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Ember

Weighting For Cars

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I hear the big "here we go again" sigh, but damn it I'm going to ask anyway.

 

I realise car handling varies greatly due to the vehicle's design and the power of the motor that drives it. But is there an optimum range to aim at? And will the optimum weight for a particular car vary with each track surface (ie. wood, Scaley Sport, Ninco etc) and style (long straights, tight and twisty etc)?

 

As you know (or maybe don't) I've been fiddling with non-magnet driving on a Scaley Sport track. Running at 10v currently, to date I have 3 cars in progress. Two of which I am happy with, one that still feels wrong.

 

Those that I'm happy with are Ninco Classic Jag at 67g (2 weights either side just in front of rear wheels, weight inside chassis. Still running Ninco tyres) and Scaley indestructible BMW Mini at 54g (small weight just behind digiplug door inside chassis, pair weights beneath chassis in front of rear wheels, running on MJKs). Mini is feeling quite nice to drive and I'm able to keep up with its magnet running un-tuned counterpart. Running body very loose on the chassis.

 

The car that I'm not happy with currently is the Ninco Classic Cobra. Current weight is 76g. Same sort of weight distribution as the Mini. Small internal weight behind guide, pair of weights beneath chassis just in front of rear wheels. Still driving on standard tyres. Haven't added PaultheTexan's bobby pin fix to the front axle yet. Its driving issues probably have as much to do with the design of the car as the weight distribution. However, comparing it to the Mini, surely the Mini has bigger handling issues due to design. Mini has shorter wheel base at similar width and much higher natural centre of gravity.

 

Other than thinking aloud, I guess I'm curious as to the theories on weighting cars. Comments have been made through the NZPR and the SCX Rally Proxy of the tendancy for Aussie cars to be brickish in weight. Why so? Doesn't common sense say the lighter the car the faster? Where does the heavy-weight tendancy come from? What is the Kiwi take on weighting cars? And internationally?

 

Ready and weighting to learn....

 

Embs


Computers. They'll never catch on.

 

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Tiny Tyers Targa - The build saga continues - Aging wood - A recipe for staining wood - Don't take a fence - Step by step paling fence - An old shed for my new cars - Wooden garage under construction

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As your motor power and torque increases, so does the requirement for intense weight tuning....

 

For std power and tire traction - I'd be looking at about 78g - with 67% on the rear wheels, 33% on the front end...

 

You need two highly accurate digital scales in alignment to check front / rear weight distribution (side to side weight dist. can also be assessed this way, but I like the 'hang a cotton thread around the guide post and see if it leans' method too...)

 

Blue Tack, for trying different weight qty's and positioning, is your new best friend.....


Cheers,

 

Tony.

 

There's only two questions:

 

1. What direction do you go

2. What's the Lap Record?

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One set of scales I have... Not two. Oh well... Looks like I hit Deals Extreme for another $15 set. (Actually, surprisingly accurate for the big outlay).

 

Hmmm.... Scaley Mini has standard Scaley mabuchi motor. Cobra has NC8 (same as Jag). Scaley motor rated at 18/- rpm, NC8 at 15/-. By that the Mini would be requiring of more weight than the Cobra (or Jag). But by trial and reaction it doesn't feel so. So obviously that's not the be-all and end of it.

 

I don't have the weighting breakdowns on each car at hand (too cold to go out to the bungalow to get my experiment record book). But I don't think the breakdown on any of them would be that far short of your suggested 1/3 to the front Bov.


Computers. They'll never catch on.

 

_AM_sig_zps00cdfd1a.jpg

 

Tiny Tyers Targa - The build saga continues - Aging wood - A recipe for staining wood - Don't take a fence - Step by step paling fence - An old shed for my new cars - Wooden garage under construction

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Hi Ember. I have one of those Ninco Cobras and they aren't bad. I just run two pieces of lead either side just in front of the rear wheels about 6x3x1mm. However we are on a very grippy track with silicone tyres so you may find you don't even need that much. How do you know? I would add just enough to stop the car tipping over. Then add a wee bit more to see if it aids traction which shows as faster lap times. If not go back to where it just stops tipping over and will slide on corner exit under gentle power. If you get better tires and it grips more, it will tip more, so more weight etc. You definately shouldn't need that piece at the front.

 

I like my cars as light as possible to help them stop, accelerate and turn well. However it may lack side grip mid corner as you feed in the power. Also for Ninco NC5 cars you should run a bit more weight on one side to offset the motor being all over one side. I only add weight just in front of the rear wheels on Ninco GT's e.g. Ascari, Mosler, NSX Honda.

 

Don't add weight if the car pulls the guide out as you accelerate mid corner. It is probably the front tires too big or out of true. Also don't add weight to get traction for out of true rear tires. If you do reassess after a few hundred laps as the tires could have self trued themslves meaning you could gain acceleration by removing some of that lead, again faster lap times.

