Rule about 3/8" underbody clearance

[gpraceman]

We had over half the cars that did not meet the 3/8 clearance rule. The big zinc weight glued to the bottom. We know those cars were not going to win so we just let them race, but did inform them that they would not be able to race a districts.

I do think that we need to look at the intent of this rule that is included in most all of the race rules that I have seen. The intent is to make sure that the car will not rub on the top of the lane strip so it has a better chance of making it to the finish line and not bottoming out. That is a helpful and practical rule.

The height of lane strips are generally 1/4" so in the flat a 3/8" clearance will provide plenty of room to prevent from bottoming out. The problem comes on the curve. The ends of the car are the most likely place that a car could bottom out, due to the curvature of the track. Even if a car does not meet the 3/8" clearance limit, in many cases the car will not bottom out on the curve. If it does, it is usually because the weights go too close to ends of the car or the screws used to secure the zinc weights hit the top of a solid lane strip.

Most tracks have a gentle curve which makes the chances of bottoming out less. The original Best Tracks had a pretty tight curve, so I did see more problems with cars bottoming out, but their current curve design isn't so tight.

I do think that this common rule should be amended to add that if a car does not meet the 3/8" underbody clearance then the car will be physically checked on the track curve. If the car doesn't bottom out then it will be allowed to race.

I know it causes a lot of grief to those that don't meet the 3/8" clearance and have to find a way to resolve it when in reality their car likely would not have a problem. I've seen cars that had the weights relocated to the top of the car, which ruins the intended design.

[Stan Pope]

I agree with Randy on this one. Let it race and compete for awards.

The main thing that should be lost by the racer for failing this specification, in my opinion, is the right to claim "track fault" if the car scrapes the track (or "launches tail over teakettle" due to scraping the track.)

"Track fault" can come into play, depending on local rules, to affect how long and by whom repairs can be effected. Damage resulting from track fault or other racer's fault might allow Dad to assist in repairs and an extended time period. Other causes of damage might restrict repair to the Cub Scout with guidance, but hands off, by Dad.

[Packdude]

We had over half the cars that did not meet the 3/8 clearance rule. The big zinc weight glued to the bottom. We know those cars were not going to win so we just let them race, but did inform them that they would not be able to race a districts.

I do think that we need to look at the intent of this rule that is included in most all of the race rules that I have seen. The intent is to make sure that the car will not rub on the top of the lane strip so it has a better chance of making it to the finish line and not bottoming out. That is a helpful and practical rule.

Let's not forget the track! Someone who has just purchased a new wooden track or even an aluminum track would probably rather not have cars gouging the track surface with low hanging weights and screws.
That being said, I agree that if the car can race down the track without damaging the track or jumping lanes then let it race.

[Mike Parrish]

The main thing that should be lost by the racer for failing this specification, in my opinion, is the right to claim "track fault" if the car scrapes the track (or "launches tail over teakettle" due to scraping the track.)...

Ahh, but what about the other cars on the track that the offending car might crash into

Sure, the car will most likely slow and the other cars will pass, but...

[nosam116]

If the car doesn't clear the plastic check-in guide, then we take it to the track and let if run down once, if it's OK, then we pass it, if not, then the scout needs to work on making adjustments.

[Mr. Slick]

For me, the 3/8" is a love/hate relationship.

For the boys, if the car drags bottom in the test jig, it is tested on the track and if it clears it is allowed to race.

I love the rule because it eliminates things scraping the track. I hate it because it is *WAY* too high for current tracks and causes alot of frustration for people who don't have the ability to recess weights into the bottom of their cars.

How about something like: A car bottom must be clear of the track on a 4' radius curve of the track. (I only used 4' since I believe that is what the BestTrack folk have stated is their curve, I don't know what the radius of the transition is for the Challenger design or other styles.)

[A1nogoslo]

Most tracks are 1/4 inch guide height.

If the car clears that, then it should run.

If it scrapes bottom then the car will be slow.

Some of the kits sold today have the shaped weights like a car frame and are ment to be put on the bottom. They are designed to clear the 1/4" guide once installed on the block.

So much fuss in the rules. It really isn't that hard to build a car to fit the track.

The rules should be if it fits the track then it can race. Pretty simple.

And there are so many track designs out there, that what ever your group is racing on then that track needs to be the rule.

Then there wouldn't be so much fuss at race time and tech in...

The inspectors just need to think is all, its really not to difficult...

Just a few thoughts.

[Darin McGrew]

The rules should be if it fits the track then it can race. Pretty simple.

That's our rule. We provide various minimum and maximum dimensions so those who want to "think outside the block" can make their creations fit the track, but the basic rule is that it must fit the track.

[Stephen's Dad]

Same here....I don't think Stephen has ever had a car with a ful 3/8" clearance. We've always tried for a lower stance & COG.

If the car fits the track (safely) it should be allowed to race.

[Jungle Jim]

If the car doesn't clear the plastic check-in guide, then we take it to the track and let if run down once, if it's OK, then we pass it, if not, then the scout needs to work on making adjustments.

Yep, that's the best and simplest way to handle it.

[PWD_addict]

I hate to resurrect this thread but I have to respectfully disagree with everyone on this.

What happens in a Pack where there is no track-time (test & tune) for the cars beforehand, no track available at check-in (Derby is staged elsewhere), and it's a brand new Tiger Cub/Dad who is building their first car?

