Front Axle Height Adjustment

Introduction

Since their introduction several years ago, Slot Car Corner (SCC) Adjustable Front Axle Blocks have been used by numerous builders to improve the overall performance of their cars. For 1:32 plastic chassis cars, the front axle height plays an important role in car handling. An increasing number of 1:32 slot car manufacturers have also introduced chassis which incorporate an adjustable front axle feature.

The following tutorial was written by John Kroppe who has graciously given Slot Car Corner permission to share it with our customers and visitors. John is widely recognized as one of the top 1:32 builders - his cars consistently finish at or near the top of the standings in proxy and organized race events.

Background

There are basically two camps when it comes to front end setup, those who use a 3-point setup ("guide riders"), and those who use 4/5 point setup (wheels planted firmly on the track supporting the weight of the car). Briefly:

The 3-point setup is geared more towards 1/24 scale cars which use foam tires and glue for traction. It allows the inside rear tire to lift in a corner bleeding off traction, allowing the car to slide. It is also used effectively racing on Ninco track which is not only rough, but very undulated and bumpy. My guess is it allows the car to absorb the bumps better without upsetting the balance of the car.

The 4/5 point setup promotes maximum grip by maintaining contact of both rear wheels with the track surface at all times. It is the best setup for a smooth track eg; wood and Carrera or Scalextric sport. The concept of the 4/5 point setup is, during cornering, while the weight shifts towards the outside of the car, the front tires prevent the car from tipping far enough to lift the inside rear wheel maintaining traction and giving more predictable overall handling. I also feel cars which ride on the front wheels instead of the guide have less rolling resistance from the front end also maintaining rear end traction.

The difference between a 4 and a 5 point setup is, the five point setup places all four tires AND the guide on the same plane, the 4 point setup allows the guide to sit just above the plane of the four tires. There is very little difference to setting up a 4 or 5 point setup other than the amount of clearance under the guide. If you are racing on a wood track and use a flat setup block to setup the car with a 5 point setup, due to the fact that the braid on wood tracks is slightly recessed, you in fact will have a 4 point setup on the track.

The following is a brief tutorial describing how I set and adjust the front axle height:

Start with the body off of the chassis with the braids completely flat against the guide (you don't want the braid holding up the front end).

Step 1: Back-off all four set screws so they are not touching the axle with the car resting on the setup block.

Step 2:tighten the upper set screw on one side until it touches the axle with the car resting on the setup block. As you tighten the screw, tap on top of the axle block to see if it is resting on the axle. It will feel solid when you tap on it with no 'clicking sound' when it is resting firmly on the axle.

Step 3: Do the same thing to the other upper set screw with the car resting on the setup block. Once both upper set screws are resting on the axle, check for clearance under the guide. Ideally the guide should be just touching or maybe a hint of clearance under the guide.

Step 4: Remove the chassis from the setup block and hold it upside down in the palm of your hand. While give the front wheels a spin and slowly tighten one side of the lower set screws. As the set screw comes into contact with the spinning axle, the wheels will stop spinning. Be careful not to tighten too fast or you could put too much pressure on the axle holders and break them (ask me how I know this). Once the bottom setup screw is just touching the axle, back it off a 1/4 turn until the axle spins freely again.

Step 5: Do the same procedure for the other side of the lower set screws. When finished, put a drop of oil on both sides of the axle and check to make sure the front wheels spin freely.

Now you are ready for the most important test. With the body re-attached to the chassis and sitting on the setup block, hold the setup block at eye level. Push down slightly on the front fender of each side of the car just above each front wheel. As you push down on the front fender, carefully examine the opposite corner rear tire's contact patch with the setup block. It should remain planted on the setup block (i.e. no lifting or gap apparent) when doing this.

If both rears remain firmly planted on the setup block, you are finished. If one/both of the rear tires are lifting, here are some things to check:

Adjust the body screws. This can be tedious so be patient!
Check for (and remove) any interference between the body, interior and chassis.
Remove the body and double check the axle height. Adjust if necessary.