 

I am not the fastest racer in the club, but Mike who beats me regularly runs virtually identical weighting. He is just a much, much better driver! Depressing eh!

 

If rules allow I like to shave my bodies paper thin to remove lots of weight from the top of the car. Time consuming but worth it and it costs nothing, but boy will your cars fly! NZPR and DUPR don't allow it. If you can get away with it use no lead!

 

My fastest cars are all around 65 grams. Group C Slot it cars we use no weight (cause National rules forbid it) and they are very, very fast like that! They weigh about 75 to 80 grams

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I like my cars as light as possible to help them stop, accelerate and turn well. However it may lack side grip mid corner as you feed in the power. Also for Ninco NC5 cars you should run a bit more weight on one side to offset the motor being all over one side. I only add weight just in front of the rear wheels on Ninco GT's e.g. Ascari, Mosler, NSX Honda.

Might just be that it's late at night and the bottle of wine is almost empty but I thought the motor on the Ditton Cobra was centred. I must have another look tomorrow. I'm sure its centred. The only car I have in the collection with a seriously offset inline motor is the Scaley Merc Gullwing. Hmmm.... Now I'm just plain confused.

 

On the truing side of things. Having difficulties truing the Ninco tyres. They don't seem to sand. Using various grades of carborundum paper, and would expect to see some sort of residual 'pixie dust' or whatever you wish to call it, either on the paper or on the wheel arches of the cars, but little or nothing to show for it. Its not just the Classics, this is the same for the Exiges as well. Obviously the same compound. HL has been given the task of designing/building a tyre truer. But at the moment, paper on the track is all I have to work with. I've not had this problem with any of the other tyres I've trued. Scaley standard, MJKs, SCXs, Slot.it P6s, even Carreras have all been successfully trued. Ah well... replacement MJKs for it should arrive tomorrow or Friday.

 

While I don't have to bother about meeting club rules and standards, I'm not really that much of a speed freak that I'll be bothered lightening the car body with the trusty dremel. Just seems a bit extreme to me at the moment.


Computers. They'll never catch on.

 

_AM_sig_zps00cdfd1a.jpg

 

Tiny Tyers Targa - The build saga continues - Aging wood - A recipe for staining wood - Don't take a fence - Step by step paling fence - An old shed for my new cars - Wooden garage under construction

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Drive the car around and do a few laps. Then try to deliberately deslot the car on corner entry and corner exit. How did it deslot? Roll over, slide out, front end lifts out. Thats it for a slot car. Cant deslot any other way. How it deslotted will dictate where you place the weight.


cheers

rick1776

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I have been playing around with some cars and find at the moment I am taking weight out rather than putting more in - I quite enjoy spending an hour or so playing around with a car trying to get it to drive a little better. I am currently tuning some Scaley JGTC cars - I have one that hums around the track and another that doesn't - ended up taking weight out of the slow one and working on the tyres. I dropped half a sec and it handles better. I must get myself a set of Digital scales that measure in 0.1 grams so I can see what the cars actually weigh.

 

I would look at the tyres on the cobra - if you want to stick with the Ninco ones you can treat them with WD-40 and make them stickier otherwise see how the MJKs go...just don't get any WD40 on your MJKs or they will melt... :aussie:

 

cheers

DM

Edited by dangermouse

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We had the International Proxy cars here recently all with NC1/NC7 power or equivilent and the best ones were around the 75 to 85 grams.

Tassie cars are the heavy cars! We like to be able to drive our cars around corners not just point and sqirt! :aussie:

We also run at 12 volts. So cars with higher powered motors range from 90 to 115 grams on an average. Be sure to keep any weight between the axles,nothing behind the rear axle at all.


Phil

 

Hobart Miniature Car Club

 

Tassie Resins

 

Email

 

 

 

 

 

 

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One of the hardest cars I have to get right is the fly porcshe 935, love the look of them go good but it hates going around corners. Ive poped about 10 grams of weight just behind the front axle which has largley stoped it from desloting. But with the motor being behind the rear axle and up so high the damn thing constantly wants to roll over rather than slide around corners. Its got MJKs ont he back and seems to grip too well on my ferrodore track. Whip the body off it and the chassis drives very well in its own right. Im lothed to add more weight to it but might need to to preserve the paint on the body.


Regards

Rob

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tighten or loosen screws first. in most cases where stock motors are involved you don't need any weight. use the screws as you would suspension in a real car to induce over/under steer. this way your acceleration is not compromised by excessive weight. putting the weight as far forward/aft as you can will again reduce the amount of necessary weight should you deem it necessary.

 

having said that high cg cars love some weight added, and the lower the better.

 

all this said my proxy car has weight beneath both axles and has a very good balance....

