rattle from tungsten weights

[msxd]

This is my first time building a pinecar with my son. We used a simple wedge design. For weights, we drilled three 3/8in holes on either side of rear axle and used 3oz round tungsten weights. After filling the holes with wood putty and sanding/sealing/painting over it, I realized there is a slight rattle in one of the holes when I shake the car. I likely did not pack in the wood putty tightly and the tungsten weights have some room.

I am worried this may cause the pinecar to wobble as it goes down the track. Should I try to remove the putty and pack it in again? Or is this not a big deal? I have not yet installed the axles and wheels. Races are this weekend.

[msxd]

Also wanted to add the race is be on a brand new 42' besttrack aluminium track.

If anyone has any experience with this, I would appreciate the feedback. Weight and COG is perfect so far and I would hate to mess up at this stage but if it could slow down the derby car, I would redo it. Thanks in advance for your input

[Speedster]

You say you drilled three 3/8" holes on each side of the rear axle. I don't understand what 3oz round tungsten weights are. Are you using 3/8" x 1/2" tungsten cylinders? If so, I'm surprised you got them into a drilled 3/8" hole. That usually requires a drill bit 25/64" so the 3/8" cylinder will fit in the hole. I doubt the rattle will affect the cars operation but you might have some trouble with the inspector.

Where does the car balance?

The Best track is a beautiful track and is an Incline track as opposed to a Circular Arc track. It has a Quick curve at the bottom of the hill. On that length of track, excellent bore prep, lubing, tuning and rail riding will probably win that race. Is the car running on 3 wheels?

I would not go less then 3/4" balance point in front of the rear axle slot.

Might we see a picture of the car.

[msxd]

Thank you for taking the time to reply.

By 3oz tungsten weight, I meant cylinder weights that add up to a total of 3oz (Four 1/2oz, two 1/4oz, three 1/8oz and two 1/16oz). These weights fit in a 3/8” hole so their diameter is likely a little less than 3/8”.

Car balances at 7/8” in front of the rear axle slot. I wanted to be conservative with the first car as I read tuning is more challenging the closer it balances to the rear axle.

We are not allowed to run the car on three wheels and all four wheels must touch the track. We also have to use the single-axles that came with the kit. I don’t know how to make it rail ride with the single axle so did not attempt it. Any suggestions would be helpful.

I have made the wheels as much lighter as was possible and have done bore prep. Will lube it adequately.

Here are some pictures:

[Speedster]

Nice pictures.
OK, I understand the weighting and shape of the cylinders. 7/8" COG is a great choice and you will have enough weight on the dfw to keep the car on the rail.
Great choice of model. It has already helped you with the COG.

We all have to use the nails that came in the kit. Rail riding is where Troy Thorne''s Magazine, "Build A Winning Pinewood Derby Car", becomes a necessity. It can be purchased from Fox Chapel Publishing for $10.00. I'm working with Hobby Lobby Stores to add it to their magazines. If you are in the Pinewood Derby for 5 years the magazine cost you $2.00 per year. After you move on to something else you can sell the magazine for $10.00. The Physics doesn't change.

A rail rider is set up with 2 1/2 degrees of Negative camber on the rear wheels and 1 1/2 degrees of Positive camber on the Dominant Right Front Wheel with Toe=in so the car will drift 2" to the left in 4'. If all 4 wheels must be on the ground then the left front wheels needs to be set with Negative Camber and slight Toe-out. It is recommended the body of the car behind the Dfw be narrowed 1/16" to help center the rear wheels over the guide strip. I don't do that. I double the wheel/body clearance of the right rear wheel with 2 credit card thickness instead of one card like the other wheels get. Because of our rules I cannot bend the nails more then 1 1/2 degrees but it still works fine. ( I just like the right front wheel as the Dfw.)

[msxd]

Thank you so much for the feedback. Unfortunately, we cannot use the nails and have to use the single-axles. Bending them is a bit more challenging. If the car does well this weekend, I will try to be more ambitious next year and try to make it rail ride with the single axle.

I will surely purchase Troy Thorne's book.

Sounds like the rattling of weights might not be a big deal so I will leave it as is and insert the axles and wheels. Thanks again for your time.

[Loud2ns]

Thank you so much for the feedback. Unfortunately, we cannot use the nails and have to use the single-axles. Bending them is a bit more challenging. If the car does well this weekend, I will try to be more ambitious next year and try to make it rail ride with the single axle.

