I originally posted this on PDDR. I got great answers, so here is a copy.
Over the coming holidays, I am going to Arizona. Two of my grandchildren, in different councils, are expecting me to help them build winning cars. Last year, we took 1st in troop, district & council in one area, and in the other area, we took first in troop, 2nd in district, but we got pounded really badly in the Council.
Problem is the rules:
1. All four wheels much touch
2. No canting
3. Only graphite.
I need suggestions on how to handle all.
E.g. How do I modify DD4H's wheel preparation?
Should I include or eliminate the fenders?
Toughest car to build Opa.
Wheel prep is the same.
Axle prep is the same except for the last spray. Do not spray them with anything.
I would still create a very light cant on the rears.
As far as the front goes, you have 2 options. Narrow the front and make it a double rail rider if that is allowed in the rules or you can drill the front axles to automatically give you the steer you need with one very slightly lifted for minimal touch. Or you can very slightly bend one front axle to try and steer. This takes some time trying to get the right bend.
I would also make sure to put up a smoke screen. Really bad paint if any (not on the bottom), cut some shallow slots directly under the drilled axle holes and fill them with a different color wood putty or something awkward. Anything else you can do to make it look like a kid just slapped it together. You get the idea?
If you are using standard BSA axles (.086") there is quite a bit of slop in the wheel bore. At axle angles less then 1.9 degrees the wheel will not angle (while stationary) as the axle angle is lost in the bore slop. So if you use an axle angle of 1.0 to 1.5 degrees the wheel tread will set flat at inspection, however, this is an unstable position - once in motion the wheel will lift and the axle will nestle into the bottom of the bore.
The hard adjustment if the fronts. Put straight axles on each front - and see which side is dominant. This will remain your dominant side. Now put a very slight bend in each axle. On the dominant side use the bend for steer and a small bit of positive cant which also increases the dominance on this side a bit. Now on the other side use the bend to adjust the wheel to barely touch.
Once in motion the DFW will steer to the rail - the nose will try to keep pushing in the direction of steer and the wheel will slide out on the axle a bit and lift the non-DFW.
I will tell you this is truly the hardest alignment to make. It can be real frustrating - but it works.
As for wheel / axle prep - do as John says above.
They are tough rules. However. Seems like you can cant the rears. You can then narrow the front and leave both front wheels uncanted. Or you can 4 wheel touching rail ride as well. How long is the track and what type is it?
Try and use 3.5 ounces of weight or more in the car.
Over the coming holidays, I am going to Arizona. Two of my grandchildren, in different councils, are expecting me to help them build winning cars. Last year, we took 1st in troop, district & council in one area, and in the other area, we took first in troop, 2nd in district, but we got pounded really badly in the Council.
Problem is the rules:
1. All four wheels much touch
2. No canting
3. Only graphite.
I need suggestions on how to handle all.
E.g. How do I modify DD4H's wheel preparation?
Should I include or eliminate the fenders?
Toughest car to build Opa.
Wheel prep is the same.
Axle prep is the same except for the last spray. Do not spray them with anything.
I would still create a very light cant on the rears.
As far as the front goes, you have 2 options. Narrow the front and make it a double rail rider if that is allowed in the rules or you can drill the front axles to automatically give you the steer you need with one very slightly lifted for minimal touch. Or you can very slightly bend one front axle to try and steer. This takes some time trying to get the right bend.
I would also make sure to put up a smoke screen. Really bad paint if any (not on the bottom), cut some shallow slots directly under the drilled axle holes and fill them with a different color wood putty or something awkward. Anything else you can do to make it look like a kid just slapped it together. You get the idea?
If you are using standard BSA axles (.086") there is quite a bit of slop in the wheel bore. At axle angles less then 1.9 degrees the wheel will not angle (while stationary) as the axle angle is lost in the bore slop. So if you use an axle angle of 1.0 to 1.5 degrees the wheel tread will set flat at inspection, however, this is an unstable position - once in motion the wheel will lift and the axle will nestle into the bottom of the bore.
The hard adjustment if the fronts. Put straight axles on each front - and see which side is dominant. This will remain your dominant side. Now put a very slight bend in each axle. On the dominant side use the bend for steer and a small bit of positive cant which also increases the dominance on this side a bit. Now on the other side use the bend to adjust the wheel to barely touch.
Once in motion the DFW will steer to the rail - the nose will try to keep pushing in the direction of steer and the wheel will slide out on the axle a bit and lift the non-DFW.
I will tell you this is truly the hardest alignment to make. It can be real frustrating - but it works.
As for wheel / axle prep - do as John says above.
They are tough rules. However. Seems like you can cant the rears. You can then narrow the front and leave both front wheels uncanted. Or you can 4 wheel touching rail ride as well. How long is the track and what type is it?
Try and use 3.5 ounces of weight or more in the car.