 

 

oh and Rob, try bracing the chassis, and fitting some slot.it p4's or equivalent on your 935. my two are much better for it, i did the bracing for a 935 for slittlehales and it runs well also, this time with stock tyres.

Edited by manimmal

My mum says I'm an excellent driver

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oh and Rob, try bracing the chassis, and fitting some slot.it p4's or equivalent on your 935. my two are much better for it, i did the bracing for a 935 for slittlehales and it runs well also, this time with stock tyres.

 

Ive braced it between the motor and rear axle to remove that flex, how much more or less did you do Manimmal?


Regards

Rob

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Rob,

as Chris said, brace the chassis along the full length, then loosen the body screws, i've got "old" Ortmmans on mine and the things corners like it's on rails

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I have left mine in the box for now... any photos of where to put the bracing would be appreciated I am bound to want to get it going someday

 

cheers

DM

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I must get myself a set of Digital scales that measure in 0.1 grams so I can see what the cars actually weigh.

 

I would look at the tyres on the cobra - if you want to stick with the Ninco ones you can treat them with WD-40 and make them stickier otherwise see how the MJKs go...just don't get any WD40 on your MJKs or they will melt... ;)

 

cheers

DM

DM, while I hate to advertise for outsiders try Deal Extreme. Cheap and nasty but I spent about $12 on a set of scales that are accurate down to 0.01g (and also measure in grain, troy oz, etc). I made the mistake of getting a little pocket job, but they have full size too. Already found it handy for matching fieldpoints and broadheads to arrow spine as well as playing with slot cars.

 

I've tried WD40 on the Nincos without any noticable variation. Perhaps I'm just not using enough. Does one coat them and let it soak or what? Anyway, MJKs should arrive soon. Will bung them on and see how the damned reptile behaves.

 

Rick the Cobra rolls out of the slot (narrow wheel base). My assumption would be weight should be on centreline of vehicle, below chassis to make up for high CoG. Yes?

 

Ok. Everyone talks of old Ortmanns being the ducks guts on placcy track. But where does one find the mythical beasts?


Computers. They'll never catch on.

 

_AM_sig_zps00cdfd1a.jpg

 

Tiny Tyers Targa - The build saga continues - Aging wood - A recipe for staining wood - Don't take a fence - Step by step paling fence - An old shed for my new cars - Wooden garage under construction

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Ok. Everyone talks of old Ortmanns being the ducks guts on placcy track. But where does one find the mythical beasts?

Try some of the orversea online shops, but they are getting pretty thin on the ground these days.

Ask rock1776 for some, i think he's been buying all he can get his hands on. ;)

 

I have left mine in the box for now... any photos of where to put the bracing would be appreciated I am bound to want to get it going someday

 

cheers

DM

I'll try take some pics tonight.

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Ortmanns? Brett you're mad!! i braced my two from the very back of the chassis to the front body posts using square styrene .1x.1. i the fitted some cross members to reduce any twist. it is some what effective, plus it looks good!!!

 

IMG_1239.jpg

 

You can see i've added a metric tonne to the front, the rear motor configuration doesn't suit me very well, as i prefer an 'oversteering' slot car. This is the chassis of the coke car, and has standard tyres, ninco guide, a wascher to lift the rear wheels off the wheel arches. waschers also used to hold the front axle in place. the dog hair is a dog hair.

 

 

 

back to the point of weight; a rear motor car is going to need weight up front, just like a front motor car tends to need weight at the rear. inline, sidewinder and anglewinder tend to be 'weight to taste'.


My mum says I'm an excellent driver

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I must get myself a set of Digital scales that measure in 0.1 grams so I can see what the cars actually weigh.

 

I would look at the tyres on the cobra - if you want to stick with the Ninco ones you can treat them with WD-40 and make them stickier otherwise see how the MJKs go...just don't get any WD40 on your MJKs or they will melt... :lol:

 

cheers

DM

DM, while I hate to advertise for outsiders try Deal Extreme. Cheap and nasty but I spent about $12 on a set of scales that are accurate down to 0.01g (and also measure in grain, troy oz, etc). I made the mistake of getting a little pocket job, but they have full size too. Already found it handy for matching fieldpoints and broadheads to arrow spine as well as playing with slot cars.

 

I've tried WD40 on the Nincos without any noticable variation. Perhaps I'm just not using enough. Does one coat them and let it soak or what? Anyway, MJKs should arrive soon. Will bung them on and see how the damned reptile behaves.

 

Rick the Cobra rolls out of the slot (narrow wheel base). My assumption would be weight should be on centreline of vehicle, below chassis to make up for high CoG. Yes?

 

Ok. Everyone talks of old Ortmanns being the ducks guts on placcy track. But where does one find the mythical beasts?