I will surely purchase Troy Thorne's book.

Sounds like the rattling of weights might not be a big deal so I will leave it as is and insert the axles and wheels. Thanks again for your time.

I've heard of guys cutting their one piece axle in half so they can run canted rears. You would need to check your rule first though.

Sent from my SM-G950U using Tapatalk

[Eagle]

All looks good! Yes on the book. I have never used the straight axle. I do have a couple in case I run across a rule set like yours. I think they would be esy to bend. And if you bend one side and then the other you could lay on flat surface to make sure it is flat before installing. Then epoxy it in straight up and down (perpendicular to bottom of car). Once dry put washers on if allowed, wheels on. and caps. Remember The rears tips up. Dominate front tip down (as long as rules allow rail riders) and non dominant straight.

If you want an additional place to race check out http://www.TheWestCoastGrandPrix.com

[Speedster]

msxd, my apologies. I need to be more careful. I didn't know anyone used a single axle even though you had told me.
Is this a kit? Where would I get one of these.

If you think about it, if the axle is bent down on the right side and up on the left side you end up with Positive camber and toe-in on the right side and Negative camber and toe-out on the left side. That's what we need. The rears would be easy to do. The Pro axle bender, using it very, very carefully, should give us what we need. Can you buy these axles separately? I'm looking forward to my summer project.

[Eagle]

Speedster Pinecar or whatever they are being called now. Available at Hobby Lobby. They come in most if not all of their kits. And, I believe they have/had a kit with just the axles.

[Loud2ns]

msxd, my apologies. I need to be more careful. I didn't know anyone used a single axle even though you had told me.
Is this a kit? Where would I get one of these.

If you think about it, if the axle is bent down on the right side and up on the left side you end up with Positive camber and toe-in on the right side and Negative camber and toe-out on the left side. That's what we need. The rears would be easy to do. The Pro axle bender, using it very, very carefully, should give us what we need. Can you buy these axles separately? I'm looking forward to my summer project.

Hey Speedster,
Are you saying positive camber and negative camber on the same single axle for the rear or did you mean for the front?

Sent from my SM-G950U using Tapatalk

[msxd]

I've heard of guys cutting their one piece axle in half so they can run canted rears. You would need to check your rule first though.

Sent from my SM-G950U using Tapatalk

Our rules state that the axles may not be modified so unfortunately that's not an option. Would have made life much easier though.

[msxd]

msxd, my apologies. I need to be more careful. I didn't know anyone used a single axle even though you had told me.
Is this a kit? Where would I get one of these.

If you think about it, if the axle is bent down on the right side and up on the left side you end up with Positive camber and toe-in on the right side and Negative camber and toe-out on the left side. That's what we need. The rears would be easy to do. The Pro axle bender, using it very, very carefully, should give us what we need. Can you buy these axles separately? I'm looking forward to my summer project.

Yes, as Eagle mentioned, the single axles came in the pinecar kit that the pack distributed. I can tell you the exact model number when I get home later today.

Not sure if you can buy these axles separately but I think there is a tires + axle kit.

[Speedster]

The only thing left in our 2 Hobby Lobby stores is a tube of spoked wheels with no axles in with the wheels. There is also a separate clear package of 4 nails for $1.99. The few things that are left are Roadway Racers. There are no kits of any kind. The manager told me either Oklahoma was out of the stuff they need or they simply weren't going to send any more things. I think the Hobby Lobby stores are finished with the Derby for this year.

The Positive camber and Negative camber was for the Front axle. The back axle would be Negative camber. On the back axle I was going to put 1 1/2 degrees on both ends and try very hard to make the bend exact on each end. If I can do it the rear wheels should migrate to the nail heads while rolling the car forward and backwards without the front wheels on and the car perfectly level to the test board. The Search function shows a way that I like to use. With a 1 1/2 degree bend the wheels tend to sit almost straight because of the clearance in the bore to axle. Anyhow, that's the way it works with the BSA wheels and axles. If I can find a kit or some axles I'll try to do it to see what happens.

If the rules say No Modified then that's what they mean. I'm going to try to do it just to see if I can.

[Eagle]

Speedster,Something wrong there. Hobby Lobby caries Pinewood Derby Supplies year round. I would ask for the general manager or the regional manager. Someone is not doing their job and reordering