harder it is to drive fast, and there is no substitute for learning to drive a 17.5 fast. That's the part that people miss. Drivers think that a slow car is just bang he throttle open and steer - that's slow. Most people jump into too fast a car too early, making up for their mistakes by capitalising on others mistakes. Slower cars crash less so winning is about the best driving.

The whole point of any club is to get as many drivers as possible. If the classes you run do that then you've won. This class isn't complex and it isn't expensive. It's just new and taking its time to settle. Anyone who got into Off-Road in the early '80s, or TC in the early '90s will know just how much change there was in the first few seasons until classes settled down. We hope that this is the way it will be for a while yet, and that will make it easy to understand.
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