 

 

Ive tried to source those old ortmanns from Russia as theyre the only country still dealing in toxic urethane catalysts. ;) So I think espsix and manimmal are the last ones to have been able to buy some. Ember youre gonna have to ask them for a set and for god's sake wash your hands after touching those tyres and vacuum all the tyre marbles from the track after use. ;)

 

 

Ember. Yes, mount it on the bottom and in the middle. Then slowly move the weight towards the front until performance drops off.


cheers

rick1776

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Ortmanns? Brett you're mad!! i braced my two from the very back of the chassis to the front body posts using square styrene .1x.1. i the fitted some cross members to reduce any twist. it is some what effective, plus it looks good!!!

 

IMG_1239.jpg

 

You can see i've added a metric tonne to the front, the rear motor configuration doesn't suit me very well, as i prefer an 'oversteering' slot car. This is the chassis of the coke car, and has standard tyres, ninco guide, a wascher to lift the rear wheels off the wheel arches. waschers also used to hold the front axle in place. the dog hair is a dog hair.

 

 

 

back to the point of weight; a rear motor car is going to need weight up front, just like a front motor car tends to need weight at the rear. inline, sidewinder and anglewinder tend to be 'weight to taste'.

 

Chris, i drive my cars very "straight", so the "mega grip" works well for me.

my bracing is in exactly the same place as Chris has his, although i don't have any weight in front of the front axle, mine is all through the center.

I've aslo got the "spacer" between the chassis and body mount at the rear to get the tyres away from the wheel arches, but i use a square of red rubber band that you get from the postie, and just poke a hole in it, the screw then becomes captive.

which just goes to prove that there is no "right" answer about weight, it's all personal preferences.

 

 

I think espsix and manimmal are the last ones to have been able to buy some. Ember youre gonna have to ask them for a set

Sorry only got enough for me, but the new "grey" compitition Ortmanns are quite good, a bit better than MJK's, i think.

Edited by espsix

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Another thing about weighting cars is where it comes in the sequence of tuning.

I try to do everything else I can before adding weight, because like magnets weight can mask other problems.

 

regards


John Warren

Slotcars are my preferred reality

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I like my cars as light as possible to help them stop, accelerate and turn well. However it may lack side grip mid corner as you feed in the power. Also for Ninco NC5 cars you should run a bit more weight on one side to offset the motor being all over one side. I only add weight just in front of the rear wheels on Ninco GT's e.g. Ascari, Mosler, NSX Honda.

Might just be that it's late at night and the bottle of wine is almost empty but I thought the motor on the Ditton Cobra was centred. I must have another look tomorrow. I'm sure its centred. The only car I have in the collection with a seriously offset inline motor is the Scaley Merc Gullwing. Hmmm.... Now I'm just plain confused.

 

On the truing side of things. Having difficulties truing the Ninco tyres. They don't seem to sand. Using various grades of carborundum paper, and would expect to see some sort of residual 'pixie dust' or whatever you wish to call it, either on the paper or on the wheel arches of the cars, but little or nothing to show for it. Its not just the Classics, this is the same for the Exiges as well. Obviously the same compound. HL has been given the task of designing/building a tyre truer. But at the moment, paper on the track is all I have to work with. I've not had this problem with any of the other tyres I've trued. Scaley standard, MJKs, SCXs, Slot.it P6s, even Carreras have all been successfully trued. Ah well... replacement MJKs for it should arrive tomorrow or Friday.

 

While I don't have to bother about meeting club rules and standards, I'm not really that much of a speed freak that I'll be bothered lightening the car body with the trusty dremel. Just seems a bit extreme to me at the moment.

 

It was not the wine! You are dead right, it is centred on the Cobra! I was referring to the Ninco GT style cars which have NC5 anglewinder "boxer" motors. The Cobra has an inline NC8

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Phew! Kind of relieved on that. Not going nuts. The only other Nincos I have are a pair of Exiges. Anglewinder NC9 Sparkers.

 

So I assume all the same theories apply for Anglewinder as the others


Computers. They'll never catch on.

 

_AM_sig_zps00cdfd1a.jpg

 

Tiny Tyers Targa - The build saga continues - Aging wood - A recipe for staining wood - Don't take a fence - Step by step paling fence - An old shed for my new cars - Wooden garage under construction

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make it too heavy for any other bugger to knock off the track! Yep - I like the Sherman Tank idea..


Captain's log: We are enroute to some planet whose name I cannot pronounce to do something really complicated that I don't understand.

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A thing many overlook when ballasting a car is; when placing you weight, it must be balanced fore and aft as well if you hope to get it to change direction easily. :huh:

 

I check this by literally balancing the WHOLE car on a piece of modelling tube, or even the barrel of a plain biro(pen). Depending on the usage of the car, a good

 

starting point on for instance, a sedan would be @ the B pillar, or slightly behind. Then it's just a compromise between bite and slide, tuning say @ 3gms per time. :unsure:


Chris

H.M.C.C

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