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Discussion Starter · #1 ·
I just pulled the magnets from my Scalex Viper and TVR as an experiment, and I really like the challenge of "driving" the car without the downforce. The TVR isn't too bad, but the Viper is a real handful.
How much weight should be added to help balance the chassis? I'm an old RC car guy used to adding/subtracting 1/4 oz at a time. (on a 1/10 scale car) Since my LHS isn't 32-scale friendly, are there any other commonly found items I can use for ballast? (golf club weights, coins, etc...)
Thanks in advance.
 

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Jim Moyes
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I put 15 grammes of lead (self-adhesive alloy wheel weights) in the back of my Hornby Viper and was quite pleased with how it performed in our GTS class which is mostly Fly cars. 10 would probably do!

Mr.M
 

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TSRF to the rescue!
This topic based on Real Life Experience (yeah!) explains where and how much plumbing material you should add.
Also look at this.
All the above applies to pretty much any slot car.
Regards,

Dokk Pea
(Major Lead Pill Himself)
 

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One thing that I think was not mentioned. Based on mathematical calculations with vector based forces. I together with my college physics teacher summed up that placing the lead weights in equal amounts and as far out to the sides of the car will have 3,5 to 4 times the effect of placing a single lumb in the middle of the car.

Racing without magnet it is importent to get the center og gravety as low as possible. Preferebly below axle height. Use a dremel to remove meterial from the inside of the body to lower the center of gravety.
 

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I just went down to my local plumbing supplier and bought a 400mm X 400mm sheet of flashing. It cost me $20 (about 8 quid) and this has given me more lead than I will ever use.

Dave
 

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Phil Kalbfell
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You don't say what sort of track you are using. Our cars weght from high 90grams up to 130 depanding on motor and gearing. Keep most of the lead just in front of rear axle and as far to the ouside of chassis as possible.
 

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Discussion Starter · #10 ·
Thanks for all of the advice. Clearly I'm new to slots, but it's quickly consuming most of my free time. A few questions;

My TVR actually handles reallly well sans magnet and no weight. Why is my Viper so much more tail-happy?

Second, where should I add weight to the Viper to remedy the oversteer? It's really a handful at corner entry. Logic would tell me rearward. (either in front of the rear axle or behind) But I'm reading a lot of racers place weight just behind the guide on their cars. What gives? Please keep the good info coming.


I'm running the cars on my plastic Scalex track at home...
 

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I would place the weight just infront of the rear wheels. Not alot but just enough to hold it down a bit better.

Also, make sure the tyres are clean. You'll be surprised how much more grip and traction you get with a bit of spit on your fingers and rubbing the tyres. Or use some sticky tape if you are worried about catching something.....
 

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Discussion Starter · #12 ·
Update- I added 1/4 ounce to the Viper and trued the tires. It still lacks rear side-bite, but it's a lot more consistant. The car now turns lap times equal to the TVR, it just requires a little more skill to do it. Thanks to all who chimed in.
 

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I find that about 15g added in front of the rear axle and about 5g just behind the guide works well, but a lot depends on how much grip you are getting from your tires and track surface. The more grip you are getting from the tires, the less weight you need to add. Also, unless you are getting unusually good grip, you will probably get better results by adding the rear weight at about axle height (on average) rather than flat on the chassis. I use those 7g (1/4 oz) tire balancing weights standing up on end, either glued to the sides of the motor or used as stiffening webs between the rear of the motor and the axle bushings (especially for Ninco in-lines). You may even find that weight on top of the motor helps, depending on how wide the rear wheel track is and how slippery the track surface is.

I don't think I agree that weight out to the sides is better than weight nearer the centreline. The centre of gravity of the added weight is what will determine the "righting moment" or resistance to tipping. The moment of inertia of the added weight (how spread out it is) will affect resistance to rotational acceleration, but I don't think this really comes into it because you generally want the car to slide before it tips. Otherwise the car is too unforgiving and hard to drive near the limit. However I do believe that cornering speed is greatly enhanced by transferring a lot of weight to the outside rear tire - as much as possible without making the car tip under hard cornering.

Duke
 
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