Should I move wheels forward?

[Tim DeBoer]

Hello. 2nd year defending my daughter's girl scout troop pinewood Derby car last year she with a lot of help from me and this forum and YouTube she took very 1st place she raced 6 times down the track and took 2nd in one race by 2" every other finish was 1st and she was champion over all. I told her this year we're not racing other kids were racing herself from last year. Anyway my question is: I am allowed to move the front and back wheels farther apart towards the back of the car and the front of the car I did this last year . Does it benefit moving the front wheels forward I know I'm taking a little bit of weight and moving it more forward. Your thoughts?

 

[Tim DeBoer]

Hello. 2nd year defending my daughter's girl scout troop pinewood Derby car last year she with a lot of help from me and this forum and YouTube she took very 1st place she raced 6 times down the track and took 2nd in one race by 2" every other finish was 1st and she was champion over all. I told her this year we're not racing other kids were racing herself from last year. Anyway my question is: I am allowed to move the front and back wheels farther apart towards the back of the car and the front of the car I did this last year . Does it benefit moving the front wheels forward I know I'm taking a little bit of weight and moving it more forward. Your thoughts?

Mmm now that I think of it the track my not be identical to last years track and even if it is it could have changed or put together different.

 

[Pinewood Outlaw]

We need to see the official Rules for your race before we could answer....your rules may state to use existing body slots or 4 3/8" wheelbase

 

[Tim DeBoer]

We need to see the official Rules for your race before we could answer....your rules may state to use existing body slots or 4 3/8" wheelbase

The question is does it benefit me to move the front tires 3/4" forward. So the tire is just behind the front of the car. Yes I can move them and did last year. Im concerned this move a little weight forward as well as in the axels and tires.

 

[KyleBCostco]

It depends on the class but I have seen 4.75" and 5" wheelbases. The rear wheel should line up with the back of the car and then set your front axle measurement off of that... Anyone else care to chime in?

 

[Thinkin'Bout Racin]

The question is does it benefit me to move the front tires 3/4" forward. So the tire is just behind the front of the car. Yes I can move them and did last year. Im concerned this move a little weight forward as well as in the axels and tires.

This may not be the answer you are looking for, but it really depends. Normally most pros build a 4 3/4" to a 5" wheelbase car. A few cars are built with a 4 1/2" wheelbase.

I would consider the condition and length of your track to be the main factor in deciding wheelbase length. A longer 5"+ wheelbase will be more stable and normally requires less steer. It may also keep your rears wheels off the center rail better than a shorter wheelbase. A shorter wheelbase will fall farther and converts more potential energy into speed (with every thing else being equal). The stock wheelbase on the block slots is 4 3/8" and on paper shows the best conversation of potential energy. There are trade offs and the pros have struck a balance on what wheel base cars works for a smooth 42' track. .... So you need to find the right balance of stability and speed that works for your track and build style.

Good luck and remember to keep teaching your daughter about the both the physics involved and about doing her best. Also, most importantly ...have some fun both building and racing!

 

[Pinewood Outlaw]

I've always used 4.75" wheelbase...1/4" body with tungsten cubes for weight...rear wheels canted 3deg..bent steering axle with 1/16" shaved off Dfw side

Kids usually place first in their class and fastest overall

 

[Charles Studer]

What they said +1

 

[Reecedad]

Hi Tim, I sent you a private message.

 

[Jimmy & his 2 Kids]

Best advice I can give you.... listen carefully to whatever Reecedad says in that PM. Trust me.

 

[Tim DeBoer]

I've always used 4.75" wheelbase...1/4" body with tungsten cubes for weight...rear wheels canted 3deg..bent steering axle with 1/16" shaved off Dfw side

Kids usually place first in their class and fastest overall

DFW side? I did sand this area last year but dont remember why.

 

[Pinewood Outlaw]

DFW side? I did sand this area last year but dont remember why.

With a rail rider (runner) you would cant your rear wheels at 3deg...this does 2 things..makes wheels run out to axle heads thus away from rubbing body and with the wheels canted keeps them further away from the rail of the track.

However whenever your car steers towards the rail (say steers to the left) the rear wheel on the right side of the car will be closer to the rail than the wheel on the left and in risk of bumping the rail.
Shaving the DFW side of the body ( from front edge to slightly behind the DFW not whole length of body) is the cure for this. After shaving a 1/16" now the DFW that rides the rail will reach the rail first (since that part of body is narrower) while the rear wheels will be centered over the rail (with equal spacing) and not at risk of bumping into the rail.

In this setup with enough steer adjusted into your car your DFW stays against the rail all the way down the track while none of your other wheels touch the rail.

I have some pics that demonstrates this if you PM me...might help it make better since

 

[Tim DeBoer]

With a rail rider (runner) you would cant your rear wheels at 3deg...this does 2 things..makes wheels run out to axle heads thus away from rubbing body and with the wheels canted keeps them further away from the rail of the track.

However whenever your car steers towards the rail (say steers to the left) the rear wheel on the right side of the car will be closer to the rail than the wheel on the left and in risk of bumping the rail.
Shaving the DFW side of the body ( from front edge to slightly behind the DFW not whole length of body) is the cure for this. After shaving a 1/16" now the DFW that rides the rail will reach the rail first (since that part of body is narrower) while the rear wheels will be centered over the rail (with equal spacing) and not at risk of bumping into the rail.

In this setup with enough steer adjusted into your car your DFW stays against the rail all the way down the track while none of your other wheels touch the rail.

I have some pics that demonstrates this if you PM me...might help it make better since

 

[Tim DeBoer]

Yes This makes sense. I did last year just didnt remebner why. It doesnt matter how far back I go just as long as no where near the back tire correct?

 

[KyleBCostco]

Correct

 

[Pinewood Outlaw]

Yes This makes sense. I did last year just didnt remebner why. It doesnt matter how far back I go just as long as no where near the back tire correct?

I think I drill my rear axle at 5/8" from back edge.....this gives me 1/2" behind the axle to cut my weight pocket to place 12 tungsten cubes behind the axle