Weight Tuning of Slot Cars

Sometimes one piece of advice about car tuning may conflict that from another source. Don’t get frustrated with that and start with the belief that any placement of ballast may work and there is no one size fits all.

Listen and absorb all gems of advice as what will work well on one car may not on another - even if they are the same make & model.

Also with different tracks probably the fine weight tuning may suit one track perfectly but will be not so good on another.

The use of Bostic Blue Tac while setting up the car is useful along with a set of small range scales. Don’t forget the magnetic down force from motors or track magnets will influence the reading on the scales designed to measure the magnet force . So I have made a Perspex stand off plate up 10mm off the original scale surface so the magnetic affect does not register.

Why do we need ballast? Well most slot cars are made for the toy market and are designed to run on steel rail “home tracks”. So every car I have has needed some ballast to perform

At its best on wood routed tracks, which do not have steel rails to attract the car magnet. The setting up cars for magnet racing is another science I won’t explore in this article.

Adding Front Weight

The most important weight position, which seems common to nearly all cars I have, is the front weight. This is usually placed just behind the front axle and as low as possible.

I generally use a 25 mm x 25mm square of 0.5mm thick lead. If you use 1mm thick make it 25mm x 12mm as a guide.

I prefer the 0.5mm as you can try more of it if the car lifts the nose on acceleration. More often than not it will need more than the one 0.5mm x 25mm x 25mm square.

Sometimes I do put some right in the front of the chassis either on top or under the chassis.

This may be necessary for 1/32 touring cars that are fairly light

Other factors to adjust when tuning.

Before doing any more it is important to get the body as low as practical on the car in respect to the scale appearance. This may involve trimming body posts carefully and removing the “cup” on the top of the chassis post. In some cares the body mount will need alteration to get the car low enough. An example is the Dodge Charger by Scalextric or Pioneer.

This car can be real difficult unless the body is lowered quite a bit. On some I have used white wall plugs with a new hole drilled in the chassis for the screw. Once the height is correct

By trimming the wall plugs. The brass M2.2mm screws do seem ok in the white wall plugs - but tape over as with all body screws so they will not drop on to the track.

Also I have cut the chassis post to the height needed for the body. Then I make a 3 mm long x # 128 (5/32”) brass tube collar. Before making the collar, taper the end of the tubing and ensure it will push into the chassis post. Also taper slightly one end of the tubing before cutting off the collar to help inserting the collar. Then find a mandrill to go in the collar to assist pushing it into the chassis post. I use a small amount of Araldite to glue the collar in place and push it in until level with the top of the post. This becomes a seat for the screw head to rest & retain the body

The screws are adjusted on all body mounting to obtain body “float” (looseness) The exception would be if the chassis has provided a body float mechanism in its design.

Adding Rear Weight

Weight alone probably won’t get the best performance on the cars only designed for “home Sets” the above body treatment is often necessary.

The next position I have found important on most is the rear weight. This is usually to assist in getting traction from the tyres and to help over come “tipping” (in conjunction with the other weight placement)

However with some cars particularly small touring and mini’s it seems not any rear weight works well as the are prone to tipping so no added weight in the rear can introduce some “slide” to over come the tipping.

With most toy set cars - Scalextric, Pioneer ect. I remove the fluting bars under the motor & make a 1mm thick lead rectangle to fill the space under the motor but flush with the chassis .

This seems really helpful to achieve good handling on these cars. Often I ads a 25 mm x 12mm rectangle behind the motor & under the axle - start with 0.5mm thick but usually 1mm is necessary.

In some difficult cases I have added some counterbalance in the rear corner of the chassis. This is for top-heavy cars like the V8 super cars and usually to get round the sweeper on LP cleaner.

Side weight.

I have used a strip in the side sill panels either inside or outside as convenient. The width can be varied to suit fitting. I usually use the 0.5mm for this but in some cares 1mm is necessary (dodge charger & other “stockers” .

This placement helps with ”tipping” on most cars due to the extra traction we have with the new BRM E22 tyres. This works on most GT cars as well.

Other Positions for adding weight

There is another possibility of adding weight in the top of the car to reduce sliding with urethane tyres. I have not used that & usually use some more weight low down in the rear to achieve traction.

Some cars like Can Am sports need quite a bit of weight in the rear. for these I fit it across the body rear panel vertically - no room elsewhere to get enough weight

Securing the weights & chassis screws.

Some people put the weights in with some Blue tack to see if they have the correct position. But I do suggest gluing if under the chassis .

Some classes like group C in 1/32 & 1/24 may not permit any added weight under the chassis close to the track.

I use Bostic Multi Bond available from some newsagents. In all cases inside or under the car I do suggest covering the weights with a good quality cloth tape. In some cases that is specified in the FPR rules This way we hopefully will not find the weights or screws laying on the track. They can cause terminal damage to the chassis that hits them if they lay in the slot. This can result in one very unhappy camper.

I have found that Tarzan’s Grip Black tape does a good job over weights & covering screw holes . It is available from some Bunnings Stores. However there are other brands which are as good.

Some time I have used Bostic Blue Tac over the body screw holes in a small quantity if access with tape is limited.

Happy Racing

John