The Cubs that have run on and seen the track before have a definite advantage (if we all agree that lower COG may be a benefit on some tracks) if they know that they are able to be as low as possible. That assumes a knowledge of the track beforehand which isn't always the case.

I know this because this is what happened to my son and I this year. We had no idea what to expect when we got to our first Derby. We didn't know the length (none of our leaders were sure about it) or brand of track. Fortunately, we built our car to 3/8" clearance and ended up winning. However, if someone else would have known that they could build it even lower, they would have had an advantage.

That's why I believe the rules should always state the minimum clearance. Even on tracks that are available beforehand, unless you can state a specific height, once those holes are drilled, it's tough to modify the car to get as low as possible on the track. It puts the new guy at a disadvantage if you don't spell it out beforehand.

That's my $0.02.
--Dave

[gpraceman]

That's why I believe the rules should always state the minimum clearance. Even on tracks that are available beforehand, unless you can state a specific height, once those holes are drilled, it's tough to modify the car to get as low as possible on the track. It puts the new guy at a disadvantage if you don't spell it out beforehand.

As I mentioned before, we allow cars that don't meet the 3/8" clearance to race, if they don't rub on the track. That was put in place with the racers in mind who just slap some weights on the bottom of the car not realizing it will affect the clearance. I have yet to see someone deliberately try to take advantage of this rule and build for a really low COG. I guess it is bound to happen down the line, so we will revisit that rule for next year, since we have an aluminum track. If we had a wood track, it would not be an issue at all due to a solid center guide.

[SuperDave]

A small story. My wife is a hospital administrator. Because of her job we occassionally attend community fund raisers/auctions where the hospital buys a table for 10 or 12 persons. After discussing the weather/traffic/sports, the inevitable question comes, "Kay, you run the hospital, what does Dave do?"

When the answer is that I make tracks, timers and software for the Pinewood Derby, chuckles are the first reaction. But then there are two stories. One guy still has his car. And, one guy, twenty or thirty years later, still doesn't want to talk about it. His Pinewood Derby involved a car he carefully crafted and lovingly painted and it never made it to the finish line in several races. The shame he suffered in front of his peers is still there. Race officials who allow that to happen should be taken out and shot.

Clearance rules or no clearance rules, no car should be accepted for racing without first being run on a track from start to finish and fixed if it can't make it. Please stop thinking you're in the Indianapolis 500 with big bucks at stake and start thinking how a 7 or 8 year old will feel. Does nobody look at Stan Pope's signature line? "If it's not for the boys, it's for the birds!"

[gpraceman]

Unfortunately, we are not always able to do a test before the race. Like last night. There was basketball practice going on in the gym while we were registering in the cafeteria. It was very late by the time we were able to get the track all setup and we had to be out of the building by 11pm, so we couldn't run cars.

We do have a procedure in place that if a car does not finish we give the owner a few minutes to tune it and then we rerun the heat. In today's race we only had 3 racers that had this problem. This was even after making sure they were close to 5.0 ounces in weight and verifying with the owner (and their adult partner) that the car had been lubed, before we even checked the cars in. All 3 of these cars were able to complete their heats when rerun (one of them even came in 2nd in the rerun).

I've seen other clubs/pack races where a much higher percentage of the racers do not finish. Usually, it is from weight and lube (lack of) issues. It is a shame, since I do feel it is preventable and correctable (most cases).

Basically, not every organization can manage a test run for the cars before the race (time and facilities constraints). If you can that is great. However, if you can't there are still things you can do to help them at least make it to the finish line.

Before you accept the car as being checked in:
1. Make sure the cars are close to the 5 ounce weight limit. Be very insistent on weight being added if significantly under the limit. Provide some weights (scrap metal, washers, commercial derby weights, fishing weights, or whatever).
2. Verify with the racer (and their adult partner) that the car has been lubed. Very easy to visually verify if your rules are "graphite only".
3. Check track clearance with a home built or commercial checker. If it rubs on the checker, check it on the track. If weights need to be relocated or recessed, provide the tools needed to do so (drill, forstner bits, hot glue gun)
4. If you can, test run the cars on the track and tune them until they are able to finish. Do no head-to-head racing and do not time.

During the race:
1. If the car doesn't finish and there is no evident problem with the track, give the racer (and adult partner) a chance to relube or to adjust wheels as necessary. Provide any help the racer/adult needs. Rerun the heat after the car is tuned. If it still doesn't finish, we give them one more chance. If the car still doesn't finish after that, then let the results stand. It is likely to be a more serious problem that cannot be corrected in a few minutes.
2. If a car crashes, inspect the car for damage (loose wheels or weight, excessive camber or positive camber) and repair if necessary.

Race organizers should do all they can to make sure that all cars will finish. As Dave pointed out, this is something that can stick in someones memory for quite a long time. With some proper planning, preps and procedures, we (as race organizers and crew) can help make it a good memory.

[PWD_addict]

In our pack, we don't usually have an option of having test runs on the track. We can only use the facility for our Derbies for that day.

The inspectors do their best to make sure that all cars will pass the finish line (48 feet) and all of them did this year. Most of what they focus on is making sure it weighs 5 ounces. They have lube available at inspection as well.